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JP2015207995

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
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DESCRIPTION JP2015207995
The present invention provides a capacitive transducer capable of reducing the occurrence of
corrosion such as wiring due to entry of an external substance, a method of manufacturing the
same, and the like. The vibrating membrane 101 including one of the pair of electrodes 102 and
103 formed in the first embodiment has one or more cells having a structure in which the
vibrating membrane 101 is vibratably supported. The cells are disposed on one surface of the
substrate 201. An acoustic matching layer 205 is provided between the water-resistant sheet
202 and the cell, and a water-resistant frame 203 is disposed to surround the periphery of the
side surface of the substrate. The sheet 202 is bonded to the end face of the frame so as to cover
the opening of the frame 203. [Selected figure] Figure 1-1
Capacitance transducer, method of manufacturing the same, and object information acquiring
apparatus
[0001]
The present invention relates to a capacitive transducer for transmitting and receiving acoustic
waves such as ultrasonic waves (in the present specification, means at least one of transmission
and reception), a method of manufacturing the same, and The present invention relates to an
object information acquiring apparatus such as an ultrasonic imaging apparatus. In the present
specification, the acoustic wave includes sound waves, ultrasonic waves, and so-called
photoacoustic waves, but may be represented by ultrasonic waves. The photoacoustic wave is an
acoustic wave generated inside the subject by irradiating the inside of the subject with light
(electromagnetic wave) such as visible light or infrared light.
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[0002]
In order to transmit and receive ultrasonic waves, a capacitive ultrasonic transducer (CMUT)
(Capacitive Micromachined Ultrasonic Transducer) has been proposed. The CMUT is
manufactured using a MEMS (Micro Electro Mechanical Systems) process to which a
semiconductor process is applied.
[0003]
The schematic diagram of the cross section of an example of CMUT (transmission / reception
element) is shown in FIG. 19 (refer nonpatent literature 1). Here, a structure including the first
electrode 102 and the second electrode 103 opposed to each other with the vibrating membrane
101 across the gap (cavity) 105 is referred to as a cell. The vibrating membrane 101 is
supported by a support portion 104 formed on the chip 201. A direct current voltage generating
means 311 is connected to the first electrode 102, and a predetermined direct current voltage Va
is applied. The other second electrode 103 is connected to the transmission / reception circuit
312 and has a fixed potential near the GND potential. Thereby, a potential difference of Vbias =
Va-0 V is generated between the first electrode 102 and the second electrode 103. By adjusting
the value of Va, the value of Vbias is made to coincide with a desired potential difference (about
several tens V to several hundreds V) which is determined by the mechanical characteristics of
the CMUT cell. By applying an AC drive voltage to the second electrode 103 by the transmission
/ reception circuit 312, an AC electrostatic attractive force is generated between the first and
second electrodes to vibrate the diaphragm 101 at a certain frequency. Ultrasound can be
transmitted. Further, when the vibrating membrane 101 receives ultrasonic waves and vibrates, a
minute current is generated in the second electrode 103 by electrostatic induction, and the
transmission / reception circuit 312 measures the current value to take out the reception signal.
be able to. In the above description, the DC voltage generating means 101 is connected to the
first electrode 102, and the second electrode 103 is connected to the transmission / reception
circuit 312, but the first electrode 102 is connected to the transmission / reception circuit 312. A
configuration in which the electrode 103 is connected to the DC voltage generating means 311
can be used similarly.
[0004]
AS Ergun, Y. Huang, X. Zhuang, O. Oralkan, GG Yarahoglu, and BT Khuri-Yakub, "Capacitive
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micromachined ultrasonic transducers: fabrication technology," Ultrasonics, Ferroelectrics and
Frequency Control, IEEE Transactions on, vol. 52, no 12, pp. 2242-2258, Dec. 2005.
[0005]
Generally, an electrode provided in a CMUT is formed of a metal thin film, and a layer having a
main component of a silicone easily transmitting ultrasonic waves is formed on the CMUT.
Although silicone is highly insulative and electrical safety can be ensured by insulation resistance
and the like, the permeability of water vapor is high, and therefore, water vapor may intrude into
the wiring in the CMUT. As a result, corrosion of the wiring or the like may occur due to the
water vapor or the ionized or permeated substance that has permeated along with the water
vapor, which may cause reliability problems such as a decrease in CMUT sensitivity. Therefore, it
is necessary to reduce the penetration of water vapor and the like from the outside while
minimizing the influence on the transmission and reception characteristics of the CMUT. In
addition, CMUT needs to fit the mounting size in a small area depending on the use. Therefore,
there is a need to reduce the penetration of water vapor or the like that causes the corrosion of
the wiring in the CMUT, and to make the mounting size as close as possible to the size of the
substrate to make the configuration small.
[0006]
Therefore, an object of the present invention is to provide a capacitive transducer or the like
which can reduce the occurrence of corrosion of wiring and the like due to the intrusion of a
substance from the outside, and the influence on the transmission and reception characteristics
is reduced.
[0007]
In order to achieve the above object, the capacitive transducer of the present invention has the
following features.
That is, one or more cells having a structure in which a vibrating membrane including one of a
pair of electrodes formed with a gap is vibratably supported, and the one or more cells are on
one surface A frame disposed on the substrate, a sheet provided with water resistance, an
acoustic matching layer provided between the sheet and the cell, and a frame provided with
water resistance and disposed so as to surround the periphery of the side surface of the substrate
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And. The sheet is bonded to the end face of the frame so as to cover the opening of the frame.
[0008]
According to the present invention, it is possible to reduce the occurrence of corrosion of the
wiring and the like due to the intrusion substance from the outside by the water resistant sheet
and the frame, and realize the capacitance type transducer in which the influence on the
transmission and reception characteristics is reduced. can do.
[0009]
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view for explaining a capacitive transducer
according to a first embodiment.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view for explaining a capacitive transducer
according to a first embodiment. The figure explaining the capacitive type transducer concerning
2nd Embodiment. The figure explaining the capacitive type transducer concerning 2nd
Embodiment. The figure explaining the capacitive transducer concerning 3rd Embodiment. The
figure explaining the electrostatic capacitance type transducer concerning 4th Embodiment. The
figure explaining the electrostatic capacitance type transducer concerning 5th Embodiment. The
enlarged view about a part of FIGS. 5-1. The figure explaining the capacitive type transducer
concerning 6th Embodiment. The figure explaining the electrostatic capacitance type transducer
concerning 7th Embodiment. The figure explaining the capacitive transducer concerning 8th
Embodiment. The figure explaining the capacitive transducer concerning 9th Embodiment. The
figure explaining the capacitive type transducer concerning 10th Embodiment. FIG. 21 is a
diagram illustrating a method of manufacturing a capacitive transducer according to an eleventh
embodiment. FIG. 26 is a view illustrating a method of manufacturing a capacitive transducer
according to a twelfth embodiment. FIG. 21 is a view illustrating a method of manufacturing a
capacitive transducer according to a thirteenth embodiment. FIG. 26 is a view illustrating a
method of manufacturing a capacitive transducer according to a fourteenth embodiment. FIG. 26
is a view illustrating a method of manufacturing a capacitive transducer according to a
fourteenth embodiment. FIG. 26 is a view illustrating a method of manufacturing a capacitive
transducer according to a fifteenth embodiment. FIG. 31 is a view illustrating a method of
manufacturing a capacitive transducer according to a sixteenth embodiment. The figure
explaining the ultrasonic probe concerning 17th Embodiment. FIG. 33 is a view for explaining
another example of the ultrasonic probe according to the seventeenth embodiment. FIG. 24 is a
view for explaining an object information acquiring apparatus according to an eighteenth
embodiment. The figure explaining the conventional capacitive transducer.
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[0010]
In the capacitive transducer according to the present invention, a water resistant sheet is adhered
to the end face of the frame so as to cover the opening of the water resistant frame disposed so
as to surround the side of the substrate provided with cells. ing. As a result, the occurrence of
corrosion of the wiring and the like due to an intrusion from the outside can be reduced.
[0011]
Hereinafter, embodiments of the present invention will be described. An embodiment of the
capacitive transducer according to the present invention has a sheet for preventing permeation
of water vapor and the like, and a frame for preventing permeation of water vapor and the like,
and the surface such as CMUT is covered by the sheet. . Further, the side surface of the substrate
forming the CMUT or the like is surrounded by a frame on the entire circumference, and one end
face of the frame is bonded to the sheet on the entire surface to be covered.
