Note: Descriptions are shown in the official language in which they were submitted.
10560Z6
BACXGR~UND A~D SVMMARY OF THE INVENTION
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The present invention relates to a novel resistor
c~mp~sition having an excellent temperature coefficient of
; resistance (TCR) and its method of preparation. More particularly,
the present invention is directed to a resistor comp~sition con--
taining a conductive material and a glass frit or a conductive
material, a glass frit and an insulating or semiconductive metal
oxide wherein the weight ratio of said conductive material and
said glass frit or said conductive material, said glass frit and
10 said metal oxide is maintained constant and the resistance value --
of the resistor composition is determined by varying the total
surface area of said conductive material and said glass frit
or by varying the total surface area of said conductive material,
,~ said glass frit and said metal oxide without substantially
changing the temperature coefficient of resistance of the
I resisto~ composition.
In the precious, well-known techniques, the preparation
of a resistor composition containing a series of varied resistance
values was obtained by controlling the weight ratio of the
20 components of the resistor composition, that is, the weight ratio
o-f the conductive material and the resistive material. However,
in following the well-known techniques for the preparation of
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resistor compositions, the variation of the resistance value was
always accompanied by a simultaneous deviation in the temperature
coefficient of resistance. Therefore, in the prior art resistor
compositions and method of manufacture, it was impossible to
obtain certain definite resistance values without varying the
temperature coefficient of resistance~
In addition, although an even surface film resistor
30 with higher resistance value is obtainable, adoption of some
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1 special devices are inevitably required in the preparation
processes of the resistor composition. With respect to resistors
having a lower resistance value, although composi-tions having
satisfactory printing ability are obtainable, the yiel~ed
resistors normally have uneven surfaces and also unstable resis-
tance values.
The present invention is directed to a resistor
composition comprising a conductive material and a glass frit, or
a conductive material, a glass frit and an insulating or semi-
tO conductive metal oxide, wherein the weight ratio of the conductivematerial and the glass frit and, when present, the said metal
oxide is constant and the resistance value of the composition is
` determined by varying the total surface area of the conductive
material, the glass frit and, when present, the said metal oxide, -
without changing the temperature coefficient of resistance of
the composition. In the process for manufacturing the resistor ~
composition of thq present in~ention, conducti~e materials, glass -
frit and insulating or semiconductive metal oxides having known
;~ specific areas are utilized and the resistance value of the
2~0 resistor comp~sition is determined by increasing or decreasing
the total surface area of said conductive material, said glass
~rit and, when present, said metal oxide, while maintaining the
weight ratio of said conductive material, glass frit and said
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metal oxide constant. Alternatively, the specific surface area
of one or two components selected from the above two or three
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~ components can be either increased or decreased while maintaining
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the specific surface area of the residual component constant -~
and while maintaining the weight ratio of said two components or
said three components constant. Advantageously, a vehicle is
provided for said two-component or three-component resistor
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1 composition of the present invention.
Thus, according ~o the present invention, the problems
encountered in the prior art resistor compositions and processes
have been overcome by the teachings of the present invention whicl
are summarized as follows:
1. A resistor composition comprising a cond~ctive
material, a glass frit and a vehicle therefor wherein the weight
ratio of said conductive material to said glass frit is constant
and the resistance value of said composition i5 established by
varying the total surface area of said conductive material and
said glass frit without changing the TCR of said composition.
; 2. A resistor composition comprising a conductive
material, a glass frit, an insulating or semiconductive metal
oxide and a vehicle therefor, wherein the weight ratio of said
conductive material, said glass frit, and said insulating or semi-
conductive metal oxide is cons~ant and the resistance value of said
composition is established by varying the total surface area of
said conductive material, said glass frit and said insulating ox
semiconductive metal oxide without changing the TCR of said
composition.
