JPH079841B2 - Method of manufacturing thick film resistor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a thick film resistor, and more particularly to a method for manufacturing a thick film resistor composed of non-reducing glass, a silicide conductor and alumina. It is a thing.

_2. Description of the Related Art Conventionally, as a resistance material provided on an insulating porcelain substrate provided with electrodes, a RuO ₂ system thick film resistor composed of ruthenium oxide (RuO ₂ ) -glass has been widely put into practical use.

This thick-film resistor is a paste in which an electrode made of silver or silver and palladium is baked on air on a sintered insulating porcelain substrate, and then RuO ₂ -glass is dispersed in a vehicle made of a resin binder and a solvent. Is printed so as to be connected to the electrodes on the insulating porcelain substrate, and is formed by firing in air at a temperature of 700 to 900 ° C. Planer Phillips: Thick film technology by Planner Phillips: Thick Film Sarkitz, London, Butte Rowers.
ick Film Circuits. LONDON BUTTE-RWORTHS].

However, in the above configuration, since precious metal is used for both the electrode and the resistor, not only is it expensive,
There is a problem in that it takes time and effort to plate the electrode parts with nickel (Ni) or the like in order to prevent the solder (solder) or migration of silver (Ag).

Further, when considering formation of RuO ₂ -glass thick film resistor in air on a base metal electrode other than a noble metal such as a silver-palladium electrode, for example, W, Mo or Cu, an oxidation phenomenon of the electrode material occurs. It is impossible to form a thick film resistor on the electrodes.

Therefore, in order to form a thick film resistor using a base metal electrode, it is necessary to sinter the thick film resistor in a reducing atmosphere or in a damaging atmosphere such as a neutral atmosphere. However, when the RuO ₂ -based thick film resistance material is treated in a non-oxidizing atmosphere due to its nature, reactions such as RuO ₂ + H ₂ → Ru + H ₂ O easily occur, and the characteristics as a resistor cannot be obtained.

On the other hand, the silicide-glass thick film resistance material can be fired in air, and at the same time, due to the nature of the silicide, the atmosphere is not chemically changed regardless of whether it is a reducing atmosphere or a neutral atmosphere. Therefore, the silicide-glass thick film resistor can be fired in a reducing atmosphere or a neutral atmosphere (Japanese Patent Publication No. 59-15481).

Certainly, in this structure, since the base metal is used for both the electrode and the resistance material, it is inexpensive, and the base metal such as copper (Cu) is easy to solder and has excellent migration resistance. In addition, resistance temperature coefficient (TCR), noise (N),
Initial resistance characteristics such as short-time overload characteristics (STOL) are Ru
It is as good as the O ₂ -based thick film resistor.

Problems to be Solved by the Invention However, although the silicide resistor as described above is initially satisfactory, there is a great concern in practical use because the resistance changes greatly with time. Especially when the amount of silicide conductor is extremely reduced (<20wt%) to achieve high resistance, when alumina is added as a filler for high resistance, and when it is kept in a high temperature and high humidity environment for a long time. In that case, the sheet resistance Rs of the resistor increases, causing a resistance change that cannot be put to practical use. Although this has not been clarified, it is considered that this is caused by a chemical reaction between the formed silicide particles on the surface of the resistor by moisture and heat.

In addition, the wettability of the oxides that make up the glass with respect to the silicide powder is originally poor. Therefore, it is necessary to form an oxide film only on the very surface of the silicide particles, but it is fired in a non-oxidizing atmosphere. No interaction between glass and silicide can be expected in the resistor.

As described above, it is difficult to increase the resistance of the conventional silicide-glass thick film resistor, and it is difficult to put it into practical use due to the instability of reliability.

The present invention solves the above-mentioned problems, and an object of the present invention is to provide an inexpensive and highly reliable method of manufacturing a thick film resistor which can be formed in a non-oxidizing atmosphere using a base metal conductor as an electrode.

Means for Solving the Problems In order to solve the above problems, the method for producing a thick film resistor of the present invention comprises kneading a non-reducing glass, a silicide conductor powder and an alumina powder, and mixing the powder after the kneading. 1000 in non-oxidizing atmosphere
~ 1200 ℃ heat treatment step, a step of crushing and pulverizing the solid mixture after the heat treatment, and then forming a paste, screen printing the paste on an insulating porcelain substrate metallized base metal electrode as an electrode, 800 It is equipped with a step of firing in a non-oxidizing atmosphere at 1100 ° C.

