JPS60169194A - Substrate for hybrid integrated circuit - 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 Industrial Application The present invention relates to a hybrid integrated circuit board for high-density packaging circuit modules composed of thick film parts, chip parts, ICs, LSIs, and the like.

Conventional configurations and their problems In recent years, the demand for smaller devices and more multi-functionality has become stronger, and in order to meet these demands, high-density mounting of circuit components has become an important technology. There is. In particular, ICi
With the development of LSIs and the development of thick film components such as resistors and capacitors, the mounting density of circuit components is becoming increasingly dense.

Furthermore, in recent years, as communication frequencies have become higher, the conductor resistance of the module wiring layer has become an important point.

For example, in a tuner module, if the wiring conductor resistance is high in the high frequency range, phenomena such as oscillation and decrease in gain will occur, so it is currently difficult to put it into practical use with the alumina tuner module with a conventional configuration due to the high conductor resistance. From the viewpoints of miniaturization of equipment, rationalization of the aceplu process, etc., there is a strong desire for modularization of these high frequency circuits using hybrid ICs.

In order to modularize circuits and realize circuit packaging that also improves characteristics in the high frequency range, it is necessary not only to reduce the size of components, but also to reduce the resistance of wiring conductors and increase wiring density as described above. Two are required. In order to increase the wiring density, it is generally considered that the wiring is multilayered, and efforts are being made actively in various fields. Conventionally, these multilayer boards can be roughly divided into combinations of resin boards and copper wiring,
Alternatively, there is a combination of alumina ceramics and Moi or W. Conventional boards with these configurations have had the following problems as high-density mounting boards.

■ Combination of resin substrate and copper wiring (a) Is it difficult to form connection peer holes between internal conductor layers in the conductor layer? Connections are made by forming through holes that penetrate both sides of the board. Therefore, when trying to mount many components, the area of the through holes cannot be ignored, and as a result, the packaging density cannot be increased.

(b) With resin substrates, it is impossible to form thick film parts, that is, thick film parts such as glaze resistors can be heated at temperatures of 800 to 900°C.
Since these parts are formed in air, these parts cannot be formed on a resin substrate, and an integrated structure of the substrate and the resistor cannot be achieved.

■ Combination of alumina and MO or W (a) Is it necessary to plate nickel, gold, etc. on the tungnuten or molybdenum layer on the surface of the multilayer board for solder connection of parts?

(b) The formation of glaze resistors and capacitors made of thick-film parts must be carried out in air at high temperatures, but if these thick-film parts are made of easily oxidized conductors such as tungsten or molybdenum, It is impossible to form such a film, making it unsuitable for use as an integrated circuit board with thick-film components.

(c) High conductor resistance of Mo and W (20 to 30 days) For the above reasons, conventional resin multilayer substrates do not have sufficient functionality as ceramic multilayer substrates as high-density mounting substrates or high-frequency module substrates. It can be said that they are not prepared.

Purpose of the Invention In view of the above-mentioned drawbacks, the present invention provides a substrate for a hybrid integrated circuit in which the conductor resistance of the internal wiring layer is low and a thick film resistor is formed, and which enables modularization of high-frequency circuits and high-density component mounting. be.

Structure of the Invention The hybrid integrated circuit board containing a copper wiring layer of the present invention is a laminate in which a copper wiring layer and a glass layer for electrical insulation are formed on a polycrystalline substrate mainly composed of alumina. A small hole is formed in the glass layer formed on the top layer so that the internal copper wiring layer is exposed, a filling material made of low melting point glass and noble metal that cannot be reduced to copper is placed in the small hole portion, and This integrated circuit board is composed of a silver-palladium conductor formed to be connected to a filling material and a ruthenium-based glazed resistor, and has a multilayer structure with an integrated resistor and has low conductor resistance. This is the result.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a cross-sectional view of a hybrid integrated circuit board according to an embodiment of the present invention.

In FIG. 1, 1 is an alumina substrate, 2 is a null hole made of copper material, 3 is a copper wiring formed on the alumina substrate, 4 is a glass layer formed for the purpose of insulating from the upper wiring layer,
Reference numeral 5 denotes a filling portion made of glass and noble metal that is not reduced to copper and filled in small holes formed in the glass insulating layer.

The functions of the hybrid integrated circuit board including the copper wiring layer of this embodiment configured as described above will be explained below.

First, the substrate configured as shown in Fig. 1 is an alumina substrate 1.
Then, screen print the null hole 2 and wiring layer 3 using copper paste. After drying this at a temperature of about 120° C., a paste of glass powder is printed with Nuclean, and then the printed glass paste is dried to form a glass layer 4. At this time, small holes 4a are formed in the glass layer 4 at necessary locations to expose the lower conductor. This small hole 4a is provided for the purpose of electrical connection with the uppermost layer later. After printing and drying the alumina substrate, copper paste, and glass paste in this way,
It was fired in a nitrogen atmosphere at 1°C.

The profile during firing was about 10 minutes at a peak temperature of 900°C. Note that a small amount of oxygen of 10 ppm or less was mixed into the nitrogen gas during firing. After that, Ba
A paste of O-B703 type glass powder and silver powder was screen printed, dried and then passed through a conventional thick film oven at 850°C.

This substrate was left in the air at 860° C. for 30 minutes, but the internal copper conductor layer was not oxidized and exhibited a conductor resistance of 2 to 3 mΩ. Further, when the resistance between the filler and the lower conductor layer was measured, it was 10 to 15 mΩ.

The principle of construction of the above embodiment will be briefly described below.

