JP2002026469A - Circuit board having directly cooling structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit board having a directly cooling structure allowing the backside of a ceramic board to directly contact a refrigerant, without inserting an intermediate such as radiating metal plate, heat sink, etc., between both. SOLUTION: The circuit board has a ceramic board (3) having a circuit (2) on the surface. The backside of the board (3) is housed (4) so as to directly contact fluidly the refrigerant. The circuit (2) is formed on at least one surface of a honeycomb-shaped ceramic board (5).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a circuit board circuit having a direct cooling structure. More specifically, the present invention relates to a circuit board in which the temperature of a module can be easily adjusted by bringing the opposite surface of a ceramic substrate on which a circuit is formed into direct contact with a refrigerant.

[0002]

2. Description of the Related Art As the output of a module in which electronic components such as semiconductor elements are mounted is increasing with the recent development of electronics technology, an important issue today is to satisfy a stable required performance in a small and lightweight module. Cooling method. For this purpose, it is necessary to efficiently and quickly release the heat generated from the electronic components to the outside of the system, and also to maintain the module temperature at a temperature at which the electronic components operate well.

Therefore, the cooling structure of the conventional module is as follows.
Since the indirect system in which the cooling plate through which the cooling water flows is brought into contact with the module (for example, Japanese Patent Application Laid-Open No. 7-154082), there was a problem that the response was delayed and sufficient temperature adjustment could not be performed. To solve this, a coolant such as cooling water may be brought into direct contact with the module, but no prior art showing the specific structure can be found.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and an object of the present invention is to provide a circuit board having a circuit formed on the surface of a ceramic substrate in order to facilitate temperature control of the module. It is another object of the present invention to provide a circuit board having a structure in which a back surface is directly brought into contact with a refrigerant without an intervening member such as a heat-dissipating metal plate.

[0005]

That is, the present invention provides a housing (4) on the back surface of a ceramic substrate (3) having a circuit (2) on the front surface so as to be in direct flow contact with a refrigerant. This is a circuit board with a direct cooling structure. Further, the present invention is a circuit board characterized in that a circuit (2) is formed on at least one surface of a honeycomb-shaped ceramic substrate (5). In this circuit board, a refrigerant is circulated through the honeycomb holes of the ceramic substrate. The circuit board has a direct cooling structure.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the drawings of embodiments.

FIGS. 1 and 2 are schematic cross-sectional views each showing an example of a circuit board of the present invention, wherein 1 is a semiconductor, 2 is a circuit, 3 is a ceramic substrate, 4 is a housing, and 5 is a ceramic substrate. In particular, it is a honeycomb-shaped ceramic substrate.

There are various methods for forming a circuit on a ceramic substrate. In the present invention, a thick film paste method in which a conductive paste is drawn into a circuit pattern and then dried and sintered, and a metal circuit pattern is used. A pattern mounting method of bonding to a ceramic substrate, an etching method of forming a circuit pattern by etching after bonding a metal plate to a ceramic substrate, and the like can be adopted (for example, see International Publication WO 91/16805).

[0009] The metal circuit pattern or metal plate and the ceramic substrate are joined by a method using copper sulfide, a method of metallizing the ceramic substrate, and then joining the aluminum nitride substrate whose surface is oxidized to the copper plate. DBC method for forming a eutectic
No. 163093), an active metal brazing method using a joining material containing a group IV element metal called titanium, zirconium, hafnium or the like in a brazing material such as copper, silver or a silver-copper alloy ( For example, JP-A-60-1776
No. 34 gazette).

Examples of the material of the ceramic substrate used in the present invention include silicon carbide, alumina, beryllia, silicon nitride, aluminum nitride and the like. In order to make the thermal conductivity sufficient, aluminum nitride or silicon nitride having a thermal conductivity of 50 W / mK or more is suitable. In the case of a ceramic substrate having a thermal conductivity of less than 50 W / mK, the temperature control becomes more difficult as the module becomes higher in power. The thickness of the ceramic substrate is generally 0.2 to 3 mm. Since such a ceramic substrate is commercially available, it can be used.

As shown in FIG. 2, when the ceramic substrate has a honeycomb shape, a well-known mixture containing ceramic powder, a sintering aid, and an organic binder is extruded into a honeycomb shape, followed by firing after removing the binder. (For example, Japanese Patent Publication No. 60-31).
800, JP-A-10-328343). The shape of the honeycomb hole is not limited to a square, a circle, a triangle, or the like. Also, the number of holes is not limited. The binder is usually removed by heat treatment in nitrogen or vacuum.