Action The present invention, as described above, uses a mixture of non-reducing glass, silicide conductor powder, and alumina powder in a non-oxidizing atmosphere at 1000
By heat treatment at ~ 1200 ° C, the heat-treated powder melts the glass and covers the silicide particles and the alumina particles, and the three components are integrated.

That is, the heat-treated powder is pulverized into fine powder and then made into a paste,
Screen printed on insulating porcelain substrate, 800-1100 ℃
Even when fired in a non-reducing atmosphere, since the wettability between the silicide and the glass is improved, it is sufficiently glaze, and at the same time, the silicide particles are not exposed on the surface of the resistance film. Is less susceptible to the effect of humidity, and further, the alumina particles act sufficiently as a filler for increasing the resistance, so that the resistance having high resistance and good moisture resistance can be obtained.

That is, an inexpensive and highly reliable thick film resistor that can be formed in a non-oxidizing atmosphere using a base metal as an electrode can be obtained.

Example An example of a method of manufacturing a thick film resistor according to the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a thick film resistor according to an embodiment of the present invention, in which 1 is an insulating porcelain substrate, 2 is a base metal electrode film, and 3 is a resistor film. 2 is a model diagram of a resistor obtained by the manufacturing method of the present invention, and FIG. 3 is a model diagram of a conventional resistor, 4a and 5a are silicide particles, 4b is glass, and 4c. 5c shows alumina particles, 4d shows heat-treated powder particles, and 5b shows glass particles.

First, the silicide conductor powder contains silicon and various metals in Ar gas.
The reaction is carried out at a temperature of 00 to 1400 ℃, and molybdenum silicide (MoS
i ₂ ), tantalum silicide (TaSi ₂ ), magnesium silicide (Mg ₂
Si), cobalt silicide (CoSi ₂ ), nickel silicide (NiSi ₂ )
Each of the silicides was obtained and wet-ground in an organic solvent. On the other hand, non-reducing glass powder is
_{3, H 3 BO 3, MgO} , using CaCO _3, a SiO _2, Al ₂ O ₃ mainly, 1200
After melting at a temperature of ~ 1300 ° C, it was rapidly cooled in pure water, coarsely pulverized and wet pulverized to obtain fine powder.

To this non-reducing glass powder, 40-80 wt% of silicide conductor powder and 10-30 wt% of alumina powder were added and mixed to obtain a mixed powder. Next, the mixed powder is dry-molded using a mold,
This molded product was heat-treated in Ar gas at 1000 to 1200 ° C. for a holding time of 10 to 60 minutes. The optimum heat treatment conditions depend on the softening point of the glass, the type of silicide, the concentration of silicide and the concentration of alumina.

This heat-treated product was coarsely crushed and then wet-ground in a ball mina using xylene and agate boulders to obtain a heat-treated powder. When this heat-treated powder was observed by SEM,
As shown in FIG. 2, the silicide particles 5a and the alumina powder 5c were confined in the glass 5b.

The heat treatment powder and the non-reducing glass powder have a silicide conductor powder / (heat treatment powder + non-reducing glass) ratio of 0.1 by weight.
The mixture was mixed to give a thickness of ~ 0.4 to obtain a thick film resistor powder.

The vehicle to be kneaded with the thick film resistor powder was obtained by weighing and dissolving polymethylmethacrylate in terpineol so that the weight ratio was 10%.

Then, the thick film resistor powder was kneaded with a vehicle of 0.6 to 0.7 cc per gram to obtain a thick film resistor paste.

This thick film resistor paste was screen printed on an alumina substrate equipped with base metal electrodes (Cu, Ni, Mo, W) using a 325 mesh stainless screen. After this 120 ℃
After drying for 10 minutes, the film was baked in a thick film furnace with controlled atmosphere. The conditions of the thick film furnace were a bell-shaped temperature profile and a maximum firing time of 45 minutes with a maximum temperature of 900-1100 ℃ for 10 minutes. At this time, the atmosphere was a nitrogen atmosphere.

Table 1 shows typical resistance characteristics of the thick film resistor thus obtained.

The sheet resistance Rs was evaluated by converting it to a film thickness of the resistor of 12 μm. In addition, a short-time overload test (STOL: Short Time
In the Over-load Test), a power of 250 mW / mm ² was applied for 5 seconds and the rate of change in resistance with respect to the initial value was evaluated. The temperature coefficient of resistance TCR (ppm / ° C) was evaluated by the rate of change of the resistance value at 125 ° C with respect to the resistance value at 25 ° C per 1 ° C. The current noise N (dB) is Quan-tech resistance noise meter 31
Measured at 5B. The humidity resistance test is performed at a temperature of 60 ° C and relative humidity.
Evaluation was made by the resistance change law ΔR (%) with respect to the initial value after being left for 1000 hours in a 95% atmosphere.

