JPH0661005A - Composition for forming thick film resistor - Google Patents

Abstract

PURPOSE:To obtain the thick film resistor having a sheet resistance value not exceeding a specific value in the least dispersion of the resistance value of a resistor and the resistance temperature coefficient immediately after baking step furthermore in the least fluctuation in the resistance value after glass coat baking step. CONSTITUTION:The thick film resistor forming composition contains flake type particles of Ag/Pd alloy so that the wt.% of RuO2 particles, glass particles, Ag/Pd as the solid component may be 95:5-30670, while the wt.% of RuO2 to the glass particles is 0.15-1.5 as well as the wt.% of the flake type particles of Ag/Pd alloy to (RuO2 + glass particles) is to be 0.03-20.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a ceramic substrate,
The present invention relates to a thick film resistor-forming composition suitable for forming a thick film resistor having an area resistance value of 1 kΩ / □ or less.

[0002]

2. Description of the Related Art A conductive powder and a glass powder are mixed so as to have a desired resistance value, and a paste prepared by dispersing this in an organic vehicle is applied on a substrate such as alumina by a screen printing method or the like to have a desired shape. After drying, baking is performed at 700 to 900 ° C. to form a resistor as an electronic circuit on the substrate. Such technology is called thick film technology,
The resistor paste is referred to as a thick film resistor forming composition.

As the conductive powder for a resistor having a low resistance value, there are Ag and Pd. Since the area resistance value of Ag and Pd greatly depends on the content rate, the stability of the resistance value is improved by using RuO ₂ having a small content rate dependence.

In the manufacturing process of a chip resistor or the like using this thick film resistor, the resistance value of the resistor is usually adjusted by laser trimming or the like, and then coated with a glass paste for glass coating, and the temperature is set to about 600 ° C. Baking is performed at a temperature.

In the step of adjusting the resistance value, if the trimming ratio is too large, the voltage characteristics and the like of the formed resistor are deteriorated. Therefore, it is desired that the resistance value of the fired resistor has a small variation. Further, if the change in resistance value during glass coat firing is large, it becomes difficult to keep the final resistance value within the target range.

In a resistor having a low resistance value, Ag, Pd
When a single powder of (1) is mixed and used, the change in resistance value after glass coating firing is large, and in order to solve this problem, coprecipitated powder of Ag / Pd is used. Ag / P
In the coprecipitated powder of d, Ag locally melts during firing or
Evaporation and poor dispersibility in the organic vehicle cause a large change in the resistance value and temperature coefficient of resistance of the fired resistor, which is a major cause of deterioration in yield and reliability of the resistor. .

[0007]

DISCLOSURE OF THE INVENTION According to the present invention, there is little variation in the resistance value and the temperature coefficient of resistance of a fired resistor, and the change in the resistance value after firing a glass coat is small.
It is intended to provide a composition for forming a thick film resistor, which can obtain a resistor having an area resistance value of 1 kΩ / □ or less.

[0008]

According to the present invention, the solid content of RuO ₂ powder, glass powder, and Ag: Pd weight ratio is 9%.
It contains Ag / Pd alloy flake powder of 5: 5 to 30:70 and the weight ratio of RuO _{2 to} glass powder is 0.5.
15 to 1.5, and the weight ratio of the flake powder of Ag / Pd alloy to (RuO ₂ + glass powder) is 0.03 to
The thick film resistor forming composition of No. 20 is used as a means for solving the problems.

The RuO ₂ powder may be one used in ordinary thick film resistors, and the particle size is preferably 1 μm or less, more preferably 0.2 μm or less. The glass powder may also be lead borosilicate type, aluminoborosilicate type, etc., which are used for ordinary thick film resistors, and the particle size is 10 μm or less, preferably 5 μm.
μm or less is preferable.

Flake powder of Ag / Pd alloy, RuO
_{In addition to 2} powders and glass powders, MnO ₂ , Nb ₂ O ₅ , Sb ₂ O ₃ and T, which have been conventionally added to adjust the temperature coefficient of resistance, are used.
iO ₂ , CuO or the like can be added. The organic vehicle may be one in which ethyl cellulose, methacrylate or the like is dissolved in terpineol, butyl carbitol or the like as in the conventional case.

[0011]

In the present invention, the flake powder of Ag / Pd alloy has an average particle size of 1 to 10 μm, preferably 1 to 3 μm.
The ones are good. Since the flake powder of Ag / Pd alloy is a uniform alloy, there is no local melting and evaporation of Ag during firing, and printing is performed in flake form, and the contact between the conductive powders after drying is stable. The resistance value and the temperature coefficient of resistance of the formed resistor are small in variation, and the change in the resistance value after baking the glass coat is small. The weight ratio of Ag: Pd of the flake powder of Ag / Pd alloy is set to 95: 5 to 30:70 because the temperature coefficient of resistance becomes large when Pd is less than 95: 5 and Pd is less than 30:70. This is because the cost increases as the number increases.

