JPH02308501A - Resistive coating - Google Patents

Abstract

PURPOSE:To form a resistor on a Cu electrode in an inert atmosphere by mixing mixed powder of Cu and Ni, alloy powder and/or their mixture, and glass powder respectively in specified amount, and dispersing a solid in a vehicle, wherein weight ratio of Cu to Ni is selected. CONSTITUTION:The power of Cu and Ni is obtained by reducing respective sulfate aqueous solutions with hydrazine, and alloy powder can be made by atomizing a mixed dissolved solution of Cu and Ni. If the weight ratio of Cu/Ni is selected as 84/16-36/64, the temperature coefficient of a resistor becomes + or -200ppm/ deg.C in the range of -55 to +125 deg.C, and a suitable resistor can be obtained. The glass powder is borosilicate lead glass, or the like, and the softening point is 550-700 deg.C, and the thermal expansion coefficient is selected as 55-75X10<-7>/ deg.C in the case where the base material is alumina, and this is used about 3-67wt.% in solid matter. For the powder, one less than 2mum in average diameter is desirable. A vehicle where ethyl cellulose, or the like is dissolved in toluene, or the like, is used by 12 to 40 weight part to solid powder 100 weight part. This coating can be baked in inert atmosphere, and there is no problem in adhesive strength with a board, and connection with Cu electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a resistive paint for forming a resistor with a low temperature coefficient by firing in an inert atmosphere.

[Conventional technology]

Hybrid ICs are often used, in which a circuit including electrodes, resistors, etc. is formed on a ceramic substrate such as alumina or mullite, and electronic components such as ICs and capacitors are mounted on this circuit. In such hybrid ICs, the electrodes are usually made of noble metal, which is formed by screen printing a conductive paint made by dispersing noble metal powder such as Ag, Ag/Pd, or Au in a vehicle on a ceramic substrate, and then firing it in air. The electrode and the resistor are made of a resistive paint made by dispersing ruthenium oxide powder and glass powder in a vehicle, or a resistive paint made by dispersing Ag powder, Pd powder, and glass powder in a vehicle, with a screen connected to the noble metal electrode. It is formed by printing and firing it in air.

By the way, noble metal electrodes have a cost problem in that they are expensive, and they also have characteristic problems such as being easily corroded by solder and having a Ag migration phenomenon. Therefore, copper, which is inexpensive, resistant to solder erosion, and less susceptible to migration phenomena, has come to be used.

Copper electrodes are printed with a paint containing copper powder dispersed in a liquid vehicle, and heated to 600 to 900 mL in an inert atmosphere such as nitrogen.
Although copper electrodes are formed by firing at °C, they are easily oxidized, so resistors are also required to be fired in a similar inert atmosphere. However, conventional resistance paints using ruthenium oxide are reduced to ruthenium metal when fired in an inert atmosphere, making it impossible to obtain the desired resistance value and temperature coefficient.On the other hand, resistance paints using Ag powder and Pd powder has the disadvantage that it does not connect well with copper electrodes because it reacts with the copper electrodes and causes the metal to curl.

[Problem to be solved by the invention]

An object of the present invention is to provide a novel resistance paint that can form a resistor on a copper electrode in an inert atmosphere.

[Means for Solving the Problems] The resistance paint according to the present invention contains 33 to 97% by weight of a conductive powder consisting of a mixed powder of copper and nickel, an alloy powder, and/or a mixture thereof, and 67 to 3% by weight of a glass powder.
and the weight ratio of copper and nickel is Cu/Ni=
It is characterized in that a solid powder having a particle size of 84/16 to 36/64 is dispersed in a vehicle.

[For production]

Here, copper powder and nickel powder can be obtained by reducing their respective sulfate aqueous solutions with hydrazine, or by atomizing a metal melt. Furthermore, if hydrazine is added to a mixed solution of copper and nickel sulfate, a coprecipitated mixture of copper and nickel can be produced. - Labor alloy powder can be produced by atomizing a mixed melt of copper and nickel.