[0012]
With reference to the drawings, an embodiment of an ultrasonic image forming apparatus which
is a kind of a capacitive transducer and an object information acquiring apparatus of the present
invention will be described in detail. With regard to the members constituting the capacitance
type transducer and the like of the present invention, members representing the same part may
be denoted by the same reference numerals even if the drawing numbers are different and may
not be described in each drawing. obtain. First Embodiment FIGS. 1-1 and 2-2 are schematic
views of a capacitive transducer according to the present embodiment. Reference numeral 201
denotes a substrate, 202 denotes a sheet, 203 denotes a frame, 204 denotes a flexible wiring
substrate, 205 denotes a silicone layer which is an acoustic matching layer, and 206 denotes a
support member. Moreover, FIGS. 1-1 and 1-2 are schematic diagrams showing the XY cross
section in FIGS. 2-1 and 2-2.
[0013]
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The CMUT 100 is formed on the substrate 201. The CMUT 100 is configured of a vibrating film
101, a first electrode 102, a second electrode 103, a support portion 104, wirings 107 and 108,
and electrodes 109 and 110. The one or more cells each have a structure in which a vibrating
membrane including one of the pair of electrodes 102 and 103 formed with a gap 105
therebetween is vibratably supported. The second electrode 103 and the support portion 104 are
disposed on the substrate 201, and the first electrode 102 is disposed on the vibrating film 101
supported by the support portion 104. The first electrode 102 and the second electrode 103 are
disposed to face each other, and the vibrating membrane 101 is configured to vibrate integrally
with the first electrode 102. The wirings 107 and 108 and the electrodes 109 and 110 are
formed by forming a metal thin film of aluminum, copper, gold, nickel, titanium or the like. The
wires 107 and 108 and the electrodes 109 and 110 have a thickness of several hundreds of
nanometers to several micrometers, and have a line width or a distance of several micrometers to
several hundreds of micrometers.
[0014]
The first electrode 102 and the second electrode 103 are connected to DC voltage generation
means (not shown) and a transmission / reception circuit (not shown) through the flexible wiring
board 204, respectively. The first electrode 102 is connected to the electrode 109 through the
wiring 107, and the second electrode 103 is connected to the electrode 110 through the wiring
108 (see also FIG. 3). The flexible wiring substrate 204 has a configuration in which a thin
conductive layer 122 is sandwiched between a thin insulating film 123 and an insulating layer
124, and the thickness of the conductive layer or the insulating layer is about several
micrometers to several tens of micrometers. , Has a configuration that is easy to bend. The
conductive layer 122 can be made of copper or the like. The insulating layers 123 and 124 can
be made of polyimide or the like. A part of the insulating layer is not formed on both ends of the
flexible substrate 204, and the electrode 121 is an exposed portion of the conductive layer 122.
The electrode 121 is connected to the electrode on the substrate 201 by electrical connection
means described later. There is. The other side of the flexible substrate 204 is connected to DC
voltage generating means (not shown) and a transmitting / receiving circuit (not shown) on the
circuit board.
[0015]
In FIGS. 1-1 and 1-2, the substrate 201 is disposed on the support member 206 in parallel with
the flexible wiring substrate 204, and the electrodes 109 and 110 and the electrode 121 are
electrically connected by the wire 131. It is done. The wire 131 is covered with a sealing material
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132, and the wire 131 is fixed to the substrate and the flexible wiring substrate 204, and is
protected from deformation due to external impact or the like. The sealing material 132 can be
easily realized using a resin adhesive such as epoxy.
[0016]
The support member 206 can be made of resin or the like. Further, the convex portion of the
support member 206 is fitted in the concave portion of a part of the frame 203, and the frame
203 and the support member 206 can be set in a desired positional relationship by assembling.
Thus, the relative relationship between the positions of the CMUTs 100 formed on the substrate
201 on the support member 206 with respect to the frame 203 can be made desired. A
configuration reverse to the above description, that is, a fitting structure or abutment structure in
which the frame 203 has a convex portion and the support member 206 has a concave portion
can be used in the same manner.
[0017]
On the surface of the CMUT on the substrate 201, a silicone film 205 is formed as an acoustic
matching layer. In the acoustic matching layer, the acoustic impedance is preferably close to the
acoustic impedance of the vibrating membrane 101. Specifically, the acoustic impedance is
preferably 1 MRayls or more and 2 MRayls or less. In the present embodiment, the silicone film
205 is used as the acoustic matching layer. The silicone film 205 is a silicone rubber obtained by
crosslinking an organic polymer containing polydimethylsiloxane (PDMS) as a main component.
Moreover, what added the silica particle etc. to PDMS, the fluoro silicone which substituted a part
of hydrogen of PDMS with the fluorine, etc. may be sufficient. The acoustic matching layer hardly
affects the vibrating membrane 101, and its thickness is preferably 10 μm to 900 μm. The
Young's modulus of the acoustic matching layer is preferably 10 MPa or less so as not to
significantly change the mechanical properties such as the amount of deformation of the
vibrating membrane 101 and the spring constant. In the case of the silicone rubber which bridge
| crosslinked the organic polymer which had polydimethylsiloxane (PDMS) as a main component,
Young's modulus is about 1 Mpa. A water resistant sheet 202 is disposed on the silicone film
205. The end surface (side surface) of the substrate 201 is completely surrounded on all sides by
a water-resistant frame 203. The entire circumference of the sheet 202 is bonded so that the gap
between the sheet 202 and the end face of the frame 203 is completely eliminated, and the
opening of the frame 203 is covered with the sheet 202 (see FIG. 2A). . The water vapor
transmission rate relating to water resistance is represented by the amount permeated per unit
area at 40 ° C. and 90% RH (relative humidity). As a result of examining the moisture
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permeability for suppressing corrosion and deterioration of wiring, it is preferable that it is 100 g
/ m <2> * day or less. The moisture permeability depends on the thickness of the member, and
since the frame member also requires mechanical strength, it is possible to lower the moisture
permeability because it has a certain thickness.
[0018]
On the other hand, since the sheet is thin, the moisture permeability tends to be large. In this
embodiment, the frame member is disposed in the vicinity of the side surface of the substrate,
and is adhered to the end face of the frame to reduce the area of the sheet. In addition, it is
desirable that the sheet 202 does not deteriorate the characteristics of the ultrasonic wave when
the ultrasonic wave transmits. In consideration of the transmission characteristics of ultrasonic
waves, it is desirable that the thickness of the sheet be about one sixteenth to one tenth or less of
the wavelength of the ultrasonic frequency used for transmission and reception. For example, in
the case of use at a general transmission and reception frequency of about 10 MHz, it is
desirable to make the thickness 30 micrometers or less. From these contradictory requirements,
the sheet preferably has a thickness of 30 μm or less and a water permeability of 60 g / m <2> ·
day or less. Therefore, the sheet 202 preferably has a characteristic that the water vapor
transmission rate is small, and polyethylene terephthalate, polyethylene naphthalate,
polypropylene, and the like are preferable.
[0019]
Further, the sheet 202 is not limited to a single resin sheet, and a sheet including a barrier layer
that reduces the permeation of water vapor can also be used. The barrier layer contained in the
sheet can be used as long as it can reduce the permeability of water vapor by forming a thin film
of an inorganic material such as an oxide film or a thin metal layer and has a necessary adhesion.
Thus, in addition to the above-mentioned sheets, various sheets such as polyethylene, PVC
(polyvinyl chloride), PC (polycarbonate), PI (polyimide) and the like can be used.
[0020]
A schematic view of a frame 203 used in the present embodiment is shown in FIG. The frame
203 is in the form of a quadrangular prism having a square cross section and a hollow (opening)
200 in the middle. The frame 203 has a characteristic that the water vapor transmission rate is
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low equal to or higher than that of the sheet 202. It can be easily formed using a plastic resin
such as polystyrene, polyethylene, polypropylene, PBT (polybutylene terephthalate), PEEK
(polyether ether ketone) or the like.
[0021]
In the present embodiment, the side surface of the substrate 201 is surrounded in four sides by
the frame 203, and the frame 203 is covered by the sheet 202. Therefore, according to the
present embodiment, it is possible to reduce the infiltration of water vapor and the like not only
from the CMUT surface side but also from the periphery and the side of the substrate 201.
Further, in the present embodiment, the sheet 202 is characterized in that it is adhered to the
entire circumference of the end face of the frame 203 without a gap, so even in the area where
the sheet 202 is not disposed Intrusion of water vapor and the like can be reduced. Therefore,
compared to the configuration in which only the sheet 202 is provided on the surface of the
substrate 201, it is possible to suppress the infiltration of water vapor and the like from the end
of the sheet 202 and a region wider than the size of the sheet 202.