The weight ratio of the RuO ₂ powder to the glass powder is set to 0.15 to 1.5 because when the RuO ₂ powder is less than 0.15, the resistance value is not stable and Ru is more than 1.5.
This is because if the amount of O ₂ powder is large, the film strength of the resistor becomes too weak.

A for (RuO ₂ powder + glass powder)
The weight ratio of the flake powder of g / Pd alloy is 0.03 to 2
The flake powder of Ag / Pd alloy is set to 0.
If it is less than 03, the resistance value becomes too high, and if it is more than 20, the resistance value becomes too low.

[0014]

[Examples] Average particle diameters of 0.3 μm and 0.1 μm, respectively
The following, and flake powder of Ag / Pd alloy of 1.5 μm, RuO ₂ powder, MnO ₂ , Nb ₂ O ₅ and glass powder (55% by weight, PbO 55%, SiO ₂ 30%, B ₂ O ₃
10% Al ₂ O ₃ 5%) was used, a terpineol solution of ethyl cellulose was added as a vehicle, and the mixture was kneaded with a three-roll mill to prepare a thick film resistor forming composition having the composition shown in Table 1.

Instead of the flake powder of Ag / Pd alloy, Ag particles having average particle diameters of 1.0 μm and 0.3 μm, respectively.
Powder and Pd powder used, A with an average particle size of 1.5 μm
The comparative examples shown in Table 2 using g / Pd co-precipitated powder were tested.

An Ag / Pd paste for an electrode was printed on an alumina substrate having a purity of 96% by weight and fired at 850 ° C., and the above-mentioned composition for forming a thick film resistor was printed on this electrode.
After drying at 50 ° C., it was fired in a belt furnace at a peak temperature of 850 ° C. for 9 minutes and a total firing time of 30 minutes to form a resistor having a width of 1.0 mm, a length of 1.0 mm and a film thickness of 7 to 10 μm.

Area resistance value (Ω / □) of the fired resistor
The fluctuation was evaluated by the coefficient of variation of 50 resistors. The coefficient of variation (%) is a value obtained by dividing the standard deviation by the average value, and is used as a measure of relative variation. The smaller the value, the smaller the variation.

The temperature coefficient of resistance is expressed by an average rate of change in resistance value at a temperature of −55 to 25 ° C. and an average rate of change in resistance value at a temperature of 25 to 125 ° C. (ppm / ° C.), the former being COLD-TCR, HO for the latter
Called T-TCR. The variation in the temperature coefficient of resistance is represented by a value obtained by subtracting the minimum value from the maximum value of each of the COLD-TCR and HOT-TCR of 10 resistors, and the smaller the value, the smaller the variation.

The change in resistance value (%) after firing the glass coat is measured by first measuring the resistance value after firing the resistor and printing a black glass paste so as to completely cover the resistor.
Dry, peak temperature 600 ° C for 5 minutes, total firing time 40
The resistance value of the resistor after firing the glass coat was measured, and the rate of change from the resistance value before firing the glass coat was determined. The above measurement results are also shown in Tables 1 and 2.

[0020]

