JP2002198203A - Resistor paste, thick-film resistor formed of the same, and circuit board equipped with the thick-film resistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lead-free resistor paste, which is capable of having very superior TCR characteristics without being loaded with a large amount of TCR adjusting agent, a thick-film resistor formed of the resistor paste, and a circuit board equipped with the thick-film resistor. SOLUTION: A lead-free resistor paste contains a lead-free glass composition, a lead-free conductive material, WO3, and a vehicle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a resistor paste,
The present invention relates to a thick film resistor formed using the resistor paste and a circuit board having the thick film resistor.

[0002]

2. Description of the Related Art In general, a resistor paste is mainly composed of a glass material for adjusting a resistance value and providing a bonding property, a conductive material, and a vehicle.
This is printed on a substrate and then fired to form a thick film resistor.

Conventionally, many resistor pastes have used lead oxide glass as a glass material and ruthenium oxide or a compound of ruthenium oxide and lead as a conductive material. Has become.

Since the use of a lead-containing resistor paste is undesirable from the viewpoint of environmental pollution, studies have been made on lead-free thick film resistor pastes and proposals have been made ( JP-A-8-24334
No. 2).

[0005]

However, in such a resistor paste in which the conductive material and the glass material are made of lead-free, the absolute value of the temperature coefficient (TCR) of the resistance value is remarkably increased. Have a problem. For this reason, TCR is reduced by adding a large number of various TCR regulators such as metal oxides, but it is difficult to lower the TCR to a sufficiently satisfactory value. Also,
Since a generally used TCR adjuster is used in a very small amount or uses various kinds of adjusters, it is extremely difficult not only to control the amount of addition but also to mix uniformly. As a result, it is difficult to manufacture, and there is a possibility that the characteristics may vary depending on the product.

Accordingly, an object of the present invention is to provide a lead-free resistor paste capable of obtaining extremely good TCR characteristics without adding a large number of TCR regulators, a thick film resistor formed using this resistor paste, An object of the present invention is to provide a circuit board having the thick film resistor.

[0007]

According to the present invention, a lead-free glass composition, a lead-free conductive material,
A resistor paste containing O ₃ and a vehicle, a thick film resistor formed by using the resistor paste, and a circuit board having at least one thick film resistor are provided.

[0008] Even if it is a lead-free resistor paste, W
The inclusion of O ₃ dramatically improves TCR properties. Since a satisfactory TCR value can be obtained without adding many types of TCR regulators, the production becomes easy, and there is no inconvenience that the electric characteristics vary from product to product and become unstable.

The glass composition contains 9.9 to 89.9% by volume,
Conductive material 10 to 90 vol%, WO ₃ is 0.1 to 45
Preferably, it is contained by volume. In the present invention, the content of WO ₃ is not particularly limited, but is preferably in this range.

It is preferable that the glass composition is a glass composition containing at least one of B ₂ O ₃ and SiO ₂ as a main component.

It is also preferable that the glass composition contains at least one of barium oxide, calcium oxide, sodium oxide, potassium oxide, lithium oxide, magnesium oxide, strontium oxide, phosphorus oxide, zinc oxide and manganese oxide.

It is also preferable that the conductive material is RuO ₂ or a composite oxide of Ru. In this case, the composite oxide of Ru is Bi ₂ Ru ₂ O ₇ , CdBiRu ₂ O ₇ , NdB
iRu ₂ O ₇ , BiInRu ₂ O ₇ , Bi ₂ IrRuO
₇ , GdBiRu ₃ O ₇ , BaRuO ₃ , BaRu
O ₄ , SrRuO ₃ , CaRuO ₃ , Co ₂ RuO ₄ ,
More preferably, it is LaRuO ₃ or LiRuO ₃ .

The conductive material is SnO₂, LaB₆, Pd
-Ag alloy, Pd, CoCrO₄, NiCrO₄, Si
C, TaC, CaB₆, BaB₆, SrB₆, YB₆,
Ta ₂N, Ta₂O₅, TiSi₂, VSi₂, CrS
i₂, TaSi₂, MoSi ₂Or WSi₂Being
Is also preferred.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In one embodiment of the present invention,
The resistor paste is composed of lead-free 9.9 to 89.9 volume% glass frit and lead-free 10 to 90 volume%.
And conductive particles, and WO ₃ of 0.1 to 45% by volume, produced from them with a vehicle that is dispersed in a medium.
There is no particular restriction on the content of WO ₃ to significantly improve TCR characteristics, by containing WO ₃ in an amount as described above, even in lead-free resistor paste, TCR is ± 120ppm / ℃ or less, TCR
The properties are dramatically improved. As described above, since a sufficient TCR value can be obtained without adding a TCR regulator, production is easy and electrical characteristics are stable without variation among products.

The composition of the glass frit is not particularly limited as long as it is lead-free. However, it is preferable that the glass frit be a glass mainly containing at least one of B ₂ O ₃ and SiO ₂ .