[0022]
Here, configurations other than the present embodiment will be considered. Due to the sheet
202, in order to wrap the CMUT, it is necessary to overlap the sheet 202 in any area. When
sheets are stacked, the structure is complicated and it is difficult to fit in a small area. In addition,
it is very difficult to prevent gaps in the area where the sheets overlap, and the reliability can not
be very high. Also, the manufacturing process is complicated and the manufacturing cost is high.
On the other hand, in the configuration in which the sheet 202 is adhered to the side surface of
the case without overlapping the sheets, the area needs to be adhered to the side surface of the
case with little bending of the sheet. , Difficult to miniaturize. In this embodiment, the sheet 202
is adhered to the end face of the frame 203 using the frame 203, and the opening of the frame
203 is covered with the sheet 202, thereby forming the CMUT 100 in a small size. Can be
surrounded by a member having a low water vapor permeability.
[0023]
As described above, by using this embodiment, it is possible to reduce the penetration of water
vapor and the like from the outside with a small mounting size, and therefore, it is possible to
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reduce the occurrence of wiring corrosion due to an intrusion substance from the outside. . Thus,
a highly reliable capacitive transducer can be provided.
[0024]
Second Embodiment In the second embodiment, the material forming the frame 203 is different.
Other than that, it is the same as the first embodiment. The frame 203 in this embodiment is
characterized by using metal. This makes it possible to significantly reduce the permeability of
water vapor as compared to the case where the frame 203 is made of resin, so it is sufficient to
consider only the intrusion of water vapor and the like from the sheet 202 on the surface side of
the substrate 201, Permeation of total water vapor and the like can be reduced. Moreover, since
mechanical strength can be made high compared with resin, it can be made smaller. Further, the
acoustic impedance of metal is close to the acoustic impedance of the substrate 201. Therefore,
the irregular reflection of the ultrasonic waves around the substrate 201 is less and the influence
on the transmission and reception characteristics of the CMUT is reduced as compared with the
case of using a resin.
[0025]
According to the form of the present embodiment, it is possible to provide a capacitive
transducer with higher reliability, smaller size, and better transmission and reception
characteristics.
[0026]
Third Embodiment In the third embodiment, the configuration of the side of the frame 203 to
which the sheet 202 is not adhered (hereinafter, referred to as the bottom side for convenience
of explanation) is partially different.
Other than that, it is the same as the first or second embodiment.
[0027]
In this embodiment, as shown in FIG. 1B, on the bottom side of the frame 203, the gap between
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the frame 203 and the support member 206 and the flexible wiring board 204 is filled with the
sealing material 210. ing. The sealing material 210 uses an epoxy resin. An epoxy resin
encapsulant is a material having a low water vapor transmission rate, and is suitable for the
encapsulant. According to the present embodiment, the entire periphery of the substrate 201 on
which the CMUT 100 is formed can be covered with a member having a low water vapor
permeability, so that intrusion of water vapor or the like into the CMUT 100 from all directions
can be prevented. it can. Therefore, a more reliable capacitive transducer can be provided
without changing the size.
[0028]
In addition, another configuration of the present embodiment will be described using FIGS. 1-2C
and 2-2C. In the present embodiment, the frame 203 has a square cross section and a hollow
inside, and has a quadrangular prism shape having a bottom surface having an elongated hole in
part. 2-2 (c) is a schematic view seen from the bottom side. The hole 220 in the bottom surface
of the frame 203 is configured such that the flexible wiring board 204 can be pulled out to the
outside of the frame 203. On the bottom surface side of the frame 203, a sealing material 210 is
filled in the gap between the hole 220 of the frame 203 and the support member 206 and the
flexible wiring board 204. According to this configuration, since the area sealed by the sealing
material 210 can be minimized, sealing can be performed more reliably. Therefore, according to
the present embodiment, it is possible to provide a more reliable and compact capacitive
transducer.
[0029]
Fourth Embodiment In the fourth embodiment, the wiring connection method between the
substrate 201 and the flexible wiring substrate 204 and the positional relationship between the
flexible wiring substrate 204 and the sheet 202 are different. Other than that is the same as any
of the first to third embodiments. This will be described with reference to FIG.
[0030]
In the present embodiment, the electrodes 109 and 110 on the substrate 201 and the electrodes
121 on the flexible wiring substrate 204 are connected using an ACF (anisotropic conductive)
resin (not shown). ACF resin is an insulating heat effect resin containing fine conductive metal
04-05-2019
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particles. By placing a pressure between the electrodes, conductive particles can intervene to
electrically connect the electrodes. On the other hand, in the adjacent electrodes, the conductive
metal particles are only dispersed and present in the insulating resin, so that the electrically
insulating state is maintained. In this state, heat is applied to the resin to cure the resin, thereby
maintaining the connection between the upper and lower electrodes and the insulation between
the adjacent electrodes.
[0031]
In the present embodiment, since the ACF resin is used for electrical connection, as shown in FIG.
4, the flexible wiring board 204 is directly disposed on the substrate 201. The present
embodiment is characterized in that the surface of the flexible wiring substrate 204 opposite to
the substrate 201 is in contact with the sheet 202.
[0032]
With this configuration, the distance between the surface of the substrate 201 and the sheet 202
can be defined by the thickness of the flexible wiring substrate 204. The thickness of the flexible
wiring substrate 204 can be selected from several tens of micrometers to several hundreds of
micrometers by changing the thicknesses of the insulating layer and the conductive layer. Here,
by using the flexible wiring substrate 204 having a desired thickness, the distance between the
substrate 201 and the sheet 202 can be made as desired. Therefore, the thickness of the silicone
layer 205 on the CMUT 100 disposed on the substrate 201 can be made to a desired thickness,
and the variation in thickness is also uniform within the variation in thickness of the flexible
wiring substrate 204 at both ends. can do. It is desirable that the silicone layer 205 have a
uniform desired thickness in order to transmit ultrasonic waves while attenuating. By using the
present embodiment, it is possible to provide a silicone layer having a uniform and desired
thickness, so it is possible to provide a small-sized capacitive transducer with more uniform
transmission and reception characteristics and high reliability.
[0033]
Fifth Embodiment The fifth embodiment is different in that a part of the sheet 202 has a recess.
That is, a recess is provided on the surface formed by the surface of the sheet 202, and a recess
is provided in the area where the CMUT 100 is disposed rather than the vicinity of the frame
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203. Other than that is the same as any of the first to fourth embodiments. Based on the
structure of 4th Embodiment, it demonstrates using FIGS. 5-1 and FIGS. 5-2.
[0034]
The present embodiment is characterized in that the sheet 202 disposed on the area of the
substrate 201 on which the CMUT 100 constituting the cell is formed is recessed more toward
the substrate 201 than the sheet 202 of the other area. In the present embodiment, as shown in
FIG. 5-1, the thickness of the silicone layer 205 which is the acoustic matching layer on the
substrate 201 is different depending on the place. FIG. 5-2 shows an enlarged view of a part of
FIG. 5-1.
[0035]
Referring to FIG. 5-2, the thickness H1 of the silicone layer 205 is thin on the area of the
substrate 201 on which the CMUT 100 is formed. The thickness H2 of the silicone layer 205 is
thick in the other area where the electrical connection portion electrically connected to the
flexible printed wiring 204 is disposed. That is, the silicone layer 205 is configured to be thicker
outside the area where the CMUT 100 is disposed. In the silicone layer 205, in order to transmit
ultrasonic waves while attenuating, it is desirable to use a silicone layer 205 which is as thin as
possible in order to avoid degradation of transmission and reception signals.
[0036]
In addition, since a resin such as PET (polyethylene terephthalate) is used as the sheet 202, the
acoustic impedance of the sheet 202 is different from that of the silicone layer 205. In addition,
the thickness of the sheet 202 is as thin as about 10 micrometers, and the thickness can not be
completely ignored for the wavelength of several megahertz to 10 megahertz used. Therefore, at
the interface between the silicone layer 205 and the sheet 202, reflection occurs in part of the
transmission and reception waves (acoustic waves). This reflected wave causes the deterioration
of the frequency characteristic of the acoustic wave because it is an acoustic wave to be received
by the CMUT or originally transmitted from the CMUT. Specifically, the characteristics at the
frequency at which the thickness of the silicone layer 205 becomes equal to the wavelength of
the acoustic wave in the silicone layer 205 are degraded by the reflected wave. Therefore, it is
desirable that the thickness of the silicone layer 205 be thinner than the wavelength of the
04-05-2019
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acoustic wave used for transmission and reception. As a concrete numerical value, in order to
make it hard to be influenced in the frequency range of 10 MHz or less, it is desirable to make
H1 24 micrometers or less in thickness. In order to be less susceptible to the effects in the
frequency range of 6 MHz or less, it is desirable to make H1 to a thickness of 40 micrometers or
less.
