JPS63181496A - Manufacture of thick film circuit board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing a thick film circuit board in which electronic components such as ICs and chip components can be mounted at high density and at low cost.

BACKGROUND OF THE INVENTION In recent years, various electronic devices have become smaller and more multifunctional, and high-density mounting technology for circuit components has played an important role in this process. In particular, with the development of ICs and LSIs, resistors, capacitors, etc. have become more chip-based and thicker, and wiring boards have become more compact and denser due to multi-layered wiring boards. Furthermore, a certain circuit block is
There has been a shift to so-called thick film hybrid ICs in which other chip-like passive components are mounted on a thick film circuit board on which thick film resistors and wiring conductors are formed.

This thick-film hybrid IC has become widely popular because the resistor is in the form of a thick film, making it easy to adjust by trimming the resistor, and because it uses a ceramic material, it has high reliability.

An example of the conventional method for manufacturing the above-mentioned thick film circuit board will be described below with reference to the drawings.

FIG. 3 shows a cross-sectional view of a conventional thick film circuit board. In the figure, 10 is a ceramic substrate, 20 is a noble metal conductor film, and 30 is a Rub-based glaze resistance film. A conventional thick film circuit board includes a sintered alumina substrate 10,
Screen printing a paste mainly composed of noble metals such as A u + A g + P d and P t,
After drying, the noble metal-based conductor film 20 was obtained by firing in air at a temperature of around 850°C, and then a paste made of RuO□-glass was screen printed so as to be in contact with the conductor film, and after drying, it was fired in air at 750°C. Baked at a temperature of ~900℃ and R
It is generally obtained by providing a uO2-based glaze resistance film 30. The thick film circuit boards obtained as described above are easily used in that they can be fired in air, and they have excellent resistor properties, so they are widely put to practical use. (For example, "Thick Film IC Technology" published by Japan Microelectronics Association, Industrial Research Association).

However, on the other hand, since both the conductor material and the resistor material are expensive and use precious metal materials whose prices fluctuate widely, there was a problem that no matter how much rationalization of manufacturing was attempted, the result was a very expensive circuit board. . Therefore, a configuration has been proposed in which both conductive materials and resistive materials are made of base metal materials, which are low in cost and have little price fluctuation, without using noble metal materials.

[For example, Proceedings of the Force
International Microelectronics Conference IMC 1986 Published by Kobe, I.M. Japan; 267-
271P (Proceedings of the4
th International Microele
ctronics conferenceINC198
6Kobe, published by ISHM Japan; 267~
271P)) This is done by metallizing a base metal conductor such as Cu on the ceramic substrate 10 in advance to form the conductor film 20, then printing a silicide-glass based glaze resistor paste so that it is in contact with the metallized conductor film, and drying it. After, 85
A glazed resistor is obtained by baking at a high temperature in a non-oxidizing atmosphere of 0°C to 1000°C. Indeed, this configuration has the following advantages: (1) It is inexpensive because base metals are used for both the electrode and the resistor material; (2) Base metals such as Cu are easy to solder and are difficult to migrate; Its properties as a resistor are as excellent as those of the RuO□ system.

Problems to be Solved by the Invention However, in the above configuration, although the resistor is satisfactory in terms of basic characteristics, the initial dispersion of the resistance value is large, which leaves a great deal of anxiety in practical use. In particular, although resistive films have the same sheet resistance (Rs), Rs differs depending on the aspect ratio of the resistive film, which is a major obstacle in designing the resistance value. Analysis of the resistive film using X-rays or the like suggests that this is because an unnecessary reaction occurs at the interface between the electrode and the resistor during firing, and variations in resistance occur due to changes in the resistance of this reaction layer.

As described above, the actual situation is that conventional silicide-glass based glaze resistors have been difficult to put into practical use due to the instability of their initial resistance.

In view of the above-mentioned problems, the present invention provides a method for manufacturing a highly reliable thick film circuit board that is inexpensive because the material used is a base metal material, and has a glaze resistor with stable resistance characteristics and an excellent conductor film. It provides:

Means for Solving the Problems In order to solve the above problems, the method for manufacturing a thick film circuit board of the present invention includes forming a silicide-glass based glaze resistive film on an insulating ceramic substrate in a non-oxidizing atmosphere. After firing at a high temperature, a conductive film made of a base metal material that contacts the resistive film is fired in a non-oxidizing atmosphere at a temperature lower than the firing temperature of the resistive film.

According to the method of the present invention, since the resistive film is formed in advance, the silicide, which is a conductive component in the resistor, is covered with glass, and furthermore, the glass in the resistive film is crystallized. Therefore, the chemical reaction between the base metal and glass or the base metal and silicide can be suppressed during the electrode firing step. Therefore, a reaction layer is not generated at the interface between the resistive film and the electrode film after electrode firing, and a thick film circuit board having a resistive film that is independent of film shape can be provided.

EXAMPLE Hereinafter, a method of manufacturing a thick film circuit board according to an example of the present invention will be described with reference to the drawings. FIG. 1 shows a sectional view of a thick film circuit board in an embodiment of the present invention.

In FIG. 1, 10 is a ceramic substrate, 40 is a base metal conductor, and 50 is a silicide-glass glazed resistive film.