The glass may be silicate glass, borosilicate glass, manganese silicate glass, manganese borate glass, manganese borosilicate glass, barium silicate glass, barium borate glass, barium borosilicate glass, calcium silicate glass,
Calcium borate glass, calcium borosilicate glass, sodium silicate glass, sodium borate glass, sodium borosilicate glass, potassium silicate glass, potassium borate glass, potassium borosilicate glass, lithium silicate glass, lithium borate glass, lithium borosilicate glass, magnesium silicate Glass, magnesium borate glass, magnesium borosilicate glass, strontium silicate glass, strontium borate glass, strontium borosilicate glass, phosphorus silicate glass, phosphorus borate glass, phosphorus borosilicate glass, zinc silicate glass, zinc borate glass, or zinc borosilicate glass is there.
Further, these glasses may be mixed and used.

The glass frit having this composition is amorphous before firing, and may be crystallized by firing.

Although the average particle size of the glass frit is not particularly limited, it is about 5 μm in consideration of screen printability.
The following is preferred.

[0019] The conductive particles are not particularly limited as long as they are lead-free.
There is no restriction on the composition. For example, RuO₂, Bi₂Ru
₂O₇, CdBiRu₂O₇, NdBiRu₂O₇, B
iInRu ₂O₇, Bi₂IrRuO₇, GdBiRu
₃O₇, BaRuO₃, BaRuO ₄, SrRuO₃,
CaRuO₃, Co₂RuO₄, LaRuO₃, LiR
uO ₃, SnO₂, LaB₆, Pd-Ag alloy, Pd,
CoCrO₄, NiCrO₄, SiC, TaC, CaB
₆, BaB₆, SrB₆, YB₆, Ta₂N, Ta₂O
₅, TiSi₂, VSi₂, CrSi₂, TaSi₂,
MoSi₂Or WSi ₂Various Ru compounds and other conductive materials
Compounds or various alloys can be used. Special
And RuO₂And BiRu₂O₇One or more of
Are preferred.

The average particle size of the conductive particles is 0.05 to 1.0.
It is desirable that the particle size is about μm in terms of improving the dispersion of the particles in the paste to improve the fluidity of the resistor paste and the noise characteristics.

The tungsten is contained, the final form of the resistor paste may be any as long as it becomes WO _3, for example, W, WO, W
It may be one or more of O ₂ , WO ₃ , WC and W ₂ C. Further, the same effect can be obtained by adding WO ₃ at the time of producing glass to make it a glass component.

As the vehicle, a binder such as ethyl cellulose, polyvinyl butyral, methacrylic resin, and butyl methacrylate, and a solvent such as terpineol, butyl carbitol, butyl carbitol acetate, acetate, toluene, alcohol, and xylene are used. Other various dispersants, activators, plasticizers and the like are appropriately selected according to the application.

In addition, the addition of WO ₃ alone has a sufficient TCR.
Although characteristics can be obtained, if necessary, various metal oxides such as oxides composed of elements of the transition metal group and oxides composed of elements of the typical metal group may be added for the TCR regulator or other purposes. good.

The resistor paste is obtained by preparing a conductive particle powder and a glass powder having the above-described compositions, respectively, weighing them together with a vehicle, mixing and kneading them.

In order to form a thick-film resistor on a substrate, a resistor paste is screen-printed on the substrate, and 850 ° C.
What is necessary is just to bake at about the temperature. The substrate is an alumina substrate,
The substrate may be an AlN substrate, another single-layer substrate, a composite substrate, or a multi-layer substrate. The thick film resistor may be formed not only outside but also inside the multilayer substrate.

[0026]

The present invention will be described in more detail with reference to specific examples.

The volume percentages of the conductive material and the glass material were changed from each other, and resistor paste samples with and without WO ₃ were prepared, respectively, and baked on an alumina substrate to form a thick film resistor. Was prepared and the electrical characteristics were measured.

Bi ₂ Ru ₂ O ₇ was used as the conductive material. As a glass material, ZnO: 65% by weight, B ₂ O
_3:22 wt%, _SiO 2: 13 was used wt% of the glass composition.

[0029]Creating conductive materials  Bi₂Ru₂O₇A predetermined amount of Bi₂O₃Powder
And RuO₂Weigh powder and mix with ball mill and dry
did. The powder obtained by this mixing is heated at 300 ° C./hr
The temperature is raised to 900 ° C at that speed, and the temperature is maintained for 10 hours.
And then cooled to room temperature (25 ° C) at a rate of 300 ° C / hr
By doing, Bi₂Ru₂O₇Compound powder
Was.

[0030]Creating glass materials  ZnO, B₂O₃, SiO₂A predetermined amount of powder is weighed and
And dried with a mill. Obtained by this mixing
The powder is heated to 1500 ° C at a rate of 300 ° C / hr.
After holding the temperature for one hour,
Quenched and vitrified. Ball the obtained vitrified material
It was pulverized with a mill to obtain a glass powder.