The most important point here is to form a filler made of glass and precious metals that cannot be reduced to copper in the filling portion shown in FIG. 5. This is because this structure allows electrical continuity with the surface layer through the copper, which is the lower conductor, and the filler, and even under high temperature conditions in the air, the lower conductor layer is oxidized by air through the filler. This is something that never happens. Of course, the copper conductor formed under the glass insulating layer will not be oxidized even during high-temperature air treatment because the glass acts as an air diffusion preventive. Generally, by dispersing conductive particles in a fluid material, a type of agglomeration phenomenon occurs between the conductive particles, resulting in a structure in which the particles maintain contact with each other. As a result, the conductive particle dispersion exhibits an electrical conduction phenomenon. Therefore, in the structure of the present invention, when a certain temperature is reached, the glass becomes fluid, and since the noble metal group is dispersed therein, electrical conduction is obtained. The reason for using noble metals as the conductive particles is that they must not be oxidized even in high-temperature air. on the other hand,
It will be described that the structure of the present invention prevents the internal copper wiring layer from being oxidized even at high temperatures in air.

In the present invention, the effect of the glass additive is significant in preventing oxidation of the internal copper wiring layer. In other words, after firing, the glass layer of the filling material in the filling part 5 in Fig. 1 wets the glass insulating layer well, and the area around the precious metal particles is still filled with glass. It is important to maintain airtightness so that air does not reach the lower conductor layer. If we consider lead-based glass, which is commonly used as a glass material, the following reaction occurs between the glass and the copper of the lower conductor.

Cu +3PbO→CuO+ 3Pb That is, copper, which is a conductor, is oxidized by lead oxide, which is the main component of glass, and the resistance of the contact area between the filled part and the copper increases. Therefore, it is important that the glass used in the present invention has a property that does not oxidize copper, or in other words, that it is a glass powder that is not reduced by copper. Some glasses that satisfy these conditions include those whose alkaline earth metal oxides are mainly Kawahara metal oxides. The BaO-B206 glass described above falls under this category.

As described above, by adopting the configuration of the present invention, electrical continuity can be established to the upper layer through the filling material formed in the small hole provided in the upper insulating layer at the same time as copper wiring is provided at the lower part. Moreover, the lower copper wiring layer of this board will not be oxidized even when exposed to high temperatures in the air. Therefore, the currently very developed thick film technology makes it possible to integrate a glaze resistor and a glaze dielectric on top of this substrate.

Here, in the embodiment, each of the copper wiring layer and the glass insulating layer is one layer, but the number of layers can be increased by repeating the process. In other words, the board structure of the present invention allows the internal wiring to be multi-layered, allowing for high-density component mounting, as well as the integration of thick-film components, thereby further improving the packaging density.

In addition, since copper wiring is used as the internal conductor layer, the conductor resistance is low and it is suitable for use in high-frequency circuit modules. ■
There are advantages such as being able to make the wiring line IJ thinner.

Next, another embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a top view of a hybrid integrated circuit board including copper wiring according to another embodiment of the present invention. In an embodiment of the present invention, a ruthenium oxide based glaze resistor 6 is formed on the substrate shown in embodiment 1 using a silver-palladium conductor 6 and a silver-palladium conductor as electrodes so as to be connected to a filler 6.

The silver-palladium conductor and the ruthenium oxide resistor were formed through the same steps as in the conventional method. That is, after printing and drying the silver-palladium base metal, it was fired in a thick film oven at 860°C in the air, and then a ruthenium oxide paste was printed on it, and after drying, it was fired in the air at 860°C. The resistance value of the glazed resistor that was created was slightly higher than that of a conventional glazed resistor formed on an alumina substrate, but it is generally enough to have a temperature coefficient of 100 to 150 ppm for a resistor of 100 Ω/hole, for example. As described above, according to this example, by forming the conventional thick film resistor on the substrate of Example 1 by the conventional method, it was possible to obtain a small internal conductor resistance. A resistor-integrated substrate with a multilayer structure has been realized.

Effects of the Invention As is clear from the above explanation, the present invention uses copper material as an internal conductor layer and galanu material as an insulating layer on an alumina substrate to form a multilayer structure, and a filler made of a glass noble metal to electrically connect the surface layer. It enables connection and is integrated with a thick film component formed on the upper layer. (1) Low internal conductor resistance improves high frequency characteristics and allows for thinner conductor line width.

■The excellent effect of being able to integrate thick film parts formed at high temperatures in air is achieved. As a result, it is possible to modularize circuits that will increasingly be used as information communication means at high frequencies, and also to enable miniaturization of circuit modules in that high-density packaging is possible.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a high-grid integrated circuit board according to one embodiment of the invention, and FIG. 2 is a sectional view of a hybrid integrated circuit board according to another embodiment of the invention. DESCRIPTION OF SYMBOLS 1... Alumina substrate, 2... Copper null hole, 3... Copper wiring layer, 4... Glass insulating layer, 6... Filling part , 6... Silver-palladium conductor layer, 7... Ruthenium oxide based glaze resistor.

Claims (1)

[Claims] A laminate in which copper wiring layers and glass layers for electrical insulation are alternately formed on a polycrystalline substrate mainly composed of alumina, and the internal copper wiring layer is exposed to the glass layer formed on the top layer. A small hole is provided, a filling material made of low-melting glass and noble metal that cannot be reduced to copper is formed in the small hole, and a silver-palladium conductor and a 7 rethenium-based glaze resistor are formed so as to be connected to this top layer filling material. A hybrid integrated circuit board consisting of: