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Патент USA US3052583

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Sept. 4, 1962
M. E. DUMESNIL
3,052,573
RESISTOR AND RESISTOR COMPOSITION
Filed March 2, 1960
2- Resistor unit
1- Ceramic bose
.FIG. 2
5- Metol oxide coating and particles
4-Gloss matrix
3—Pd 0 p?r?cles
l-Ceromic base
‘
INVENTOR
MAURICE E. DUME‘SNIL
BY
ATTORNEY
United States Patent 0
3,052,573
pn
1C6
‘ Patented Sept. 4, 1962
2
1
Finely divided palladium oxide for use in accordance
with this invention may be prepared by heating ?nely
divided palladium metal in air. The palladium metal may
be produced by chemical precipitation or by mechanical
3,052,573
RESISTOR AND RESISTOR COMPOSITION
Maurice Edward Dumesnil, Metuchen, N.J., assignor to
E. I. du Pont de Nemours and Company, Wilmington,
Del., a corporation of Delaware
comminution or disintegration in known manner.
It is
highly desirable, however, that the ?neness of division be
Filed Mar. 2, 1960, Ser. No. 12,256
13 Claims. (Cl. 117-221)
less than 325 mesh and preferably of an average particle
size of between 0.1 and 50 microns. When palladium
metal powder is heated in air it begins to oxidize readily
This invention relates to ceramic electrical resistor com
positions and to electrical resistor ?lms produced there 10 at 300° C. and reaches a maximum Weight gain at 700°
C. to 750° C. to form the non-stoichiometric structure
with. More particularly, the invention relates to vitreous
PdO (1“), being essentially palladium monoxide. Beyond
enamel-palladium oxide compositions which may be ap
this temperature the oxide becomes unstable and reverts
plied to and ?red on a ceramic dielectric material to
to the metal in the same way that silver oxide decomposes
produce an electrical resistor, and electrical resistors so
15 to metal at about 300° C. The use of PdO in place of
produced.
metallic Pd in vitreous resistor compositions oifers the ad
The recently issued patent to J. B. D’Andrea, No.
2,924,540, discloses a new type of ceramic resistor com
vantage of using very soft vitreous enamel (450—600° C.)
position and electrical resistors produced therefrom, com
prising ?nely divided palladium metal, with or without
point (700—800° C.) without completely varying the re
as well as vitreous enamel having a fairly high melting
addition of silver, in combination with a vitreous enamel 20 sistance values of the ?nished resistors produced there
from.
?ux. Although the D’Andrea type resistor material con
The ?nely divided palladium oxide with or without
stituted a great improvement over previously known types
silver, gold or platinum powder, is mixed with the ?nely
of printed ceramic resistor material, it was not altogether
divided (less than 325 mesh) vitreous enamel ?ux in the
satisfactory since the use of different vitreous enamel frits
of different maturing temperatures gave resistors of rather 25 following proportions:
widely divergent resistances.
[Percentages by weight]
It is an object of this invention to produce vitreous
enamel containing resistor compositions that will have
Operable
substantially uniform resistances even when mixed with
vitreous enamels of varying maturing temperatures and ‘
Preferred
proportions proportions
?red at such varying temperatures.
It is another object of this invention to produce vitreous
4 to 90
0 to 50
8 to 90
92 to 10
enamel containing resistor compositions of high stability
4
0
8
92
to 15
to 12
to 27
to 73
to ?ring temperatures.
It is yet another object to produce a more easily re 35
producible electrical resistor.
Other objects of the invention will appear hereinafter.
