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Патент USA US3079547

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Feb» 26, 1963
Filed Deo. 4. 1959
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Patented Fei). 26, 1953
Ichiro Sato, Eiichi Okamoto, and Yasuo Seki, all of
Tokyo, Japan, assignors to Nippon Electric Company
Limited, Tokyo, Japan, a corporation of `iapan
Fiied Dec. 4, 1959, Ser. No. 857,345
Claims priority, application Japan Dec. 9, 1958
6 Claims. (Qi. S17-25S)
layer 4 by the same method as the semi-conductor 4. The
above-mentioned base metal 1 acts as one electrode of the
This first part of the capacitor is actually the effective
part, the base metal 1 and the conductive layer 5 forming
the two electrodes. However, since the layer 5 is extreme
ly thin, it is not only difficult to make connection to it, but
it ha-s a considerable resistance so that other means must
be provided to obtain -a uniform potential difference be
This invention relates to capacitors of the rolled type 10 tween corresponding points on the two electrodes. More
in which very thin films of metal and dielectric are used.
over it is diiiicult to protect the film against damage in
A capacitor in which an anodic oxide film is formed as
rolling the capacitor. These 'difficulties are solved by the
a dielectric on a metal surface of tantaium, aluminum,
addition of the second part of the capacitor.
zirconium or titanium etc., and with a semiconductor layer
This second part of the capacitor is composed of four
like germanium, or an insulator layer like magnesium
parts, as follows: the base metal 9 which is different from
fluoride, or their conjugate layer, coated on the anodic
the above-mentioned base metal 1, an anodic oxide layer
oxide film by a method of evaporation or cathode sputter
8, formed on the -base metal 9, a layer of an organic insu`
ing, and further with a conductive layer like aluminum
lating material 7 on the anodic oxide layer 8, and a layer
formed thereon by the saine method, whereby the above
of conductive material 6 on the layer of an organic insu
mentioned basic metal and coated conductive layer con
latin g material 7.
stitute the two electrodes of the said capacitor, has the
One end of the layer of the «conductive material 6 is
advantages of being usable at specially high or low tem
then brought into contact with the base metal 9. The
peratures since it does not have an electrolyte as does the
capacitor is completed by bringing the layers of conductive
usual electrolytic capacitor, of also having good tempera
:materials 5 and 6 of the two different parts into Contact
with each other.
ture characteristics of capacitance and power factor, and
of being stable without deterioration. The principles in
The layer of organic insulating material '7 is used to
volved are explained in U.S. Patent No. 2,836,776, grant
improve the mechanical properties of the oxide layer 8.
ed May 27, 1958.
If the anodic oxide layer S is not present or is imperfect
Formerly where the coated conductive layer of alumi
for insulating purposes, instantaneous spark caused by a
num applied by evaporation is regarded as an electrode, a
short circuit at the imperfect parts of the anodic oxide
practical method of providing a lead-out terminal is to
film 2 will be apt to make the base metal 9 irregularly
bring into contact with said layer an organic insulating
deform by thermal and mechanical shocks and contact
film, for example, a polyethylene terephthalate resin film
with the so deformed base metal 1, and so self-healing
on which aluminum has been evaporated. The aluminum
action, which is found in the case of metallized paper
evaporated layer formed on the resin film is regarded as
capacitors cannot be obtained.
an outlet leading wire for the electrode. Further, a metal
But if the layer of organic insulating material 7 is
leaf, such as silver, is brought in contact with one end of
applied on the anodic oxide layer 3, the layers 7 Iand 3
the evaporated layer, and has a metal wire connected to
together will withstand the shock of the above-mentioned
it which acts as the electrode terminal.
spark caused by a short circuit between the base metal 1
However, the above type terminal is not completely
and the layer of conductive material 5, and only a limited
effective since an unstable contact between the metal leaf
`area of the thin layers of conductive materials 5 and 6
and the aluminum evaporated layer is formed, i.e., with
around the spark point is destroyed and so the short circuit
an applied voltage portions of the evaporated layer and
is self-healed.
edges of the metal leaf selectively short circuit, causing
these portions to disappear, and insulating pockets to be
An object of the present invention is to provide a dry
type capacitor using very thin metal films and having
The layer of organic insulating material 7, by itself, has
poor tensile strength and elasticity in a membranous state
'and is «delicate in rolling operations. But when it is coated
and combined on a metal surface having anodic oxide
film, it can be satisfactorily used. Organic insulating ma
favorable temperature characteristics in which the con
terial, such as silicon resin, that is too hard to make a
50 thin and strong film by itself, but has superior thermo
nections to the electrodes may be easily made,
Another object of the invention is to provide a capacitor
stability, can also be used, and the deformation of the
of the dry type having electrodes of very thin metal films
layer of organic insulating material by expansion and
in which the danger of short circuits in use is reduced and
contraction due to heat is reduced, because it is coated and
the effects are less harmful.
