JPS60120592A - Ceramic circuit board and method of producing ceramic 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 The present invention relates to a ceramic wiring board and a method for manufacturing a ceramic wiring board.

Conventional ceramic wiring boards are made of ceramic green sheets (
A circuit is formed on one surface of the green sheet (hereinafter referred to as a green sheet) using a conductive paste such as tungsten or molybdenum. In such ceramic wiring boards, the adhesive strength of the metallized layer in the circuit is sufficient, but the thickness of the ceramic is about 0.4 to 0.8 mm, and the thermal conductivity of ceramic is lower than that of metal. It has the disadvantage of poor heat dissipation. For example, power semiconductor elements such as power transistors, power thyristors, and power diodes are mounted on the circuit of a ceramic wiring board, and the wiring.

It is used after being made into a power module through processes such as resin encapsulation. The heat generated by these power semiconductor elements during operation is dissipated through the ceramic wiring board, but due to the poor heat dissipation properties of ceramics, the area directly under the power semiconductor elements is exposed to high temperatures, and the solder used to braze the power semiconductor elements When the silver solder etc. is partially exposed to high temperatures, defects such as peeling of the solder sealing part due to thermal deterioration occur, reducing the lifespan of the power module.

In order to improve heat dissipation, a conductive paste was printed on the back side of the ceramic wiring board (the surface opposite to the part where the circuit was formed) to form a surface heat dissipation conductor part that was used as a heat dissipation surface, but in order to have sufficient heat dissipation. I couldn't.

An object of the present invention is to provide a ceramic wiring board and a method for manufacturing the ceramic wiring board that are free from these drawbacks.

The present invention includes a circuit section formed on one surface, a surface heat dissipation conductor section formed on the other surface, a heat transfer conductor section embedded in a ceramic substrate, and a metal fixed to the heat transfer conductor section. A ceramic wiring board made of a plate or a highly thermally conductive ceramic, and a circuit-forming ceramic board with a circuit part formed on one surface, or a circuit-forming ceramic board with a circuit part formed on one surface and a heat transfer conductor part on the other surface. A ceramic plate and a conductor-formed ceramic plate with a surface heat dissipation conductor portion formed on one surface, or a surface heat dissipation conductor portion formed on one surface.

A conductor-forming ceramic plate with a heat transfer conductor portion formed on the other surface is fired, and then the surface of the circuit-forming ceramic plate on which the circuit portion is formed and the surface of the conductor-forming ceramic plate on which the heat dissipation conductor portion is formed are placed on the surface ( The present invention relates to a method for manufacturing a ceramic wiring board, in which a metal plate or a part of a highly thermally conductive ceramic is interposed between a circuit-forming ceramic board and a conductor-forming ceramic board, and the ceramic wiring board is heated and fixed.

- In the present invention, the circuit section refers to wiring for supplying and propagating voltage signals and current, and the surface heat dissipating body section refers to a metal layer for promoting heat dissipation.

The heat transfer conductor portion embedded between the circuit-forming ceramic board and the conductor-forming ceramic board is not limited to one layer, but may be formed in a plurality of layers.

After firing, the circuit portion and/or the surface heat dissipation conductor portion may be plated. Plating treatments include nickel plating, double plating with nickel plating and copper plating, and double plating with nickel plating and gold plating. It is preferable to carry out heavy plating treatment. There are no particular restrictions on the thickness of the plating, but if only nickel plating is done, 1 μm or more is sufficient, but 10 μm or more is sufficient.
It is more preferable if the condition is above. In addition, in the case of double plating treatment of nickel plating and copper plating, nickel plating is
It is preferable to plate in the range of ~4 μm, preferably 50 μm.
It is even more preferable if it is above. There are no particular restrictions on the plating method; any conventionally known method may be used.

Tungsten and molybdenum are used as materials for forming the heat dissipation grooves on the surface of the circuit section 2 and the heat transfer conductor sections.

Silver, silver-palladium, gold, etc. are used, and the circuit-forming ceramic plate and the conductor-forming ceramic plate may be a green sheet, or a ceramic plate obtained by sintering this may be used. When using green sheets, it is preferable to press both ceramic plates together before firing. Incidentally, the firing is performed by a conventionally known method and is not particularly limited.

It is preferable that the circuit portion be formed almost entirely over the entire surface, leaving a little green in order to maintain insulation with the metal plate or the highly thermally conductive ceramic.