Although the preparation of resistor compositions with
?nely divided PdO is an improvement and has distinct
advantages over the use of ?nely divided Pd, both Pd
The resistor compositions of this invention may be pre
pared by mixing ?nely divided palladium oxide Wi-th ?nely
divided vitreous enamel frit. The dry ?nely divided pal
ladium oxide-enamel frit composition may, if desired, be
-miXed with a liquid or pasty vehicle for application to a
40
and PdO interact with the vitreous enamel more or less at
varying elevated temperatures. This factor creates dif
?culty in reproducing a desired resistance value under
commercial ?ring conditions. The resistance value may
ceramic dielectric.
vary by 20 to 40 fold over a 200° F. ?ring range at a given
The palladium oxide may, if desired, be replaced by
?ring
period and a 10 fold variance with a varying ?ring
rhodium oxide with substantially like results. Since RhO 45
has substantially the same characteristics as PDO for the
purposes and objects of ‘this invention, where reference is
made to Pd or PdO throughout the speci?cation and
period of 30 to 90 minutes under a constant ?ring tem
perature.
It is therefore greatly to be preferred to prepare the
resistor compositions with PdO modi?ed by the presence
50 of certain other metal oxides. For examples, ?nely
respectively replaced by Rh or RhO.
divided PdO containing 10% by weight of Zr02 will pro
As in the D’Andrea patent, so that the voltage and
duce a resistor the resistance of which will vary by only
temperature coefficients of the resulting resistors may be
more readily controlled, it is usually preferred that a
20% when ?red during a given period at a temperature
quantity of ?nely divided (less than 325 mesh) silver, gold
varying between 1300° F. and 1500“ F., and will vary
or platinum be added to the palladium oxide in the resistor 55 by about 2 fold when ?red at periods varying between 30
claims it is to be understood that the Pd or PdO may be
composition.
The ?nished resistor may be produced by applying the
resistor composition to a ceramic dielectric and ?ring
the same at a temperature that will fuse (mature) the
vitreous enamel to the dielectric surface.
A still further improvement in reproducibility of re
sistors of a given resistance value maybe obtained by the
use of ?nely divided palladium oxide with an oxide of a
and 90 minutes at a constant temperature between 1300"
F. and 1400° F. and less than 3 fold at similar varying
periods at 15001" F. The similar addition of the other
listed metal oxides to PdO will produce improvements of
the same order.
Where a palladium oxide is desired that is associated
with a metal oxide of the kind referred to above, it may
be obtained in any manner whereby at least a portion
metal from the group consisting of Zr, Al, Sr, Ca, Sn,
65 of the surface of the PdO particles is ‘coated with ‘an ad—
Mg, Zn, and the rare earth metals bonded to it.
3,052,573
3
herent coating of the metal oxide additive. ‘The follow
ing proportions of the metal oxides to PdO may be used:
[Percentages by weight]
milled in the presence of an inert liquid for a period of 2
to 20 hours.
Another method consists in adding the nitrate solution
of the additive salt to palladium oxide powder and heat
treating as above described.
Operable Preferred
proportions proportions
PdO (replaceable with RhO) ________________ __
65 to 99. 9
85 to 92
35 to 0.1
15 t0 8
A third method that is particularly applicable with
aluminum nitrate solution comprises the addition of an1~
monium hydroxide to palladium chloride solution to form
Metal oxide 01' the group Zr, Al, Sr, Ca, Sn,
Mg, Zn, and rare earth metals _____________ -_
a ?ne suspension of ammonium chloropalladate to which
10 is then added a measured amount of colloidal hydrous
aluminum oxide (formed by adding ammonium hydroxide
Resistor formulations prepared with PdO modi?ed with
one of said metal oxides, silver and Vitreous enamel frit
to aluminum nitrate solution). The mixture is thoroughly
stirred and ?ltered. The residue from the ?lter is heated
may contain the following proportions:
at about 750° C. for 90 minutes to produce a ?nely
[Percentages by weight]
15
Operable Preferred
proportions proportions
PdO plus metal oxide _______________________ __
Silver, gold or platinum _____________________ ._
10 to 70
0 to 30
15 to 35
5 to 25
10 to 70
20 to 60
90 to 30
80 to 40
Total PdO plus metal oxide plus Ag, Au and
Pt.
Enamel frit _________________________________ __
divided Al2O3~PdO powder.