combined with the porous surface of the anodic oxide lilm
Another object of the invention is to provide a capacitor 55 according to the invention.
of the dry type having at least one very thin metal ñlm
The metal layer 9' acts as the actual lead-in for the
electrode with means for materially decreasing the resist
electrode 5, since the coating 6, is a very thin vacuum
ance of said electrode.
evaporated metal ñlm. Hence the coating 6 must be short
The invention is illustrated in the single figure which
circuited to the metal 9, and in such a construction, a
represents a greatly enlarged cross section of a capacitor
good effect is obtained. The high electrical resistance be
embodying the invention. The capacitor shown in the
tween the ends of the layer of conductive material 5v
ligure is constructed of two different parts. One of them
can be remarkably lowered by the short circuit of the
is composed of five parts as follows: the base metal 1 of
layer 6 to the metal 9 through the entire surface.
tantalurn (aluminum, zirconium, titanium, or the like),
The anodic oxide film S is formed, for instance, of the
an anodic oxide iilm 2 as a dielectric formed on the base
so-called “Alumite” .'hich is in an extremely porous state.
metal 1, a layer of insulating material 3, such as magnesi
The layer 7 is produced thereon in a pinhole state accord
um iluoride, on the anodic oxide film 2, a semiconductor
ing to a known method. Hence, when the conductive
layer 4, such as germanium, which is deposited on the
layer 6 is applied by a method, as, for instance, vacuum
layer 3 of insulating material by vacuum evaporation,
cathode sputtering, or the like, and a layer of conductive
material ‘5, such as aluminum, which is deposited on the
evaporation, evaporating metal grains get «into the holes,
and thus the conductive layer 6 and basic metal 9, not
only come into contact electrically with each other at the
one end, but also come into contact all over the surface
our invention asset forth in the objects thereof and in the
through the holes, and the electrical resistance between
the ends of the evaporating conductive layer 6 is remark
accompanying claims.
ably decreased. For instance, the resistance yis decreased
from 1/5 toi/10 of the resistance of one formed With'a'n alu
1. A capacitor of the dry type comprising first and sec
ond juxtaposed parts, said íirst part comprising a metal
base, an anodic layer on >said base, an insulating layer on
What We claim iS:
minum evaponating conductive layer fon ethylene tetraiiuo-~
rideresin iilm of 0.05 mm. thickness, Thus, _in construct
Ving a capacitor, We> can obtain one whichy has low loss,
said anodic layer, „a semi-conductor _layer on said insulat
inglayer, and a metal layer on said semi-conductor‘layer,
and 'stablek and superior characteristics owing to thede
crease 'ofthe resistance lof conductive layer, andthe su.
10 anodic layer on said metal leaf, a layer of insulating ma
and said second part comprising a metal leaf, a porous
terial having a plurality of pinholes on said anodic layer,
perior feature that it can be’used even atZOU”. C, or more.
and a film of metal deposited on said insulating layer by
>‘An example of th’einve'ntion will nov( be given., Anodic
evaporation, whereby grains of the metal will penetrate
the. holes in saidA porous anodic layer and said layer of
insulating` material having the pinholes,v saidparts being
juxtaposed with said last jmentionedV _metal ,filmy of said
secondpart incontact'vvith'said m'etaljlayerv of said first
oxidation is' Vformed on'a tantalum leaf of` O_Olîmm.
thickness ' at l10_`v_. -in, amoniumz ` carbonate aqueous; solu
tion, after which layers' of magnesiumñuoridg germa?
niuin, and aluminum are formedfonsthe 'surface by vacu
um evaporation. The tantalumï leaf '_isj regardedlas-»an
anode. Anodic oxidation of an aluminum llea-fof 0202
v2. A capacitor comprising a pair of electrodes at least
nim. thicknessr is produced by direct current in sulphuric
acid, which forms a so-called “Alumite”y film, after which
a layer of silicon` polymer of0ß04 mm'. t`o'0.0‘6'm`rn. thick
arating said electrodes, _a metal leaf spacedfrom said thin
lilrn of' metal, and separating meansA maintaining said _film
nessis applied _tothe surface. j;then heated and dried
andan aluminum layer is formed'on itbyI evaporation.