[0037]
On the other hand, if the thickness H1 of the silicone layer 205 on the CMUT 100 is too thin, the
sheet 202 comes close to the CMUT 100, the radiation impedance of the CMUT is influenced by
the sheet 202, and the transmission and reception characteristics change. Therefore, it is
desirable that the silicone layer 205 on the CMUT 100 be 20 micrometers or more.
[0038]
From these facts, it is desirable that the thickness of the silicone layer 205 on the CMUT 100 be
in the range of 20 micrometers to 24 micrometers for ultrasonic transmission / reception
applications centered on the most commonly used 8 MHz frequency. . Also, for ultrasonic
transmission and reception applications centered on relatively low frequency 4 megahertz
frequencies, it is desirable to be in the range of 20 micrometers to 40 micrometers.
[0039]
The distance between the surface of the substrate 201 and the lower surface of the sheet 202 is
the height of the wiring extraction portion from the electrodes 109 and 110 on the substrate
201, specifically, the height of the sealing material 132 in the first embodiment, In the fourth
embodiment, the thickness of the flexible wiring substrate 204 determines the lower limit.
[0040]
Here, although the sealing material shown in the first embodiment is not used in the mode shown
in FIG. 5-2, in the present embodiment, it is also possible to use a sealing material.
Since the sealing material needs to be disposed and cured so as to cover the bonding wire, it has
04-05-2019
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a thickness of about 100 micrometers to 300 micrometers. In addition, since the flexible wiring
substrate 204 is formed of an insulating film thicker than 15 micrometers and sandwiching a
metal thin film of about 10 to 40 micrometers, the thickness becomes about 40 micrometers to
100 micrometers. Therefore, in the configuration in which the sheet 202 does not have a recess,
the thickness of the silicone layer 205 on the area where the CMUT 100 is disposed is equal to
the height of the wiring extraction portion.
[0041]
Therefore, only the thickness of the silicone layer 205 on the CMUT 100 according to the
present embodiment is reduced by thinning the thickness of the silicone layer 205 on the CMUT
100 without changing the wiring extraction portion. be able to. Therefore, even with the
configuration in which the sheet 202 having moisture resistance is disposed on the CMUT 100,
in the area of the CMUT 100 where transmission and reception of ultrasonic waves are
performed, the deterioration characteristics at the time of ultrasonic transmission in the sheet
202 and the silicone layer 205 are improved. it can. Therefore, excellent transmission and
reception characteristics can be obtained.
[0042]
According to the present embodiment, since the thickness H1 of the silicone layer on the CMUT
100 can be reduced, deterioration of the transmission and reception ultrasonic waves in the
sheet portion is small, so that the small size static of excellent in transmission and reception
characteristics and high in reliability. A capacitive transducer can be provided.
[0043]
Sixth Embodiment The sixth embodiment is different in the place where the electrodes 109 and
110 are disposed on the substrate 201.
Other than that is the same as any of the first to fifth embodiments. Based on the configuration of
the fourth embodiment, description will be made with reference to FIG.
[0044]
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The feature of this embodiment is that the electrodes 109 and 110 are disposed on the surface of
the substrate 201 opposite to the surface on which the CMUT 100 is formed. As shown in FIG.
6A, the wirings 107 and 108 do not form the CMUT 100 from the substrate surface on which the
CMUT 100 is formed through the through wiring 111 electrically connecting between the both
surfaces of the substrate 201. It is pulled out to the substrate side. The wiring drawn to the
substrate surface side where the CMUT 100 is not formed is connected to the electrode 109 and
electrically connected to the flexible wiring substrate 204. In FIG. 6A, the wiring connection
using ACF resin is used, and the flexible wiring board 204 is disposed on the substrate surface
(rear surface) on which the CMUT 100 of the substrate 201 is not formed.
[0045]
In this embodiment, since the flexible wiring board 204 is not provided on the side of the
substrate 201 on which the CMUT 100 is formed, there is no restriction on bringing the surface
of the substrate 201 close to the lower surface of the sheet 202. Therefore, the thickness of the
silicone 205 layer can be reduced to a thickness that does not cause a problem when
mechanically fixing the substrate 201 and the sheet 202. Therefore, the attenuation of the
ultrasonic wave transmitted through the silicone layer 205 is extremely small, and the
deterioration of the transmission and reception characteristics of the silicone layer 205 can be
extremely reduced. Further, since only the CMUT 100 is disposed on the surface of the substrate
201, deterioration of the transmission and reception characteristics due to diffuse reflection of
ultrasonic waves due to the wiring in the vicinity of the substrate 201 does not occur, and
excellent transmission and reception characteristics can be obtained.
[0046]
In the present embodiment, the distance between the surface of the substrate 201 and the lower
surface of the sheet 202 is defined by the position of the substrate 201 and the position of the
frame 203 by the concave portion of the frame 203 and the convex portion of the support
member 206. It can be set to a desired value. According to the present embodiment, it is possible
to provide a small-sized capacitive transducer with excellent transmission and reception
characteristics and high reliability.
[0047]
04-05-2019
16
Another form of the present embodiment will be described using FIG. 6 (b). In FIG. 6 (b), 222 is a
spacer. The spacers 222 are arranged in pairs on the end face of the substrate where the CMUT
100 is not formed on the substrate 201. The spacer 222 has the same thickness as the desired
thickness of the silicone layer 205. With this configuration, the distance can be determined only
by the spacer 222 as compared to the configuration in which the distance relationship between
the substrate 201 and the sheet 202 is determined by the frame 203 and the support member
206, so the substrate 201 and the sheet can be more accurately. The distance between 202 can
be determined. In addition, since the thickness of the spacer 222 can be selected arbitrarily (for
example, several micrometers to several tens of micrometers), the thickness of the silicone layer
205 can be set thin and with high precision. Therefore, the attenuation of the ultrasonic wave
transmitted through the silicone layer 205 is extremely small, and the deterioration of the
transmission and reception characteristics of the silicone layer 205 can be extremely small and
uniform. According to the present embodiment, it is possible to provide a small-sized capacitive
transducer with excellent transmission and reception characteristics and high reliability.
[0048]
Seventh Embodiment The seventh embodiment is different in that a part of the sheet 202 has a
convex portion. Other than that is the same as any of the first to sixth embodiments. Based on the
configuration of the sixth embodiment, description will be made with reference to FIGS. 7 (a) and
7 (b).
[0049]
The present embodiment is characterized in that the surface of the substrate 201 on which the
CMUT 100 is formed protrudes outward from the end surface of the frame 203. Therefore, the
surface of the sheet 202 in the area on the substrate 201 is disposed farther to the outside of the
transducer than the thickness of the silicone layer 205 than the surface of the sheet 202 in the
area on the frame 203. According to this configuration, the CMUT 100 is disposed outside the
end face of the frame 203, in other words, on the side of the measurement target (not shown)
which is an object that transmits and receives ultrasonic waves. Therefore, when the ultrasonic
waves are transmitted from the CMUT 100, it is possible to substantially ignore that the
transmitted ultrasonic waves are reflected at the end face of the frame 203 and the transmission
waveform of the ultrasonic waves reaching the measurement object is degraded. In addition,
when the CMUT 100 receives an ultrasonic wave from a measurement target, even if the
received wave is reflected by the end face of the frame 203, the signal received by the CMUT
04-05-2019
17
100 can be substantially ignored. Thus, in the present embodiment, the surface of the substrate
201 on which the CMUT 100 is formed is disposed outside the end face of the frame 203.
Therefore, the influence of the frame 203 on the ultrasonic waves at the time of transmission and
reception can be extremely reduced, and a highly reliable, small-sized capacitive transducer with
very excellent transmission and reception characteristics can be provided.
[0050]
Although the present embodiment has been described based on the sixth embodiment, the
present invention is not limited to this. The present invention can be applied to a configuration in
which the flexible wiring board 204 is disposed on the wire 131 on the substrate 201 of the first
embodiment and on the substrate 201 of the fourth embodiment, and similar effects can be
obtained. Can.