Table 1 Example 1 2 3 4 5 6 -------------------------------------- Ag--Pd. Flake powder 89.7 95.0 90.2 55.0 61.9 61.0 RuO ₂ powder 3.5 2.2 5.7 15.4 13.0 13.3 glass powder each weight% 6.5 2.6 3.8 28.6 24.1 24.7 MnO ₂ 0.15 0.1 0.2 0.5 0.5 0.5 Nb ₂ O ₅ 0.15 0.1 0.1 0.5 0.5 0.5 − − −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− Ag: Pd weight ratio 70:30 40:60 70:30 70:30 40:60 30:70 RuO ₂ / glass weight ratio 0.54 0.84 1.50 0.54 0.54 0.54 Ag / Pd flake powder / (RuO ₂ + glass) weight ratio 8.97 20.00 9.49 1.25 1.67 1.61 −−−−−−−−−−− −−−−−−−−−−−−−−−−−−−−−−−−− Area after resistor firing Resistance value (Ω / □) 0.07 0.09 0.07 1.02 1.09 0.88 Area after resistor firing Coefficient of resistance variation (% 3.6 3.3 4.5 3.5 3.2 2.9 COLD-TCR (ppm / ℃) +555 +250 +530 +299 +170 +240 COLD-TCR maximum value-Minimum value (ppm / ℃) 40 40 42 20 20 19 HOT-TCR ( ppm / ℃) +524 +229 +500 +292 +191 +243 HOT-TCR maximum value-minimum value (ppm / ℃) 35 25 40 16 15 14 Glass coat Resistance change rate after firing +6.4 +5.9 +9.0 +3.0 +3.2 +3.4 ==================================== Example 7 8 9 10 11 −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− Ag / Pd flake powder 38.6 19.1 17.0 12.1 2.7 RuO ₂ powder 21.0 20.0 20.5 16.9 18.4 Glass powder Each weight% 39.0 60.0 61.5 70.2 78.5 MnO ₂ 0.7 0.5 0.6 0.2 0.3 Nb ₂ O ₅ 0.7 0.4 0.4 0.6 0.1 −−−−−−−−−−−−−−−−−−−−− −−−−−−−−−−−−−−− Ag: Pd weight ratio 70:30 70:30 95: 5 70:30 70:30 RuO ₂ / glass weight Ratio 0.54 0.33 0.33 0.24 0.23 Ag / Pd flake powder / (RuO ₂ + glass) Weight ratio 0.64 0.23 0.21 0.14 0.03 −−−−−−−−−−−−−−−−−−−−−−−− −−−−−−−−−−−− Area resistance after firing resistor (Ω / □) 11.1 86.4 93.7 400 648 Area after firing resistor Resistance coefficient of variation (%) 1.7 3.0 2.4 1.8 2.1 COLD -TCR (ppm / ℃) -1 +5 -2 -28 +1 Maximum value of COLD-TCR-Minimum value (ppm / ℃) 20 15 13 20 15 HOT-TCR (ppm / ℃) +54 +65 +61 +39 +64 Maximum value of HOT-TCR-Minimum value (ppm / ℃) 17 11 7 16 11 Glass coat Resistance value after firing Change rate (%) +0.9 +1.3 +1.7 +1.0 +0.9 ===== ================================

[0021]

[Table 2] Comparative Example 1 2 3 4 5 6 7 ---------------------------- Ag-powder 64.4 42.7 27.3 Pd powder 27.6 18.3 11.7 Ag-Pd co-precipitated powder 90.0 63.0 39.0 19.1 RuO ₂ powder 2.7 13.3 21.0 3.4 12.6 21.0 20.0 Glass powder each weight% 5.0 24.7 39.0 6.3 23.4 39.0 60.0 MnO ₂ 0.15 0.5 0.5 0.15 0.5 0.5 0.5 Nb ₂ O ₅ 0.15 0.5 0.5 0.15 0.5 0.5 0.4 −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− Ag: Pd weight ratio 70:30 70:30 70:30 70:30 70:30 70:30 70:30 RuO ₂ / glass weight ratio 0.54 0.54 0.54 0.54 0.54 0.54 0.54 −−−−−−−−−−−−−−−−− −−−−−−−−−−−−−−−−−−− Area resistance after firing resistor (Ω / □) 0.09 1.17 11.7 0.14 1.21 14.5 100.2 Coefficient of variation in resistance after firing resistor (%) 3.3 4.0 3.0 6.8 5.6 5.7 4.9 COLD-TCR (ppm / ℃) +479 +3 12 -14 +450 +276 -22 -39 COLD-TCR maximum value-minimum value (ppm / ℃) 54 24 21 61 58 35 27 HOT-TCR (ppm / ℃) +444 +313 +46 +423 +283 +39 +40 Maximum value of HOT-TCR-Minimum value (ppm / ℃) 34 14 18 50 42 31 24 Glass coat Resistance change rate after firing (%) +19.8 +7.2 +2.4 +6.2 +3.9 +2.0 + 1.5 ====================================

As shown in Comparative Examples 1 to 3, Ag powder, Pd
When the powder is mixed and used, the variation in the sheet resistance value and TCR after firing the resistor is small, but the resistance value change after firing the glass coat is large. As shown in Comparative Examples 4 to 7, A
When the g / Pd coprecipitated powder was used, the change in resistance value after baking the glass coat was small, but the sheet resistance value after baking the resistor, T
The variation of CR becomes large.

On the other hand, in Examples of the present invention, as shown in Examples 1 to 11, the sheet resistance value T after firing the resistor, T
The variation in CR is small and the change in resistance value after baking the glass coat is small.

[0024]

EFFECT OF THE INVENTION According to the composition for forming a thick film resistor of the present invention, variation in sheet resistance and TCR after firing a resistor, which is difficult with the prior art, is small, and the resistance value after firing a glass coat is small. A resistor with little change can be formed.

Claims (1)

[Claims] 1. A RuO ₂ powder as a solid content, a glass powder, and a flake powder of Ag / Pd alloy having a weight ratio of Ag: Pd of 95: 5 to 30:70, wherein the weight ratio of RuO _{2 to} the glass powder. Is 0.15 to 1.5, and (R
A composition for forming a thick film resistor, wherein the weight ratio of the flake powder of Ag / Pd alloy to (uO ₂ + glass powder) is 0.03 to 20.