If the ratio of copper to nickel is changed, the resistance value and temperature coefficient will change, so this ratio should be selected appropriately to achieve the target resistance value and temperature coefficient, but if the Cu/Ni weight ratio is 84/16~ -55 to + when 36/64
Temperature coefficient of resistance is ±200pp over a temperature range of 125°C
A preferred resistor of m/"C is obtained.

Glass powder is necessary for adhering the resistive film to the ceramic substrate and for adjusting the resistance value. Just use it,
The softening point of the glass is preferably 550 to 700°C, and the coefficient of thermal expansion is preferably 55 to 75 x 10-'/'C when the base is alumina. In order for the resistive film to adhere to the ceramic substrate, glass must be contained in the solid substance in an amount of 3% by weight or more, and the amount of glass may be increased as appropriate to increase the resistance value. However, if it exceeds 67% by weight, it becomes an insulator, so it is necessary to keep it below this value.

Solid powders such as conductive powders and glass powders are kneaded with a vehicle to form a paste composition. This composition is usually 1
Since it is applied to the substrate by a printing screen with 50 to 400 meshes, the powder used should have a particle size that can pass smoothly through this printing screen, with an average particle size of 2 microns, with almost no particles larger than 10 microns. The following are suitable:

terpineol, butylcarpitol as vehicle;
A solution of ethyl cellulose, methacrylate resin, etc. in a solvent such as toluene can be used. To obtain a paste suitable for screen printing, the amount of vehicle should be 12 to 40 parts by weight per 100 parts by weight of solid powder.

〔Example〕

Various resistance paints prepared as described below were evaluated using a test substrate on which electrodes were formed by screen printing a copper paint on an alumina substrate and baking it at 900° C. for 10 minutes in a nitrogen atmosphere.

The resistance paint is copper powder with an average particle size of 1.88m and 0.6m in average particle size.
μm nickel powder and barium borosilicate glass powder (
Softening point 617 ``C1 thermal expansion coefficient 66 x 10-'/''C
) were blended in the proportions shown in Table 1 and kneaded together with the vehicle using a three-roll mill. Vehicle is butyl methacrylate 2
A solution of terpineol with a concentration of 6% by weight and a solid powder of 10%
32 parts by weight was used compared to 0 parts by weight. Each resistance paint was screen printed between the copper electrodes of the above test board in a size of 1.0 mm long x 2.0 mm wide, dried at 125° C. for 10 minutes, and then baked at 900° C. for 10 minutes in a nitrogen atmosphere.

Regarding the obtained resistive film, the sheet resistance value, temperature coefficient, and adhesive strength between the resistive film and the alumina substrate were measured.

The results are shown in Table 1.

The temperature coefficient indicates the rate of change in resistance value from +25°C to -55°C or +125°C.

For adhesion strength, the resistance film was strongly rubbed with tweezers, and the resistance film was determined to pass if it did not peel off from the alumina substrate.

From the results in Table 1, the conditions for the temperature coefficient to be ±200 ppm/'C are that the conductive powder is 33 to 97% by weight in the solid content.
And it can be seen that the Cu/Ni weight ratio is 84/16 to 36/64.

C Effects of the Invention The resistance paint according to the present invention is: - A new resistance paint that can be fired in an inert atmosphere. With this paint, there is no problem in the adhesive strength with the substrate and the connection with the copper electrode, and it is possible to form a highly practical resistor.

Claims (1)

[Claims] (1) Copper and nickel mixed powder, alloy powder and/or
or a conductive powder consisting of a mixture of these in an amount of 33 to 97% by weight and a glass powder of 67 to 3% by weight, and the weight ratio of copper and nickel is Cu/Ni=84/16 to 36/6.
A resistance paint made by dispersing solid powder No. 4 in a vehicle.