The vitreous enamel frit used in the production of
the vitreous enamel resistor compositions of the inven
tion may be composed of any glass frit, such as a boro
silicate frit, lead borosilicate frit, cadmium, barium,
20 calcium, or other borosilicate frit.
The preparation of
such frits is well known and consists, for example, in
melting together boric oxide, silicon dioxide and lead
oxide, cadmium oxide, or barium oxide and pouring such
molten composition into Water to form the frit. The batch
As above stated, the additive metal oxide may be the
oxide of Zr, Al, Sr, Ca, Sn, Mg, Zn or a rare earth or com 25 ingredients may, of course, be any compound that will
binations thereof. The rare earths consist of the metals
yield the desired oxides under the fusing conditions of frit
scandium, yttrium, lanthanum, cerium prascodymium, neo
dymium, Samarium, europium, gadolinium, terbium,
dysprosium, holmium, erbium, thulium, neoytterbium, and
production, i.e., boric oxide will be obtained from boric
acid or borax, silicon dioxide will be produced from ?int,
lead oxide will be produced from red lead or white lead,
Of these the most common are probably lan 30 barium oxide will be produced from barium carbonate,
etc.
thanum and cerium, both of which have given good results
lutecium.
as PdO additives in accordance with this invention. The
The coarse frit is preferably milled for 2 to 20 hours,
characteristics of the rare earths are very much alike
for example, in a ball-mill with water. The frit may
contain varying amounts of other oxides, such as zinc
and although they would undoubtedly all be operative
for the purposes of this invention, many of them are
probably too rare and expensive to be practical.
Resistors prepared in accordance with this invention
are illustrated in the accompanying drawings, in which,
FIGURE 1 is a cross-sectional view, on a highly ex
oxide, magnesium oxide, or the like.
The vitreous enamel frit and palladium oxide powder,
with or Without silver, gold or platinum powder, may be
mixed in any manner, for example, in a ball-mill, and the
resulting dry composition sold as such. The dry com
aggerated scale, of a resistor produced in accordance 4.0 position is, however, preferably ?rst mixed with a liquid
vehicle and sold in the form of a liquid or paste. The
with this invention.
vehicle may vary widely in composition. Any inert liquid
FIGURE 2 is a smaller cross-sectional view of a second
may be employed for this purpose, for example, Water,
embodiment of the resistor of this invention.
organic solvents, with or without thickening agents, stabil
Referring to the drawings, 1 designates a ceramic di
electric base such as a glass, porcelain, refractory, barium 45 izling agents, or the like, for example, methyl, ethyl, butyl,
propyl or higher alcohols, the corresponding esters such
titanate or a similar dielectric base. A resistor unit 2 is
as the acetates, propionates, etc., the terpenes and liquid
formed on the base 1 by ?ring a resistor composition of
resins, for example, pine oil, alpha-terpineol, beta
the invention and comprising PdO or RhO particles mixed
terpineol, and the like, and other liquids without limita
with a glass frit. The resulting resistor unit 2 is com
prised of the PdO or RhO particles 3 bonded in a glass 50 tion, the function of the liquid vehicle being mainly to
form a liquid or paste of the desired consistency for ap
matrix 4.
FIGURE 2 shows a similar resistor comprised of a
plication purposes. The vehicles may contain or be com
ceramic base 1 and containing metal oxide particles 5
posed of volatile liquids to promote fast setting after ap
plication, or they may contain waxes, thermoplastic resins,
both coated on at least parts of the surfaces of the PdO
particles 3 and also interspersed bet-ween the PdO particles, 55 or wax-like materials Which are thermofluid by nature
all in a glass matrix 4. The metal oxide particles 5 as
whereby the composition may be applied to a ceramic in
stated in the speci?cation may consist of Zr, Al, Sr, Ca,
sulator while at an elevated temperature to set immedi
ately upon contact with the ceramic base.