Kovar, 42 alloy, copper, aluminum, etc. are used as the metal plate interposed and fixed between the circuit-forming ceramic plate and the conductor-forming ceramic plate, and high thermal conductive ceramics are ceramic wiring based on thermal conductivity. Point higher than the board.

For example, B6Q, SiC, 5isN4, etc. are used, and these are fixed by methods such as brazing and glass sealing.

It is preferable to expose one end of these metal plates and highly thermally conductive ceramics to the outside of the ceramic wiring board because heat dissipation is improved.

The heating temperature for fixing the metal plate or highly thermally conductive ceramic mentioned above shall be appropriately determined depending on the material used.

The thickness of the obtained ceramic wiring board is preferably 0.3 to 0.8 aim from the viewpoint of strength and heat dissipation.

In the present invention, it is preferable to form a through hole (hole) between the heat transfer conductor part and the surface heat dissipation conductor part to further improve heat dissipation, and the pore size is preferably 1 inch or more relative to the area of the ceramic plate. Although it is sufficient if the thickness is 5 or more, it is preferable because the heat dissipation property is further improved. The hole diameter is 0.2 to 2 for workability and densification of the conductive paste used.
．． It is preferable that it is 0uun, and it is more preferable that it is 0.2-1.0 fence.

Further, in the present invention, it is preferable to form a surface heat dissipation conductor portion on the side surface of the ceramic wiring board, since this further improves heat dissipation.

The present invention will be explained below with reference to Examples.

Example 1 Materials having the composition shown in Table 1 were uniformly mixed in a ball mill for 50 hours, and then tape cast using a doctor blade method to obtain a green sheet with a thickness of 0.35 mm.

Table 1 Next, as shown in FIG. 1, tungsten paste (3TW-1200, manufactured by Hitachi Chemical, trade name) was printed on one surface of the green sheet 1 to form the circuit section 2, and the circuit section 2 was formed on the other surface. A heat transfer conductor portion 3 was formed on the ceramic plate 4 to form a single circuit.

Separately from the above, as shown in Fig. 2, holes (through holes) 5 with a diameter of 1.0 m were made in a 1.5 m grid in another green sheet 1, and the tungsten paste described above was densely filled into the holes. Further, a surface heat dissipation conductor portion 6 was formed on one surface, and a heat transfer conductor portion 3' was formed on the other surface, thereby obtaining a conductor-formed ceramic plate 7.

Next, the circuit-forming ceramic board 4 and the conductor-forming ceramic board 7 described above were heated to 200°C in air at a temperature increase rate of 50°C/hour, held at 200°C for 1 hour, and then heated in a hydrogen atmosphere from 200°C. 1550 at a heating rate of 30℃/hour in
The temperature was raised to 0.degree. C. and fired, and then a plating film was applied to a thickness of 2 .mu.m by electroless nickel plating.

Next, as shown in FIG. 3, the surface of the single-circuit-forming ceramic board 4 on which the circuit part 2 is formed and the surface of the conductor-forming ceramic board 7 on which the surface heat dissipation conductor part 6 is formed are stacked so that they become the front surfaces (outer surfaces). At the same time, a Kovar plate 8 having a thickness of 0.2 Inl11 was interposed between the circuit-forming ceramic plate 4 and the conductor-forming ceramic plate 7, and the ceramic wiring board was brazed at 850° C. in a hydrogen atmosphere.

The thermal resistance of the above ceramic wiring board was measured using a laser-flash method thermal constant device.
/W (watt).

Example 2 The green sheet obtained in Example 1 was fired at 1520° C. in the atmosphere to obtain a sintered ceramic plate.

1. Hole with a diameter of 1.2 fence in a green sheet different from the above.
A sintered ceramic plate was obtained by opening an 8 mm grid and firing under the same conditions as above.

Next, a circuit section similar to that in Example 1 was formed using the same tungsten paste as in Example 1 on one surface of the ceramic plate, and a heat transfer conductor section similar to that in Example 1 was formed on the other surface. It was made into a 9-circuit-forming ceramic board.

In addition, the holes of the ceramic plate with holes are densely filled with tungsten paste as in Example 1, and a surface heat dissipation conductor is formed on one surface, and a heat transfer conductor is formed on the other surface. was formed into a conductor-forming ceramic plate.