On the other hand, the material of the circuit is generally copper or its alloy, aluminum or its alloy, but is not limited to this. The thickness of the circuit is usually designed to be thinner than that of the ceramic substrate.

A feature of the present invention resides in the above-described circuit board cooling structure. The conventional heat dissipating structure is a structure in which a heat dissipating metal plate is further attached to the back surface of the ceramic substrate and attached to a heat sink. It was an indirect structure that cooled the cooling plate by passing water through it.

On the other hand, in the cooling structure of the present invention, as shown in FIG. 1, a housing 4 is provided on a back surface of a ceramic substrate 3, and a coolant such as water is directly in contact with the back surface of the ceramic substrate in the housing. It is made available for distribution. Although not shown, the housing may be divided into small rooms.

The material of the housing is the above ceramics,
It may be any of metals such as copper, aluminum and stainless steel, and various plastics, and may have a structure in which these materials are appropriately combined. The housing can be formed by attaching it to the back surface of the ceramic by screwing or the like using packing such as an O-ring.

According to the honeycomb-shaped ceramic substrate shown in FIG. 2, the upper portion of the honeycomb structure can serve as the ceramic substrate and the other portions can serve as the housing. When a coolant such as water is allowed to flow, a cooling structure integrated circuit board is used.
According to this structure, the labor for assembling the circuit board and the housing can be omitted.

In the present invention, a structure in which a circuit is further formed on the lower surface (back surface) of the housing 4 or the honeycomb-shaped ceramic substrate 5 may be employed.

[0018]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples.

Example 1 An aluminum circuit was joined to a commercially available aluminum nitride substrate (thickness: 1 mm) with a brazing material.
3 mm x 13 mm) was soldered and wire-bonded. An aluminum housing was fixed to the back surface of the aluminum nitride substrate using an O-ring and a screw to produce a circuit board having a direct cooling structure shown in FIG.

When water was passed through the housing of the obtained circuit board, it could be performed without any trouble, and the amount of water was easily adjusted. In addition, a test was performed in which a load was applied to the semiconductor and the temperature was maintained within a specified temperature range, and it was possible.

Example 2 96 parts of aluminum nitride powder, 4 parts of yttria powder, 6 parts of organic binder (methylcellulose),
A kneaded product containing 5 parts of a plasticizer is weighed 60 mm × 5.4 m in height.
After extrusion-molding into a honeycomb shape having a thickness of m (1.2 mm in thickness) and 16 honeycomb holes, the binder was removed, and then fired at a temperature of 1800 ° C. in a nitrogen atmosphere to produce a honeycomb-shaped aluminum nitride substrate.

On the surface of the obtained honeycomb-shaped aluminum nitride substrate, a copper circuit is bonded and formed with an active metal brazing material, and a semiconductor (13 mm × 13 mm) is soldered on the upper surface thereof.
By performing wire bonding, a circuit board having a direct cooling structure as shown in FIG. 2 was produced. When water was passed through the honeycomb holes, it could be performed without any trouble, and the amount of water was easily adjusted. In addition, a test was performed in which a load was applied to the semiconductor and the temperature was maintained within a specified temperature range, and it was possible.

[0023]

According to the present invention, there is provided a circuit board having a direct cooling structure in which the back surface of a ceramic substrate can be brought into direct contact with a coolant such as water without intervening an intervening material such as a radiating metal plate or a cooling plate. Provided.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a circuit board having a direct cooling structure according to the present invention.

FIG. 2 is a schematic sectional view showing an example of another circuit board having a direct cooling structure of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor 2 Circuit 3 Ceramic substrate 4 Housing 5 Honeycomb-shaped ceramic substrate

Continued on the front page (72) Inventor Go Iwamoto 1 Shinkaicho, Omuta-shi, Fukuoka Prefecture F-term in the Omuta Plant of Electrochemical Industry Co., Ltd. BA10 BA23 BB08 BB41

Claims (3)

[Claims] 1. A circuit board having a direct cooling structure, characterized in that a housing (4) is provided so that a back surface of a ceramic substrate (3) having a circuit (2) on a front surface can be in direct flow contact with a refrigerant. 2. A circuit board comprising a circuit board (2) formed on at least one surface of a honeycomb-shaped ceramic substrate (5). 3. A circuit board having a direct cooling structure, wherein a refrigerant is circulated through the honeycomb holes of the circuit board according to claim 2.