Any desired amount of vehicle or organic binder may
for preparing the ?nely divided PdO (replaceable wholly 60 be added whereby to stencil, spray or brush the ?nely
divided metal oxide onto a ceramic dielectric base ma
or partially with RhO) containing the additive metal
terial. For stencil screen application the concentration
oxide. These methods are not, however, to be taken as
of solids and the viscosity of the paste must be controlled
limitative of the invention, other methods being equally
since these will affect the thickness of the prints and
applicable to the production of the metal oxide modi?ed
the resistance value of the resistors. The viscosity of the
PdO.
r
65
compositions (preferably about 120 to 150 thousand centi
‘Preferably, the additive metal oxide is produced from
poises) may be adjusted so that the ?red ?hn is of the
a Water~soluble salt of the metal by decomposition to the
desired thickness. A very suitable thickness would be
oxide on the surface of the PdO particles. This may be
of the order of 15 to 25 microns.
accomplished, for example, by dissolving the nitrate salt
The ceramic dielectric base material may be comprised
of the desired metal oxide in water and mixing therewith
?nely divided palladium metal (less than 325 mesh). The
of any ceramic material that can withstand the ?ring tem
water is then evaporated from the mixture and when dry
perature of the vitreous enamel-palladium oxide com
the residue is placed in a furnace and ?red at 750° C. for
position. For example, glass, porcelain, refractory,
11/2 to 20 hours. The resulting homogeneous mixture of
barium titanate, or the like may be used. Preferably, the
PdO and the additive metal oxide is crushed and ball 75 ceramic insulating materials should have a smooth, sub
Sn, Mg, Zn or a rare earth or combinations thereof.
The following methods are given as suitable methods
3,052,573
.5
6
The resulting resistors had the following resistances per
square at the given times and temperatures of ?ring:
stantially uniform surface structure but this is not ab
solutely necessary.
The resistor composition is then applied in a uniform
thickness on the ceramic dielectric. This may be done
Firing time
1,300° F. 1,400" F. l,500° F.
by any of the application methods above disclosed. The
dielectric and applied resistor composition is then dried,
K
30 minutes __________________________ __
if necessary, to remove solvent from the vehicle and then
2. 1
3. 7
v60 minutes___
?red in a conventional lehr or furnace at a temperature at
which the enamel frit is molten, whereby the conductive
Example V
material is bonded to the ceramic dielectric.
10
A resistor composition was prepared by the procedure
The following examples are given to illustrate certain
of Example IV but containing the metal oxide product
preferred details of the invention, it being understood
that the details of the examples are not to be taken as
of Example II ball-milled 16 hours in acetone and bead
in any way limiting the invention thereto. In all of the
milled further for 16 more hours. A resistance per square
examples the particle size of the palladium, palladium
ranging from 10K to 15K was obtained using the ?ring
oxide, metal oxides, silver, gold, platinum, and frit aver
conditions of Example IV.
aged between about 1 and 5 microns. Although it is
Example VI
desirable to maintain the particle sizes fairly consistent to
obtain good reproducible results, the actual particle sizes
used are not critical.
20
Example I
10.44 grams of zirconyl nitrate are dissolved in water in
a large evaporating dish. To this is added 23.47 grams
Following the procedure of Example III using the metal
oxide product of Example II, the glass frit of Example III,
?nely divided silver powder having a particle size of
about 2 microns, in the proportions by weight given in
the following table and ?ring the printed resistors at 1400°
F. for 60 minutes, the resistance Values set forth in the
of ?nely divided palladium metal. The resulting mixture
is heated with continuous stirring until all the water is 25 table were obtained:
‘evaporated therefrom, after which the dry mixture is
12345678
placed in a furnace and ?red for ‘90 minutes at a tem
perature of 750° C. The ?red product, after cooling,
Pd0(85), A1zO3(l5)OfEXaD1~
is then ball-milled in acetone for a period of 16 hours.
The resulting ?nely divided ‘metal oxide contained about 30
90% PdO and 10% ZrOz.