[0031]Creating resistor paste  Bi created as described above₂Ru₂O₇Compound powder
And glass powder and WO ₃Powder and resin are ethyl cellulose
Terpineol as an organic vehicle
Weigh so that it becomes the composition, mix with a grinder,
By kneading with a three-roll mill, resistor paste
I got

[0032]Preparation of thick film resistors and measurement of electrical characteristics  Ag-Pd conductor pace on 96% pure alumina substrate
The screen was screen-printed in a predetermined shape and dried. Ag-
Ag in the Pd conductor paste was 85% by weight, and Pd was 1%.
It was 5% by weight. This alumina substrate is put into a belt furnace.
And burned in a one hour pattern from input to discharge
Was. The baking temperature is 850 ° C and the holding time at that temperature is 1
0 minutes.

The resistor paste prepared as described above was screen-printed in a predetermined shape on the alumina substrate on which the conductor was formed and dried. Next, the resistor paste was baked under the same conditions as the conductor baking to obtain a thick film resistor.

The electrical characteristics of this thick film resistor, that is, sheet resistance and TCR characteristics were measured. The TCR is the cold TCR for the change in resistance from 25 ° C. to −55 ° C. and 2
Hot TCR for resistance change from 5 ° C to 125 ° C
And were measured.

Table 1 shows the measurement results. Note that the TCR value described in Table 1 is the larger of the absolute value of the cold TCR and the absolute value of the hot TCR. Also,
The number of samples for each composition is 10.

[0036]

[Table 1]

From Table 1, it can be seen that when WO ₃ is contained, the TCR value is dramatically improved to ± 120 ppm / ° C. or less as compared with the case where WO ₃ is not contained. Therefore, even in lead-free resistor paste, by the inclusion of WO _3, T
It has been found that a satisfactory TCR value can be obtained without adding many types of CR regulators.

[0038] Although no particular limitation is imposed on the content of WO _3, glass material from 9.9 to 89.9% by volume, the conductive material is 10 to 90 vol%, WO ₃ is contained from 0.1 to 45 vol% It is preferable that it is in the range.

The embodiments and examples described above all illustrate the present invention by way of example and not by way of limitation, and the present invention can be embodied in various other modified and modified forms. . Therefore, the scope of the present invention is defined only by the appended claims and their equivalents.

[0040]

As described in detail above, according to the present invention, even if it is a lead-free resistor paste, the inclusion of WO ₃ dramatically improves the TCR characteristics.
TCR that can be satisfied without adding many types of TCR regulator
Since the value can be obtained, the production becomes easy and there is no inconvenience that the electrical characteristics vary from product to product and become unstable.

Claims (9)

[Claims] 1. A resistor paste comprising a lead-free glass composition, a lead-free conductive material, WO ₃ and a vehicle. 2. The glass composition contains 9.9 to 89.9% by volume, the conductive material contains 10 to 90% by volume, and the WO ₃
2. The resistor paste according to claim 1, wherein 0.1 to 45% by volume is contained. 3. The method according to claim ₂ , wherein the glass composition is B ₂ O ₃ and Si.
_3. The resistor paste according to claim 1, wherein the resistor paste is a glass composition containing at least one of O ₂ as a main component. 4. 4. The glass composition contains at least one of barium oxide, calcium oxide, sodium oxide, potassium oxide, lithium oxide, magnesium oxide, strontium oxide, phosphorus oxide, zinc oxide and manganese oxide. The resistor paste according to any one of claims 1 to 3, characterized in that: 5. The resistor paste according to claim 1, wherein the conductive material is a composite oxide of RuO ₂ or Ru. 6. The composite oxide of Ru is Bi₂Ru₂
O₇, CdBiRu ₂O₇, NdBiRu₂O₇, Bi
InRu₂O₇, Bi₂IrRuO₇, GdBiRu₃
O₇, BaRuO₃, BaRuO₄, SrRuO₃, C
aRuO₃, Co₂RuO₄, LaRuO₃Or LiR
uO₃The resistor according to claim 5, wherein
paste. 7. The conductive material is SnO ₂ , La
B ₆ , Pd-Ag alloy, Pd, CoCrO ₄ , NiCr
O ₄ , SiC, TaC, CaB ₆ , BaB ₆ , Sr
B ₆ , YB ₆ , Ta ₂ N, Ta ₂ O ₅ , TiSi ₂ , V
Si ₂ , CrSi ₂ , TaSi ₂ , MoSi ₂ or WS
resistor paste according to any one of claims 1 4, characterized in that the i _2. 8. A thick-film resistor formed using the resistor paste according to claim 1. Description: 9. A circuit board comprising at least one thick film resistor according to claim 8.