[0051]
Eighth Embodiment In the eighth embodiment, the surface of the sheet 202 is different. Other
than that is the same as any of the first to seventh embodiments. Based on the configuration of
the fourth embodiment, description will be made with reference to FIG.
[0052]
The present embodiment is characterized in that the surface of the sheet 202 has a reflective film
207 that reflects specific light. When the object to be measured is irradiated with pulsed light
and the generated photoacoustic wave is received by the transducer, when the irradiated pulsed
light also reaches the transducer, the photoacoustic wave is generated in the transducer to
deteriorate the reception characteristics. In the present embodiment, since the reflection film
207 that reflects pulse light is provided and the member that holds the reflection film 207 is also
used as the sheet 202 having a low water vapor transmission rate, it can be realized with a
simple layer configuration. it can. Therefore, since the number of layers through which the
ultrasonic waves pass can be reduced, the deterioration of the ultrasonic waveform received by
the CMUT 100 can be reduced.
[0053]
04-05-2019
18
The reflective film 207 of the present embodiment is a member for suppressing the incidence of
light on the CMUT 100. Specifically, it is a member for reflecting the irradiation light to the
subject or the scattered light thereof. When diagnosing a living body such as a breast as a
subject, a near infrared region with a wavelength of 700 nm or more and 1000 nm or less is
often used as laser light. The reflective film 207 preferably has high reflectance (preferably 80%
or more, and more preferably 90% or more) to light in a wavelength range to be used (eg, 700
nm to 1000 nm). Specifically, the reflective film 207 is preferably made of a metal thin film, and
a metal containing at least one element of Au, Ag, Al, and Cu, or an alloy thereof can be used.
[0054]
The thickness of the reflective film 207 is preferably 150 nm or more. If it is 150 nm or more,
sufficient reflectance can be obtained. However, in consideration of acoustic impedance, it is
preferably 10 μm or less. For example, in the case of Au, since the acoustic impedance is as high
as about 63 × 10 6 [kg · m <−2> · s <−1>], it is necessary to make it thin to some extent to
prevent reflection of acoustic waves due to acoustic impedance mismatch. There is. Therefore, in
the case of Au, the film thickness is preferably 1/30 or less of the wavelength of the acoustic
wave in the material. In particular, the thickness of the Au film is 5 μm or less, considering that
the reception band of the acoustic wave generated by the photoacoustic effect is usually about
10 MHz and the wavelength in water at 10 MHz is about 150 μm. Is preferred. Vapor deposition
or sputtering can be used as a formation method. Further, in order to increase the adhesion, an
underlayer of Cr or Ti may be provided.
[0055]
Further, as the reflective film 207, not only a metal film but also a dielectric multilayer film can
be used. Furthermore, a laminated structure in which a dielectric multilayer film is formed on a
metal film can also be used. Such a laminated structure is preferable because the reflectance can
be further improved. According to the present embodiment, it is possible to provide a capacitive
transducer that is highly reliable, small in size, and excellent in transmission and reception
characteristics even when used for receiving a photoacoustic wave.
[0056]
04-05-2019
19
(Ninth Embodiment) The ninth embodiment differs in that a member is disposed on the outside
of the transducer. Other than that, it is the same as any of the first to eighth embodiments. Based
on the configuration of the fourth embodiment, description will be made with reference to FIG.
[0057]
The present embodiment is characterized in that the resin cover 208 is provided on the sheet
202 of the transducer. By having the resin cover 208, it is possible to prevent the shock from
being transmitted to the sheet 202 and the sheet 202 from being damaged even when an
external shock is applied. Therefore, it is possible to prevent the corrosion of the wiring and the
like due to the damage of the sheet 202 and the infiltration of moisture from the outside. The
resin cover 208 can be used as long as it is resistant to external impact and abrasion. In addition,
a material having a necessary thickness such as silicone resin and plastic can be used within a
range that does not cause a problem due to deterioration of the transmission and reception
characteristics of the ultrasonic wave. Further, as shown in FIG. 9, the resin cover 208 may be
disposed not only on the sheet 202 but also continuously on part of the side surface of the frame
203. The resin cover is adhered to the sheet 202 and the frame 203 with an adhesive. The
adhesive can be used if it has little influence on the transmission and reception characteristics of
ultrasonic waves and has sufficient adhesive strength.
[0058]
According to the present embodiment, it is possible to provide a capacitive transducer that is
resistant to external impact, has high reliability, is small, and has excellent transmission and
reception characteristics.
[0059]
Tenth Embodiment The tenth embodiment is different in that a member is disposed outside the
transducer.
Other than that, it is the same as any of the first to eighth embodiments. Based on the
configuration of the fourth embodiment, description will be made with reference to FIG.
04-05-2019
20
[0060]
The present embodiment is characterized in that an acoustic lens 209 is provided on the sheet
202 of the transducer. By using the acoustic lens 209, it is possible to increase the intensity of an
ultrasonic wave transmission waveform in a certain range at a specific distance. Similarly, for
reception, it is possible to receive a received waveform from a certain range of specific distance
with high sensitivity. The acoustic lens 209 is molded using silicone having a high water vapor
transmission rate, and is adhered onto the sheet 202. According to the present embodiment,
since the CMUT 100 on the substrate 201 is surrounded by the sheet 202 and the frame 203
having low water vapor transmission rates, corrosion of the wiring portion and the like hardly
occur.
[0061]
Here, it is desirable that the acoustic impedances of the sheet 202 and the acoustic lens 209 be
as close as possible, and that reflection be less likely to occur at the interface. However, the
acoustic lens has limitations from the medium in contact with the surface of the acoustic lens and
limitations of the acoustic impedance inherent to the sheet material, and it is difficult to make the
respective acoustic impedances completely match. Therefore, at the interface between the sheet
202 and the acoustic lens 209, reflection of ultrasonic waves occurs, and the transmission
characteristics of the ultrasonic waves are likely to be degraded. In the case where the sheet 202
is disposed on the surface of the acoustic lens 209, the interface at which the reflection occurs is
such that the distance from the CMUT 100 to the portion on the curved surface of the acoustic
lens 209 differs depending on the location. It will be separated by more than the distance of
thickness. This distance is set to be sufficiently long with respect to the wavelength of the
ultrasonic wave to be used, and thus has a great influence on the transmission characteristics
during transmission and reception. However, according to the present embodiment, compared to
the configuration in which the sheet 202 is disposed on the surface of the acoustic lens 209, the
distance between the substrate 201 on which the CMUT 100 is formed and the sheet 202 can be
significantly shortened. Therefore, since the place where the reflection occurs can be at a
uniform distance from the CMUT 100 and at a distance sufficiently shorter than the wavelength
of the ultrasonic wave, the influence on the transmission characteristics at the time of
transmission and reception can be reduced.
[0062]
04-05-2019
21
According to the present embodiment, it is possible to provide a capacitive transducer which is
high in reliability, small in size, and excellent in transmission and reception characteristics even
in a configuration having an acoustic lens. In the fifth to tenth embodiments, the connection
between the electrodes 109 and 110 on the substrate 201 and the electrode 121 on the flexible
wiring substrate 204 has been described using the electrical connection means of ACF resin. The
embodiment is not limited to this. The electrical connection means using a wire described in the
first embodiment can be applied as long as the electrical connection between the electrodes can
be performed.
[0063]
Eleventh Embodiment In this embodiment, a method of manufacturing a capacitive transducer
according to any of the first to tenth embodiments will be described.
[0064]
The manufacturing method of the present embodiment is characterized in that the step of
bonding the sheet 202 to the end face of the frame 203 is performed after the step of fixing the
substrate 201 on which the CMUT 100 is formed and the sheet 202 using the silicone layer 205.
The manufacturing process will be specifically described with reference to FIG. Although the
CMUT 100 on the substrate 201 is omitted in the drawings for explaining the manufacturing
process, the CMUT 100 is actually formed on the upper surface of the substrate 201 in the
drawing. In addition, although the frame 203 and the support member 206 are actually
complicated structures as shown in the drawings of FIGS. 1-1 etc., in the drawings for explaining
the manufacturing process, the concavo-convex portion actually provided Etc. are omitted, and it
has described by simple composition. Further, in the drawings for explaining the manufacturing
process, the flexible wiring substrate 204 is omitted except when necessary for the explanation.