20
20
30
25
20
25
25
10
Silver powder, percent ______ __ 1O
15
7.5
15
17.5
20
25
30
65
62.5
60
62.5
55
50
60
10
20
6
4.5
3
ple II, percent _____________ __
Glass frit of Example III,
percent ____________________ __ 70
Resistance per square (taken
to nearest whole numbers),
Example 11
44 grams of aluminum nitrate is dissolved in water
and 30 grams of ?nely divided palladium powder is add 35
ed thereto. The mixture is dried, ?red and ball-milled
in the manner described in Example I. If a still ?ner
20
1110
Example VII
1Following the procedure of Example III but replacing
particle size is desired, the ball-milled product may be
the metal oxide product of Example I with the following
further milled with glass ‘beads for 16 to 70 hours. The
dried ball-milled product contained about 85% PdO 40 metal oxide combinations, produced substantially in ac
and
cordance with the procedure of Example I, the following
% A1203
resistance values were obtained at the various given times
Example III
A resistor composition was prepared by blending: 60
and temperatures of ?ring:
grams of the ball-milled product of Example I, 40 grams 4:5
of commercial precipitated silver having a particle size
Time, 1,ao0° F. 1,4o0° F. 1,500° F.
1111115.
of about 2 microns, 180 grams of lead borosilicate frit
consisting of 65% PbO, 10% B203 and 25% SiO2, and
90% PdO-10% lanthanum
130 grams of a vehicle composed of beta-terpineol vis
‘W16 ---------------------- -- i
cosi?ed with 6% by weight of ethyl cellulose. The ethyl 50 90% Rio-10% 0&0 .......... .. {
cellulose used was that sold under the designation T-200
90% rec-10% strontia ....... __ {
lay Hercules Powder Company of Wilmington, Delaware.
The resulting composition was roll-milled thoroughly
barium titanate dielectric disc and ?red to produce elec
tric resistors. The following table gives the resistance
per square in K ( 1000 ohms) of the resulting resistors ob
K
6. 7
28
2; 35
g; ,7,“
g; E5
i135
5.0
5.2
5. 85
6.0
8.2
8.0
8. 7
8.9
13. 6
12.5
12. 8
16.8
Two resistor compositions were prepared by the pro
at 750° C. for 16 hours and ball-milled for 16 hours. The
two compositions contained the following compositions of
6 total metal oxide, silver powder and lead borate frit.
Similar results were obtained by using alumina or
Composition Composition
I (PdO, 85;
II (PdO)
A1203, 15)
steatite dielectric discs in place of the barium titanate
dielectric.
70
Example IV
Percent
Metal oxide ___________ -_
A paste resistor composition was prepared ‘by the pro
cedure of Example III with the sole exception that the
16-hour ball-milled product of Example H replaced the
product of Example I.
1
Example II and the other composition with PdO prepared
by heat treating ?nely divided Pd in normal atmosphere
K
60 minutes ___________ _.
90 minutes _________________ -_
K4_ 3
2 microns, and as the metal oxide, one of the compositions
is formulated with the aluminum oxide modi?ed PdO of
30 minutes _________________ ._
_
5. 6g
glass having a softening point of 430° C., a ?nely divided
precipitated silver powder having a particle size of about
1,200“ F. 1,300° F. 1,400° F. 1,500° F.
K
65
4. 7
cedure of Example III using as the glass frit a lead borate
tained using given ?ring times and temperatures.
K
2
60
Example VIII
and then printed with a thickness of about 1 mil. with a
200 mesh stainless steel squeegee stencil screen onto a 55
Firing time
30
Silver powder“
Lead borate frit. _ __
75
20. 7
_._-.
Percent
21. 4
17. 5
14. 6
61. 8
64. 0
The compositions were placed on barium titanate
3,052,573
7
8
alumina and steatite dielectric discs by the procedure of
of 8% to 27% of said conductive component and 73%
to 92% ?nely divided vitreous enamel frit.
4. A vitreous enamel resistor composition as de?ned
in claim 3 in combination with suflicient inert liquid ve
hicle to form a paste with said composition components.