Byforming an aluminum ylayer onto~the._ endportionìat
which point the lsilicon .polymeris vnot applied, an electri
and leaf in spaced relation and comprising. an organic `in
sulating layer having a pluralityr of pinholesthereth-rough
and means for yelectrically connecting4 corresponding
points on said `iilmand said‘leaf through said pinholes.
cal4 connection is lmade between `it_ andthe .aluminum leaf.l
Therrietal -leaves thu'sjñnished lare rolled together, and
an anode terminal is made by Welding 'Kovar' alloy wire
to one end of the tantalum leaf .which Wire is ledout _for
the'anode terminal'. ' A_'cathode terminal is provided .by
one of which is a thin lilmfof metal, insulating _means sep
3. A capacitor as deiinedjinïclaim ZAinMWhich the otherv
of the'pair of electrodes’is'ametal' leaf. with an anodic>
oxidefilm formed thereon.I
4.~ A-,capacitor a-‘s'delinefd in claim`2 ’further comprising
aporous anodic layer on‘the` metal leaf, the lastmen
Welding' Kovar alloyywire to oneend ofthe valuminum leaf.
The; capacitor is` tlijenjseale‘d in a lc'y'flin‘di'ical metalcase
tioned >means v comprising lgrains of*` metaly extending
by'usi'ng'glass terminals.y „ '
through the'pinhol'es and the pores Iof saidporous, anodic
-, l
.v n..
, _The capacitor formed above 'had capacity of"1.5/p. F.,
and‘withstood 35 v..,at'normal temperature. _Whileap
plyinga .voltageof v2() v. about vlllûìhours. at 20.9? _Q.,an'd
äfboutS hours at 250,"~ C., no 'increa'sefof'.leakage'cu-rrent,
short circuit, or other abnormal» _occurrences could be
observed.,Í Up to the present,V the highest temperature to
vwhich a solid_`electrolyti__c_ capacitor havirigan anodic >oxide
5. A capacitor, as," defined in’claim 4, in which the
grainsof metal-.arepartof _and auxiliary metal iilm depos
ited on the organic insulating Vlayermby evaporation, , ,
6; A‘dry, electrolyïiscapacitor comprîsinsñrst and sec
ond coexte'ns'ive> parts,_„s§aid first part comprising. a ymetal
basi@ Seleëted from tlielsrrnin` _consisting .ofgtantalum zir
ñlm asadielectric couldÍbe' raised vfvfa's 150°.'C.l i I f l,
conium, aluminum ,and titanium, an anodiooxide film on
,` vIn theabove-mentioned Yexample ananodic oxide Vfilm
wasftirstjfo?med on .thesurffacefofI the aluminum leaf.
When, howeven'a thickenedv coating of`„silicon polymer
Was applied directly- to the aluminum leaf Vapproxi
said base, an insulatingl'ayeronqsaidulilm, a `semiconductor
mately the same'result" was achievedv butv lthe'.thermosta
lthe above group, Va porous „anodi-c’foxide rfilm, on said leaf,
a'layer ofpinsulating material _having a plurality` of> pin
bility seemed to besomewhat inferior.
layerY `on saidA insulatingvlayer andan/,aluminum film de
posited -'on 4 said I 'serniconductorA~ layer,- said _second Vpart
cpmpriisins‘ametalileafiselected'from aditïerentmeîalßf
' Í Ä __»
Fluo'rine polymers, Yalkyds polymers, and fúran poly
holes 'fharâthrßuehon .Saldi .arHQdîCîtìlm and being .Selected
mers etc., are also usabley as 'an organic insulating mate~
from the group consisting of silicon polymers, iiuorine
riallioweve‘r, >it hasnbeen found thatsilicon polymers »are
thelniost’suitable in order to produce -acapacitor.with the
best thermostability and one which isI stable .at high temá
polymers, `alkydsV polymers and yfuran polymers, and a lilm
¿` f.
of'ìalurminum deposited -,onsaid insulating layeryvhereby
Èfëinâpf theralumirlmm' penetrate the pinholes in the `in
sulating layer andftlie holes inthe porous .anodic_ñlm, said
Parts, ibansiuxtaavßed with Said aluminum ñhu of. said
second part inj contact with the aluminumtilm of said first
. ` Í i.
v’Although manifold layers of an >insulator anda semi
conductor on an anodic oxide film for the dielectric are
preferred, _anfinsulator layer alone, like ymagnesium liuc
ride 'ans calcium fluoride; or a 'semic’ónduetor' layer alone,
References Cited in the tile of this patent.
like'germanium and lead sulphate, arelfsuñ‘icient. Í But
capacitors so made have the disadvantages'of being-'Some
‘vi/hat'A unstable, befin'g'easy toshort circuit,Í andÍinmass
`production’tending tofpr‘oducewa large rfraotioii of Ídefec
,l While'we have described aboveth'e principles of our in
vention'in connection with speoiiicapparatus, it is to> be
lclearly lunderstood that -this descriptionl islmade. only by
Way of >'example and. not ‘as aÍ'limitation'to> thc- 'scope’ of
. Liiienfeld ten-„M_“ _-__--__ May 2, i933
Yoshioki _________ --->___-May. 27, 1958
Australia __..'__'__v_`_.._.._`._.. Feb. 4, 1954
_Great-.Britain .___-___,.f- Mar. 1o, .1954
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