[0065]
First, the CMUT 100 is formed on the substrate 201, and then the substrate 201 is attached on
the support member 206 (FIG. 11A). This process can be easily implemented by using a
technique called die bonding for bonding a chip of an integrated circuit. Next, the silicone resin
240 before curing is applied onto the substrate 201 (FIG. 11B). By using a dispenser or the like,
04-05-2019
22
local application on the substrate 201 can be easily performed. As the silicone resin, any of room
temperature curing and heat curing types can be used. When using a cold curing type, it can be
produced without problems by carrying out the process in a time shorter than the curing time.
[0066]
Subsequently, the sheet 202 is fixed, the substrate 201 is brought close to the sheet 202, and the
upper surface of the silicone resin 240 before curing on the substrate 201 is brought into
contact with the lower surface of the sheet 202. At this time, the substrate 201 is stopped at a
position where the sheet 202 and the substrate 201 are at a predetermined distance. By
adjusting the positional relationship between the portion fixing the sheet and the portion holding
the support member 206 with the fine adjustment stage, the stopping position can be easily
determined. Thereafter, the silicone resin 240 is cured, and the substrate 201 and the sheet 202
are fixed by the cured silicone layer 205 (FIG. 11C). The positional relationship between the
substrate 201 and the sheet 202 is kept fixed until curing is completed in both the room
temperature curing type and the heating type.
[0067]
Next, the adhesive 230 before curing is applied to the end face of the frame 203 (FIG. 11 (d)). By
using a dispenser or the like, local application on the end face of the frame 203 can be easily
performed. Any adhesive can be used as the adhesive 203 as long as it can bond between the
sheet 202 and the frame 203, and can be easily configured with an epoxy adhesive or the like. In
addition, in order to improve the adhesive force of an adhesive agent and the sheet | seat 202 or
the frame 203, the structure which primer-treats the surface can also be taken. The primer is a
low viscosity liquid to facilitate adhesion of the surface, and it is preferable to use one more
suitable for the type of adhesive. Here, after the primer is applied, the solvent is volatilized, heat
treatment for fixing is performed, and an adhesive is applied.
[0068]
Finally, the sheet 202 fixed to the substrate 201 is brought close to the frame 203, and the end
surface of the frame 203 coated with the adhesive is stopped in contact with the lower surface of
the sheet 202 and cured (FIG. 11 (e)) ). Thereby, the sheet 202 and the frame 203 are fixed by
the cured adhesive 231.
04-05-2019
23
[0069]
In the drawings for explaining the manufacturing process, the substrate 201 is held by the frame
203 via the sheet 202, but the present invention is not limited to this, and in fact, the substrate
201 and the frame 203 It is desirable that the gap be fixed by an adhesive. In addition, the frame
203 has a recess (or a protrusion), and the support member 206 has a protrusion (or a recess),
and by bonding at the portion where the protrusion and the recess are fitted, more mechanical
strength can be achieved. It can be fixed high, and can be made more reliable.
[0070]
Twelfth Embodiment The present embodiment will also be described with reference to a method
of manufacturing a capacitive transducer according to any one of the first to tenth embodiments.
The manufacturing method of the present embodiment is characterized in that the step of fixing
the substrate 201 and the sheet 202 on which the CMUT 100 is formed by a silicone layer and
the step of adhering the sheet 202 to the end face of the frame 203 are simultaneously
performed. The manufacturing process is specifically described with reference to FIG.
[0071]
First, the CMUT 100 is formed on the substrate 201, and then the substrate is attached on the
support member 206 (FIG. 12A). This process can be easily implemented by using a technique
called die bonding for bonding a chip of an integrated circuit. Next, the silicone resin 240 before
curing is applied onto the substrate 201 (FIG. 12B). By using a dispenser or the like, local
application on the substrate 201 can be easily performed. As the silicone resin, any of room
temperature curing and heat curing types can be used. When using a room temperature curing
type, it can be produced without problems by performing the subsequent steps in a time shorter
than the curing time.
[0072]
Subsequently, the adhesive 230 before curing is applied to the end face of the frame 203 (FIG.
04-05-2019
24
12C). By using a dispenser or the like, local application on the end face of the frame 203 can be
easily performed. As the adhesive 230, any adhesive can be used as long as it can bond between
the sheet 202 and the frame 203, and can be easily configured by an epoxy adhesive or the like.
In addition, in order to improve the adhesive force of an adhesive agent and the sheet | seat 202
or the frame 203, the structure which primer-treats the surface can also be taken.
[0073]
Next, the sheet 202 is fixed, the frame 203 is brought close to the sheet 202 (FIG. 12D), and the
surface of the adhesive 230 before curing on the end face of the frame 203 is brought into
contact with the lower surface of the sheet 202. Make it thick. In addition, the substrate 201 is
brought close to the sheet 202, and the surface of the silicone resin 240 before curing on the
substrate 201 is brought into contact with the lower surface of the sheet 202 (FIG. 12 (e)). At this
time, the substrate 201 is stopped at a position where the sheet 202 and the substrate 201 are at
a predetermined distance. By adjusting the positional relationship between the portion fixing the
sheet and the portion holding the support member 206 with the fine adjustment stage, the
stopping position can be easily determined. Thereafter, the adhesive 230 and the silicone resin
240 are simultaneously cured, and the frame 203 and the sheet 202 are fixed by the cured
adhesive 231, and the substrate 201 and the sheet 202 are fixed by the cured silicone layer 205
(see FIG. 12 (f)).
[0074]
According to the present embodiment, since curing of the adhesive 230 and the silicone 240 is
performed in the same process, simplification of the process and shortening of the process time
can be realized. In the above description, the frame 203 is made to approach the sheet 202 first,
and then the substrate 201 is made to approach the sheet 202. However, the present
embodiment is not limited to this, and the reverse procedure may be performed. You can also. In
addition, it is possible to adopt a configuration in which the frame 203 and the substrate 201 are
simultaneously brought close to the sheet 202 side. Thereby, simplification of a process and
commonization of a jig can be achieved.
[0075]
Thirteenth Embodiment The present embodiment describes a method of manufacturing a
04-05-2019
25
capacitive transducer according to any of the first to tenth embodiments. The manufacturing
method of the present embodiment is characterized in that after the step of bonding the sheet
202 to the end face of the frame 203, the step of fixing the substrate 202 on which the CMUT
100 is formed and the sheet 202 with a silicone layer 205 is performed. The manufacturing
process will be specifically described with reference to FIG.
[0076]
First, the adhesive 230 before curing is applied to the end face of the frame 203 (FIG. 13A). By
using a dispenser or the like, local application on the end face of the frame 203 can be easily
performed. Any adhesive can be used as the adhesive 203 as long as it can bond between the
sheet 202 and the frame 203, and can be easily configured by an epoxy adhesive or the like. In
addition, in order to improve the adhesive force of an adhesive agent and the sheet | seat 202 or
the frame 203, the structure which primer-treats the surface can also be taken. Next, the sheet
202 is fixed, the frame 203 is brought close to the sheet 202 side, and the surface of the
adhesive 230 before curing on the end face of the frame 203 is brought into contact with the
lower surface of the sheet 202 to have a predetermined thickness. Thereafter, the adhesive 230
is cured and fixed between the frame 203 and the sheet 202 with the cured adhesive 231 (FIG.
13B).
[0077]
Subsequently, silicone 240 before curing is applied to the area surrounded by the frame 203 and
the sheet 202, and the inside is filled with the silicone 240 (FIG. 13 (c)). Application can be
performed easily and quantitatively by using a dispenser or the like. As the silicone resin, any of
room temperature curing and heat curing types can be used. When using a room temperature
curing type, it can be produced without problems by performing the subsequent steps in a time
shorter than the curing time.
[0078]
Thereafter, the CMUT 100 is formed on the substrate 201, and then the substrate is attached on
the support member 206 (FIG. 13 (d)). This process can be easily implemented by using a
technique called die bonding for bonding a chip of an integrated circuit. Next, the substrate 201
is slightly inclined with respect to the sheet 202, and the substrate 201 is immersed in a region
04-05-2019
26
surrounded by the frame 203 and the sheet 202 and coated with silicone 240 while keeping the
angle (FIG. 13 (e )). When all the surface of the substrate 201 is immersed in silicone, the
substrate 201 is returned parallel to the sheet 202, and the distance between the sheet 202 and
the substrate 201 is further reduced (FIG. 13 (f)).
[0079]
Finally, the substrate 201 is stopped at a position where the sheet 202 and the substrate 201 are
at a predetermined distance (FIG. 13 (g)). By adjusting the positional relationship between the
portion fixing the sheet and the portion holding the support member 206 by the fine adjustment
stage, the stopping position can be easily determined. Thereafter, the silicone resin 240 is cured,
and the substrate 201 and the sheet 202 are fixed by the cured silicone layer 205 (FIG. 13 (h)).