5. A resistor composition adapted to be applied to and
Example III. The resistance values of the resulting re
sistors ?red at the given times and temperatures were as
follows:
Time, 1,000° F. 1,100° F. 1,200° F.
mins.
~ c‘mlposltlon
I --------------
30
so
K 9
23.46
Composition II ______________ __ {
28
3'5
18.1
K 3
26.14
19. 5
K 46
15.
10
18.25
[11:35
?red on a ceramic dielectric to form readily reproducible
electric resistors consisting essentially of 10% to 70%
?nely divided metal oxide taken from the group consisting
of PdO and RhO containing bonded thereto 0.1% to 35 %
by weight of a metal oxide taken from the group consist
ing of Zr, Al, ‘Sr, Ca, Sn, Mg, Zn and the rare earth metals,
as a conductive component, 0% to 30% ?nely divided
metal taken from the group consisting of Ag, Au and Pt,
Throughout the examples where silver is used, it can be
replaced wholly or partially with either gold or platinum 15 as a conductive component, a total of 10% to 70% of
said conductive component, and 30% to 90% ?nely ‘di
or both with substantially similar results, and where PdO
vided vitreous enamel frit.
is used it can be replaced wholly or in part by RhO.
The resistor compositions of this invention are out
6. A vitreous enamel resistor composition as de?ned
in claim 5 in combination with su?icient inert liquid ve
standingly useful for the production of electrical resistors
hicle to form a paste with said composition components.
20
having good stability, low temperature coe?icient of re
7. A resistor composition adapted to be applied to and
sistance (the percentage change in resistance at two given
?red on a ceramic dielectric to form readily reproducible
temperatures divided by the ditference in temperature be
‘electric resistors consisting essentially of 10% to 70%
tween said two temperatures in degrees centigrade) low
?nely divided metal oxide taken from the group con~
voltage coefficient of resistance (the percentage change in
resistance ‘at two given voltages divided by the difference 25 sisting of PdO and R110 containing bonded thereto 8% to
15 % by weight of a metal oxide taken from the group con
between said two voltages) being readily reproducible and
sisting of Zr, Al, Sr, Ca, Sn, Mg, Zn and the rare earth
being relatively non-sensitive to times and temperatures of
?ring.
metals, as a conductive component, ‘0% to 30% finely
‘divided metal taken from the group consisting of Ag,
A resistor composition formulated with PdO and a‘
vitreous enamel (glass) frit will produce resistors having 30 Au and Pt, as a conductive component, a total of 10%
to 70% of said conductive component and 30% to 90%
a positive temperature coefficient of resistance (TCR)
?nely divided ‘vitreous enamel frit.
varying between 0.05% and 0.08% per degree C. On the
8. A vitreous enamel resistor composition as de?ned
other hand, a resistor composition formulated with PdO
in claim 7 in combination with sufficient inert liquid
modi?ed with another of the aforesaid metal oxides will
produce resistors with either a positive or negative TCR. 35 ehicle to form a paste with said composition compo
nents.
This TCR is dependent on the type of the added oxide and
9. A resistor composition adapted to be applied to
its relative proportion to the PdO, on the heat treatment
and ?red on a ceramic dielectric to form readily reproduci
and ?neness of division of the metal oxide combination,
ble electric resistors consisting essentially of 15% to 35%
the resistor formulation (i.e., ratio of metal oxide, silver
and glass frit) and the type of dielectric on which the 40 of ?nely divided metal oxide taken from the group con
resistor composition is printed. It has been found that
sisting of PdO and RhO containing bonded thereto 0.1%
to 35% by weight of a metal oxide taken from the group
by suitable control of these variables the TCR does not
consisting ‘of Zr, Al, Sr, Ca, Sn, Mg, Zn, and the rare
vary widely with the ?ring conditions of the resistor. In
earth metals, as a conductive component, 5% to 25%
this way a uniform and reproducible TCR of less than
45 ?nely divided metal taken from the group consisting of
0.01% per degree C. may be maintained, if desired.