As described above, according to the present embodiment, a step of kneading the non-reducing glass, the silicide conductor powder, and the alumina powder, and heat-treating the kneaded powder at 1000 to 1200 ° C. in a non-oxidizing atmosphere is provided. Therefore, after a step of pulverizing and pulverizing the solid mixture after the heat treatment, it is made into a paste, and after screen printing on an insulating porcelain substrate where a base metal conductor is metallized as an electrode, in a non-oxidizing atmosphere at a temperature of 800 to 1100 ° C. In the firing process, a highly reliable thick film resistor that can withstand practical use can be easily formed.

Next, in order to clarify the effect of the present invention, a thick film resistor powder obtained by simply mixing a silicide conductor powder, an Al ₂ O ₃ powder, and a non-reducing glass powder was used as a conventional example, as in the example. Table 2 shows various resistance characteristics of the thick film resistor fired in the thick film furnace.

As shown in the above-mentioned conventional examples, some of these resistors are initially satisfactory, but there are drawbacks such as a large change over time. That is, the resistors of the examples shown in Table 1 (2)
Δ of data for 1000 hours when left in the atmosphere of 60 ° C and 95% RH
While R is + 0.5% or less, in the conventional example shown in Table 2 (2), ΔR is +1.8 to + 5.3%, which is a large change amount. Moreover, the values shown in Table 2 (2) do not satisfy the characteristics (0.5% or less) as a resistor. Similarly in the TCR, the TCR is within ± 250 ppm / ° C in the Table 1 (2) of the example, while the large value such as -300 and -500 ppm / ° C is shown in the table 2 (2) of the conventional example, which is a practical value. Can not stand. Also, alumina does not work well as a filler for increasing resistance.

In the examples, polymethylmethacrylate was used as the organic polymer, but any polymer may be used as long as it depolymerizes at low temperature and causes sublimation and scattering.

Further, in the examples, the heat treatment was carried out in Ar, but a non-oxidizing atmosphere may be used, and the heat treatment can be carried out in a reducing atmosphere containing less than 7% hydrogen or a nitrogen atmosphere.

Further, borosilicate glass was used in the examples, but the nature of the glass may be non-reducing.

In addition, although firing was performed in a nitrogen atmosphere in the examples, a non-oxidizing atmosphere may be used, and firing can be performed even in a reducing atmosphere containing less than 7% hydrogen.

As described above, the method for manufacturing a thick film resistor of the present invention is performed by kneading a non-reducing glass, a silicide conductor powder, and an alumina powder, and mixing the kneaded powder in a non-oxidizing atmosphere at 1000 to 1200 ° C. In the step of heat treatment, a step of pulverizing and finely pulverizing the solid mixture after the heat treatment, and paste-screen printing the paste on an insulating porcelain substrate in which a base metal conductor is metalized as an electrode, 800 to 1100 ° C. Since it has a step of firing in a non-oxidizing atmosphere, it is possible to provide an inexpensive and highly reliable thick film resistor that can be formed in a non-oxidizing atmosphere using a base metal conductor as an electrode, which is extremely useful industrially. Is.

[Brief description of drawings]

FIG. 1 is a sectional view of a thick film resistor in one embodiment of the present invention, FIG. 2 is a model view of SEM observation of heat treated powder obtained by the manufacturing method of the present invention, and FIG. 3 is a conventional resistor powder. 3 is a model diagram of SEM observation of FIG. 1 ... Insulating porcelain substrate, 2 ... Base metal electrode film, 3 ... Resistor film, 4a, 5a ... Silicide particles, 4b ... Glass, 5b ...
Glass particles, 4c, 5c ... Alumina particles.

Claims (2)

[Claims] 1. A step of mixing a non-reducing glass, a silicide conductor powder, and an alumina powder, heat treating the mixed powder at 1000 to 1200 ° C. in a non-oxidizing atmosphere, and the solid mixture after the heat treatment. It was provided with a step of crushing and pulverizing and then forming a paste, and a step of screen-printing the paste on an insulating porcelain substrate on which a base metal conductor was metallized as an electrode and firing it in a non-oxidizing atmosphere at 800 to 1100 ° C. A method for manufacturing a thick film resistor, comprising: 2. The thickness according to claim 1, wherein the silicide conductor powder is formed of one or more of molybdenum silicide, tantalum silicide, magnesium silicide, cobalt silicide, and nickel silicide. Method for manufacturing a film resistor.