At this time, the silicone 205 partially flows into the space between the frame 203 and the
substrate 201 and the support member 206 to be cured. This range can be adjusted by adjusting
the amount applied first. In addition, the silicone 205 cured between the frame 203 and the
substrate 201 or the support member 206 also functions as an adhesive that mechanically holds
between the frame 203 and the substrate 201 or the support member 206, which leads to
improvement in reliability. .
[0080]
Here, the general silicone resin 240 before curing has a problem that the viscosity is high and air
is easily caught. When the air layer remains in the silicone layer 205, when ultrasonic waves are
transmitted, a large ultrasonic wave attenuation occurs due to the difference in acoustic
impedance between the silicone layer and the air layer. In the step of applying the silicone 240
on the substrate 201 and then sticking the sheet 202 described in the steps of the eleventh and
twelfth embodiments, air can be easily caught in the silicone 240. In order to avoid that,
complicated processes, such as performing a process in a reduced pressure atmosphere and
affixing a sheet using a roll, may be required. On the other hand, according to the present
embodiment, since the substrate 201 is obliquely immersed in the area surrounded by the frame
203 and the sheet 202 and filled with the silicone 240, air is less likely to be caught in the
silicone 240. Therefore, the formation of an air layer can be prevented in the silicone layer 205
between the sheet 202 and the substrate 201 in a simple process without using complicated
processes, and a capacitive transducer excellent in transmission and reception characteristics is
obtained. It can be manufactured.
04-05-2019
27
[0081]
Fourteenth Embodiment The present embodiment relates to the step of fixing the sheet 202 to
the substrate 201 on which the CMUT 100 is formed, via the silicone layer 205. Other than that
is the same as the manufacturing method according to any of the eleventh to thirteenth
embodiments. The present embodiment is characterized in that the film thickness setting means
disposed on the substrate 201 defines the film thickness of the silicone 205. A process is
concretely demonstrated using FIGS. 14-1 and 14-2.
[0082]
First, the sheet 202 is fixed to the holding jig 260 having a flat surface. At this time, the sheet
202 is held flat along the surface shape of the holding jig 260. The holding jig can be made of
metal, resin, or the like as long as the holding jig does not cause deformation by an external force
applied to the substrate. Next, the substrate 201 coated with the silicone 240 before curing is
brought close to the sheet 202. On the substrate 201, a member (film thickness setting means)
having a predetermined height is disposed in order to define the height between the sheet 202
and the substrate 201. In FIG. 14-1 (a), the sealing material 132 which is sealing the wire 131 is
used.
[0083]
Further, as the substrate 201 is moved closer to the sheet side, the silicone 240 on the substrate
201 comes in contact with the lower surface of the sheet 202. As they are brought close to each
other, the sealing material 132 comes in contact with the lower surface of the sheet 202, and the
distance between the substrate 201 and the sheet 202 is no longer reduced, and the movement
of the substrate 201 is stopped here (FIG. 14-1). (B). Thereby, the thickness of the silicone 240
between the substrate 201 and the sheet 202 becomes the same as the height of the sealing
material 132 which is the film thickness setting means. The means for stopping can be easily
realized by a configuration in which a constant external force is applied to the substrate 201
using a spring or the like. Finally, by curing the silicone 240 in this state, the silicone 205 can be
fixed while keeping the distance between the substrate 201 and the sheet 202 the same as the
height of the sealant 132.
[0084]
04-05-2019
28
In this embodiment, in order to define the distance between the sheet 202 and the substrate 201
by the film thickness setting means disposed on the substrate, compared to the case where the
height is defined by fitting the movable stage or the frame-support member, The distance
between the sheet 202 and the substrate 201 can be defined more accurately.
[0085]
As the film thickness setting means, not only the sealing material 132 which seals the wire 131,
but also a member determined to a predetermined height can be used.
As shown in FIGS. 14-1 (c) and (d), the flexible wiring board 204 can also be used. In this case,
since the flexible wiring substrate 204 can be made lower in height and uniform than the sealing
material 132 which seals the wire 131, a thinner and more uniform film thickness of the silicone
205 can be obtained. Further, as shown in FIGS. 14-1 (e) and (f), by using the spacer 222, a film
can be formed at any optimum position without being restricted by the arrangement position of
the electrodes 109 and 110 on the substrate 201. Thickness setting means can be arranged.
Also, the thickness of the spacer 222 is not restricted by the lead wiring, so that an optimum
thickness can be used, and a more suitable film thickness can be obtained. 14-2 (g) and (h) are
the figures which showed the process of FIGS. 14-1 (a) and (b) on the whole.
[0086]
In the present embodiment, the process using the configuration in which the silicone 240 before
curing is applied to the substrate 201 described in the eleventh embodiment and the twelfth
embodiment has been described. Not exclusively. It can also be a process using the configuration
in which the silicone 240 shown in the thirteenth embodiment is applied to the sheet 202 side.
According to the present embodiment, since the distance between the sheet 202 and the
substrate 201 can be defined more accurately, the thickness of the silicone layer 205 between
the sheet 202 and the substrate 201 can be set more accurately.
[0087]
(Fifteenth Embodiment) The present embodiment differs from the fourteenth embodiment in the
surface shape of the holding member. FIG. 15 is a schematic view for explaining the present
04-05-2019
29
embodiment. The present embodiment is characterized in that the surface shape of the holding
jig 270 has a convex shape. The convex-shaped flat surface of the holding jig 270 is configured
to cover the area where the CMUT is formed on the substrate 201. The fourteenth embodiment
and the manufacturing process itself are the same except that the shape of the holding jig 270 is
different. However, before bringing the substrate 201 closer to the sheet 202 side, it is necessary
to add a jig for determining the positional relationship between the holding jig 270 and the
substrate 201 on which the CMUT is formed, or a process of adjusting the positional relationship.
These can be easily realized by using a general-purpose mounting technique and a jig with a
highly accurate positioning function, a stage with a fine adjustment function, and the like. By
using the holding jig 270 of this embodiment, the thickness of the silicone layer 205 between the
plane on which the CMUT is formed and the sheet on the CMUT can be made thinner than the
height of the sealing material 132 (film thickness setting means). .
[0088]
As the film thickness setting means, not only the sealing material 132 which seals the wire 131,
but also a member determined to have a predetermined height may be used. Similar to the
fourteenth embodiment, the flexible wiring board 204 (FIGS. 15C and 15D) and the spacer 222
(FIGS. 15E and 15F) can be used.
[0089]
According to this embodiment, since the distance to the sheet on the CMUT can be narrowed, it is
possible to provide a method of manufacturing a capacitive transducer with less deterioration of
ultrasonic characteristics and better transmission and reception characteristics. .
[0090]
Sixteenth Embodiment The present embodiment relates to a manufacturing method having a step
of fixing a substrate 202 on which a CMUT 100 is formed and a sheet 202 with a silicone layer
205 in the manufacturing method described in the thirteenth embodiment.
In the present embodiment, the film thickness setting means disposed on the substrate 201
defines the film thickness of the silicone 205, and the surface of the sheet 202 on the substrate
201 is outside the surface of the sheet on the frame 203. Is characterized by applying an external
force to the substrate. The process will be specifically described with reference to FIG.
04-05-2019
30
[0091]
In order to define the height between the sheet 202 and the substrate 201, a member (film
thickness setting means) having a predetermined height is disposed on the substrate 201 of the
present embodiment. In FIG. 16, the sealing material 132 which seals the wire 131 is used. The
steps after the step of FIG. 13F of the thirteenth embodiment will be described. The difference
from the thirteenth embodiment is that the frame 203 is held by the holding jig 290, and the
frame 203 does not move even if an external force is applied to the upper side of the frame 203
(in the drawing). That is the point. Further, the sealing material 132 on the substrate 201 does
not stop even after contacting the surface of the sheet 202, and the substrate 201 moves
upward. Therefore, when the external force applied to the upper side of the substrate 201 is
transmitted to the sheet 202, the frame portion is held by the holding jig 290, and thus the
external force is transmitted to the sheet via the sealing material 132 on the substrate. Here,
since the sheet is very thin and highly stretchable, it is slightly deformed so as to have a convex
shape on the upper side on the substrate without breaking (Fig. 16 (b)). Here, the height of the
convex portion can be several micrometers to several hundreds of micrometers.