Throughout the speci?cation and claims, any reference
Ag, Au and Pt, as a conductive component, a total of
to parts, proportions and percentages refers to parts, pro
20% to 60% of said conductive component, and 40% to
portions and percentages by weight unless otherwise speci
80% ?nely divided vitreous enamel frit.
?ed.
10. A vitreous enamel resistor composition as de?ned
Since it is obvious that many changes and modi?cations 50 in claim 9 in combination with suf?cient inert liquid ve_
can be made in the above-described details without de
hicle to form a paste with said composition components.
parting from the nature and spirit of the invention, it is
11. An electrical resistor comprising a ceramic dielec
to be understood that the invention is not to be limited to
tric
containing on the surface thereof a vitreous enamel re
said details except as set forth in the appended claims.
55 sistor element comprising between 10% and 70% of a
I claim:
metal 1oxide taken ‘from the group consisting of PdO and
1. A resistor composition adapted to be applied to and
RhO containing bonded thereto 0.1% to 35 % by weight
?red on ‘a ceramic dielectric to form readily reproducible
of a metal oxide taken from the group consisting of Zr,
electric resistors consisting essentially of 4% to 90%
Al, Sr, Ca, Sn, Mg, Zn and the ‘rare earth metals, as a con
?nely divided metal oxide taken from the group consisting
of PdO and RhO, as a conductive component, 0% to 60 ductive component, 0% to 30% metal taken from the
50% ?nely divided metal taken from the group consisting
group consisting of Ag, Au and Pt, as a conductive com
of Ag, Au and Pt as a conductive component, ‘a total of
ponent, a total of 10% to 70% of said conductive com
ponent, said conductive component embedded in a glass
matrix.
92% ?nely divided vitreous enamel frit.
2. A vitreous enamel resistor composition as de?ned in 65
12. An electrical resistor comprising a ceramic dielec
claim 1 in combination with sufficient inert liquid vehicle
tric containing on the surface thereof, a vitreous enamel
to form a paste with said composition components.
resistor element comprising between 15 % and 35 % of a
3. A resistor composition adapted to be applied to and
metal oxide taken from the group consisting of PdO and
?red on a ceramic dielectric to form readily reproducible
70 F110 containing bonded thereto 0.1% to 35 % by weight
electric resistors consisting essentially of 4% to- 15%
of a metal oxide taken from the group consisting of Zr,
?nely divided metal oxide taken from the group con
Al, Sr, Ca, Sn, Mg, Zn, and the rare earth metals, as a
sisting of PdO and RM), ‘as a conductive component, 0%
conductive component, 5% to 25% metal taken from the
to 12% ?nely divided metal taken from the group consist
group consisting of Ag, Au and Pt, as a conductive com
ing of Ag, Au and Pt, as a conductive component, a total 75 ponent, a total of 20% to 60% of said conductive com
8% to 90% of said conductive component and 10% to
3,052,573
10
ponent, said conductive component embedded in a glass
matrix.
13. An electrical resistor comprising a ceramic dielec
References Cited in the ?le of this patent
UNITED STATES PATENTS
resistor element consisting essentially of 4% ‘to 90% of a 5
2,440,691
2,461,878
?nely divided metal oxide taken from the group consist
ing of PdO and RhO, as a conductive component, 0% to
50% ?nely divided metal taken from the group consist
2,837,487
2,924,540
2,950,995
tric containing on the surface thereof a vitreous enamel
ing of Ag, Au and Pt, as a conductive component, a total
of 8% to 90% of said ‘conductive component, said 0011- 10
ductive components embedded in a glass matrix.
Iira __________________ __ May 4,
Christensen et a1. ______ __ Feb. 15,
1948
1949
Huttar _______________ __ June 3, 1958
D’Andrea ____________ __ Feb. 9, 1960
Place et al. __________ __ Aug. 30, 1960
FOREIGN PATENTS
486,639
Great Britain __________ __ June 8,
1938
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