JPS6258664A - Heat-dissipasive insulation substrate - Google Patents

Abstract

PURPOSE:To improve the heat dissipation characteristics, by utilizing a heat- dissipating substrate constituted by an aluminum nitride ceramics substrate having Cu plates directly bonded on both sides of the substrate. CONSTITUTION:A heat-dissipating substrate A is provided between a semiconductor element and a cooling fin. The substrate A is constituted by a substrate B formed of aluminum nitride ceramics and having Cu plates directly bonded on both sides thereof. The substrate B is composed of aluminum powder and, if required, one or more of sintering assistants such as yttrium oxide or aluminum oxide, which are formed by compression molding and sintering. According to this constitution, the heat dissipation characteristics can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a heat dissipating insulating substrate, particularly to a heat dissipating insulating substrate used between a power semiconductor element such as a thyristor and a cooling fin.

[Technical background of the invention and its problems] Aluminum nitride ceramics have attracted attention in recent years as materials for various parts such as semiconductor substrates because they have high strength and heat dissipation properties comparable to metals, as well as electrical insulation properties. One such use is as an insulating substrate between a power semiconductor device such as a thyristor and a cooling fin.

When using an aluminum nitride ceramic substrate as such an insulating substrate, conventionally, as shown in the figure, both sides of the substrate 1 are sandwiched between Cu plates serving as terminals 2 or cooling fins 3, and these are pressed together using pressure welding screws or the like. For this reason, bold measures were taken to insulate them. In the figure, reference numeral 4 indicates a semiconductor element, 5 an insulating spacer, 6 a pressure contact, 7 a bolt, 8 a retaining plate, 9 a disc spring, 10 a retaining dog, and 11 a pressure contact screw.

However, in this structure, the aluminum nitride ceramic substrate is required to have a certain level of strength, so the thickness of the substrate must be at least 2 mm, which results in a loss of heat dissipation. In addition, the adhesion to the Cu plate was insufficient, resulting in increased thermal resistance, which sometimes caused similar problems.

Another disadvantage is that the overall structure of the semiconductor device becomes complicated because a jig is required for pressure-welding.

[Purpose of the Invention] The present inventor has developed a heat-dissipating insulation that can achieve thinning of the insulating substrate by directly bonding Cu plates to both sides of an aluminum nitride-based ceramic substrate, is easy to handle, and does not require a jig for pressure bonding. It was discovered that a substrate can be obtained.

The present invention was made based on the above findings, and
The purpose is to provide a heat dissipating insulating substrate with improved heat dissipation and a simplified structure.

[Summary of the Invention 1 In other words, the heat dissipating insulating substrate of the present invention is a heat dissipating insulating substrate provided between a semiconductor element and a cooling fin, and the heat dissipating insulating substrate has Cu plates on both sides of an aluminum nitride ceramic substrate. are directly joined.

In the present invention, the aluminum nitride-based Relamix substrate is made by compressing and sintering aluminum nitride powder with one or more sintering aids such as yttrium oxide, aluminum oxide, and calcium oxide added as needed. use.

The thickness of the aluminum nitride substrate is not particularly limited, but thin-walled ones, such as 0.6 to 1.5
Even with a plate thickness of mm, it will not be damaged and can fully demonstrate its insulation function. Further, in order to achieve sufficient bonding, it is preferable that the aluminum nitride ceramic substrate be caulked and the surface oxidized, or that oxygen as a binder be contained in the substrate.

Cu to be bonded to aluminum nitride-based lamic substrate
The board contains oxygen-free copper or oxygen at 100 to 2000 ppm.
It is preferable to use tough pitch electrolytic copper containing 300 to 500 ppm, and this Cu plate is placed on both sides of an aluminum nitride ceramic substrate.
A heat dissipating insulating substrate is manufactured by heating to 83°C.

The resulting heat-dissipating insulating board can be easily attached with screws, etc., and the Cu plates placed on both sides can be used as they are as cooling fins or terminals, or they can be used as cooling fins or terminals made of different materials or the same material. A Cu plate may be bonded to a fin or the like.

[Embodiments of the invention] Next, the present invention will be explained by examples.

Example A mixed powder of aluminum nitride powder added with 2 wt% of Y203 was molded into a size of 100 mm in diameter and 2 mm in thickness.
Sintered at 00'C. The upper and lower surfaces of the obtained aluminum nitride ceramic disk were ground with a diamond grindstone to obtain a flat plate with a diameter of 80 mm and a thickness of 1 mm. Tough pitch electrolytic copper with a diameter of 80 holes and a thickness of 3 inches was sandwiched between the upper and lower surfaces of this disk, and pretreated at 1070° C. for 5 minutes in a nitrogen atmosphere. After cooling to air temperature and examining the bonded state, it was found that the bond was strong.

When this substrate was sandwiched between a power semiconductor element and a cooling fin and used as a heat dissipating insulating substrate, it was found that it had excellent heat dissipation properties and was able to maintain and exhibit the high performance of the semiconductor.

[Effects of the Invention] As explained above, in the present invention, it is possible to achieve a thinner aluminum nitride ceramic substrate, and there is a substance that inhibits heat conduction in the bonding layer between the aluminum nitride ceramic substrate and the Cu plate. Therefore, a heat dissipating insulating substrate that has both heat dissipation properties and high electrical insulation properties can be obtained.

In addition, since the Cu and ceramics are directly bonded, the adhesion is good, and there is no need to press the insulating substrate and the Cu plate as in the conventional case, so for example, the part surrounded by A in the figure for press contact can be omitted. , and the structure is simplified.

[Brief explanation of drawings]

The figure is a schematic diagram showing a conventional Cyrisk insulated cooling WI structure. 1......Aluminum nitride ceramic substrate 2.2...Terminal 3...Cooling fin 4...
...Semiconductor device patent attorney Nori Chika
Yukio Katayama

Claims (1)

[Claims] (1) A heat dissipating insulating substrate provided between a semiconductor element and a cooling fin, characterized in that the heat dissipating insulating substrate is made of an aluminum nitride ceramic substrate with Cu plates directly bonded to both sides. Insulated substrate.