[0092]
When the substrate 201 is at a desired position with respect to the frame 203, the movement of
the substrate 201 is stopped. By holding silicone in this state, the sheet 202 is fixed while having
a convex shape by curing the silicone (FIG. 16C). At this time, the distance between the flat
surface on which the CMUT is formed on the substrate 201 and the sheet 202 thereon is the
same value as the height of the sealing material 132 (film thickness setting means). Therefore,
the thickness of the silicone layer 205 between the plane on which the CMUT is formed and the
sheet on the CMUT also has the same value as the height of the sealing material 132 (film
thickness setting means). Here, the sheet 202 is pressed upward by the substrate 201 and fixed
with the end fixed to the frame, and therefore, the sheet 202 is in a tensioned state as compared
with the case where the sheet 202 is not pressed. Therefore, the sheet 202 is in a state of being
stuck firmly and tensioned, and as described in the fourteenth and fifteenth embodiments, the
film of the silicone 205 is used without using a holding jig having a flat shape on the upper side
of the sheet. The thickness can be made constant. Therefore, since it is not necessary to contact
the surface of the sheet 202 on the CMUT, the sheet 202 is not damaged by dust or the like
attached to the surface of the holding jig, and the water vapor permeability of the sheet 202 is
not deteriorated. That is, the water resistance of the sheet 202 is maintained.
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[0093]
As the film thickness setting means, not only the sealing material 132 which seals the wire 131
but also a member determined to have a predetermined height can be used. The flexible wiring
board 204 can also be used as in the fourteenth embodiment. In this case, since the flexible
wiring substrate 204 can be made lower in height and uniform than the sealing material 132
which seals the wire 131, a thinner and more uniform film thickness of the silicone 205 can be
obtained. Further, by using the spacer 222, the film thickness setting means can be arranged at
any optimum position without being restricted by the arrangement position of the electrodes
109 and 110 on the substrate 201. In addition, since the thickness of the spacer is not restricted
by the lead wiring, an optimum thickness can be used, and a more optimum film thickness can be
obtained.
[0094]
In the present embodiment, the holding jig 290 for holding the frame 203 is described as being
pressed from the upper side of the frame 203, but the present embodiment is not limited to this.
The frame 203 can be used as long as the frame 203 does not move due to an external force
applied to the substrate 201 in the process, including a case in which the frame 203 is held by
holding the frame 203 from the side.
[0095]
According to the present embodiment, it is possible to provide a method of manufacturing a
capacitive transducer that is highly reliable, compact, and has excellent transmission and
reception characteristics without damaging the surface of the sheet 202. In the above description
of the manufacturing process, the sheet 202 is disposed above the frame 203 toward the upper
side in the drawing, but the present embodiment is not limited to this. The sheet 202 can be
manufactured downward or sideways with respect to the frame 203. At this time, any direction
can be used as long as the adhesive before curing and the liquid dripping when applying the
silicone resin before curing do not become a problem.
[0096]
(Seventeenth Embodiment) The seventeenth embodiment is the capacitive transducer according
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to any of the first to tenth embodiments, or the manufacturing method according to any of the
eleventh to sixteenth embodiments. The present invention relates to an ultrasonic probe using a
capacitive transducer.
[0097]
Here, the configuration of the ultrasonic probe using the capacitive transducer of the present
invention will be described with reference to FIGS. 17-1 and 17-2.
FIG. 17A is a schematic view of an ultrasonic probe using the capacitive transducer of the
present embodiment. In FIG. 17A, 300 is an ultrasonic probe, 301 is a housing, 302 is a circuit
board, 303 is a transmitting / receiving circuit, and 304 is a cable. A frame 203 provided with a
CMUT and a circuit board 302 are surrounded by a housing 301 and adhered and held. The
flexible wiring board 204 connected to the electrodes in the CMUT 100 is connected to the
circuit board 302, and the electrodes in the CMUT are electrically connected to the transmission
/ reception circuit 303 on the circuit board 302, respectively. The transmission / reception
circuit connected to each electrode is pulled out of the housing 301 via the cable 304 connected
to the circuit board 302, and is connected to an object information acquiring apparatus such as
an ultrasonic image forming apparatus (not shown). , And can exchange transmission and
reception signals.
[0098]
The housing 301 can be easily configured by using a general resin, and by using a material
having a low water vapor transmission rate, wiring included in the circuit board 302, the flexible
wiring board 204, the cable 304, and the like can be obtained. It is possible to prevent the
deterioration of the electrical characteristics. By using the capacitance type transducer of the
present invention, it is possible to reduce the penetration of water vapor and the like from the
outside with a compact configuration, so that the probe itself can be miniaturized and the
intrusion of water vapor and the like can be prevented. . Therefore, by using the capacitance type
transducer of the present invention for an ultrasonic probe, a highly reliable and compact probe
can be provided.
[0099]
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In the present embodiment, as shown in FIG. 17B, a configuration in which the inside of the
ultrasonic probe 300 is completely filled with the sealing material 304 can also be used. Thus,
even if water intrudes from the joint of the housing 301 or the like, the sealing material 305 can
prevent further infiltration of water. Therefore, even when used in water, a highly reliable
ultrasonic probe 300 can be provided.
[0100]
Eighteenth Embodiment In an eighteenth embodiment, the capacitive transducer according to
any of the first to sixteenth embodiments or the ultrasonic probe according to the seventeenth
embodiment is used. The present invention relates to an object information acquiring apparatus
such as a sound wave image forming apparatus. Here, an ultrasonic image forming apparatus will
be described.
[0101]
The ultrasonic image forming apparatus of this embodiment will be described with reference to
FIG. Reference numeral 400 denotes an ultrasonic image forming apparatus, and reference
numeral 401 denotes a capacitive transducer (ultrasound probe) that receives an acoustic wave
from a subject and converts it into an electric signal. Reference numeral 402 denotes a subject or
a measurement target, 403 denotes an image information generation unit which is a processing
unit for acquiring information of the subject using the electric signal, and 404 denotes an image
display unit. Also, reference numeral 501 denotes a transmission ultrasonic wave, 502 denotes a
reflected ultrasonic wave, 503 denotes ultrasonic wave transmission information, 504 denotes an
ultrasonic wave reception signal, and 505 denotes reproduced image information.
[0102]
Hereinafter, an operation at the time of ultrasonic measurement using the transmitted ultrasonic
wave will be described. The ultrasonic wave 501 is output (transmitted) from the capacitive
transducer (ultrasound probe) 401 toward the measurement target 402. Ultrasonic waves are
reflected on the surface of the measuring object 402 due to the difference in specific acoustic
impedance at the interface. The reflected ultrasonic wave 502 is received by a capacitive
transducer (ultrasound probe) 401, and information on the size, shape, and time of the received
04-05-2019
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signal is sent to the image information generation unit 403 as an ultrasonic wave received signal
504. On the other hand, information on the size, shape, and time of transmission ultrasonic
waves is stored in the image information generation unit 403 as ultrasonic transmission
information 503. The image information generation unit 403 generates an image signal of the
measurement object 402 based on the ultrasonic wave reception signal 504 and the ultrasonic
wave transmission information 503, and outputs it as the reproduction image information 505.
The image display unit 404 displays the measurement object 402 as an image based on the
reproduced image information by ultrasonic wave transmission and reception.
[0103]
The image processing apparatus may further include a light source, and the capacitive
transducer may be configured to receive a photoacoustic wave generated when the light from the
light source is irradiated to the subject and convert it into an electrical signal. In such a
configuration, the image display unit 404 displays the measurement object 402 as an image
based on the reproduced image information by the reception of the photoacoustic wave.
Alternatively, the measurement object 402 can be displayed as an image based on two pieces of
information of reproduced image information by ultrasonic transmission and reception and
reproduced image information by a photoacoustic signal.
[0104]
The ultrasonic imaging apparatus 400 of this embodiment is characterized by using the
capacitive transducer 401 of the present invention. This is a capacitive transducer 401 with high
reliability, small size, and excellent transmission and reception characteristics. Therefore, it is
possible to provide an object information acquiring apparatus such as an ultrasonic image
forming apparatus capable of forming a high-quality image with high reliability, a small
ultrasonic measurement unit, and good transmission and reception characteristics of ultrasonic
waves. it can.
[0105]
100 · · CMUT (capacitance type transducer), 101 · · diaphragm, 102 · · first electrode (one
electrode), 103 · · second electrode, 105 · · · · · · · · · (cavity (aperture) · · · · · · · · · · · · · · · · · · · · · · · · · ·
· · · · · · · · · · · · 205 · · acoustic matching layer
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