A silicide powder having three types of silicide compositions was developed in Japanese Patent Application Laid-Open No. 1986-
It was obtained by the procedure shown in Japanese Patent No. 153702. This silicide powder contains Bad, BzOx, MgO, and Cab.

A glass lift made of SiO□ and a vehicle in which 10% of an acrylic binder was dissolved in turpentine oil were added and thoroughly kneaded to obtain a silicide-glass glaze resistance paste. At this time, the amount of silicide powder was adjusted to 5 to 50% by weight based on the total amount of silicide powder and glass lift.

Further, as the organic binder used when preparing the paste, a thermally decomposable acrylic binder is preferable since baking is performed in a non-oxidizing atmosphere. The resistor paste produced as described above was screen printed on a ceramic substrate 10 which is a sintered body with an alumina purity of 96%, and after drying at 120°C for 10 minutes, N2 A silicide-glass based glaze resistor 50 was formed by firing in a continuous belt furnace maintained in a non-oxidizing atmosphere of a mixed gas of N2 and N2. At this time, the baking temperature varies depending on the combination of glass composition and conductor material.

Next, a paste mainly composed of Cu as a conductive material was screen printed so as to be in contact with the resistive film 50, and the paste was heated to 120°C.
After drying for 10 minutes, the maximum temperature is 850-950℃
(However, at a lower temperature than resistance firing), only N2 or
Alternatively, the conductive film 40 of Cu was formed by passing it through a continuous belt furnace maintained in a non-oxidizing atmosphere of N2 and N2 mixed gas and firing it. The distance between the electrodes (L) at this time is 0.5 to 101 m.
, 5n+, and the resistor width was constant at lll.

The sheet resistance Rs (Ω/hole) of the glaze resistor of the thick film circuit board thus obtained, R5=RO/L, the temperature change rate of resistance at 25°C and 125°C TCR (ppm/”
C), current noise (dB), and resistance change rate ΔR (%) when a load of 150 mW/mu2 was applied for 5 seconds were investigated. In addition, in order to clarify the influence of the electrode interface on Rs, the areal resistance RIG when L = 101 m
and the ratio of area resistance R0,5 when L=0.5mm (AR)
I took it and looked it up.

(AR)”RIG/RO,S Table 1 shows the material composition of the resistor obtained in the example and the typical resistor characteristics Rs, TCR, N, and ΔR1AR. It can be seen that the shape dependence of the resistance value is extremely small regardless of the difference.

Table 1 Comparative Examples In order to clarify the effects of the present invention, representative resistances of thick film circuit boards obtained by a conventional method, that is, a method of forming a silicide-glass based glazed resistor after forming a base metal electrode. The typical characteristics are shown in Table 2 together with the typical characteristics of the examples, and the two are compared.

A comparison with the comparative example shown in Table 2 shows that the manufacturing method of the present invention provides a thick film circuit board with excellent resistor properties. In particular, it is possible to form a resistor that has little reaction with the electrode (and has little film shape dependence (AR is close to 1). Furthermore, in Figure 2, the distance between the electrodes (L) and the sheet resistance Rs The relationship is shown for typical examples of Example (a) and Comparative Example (b).It can be seen from FIG. 2 that the resistor formed by the manufacturing method of the present invention has no dependence on film shape. Furthermore, Table 1 shows that in the manufacturing method of the present invention, the resistor may be a silicide-glass glazed resistor, and the effect does not change significantly depending on the type of silicide.

In this embodiment, a barium borosilicate glass component was used as the glass component of the glaze resistor, but the glass component is not limited to this as long as it can form a stable resistive film at high temperatures in a non-oxidizing atmosphere.

Effects of the Invention As described above, in the manufacturing method of the present invention, after firing a silicide-glass based glazed resistive film on an insulating ceramic substrate at a high temperature in a non-oxidizing atmosphere, a base metal material in contact with the resistive film is heated. By firing a conductor film consisting of the above in a non-oxidizing atmosphere at a temperature lower than the firing temperature of the resistive film, we can produce a highly reliable resistor with little dependence on film shape and a thick film circuit board with an excellent conductor film. can be provided.

Furthermore, as a conductive film, Cu's low conductor resistance, good soldering properties, good migration resistance, and low cost can be fully utilized, making it an extremely effective invention industrially.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a thick film circuit board according to an embodiment of the present invention, Fig. 2 is a characteristic diagram showing the relationship between the distance between electrodes and the sheet resistance Rs, and Fig. 3 is a cross-sectional view of a conventional thick film circuit board. It is a diagram. 10...Ceramic substrate, 20...Conductor film, 30...Glaze resistance film, 40...
...Base metal conductor film, 50... Silicide-glass-based glaze resistance film. Name of agent: Patent attorney Toshio Nakao and 1 other person L (xq
vinegar

Claims (1)

[Claims] After firing a silicide-glass-based glazed resistive film on an insulating ceramic substrate at high temperature in a non-oxidizing atmosphere, a conductive film made of a base metal material in contact with the resistive film is heated at a temperature lower than the firing temperature of the resistive film. A method for producing a thick film circuit board, characterized by firing in a non-oxidizing atmosphere.