Next, the aforementioned circuit-forming ceramic board and conductor-forming ceramic board were heated in air to 200°C from room temperature in 10 hours, and from 200°C to 1450°C at a heating rate of 30°C/hour in a hydrogen atmosphere. After that, a plating film was applied to a thickness of 2 μIn by electroless nickel plating.

Thereafter, a Kovar plate having a thickness of 0.2 mm was brazed in the same manner as in Example 1 to obtain a ceramic wiring board.

The thermal resistance of the above ceramic wiring board was measured using a laser flash method thermal constant device and was 0.8°C/W.
Met.

Example 3 Plating treatment was electroless nickel plating with a thickness of 2 μm,
A ceramic wiring board was obtained through the same steps as in Example 1 except that a plating film was applied to a thickness of 100 μm using copper sulfate plating. The thermal resistance of this ceramic wiring board was measured using the same device as in Example 1 and found to be 0.55°C/W.

Example 4 Plating treatment was electroless nickel plating with a thickness of 2 μm,
A ceramic wiring board was obtained through the same steps as in Example 2 except that a plating film was applied to a thickness of 20 μm using copper sulfate plating. The thermal resistance of this ceramic wiring board was measured using the same device as in Example 1 and found to be 0.7°C/W.

Comparative Example 1 Two green sheets obtained in Example 1 were laminated to a thickness of 0.
．． It was made into a 70m green sheet. A circuit part similar to that in Example 1 was formed on one surface of this green sheet using the same tungsten paste as in Example 1, and a surface heat dissipation conductor part similar to that in Example 1 was formed on the other surface. A ceramic wiring board was obtained through the same firing and plating steps as in Example 1. The thermal resistance of this ceramic wiring board was measured using the same device as in Example 1 and found to be 1.20° C./W.

Comparative Example 2 Comparative Example 1 except that the plating treatment was performed by the method of Example 3.
A ceramic wiring board was obtained through the same process. The thermal resistance of this ceramic wiring board was measured using the same device as in Example 1 and found to be 1.05° C./W.

According to the present invention, the ceramic wiring board according to the embodiment of the present invention can improve the thermal resistance by about 20 to 40q6 compared to the conventional ceramic wiring board that does not form a heat transfer conductor part, so it has good heat dissipation. A ceramic wiring board can be obtained.

[Brief explanation of drawings]

FIGS. 1, 2, and 3 are longitudinal cross-sectional views showing the manufacturing process of a ceramic wiring board according to two embodiments of the present invention. Explanation of symbols 1...Green sheet 2...Circuit section 3...-heat transfer conductor section 4...Circuit forming ceramic plate 5...Hole 6.
...Surface heat dissipation conductor part 7...Conductor-forming ceramic plate 8...Kovar board agent Patent attorney Hiko Wakabayashi

Claims (1)

[Claims] 1. A circuit section formed on one surface, a surface heat dissipation conductor section formed on the other surface, a heat transfer conductor section embedded in a ceramic substrate, and this heat transfer conductor. A ceramic wiring board consisting of a metal plate or highly thermally conductive ceramics fixed to the parts. 2 A circuit-forming ceramic plate with a circuit section formed on one surface or a circuit-forming ceramic plate with a circuit section formed on one surface and a heat transfer conductor section on the other surface, and a surface heat dissipation conductor on one surface. or a conductor-forming ceramic plate having a surface heat dissipation conductor portion formed on one surface and a heat transfer conductor portion formed on the other surface.
Next, a circuit part of the circuit-forming ceramic board is formed, and a surface heat dissipating conductor part of the surface and the conductor-forming ceramic board is formed, and the circuit-forming ceramic board and the conductor-forming ceramic board are overlapped so that the front surface becomes the front surface (outer surface), and the circuit-forming ceramic board and the conductor-forming ceramic board are A method for manufacturing a ceramic wiring board, which comprises interposing a part of a metal plate or a highly thermally conductive ceramic plate and heating and fixing the board. 3. The method for manufacturing a ceramic wiring board according to claim 2, wherein the circuit portion and/or surface heat dissipation conductor portion of the ceramic wiring board is plated after firing. 4. The method for manufacturing a ceramic wiring board according to claim 2 or 3, wherein the plating treatment is nickel plating treatment. 5. The method for manufacturing a ceramic wiring board according to claim 2 or 3, wherein the plating process is a double plating process of nickel plating and copper plating.