3. A process for manufacturing a resistor composition
characterized by using a conductive material and a glass frit
having known specific surface areas, respectively, and establishing
the resistance value of said resistor composition by increasing
or decreasing the total surface area of said conductive material
and said glass frit while maintaining the weight ratio of said
conductive material to said glass frit constant
4. A process for manufacturing a resistor composition
characterized by using a conductive matérial, a g7ass frit and an
insulating or semiconductive metal oxide having known specific
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lOS6026
1 surEace areas, respectively, and establishing the resistor value
of said resistor composition by increasing or decreasing the total
surface area of said conductive material, glass frit and insula-
ting or semiconductive metal oxide while keeping the weight ratio
of said conductive material, glass frit and insulating or semi-
conductive metal oxide constant.
5. A process for manufacturing a resistor composition
characterized by using a conductive material and a glass frit
having known specific areas, respectively, and establishing the
resistance value of said resistor composition by increasing or
decreasing the specific surface area of ~ne component and main-
taining the specific surface area of the other component constant
while keeping the weight ratio of said conductive material to
said glass frit constant. -
6. A process for manufacturing a resistor composition
characterized by using a conductive material, a glass frit and
an insulating or semiconductive metal oxide having known speci~ic
surface areas, respectively, and esta~lishing the resistance value
of said resistor composition by increasing or decreasing the
specific surface area of ;one or two components and maintaining
the specific surface area of the residual compon~nt or components
constant while keeping the weight ratio of said conductive
: . .
material, glass frit and insulatlng or semiconductive metal oxide
~; constant.
As mentioned above, one of the main features of the
present invention is that a definite resistance value is easily
obtained by controlling the total surface area while the tempera-
ture coefficient of resistance is maintained substantially constant.
However, the theoretical reasons why this phenomena exists is
uncertain. One possible assumption in this connection is an
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1 explanation based upon the contact area between the resistive
material and the conductive material. But the effects cannot be
fully understood from only the above assumption. In any event,
the amount of reproducibility involved in the present invention
suggests that this is an entirely novel and widely applicable
technical contribution which has not yet been fully supported by
theoretical bases.
The term "specific surface area" as referred to herein-
above shall be defined as the surface area of each l-gram of
finely divided particles, and accordingly, the "total surface area"
can be defined by the following equation:
Total surface area = specific surface area X total wt. of particles.
The conductive ma~erial or component which can be
utilized in the present invention can be, for example, Au (gold),
Ag (silver), Pt (platinum), Rh (rhodium), Ru (ruthenium), Os
(osmium), Ir (iridium), V (vanadium), Sn (tin), W (tungsten),
C ~carbon), and alloys mixtures, and oxides thereof. These con-
ductive materials, after the composition has been fired, become
highly conductive particles.
The glass frits which can be used in the resistor
composition of the present invention are, generally speaXing,
conventional glass frits. Examples of such glass frits include
~-~ the borosilicates and particularly the lead-borosilicates.
The insulating or semiconductive metal oxide which
can be used in the resistor composition of the present invention
should be capable of producing, after firing, finely divided
particles with insulating or semiconductive properties. Exemplary
;~ of suitable insulating or semiconductive metal oxides include
palladium oxidej copper oxide, aluminum oxide, zinc oxide, iron
oxide, chromium oxide, cobalt oxide, tantalum oxide, nickel oxide,
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10560Z6
niobium oxide, silicon oxide and the like. Th~ finely divided
particles of the said c~nductive material, glass frit and metal
oxide are those containing a diameter of about 100 ~ to 50Jff.
The vehicle which can be used in combination with the
conductive material, glass frit and the insulating or semiconduc-
tive metal oxide in forming the resistor composition of the
present inven~ion can be an organic binder, such as, for example,
ethyl cellulose, alkyd resins, butyral resins, nitrocellulose,
and the like. Any vehicles which are normally used in the
resistor field of technology are applicable to the resistor
composition and method of the present in~ention.
Examples of suitable solve~ts which can be included
in the resistor composition of the present invention include
organic solvents such as butyl carbitol, butyl carbitol acetate,
terpineol, tetralin, and the like~
In the resistor composition of the present invention,
' the conductive material can be present in an amount of about 10
to 60 parts by weight and the resistive material, which includes
the glass frit alone or the glass frit and the insulating or
; 20 semiconductive metal oxide can be present in an amoun~ of about 40
` to 90 parts by weight.
The specific surface area of the conductive material,
- glass frit and insulating or semiconductive metal oxide can be
varied from 0.02 to about 270 m2/g. Within this range, the
specific surface area of the conductive material can vary from
about 0.02 to about 85; the specific surface area of the glass
frit can vary from about 0.05 to 2.0, and the specific surface
area of the insulating or semiconductive metal oxide can vary
from about 0.5 to 265.
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DESCRIPTION OF TE:~E PREFERRED EMBODIMENTS
The following examples are given merely as being
illustrative of the presen-t invention and thus are not to be
considered as limiting.
EXAMPLE 1
Parts by weight
Ag (specific surface area, 0.1 m2/g) 24
RuO2 (specific surface area, 0.1 m2/g) 36
Glass frit (specific surface area, 2.0 m2/g) 40
10 Ethylcellulose 10
Tetraline 40
The above composition was well milled to make a
homogeneous paste which was then printed onto an alumina substrate
in an area of 5 mm x 5 mm. After the composition was dried at
a temperature of 150C for 10 minutes, it was gradually heated up
to 800C and maintained at that temperature for 10 minutes. Then
! the composite was slowly cooled to room temperature. Silver
electrodes were formed on the cooled substrate to produce a
composite resistor.
EXAMPLES 2 - 11
With the use of the same components, and utilizing a
similar treatment as in Example 1, a series of resistors were
obtained according to the composition ratio given in the table
shown on page 11.
EXAMPhE 12
Parts b~ weight
RuO2(specific surface area, 4 m /g) 25
Glass frit (specific surface axea, 0.3 m2/g) 75
Ethylcellulose 7 -~
30 Terpineol 19
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10560Z6
1 The above composition was milled to make a homogeneous
paste and was then printed onto an alumina substrate, on which
Ag-Pd electrodes (ag; Pd = 70:30) were previously formed in a
desired pattern, in an area of 4 mm x 2 mm. After the composition
was dried at a temperature of 150C for 10 minutes, it was ~radually
heated up to 760C and maintained at that temperature for 10 min-
utes. Then the composition was slowly co~led to room temperature
to produce a composite resistor.
EXAMPLES 13 - 15
With the use of the same components, and utilizing
a similar treatment as in Example 12, a series of resistors were
o~tained according to the composition ratio given in the table
shown on page 10~
EXAMPLE 16
Parts hy we_~ht
~U2 (specific surface area, 10 m2/g) 10
Glass frit (specific surface area, 0.3 m2/g) 67
A1203 lspecific surface area, 20 m2/g) 23
Ethyl cellulose 5.5
20 Terpineol 22
The above composition was well milled to make a homo-
geneous paste and was then printed on an alumina substrate, on
which Ag-Pd electrodes (Ag:Pd = 70:30) were previously formed in
a desired pattern, in an area of 4 mm x 2 mm. After the composi-
tion was dried at a temperature of 150C for 10 minutes, it was
gradually heated up to 760C and maintained at that temperature
for 10 minutes. Then the composite was slowly cooled to room
temperature to produce a composite resistor.
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EX~MPLES 17 - 21
With the use of the same components and utilizing a
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similar treatment as in Example 16, a series of resistors wexe
obtained according to the composition ratio given in the table
shown on page 10.
EXAMPLE 22
Parts by weiqht
Ru02 (specific surface area, 10 m /g) 21
Glass frit (specific surface area, 0.3 m2/g) 74
SiO2 (specific surface area, 265 m2/g) 5
Ethyl cellulose 5.5
10 Terpineol 22
The above composition was well milled to make a homo-
geneous paste and was then printed on an alumina substrate, on
which Ag-Pd electrodes (Ag:Pd = 70:30) were previously formed in
a desired pattern, in an area of 4 mm x 2 mm. After the composi-
tion was dried at a temperature of 150C for 10 minutes, it was
gradually heated up to 760C and maintained at that temperature
! for 10 minutes Then the composite was slowly cooled to room
temperature to produce a composite resistor.
EXAMPLES 23 - 27
With the use of the same components and utilizing a
similar treatment as in Example 22, a series of resistors were
obtained according to the composition ratio given in the table ~:
shown on page 10.
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ll~S6026
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10560Z6
1 Measurement of the specific surface area referred
to in the Examples was performed by following the Blaine
Permeability Method and the BET Method. The resistance value,
R, was obtained by using a conventional Wheatstone bridge
apparatus. The TCR is represented in ppm/C) unit according
to resistance values measured in the range from 25C - 125C.
The weight ratio of the conductor, glass frit and
the insulating or semiconductive metal oxide, based on total
of 100 parts by weight. of either the two or three components,
the specific area (m2/g), the resistance (Q /~), and the
TCR (ppm/C) in each of the examples are shown in the table
where the results of the present invention are cleverly shown.
In the table, WA , WR , W W
. g uO2, glass, A1203, and SiO
.re.present.pa~.ts by weight of the Ag, Ru02, glass frit, ~ :.
: A1203, and SiO2 and furthermore S S , S S
Ag, Ru02 glass' A12o3'
and SSiO , represent specific surface area of Ag, Ru02, glass ~.
frit, A1203, and SiO2.
As can be seen from the table, the following.
~:~ conclusions.can be readily understood from Examples 1, 4 and 8. ::
In these Examples, the specific surface areas of Ag,
Ru02, and glass frit are maintained constant but the weight
ratio of these components are varied: 24, 36, 40; 12, 18, 70;
and 8, 12, 80. Such variations in the weight ratio result in
resistance values l~L , lOk ~L and lOOk Q , and greatly varied ..
TCR, ~300, ~10, and -100. ~ariations in resistance values
were inevitably accompanied by a considerable variation in
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~` : TCR. The above phenomena is representative of the prior art.
However, in Examples 1, 2 and 3, where the weight ratio is
maintained constant, the resistance value varies, only
~30 depending upon the variation of the specific surface area,
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1 with the TCR being maintained substantially constant.
In these Examples, the resistance value greatly
varied from l~L/~ , lO~L/ D , 80~/L~ , but the TCR varied
little from +300 ppm/C,to +290 ppm/C to +305 ppm/C.
In the prior art, when the contact area was varied by
con~rolling the weight ratio of the resisti~e material and
the conductive material, the variation in the resistance value
was always accompanied by a simultaneous variation deviation
in the TCR. With respect to TCR, it should be known that the TCR ,~
increases with an increase in the amount of conductive material
and decreases with an increase in the amount of glass frit and
insulating or semiconductive metal oxide. In previous
techniques, the addition of a small amount of semiconductive
metal oxide was employed in order to minimize the de~iation
of the TCR. However, satisfactory results in reproduc,ibility and
and stability could not he obtained by following the previous
technique and thus the complicated process ~o obtain a
definite resistance could not be avoided.
In the case of our lnvestigations which were aimed at the ' ~-
settlement of the above-mentioned difficulties, it was found that
appropriate adjustment of both conductor and resistor components
could exhibit desired resistance values depending upon the nature ~ ~'
of the components. The above Examples have shown that a wide range
of resistance values from ~RL to M~ with low TCR are more easily
attained by only modifying and adjusting the specific surface area
of the binary or occasionally ternary components. The "resistor
composition" in the present invention implies a composite material
which produces a firm resistor film on an insulating substrate, by
firing.
The invention being thus described, it will be obvious '~
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1 that the same may be varied in many ways. Such variations are not
to be regarded as a departure from the spirit and scope of the
invention, and all such modifications as would be obvious to one
skilled in the art are intended to be included within the scope
of the following claims.
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