JP7296122B2 - Heat radiators and heat radiators for power semiconductors - Google Patents

Description

The present invention relates to a heat radiator and a heat radiator for power semiconductors, which is obtained by cutting a sintered body of a composite material of natural graphite and copper, and plating the outer circumference of the heat sink main body with a thin copper plate or plating.

形してしまう。When the heat sink main body cut as described above is used for, for example, a power semiconductor (IGBT), processing such as brazing cannot be performed.
In addition, the carbon (copper) that appears on the surface of the heat sink body is easily peeled off because the carbon is wrapped in copper by natural flake graphite and copper powder, and there is a danger that it will fall on the surroundings. If there is a current-carrying part such as a short-circuit, there is a problem in practical use.
Furthermore, when using the IGBT, a copper plate is provided as a material to conduct electricity on the lower surface. However, the coefficient of thermal expansion of copper is as high as 17.7×10 ⁻⁶ /k, and the insulating material provided on the IGBT and the bottom surface

shape.

As described above, there is a risk of short-circuiting or the like with the existing radiator plate main body, especially when it is used for a power semiconductor (IGBT).
The present invention is intended to solve the problems of such a conventional structure. By doing so, carbon (flaky graphite, etc.) is less likely to peel off, and it can be used in places where electricity is required.

In order to achieve the above object, the present invention provides a radiator plate main body made by cutting vertically or horizontally a sintered body obtained by layering a composite material of natural flake graphite and copper powder. Second, after removing the natural scale-like graphite with a wire brush, copper powder is applied and sintered.
A thin copper plate is provided on the upper and lower surfaces of the radiator plate main body which is tilted at an angle of 90°.
In order to wrap the entire outer circumference of the heat sink main body, the outer edge of the thin copper plate is bent to form lids at two locations.
The entire surface of the radiator plate body is electroplated.
A radiator is attached to a power semiconductor.

かつ放熱機能と導電機能を高機能化している。
３）、放熱板の上下及び外周面全体を薄銅板で包み込むことにより、側面より天然鱗片状 黒鉛等が落下することがなく、安全・安心して使用できる。
４）、放熱板の全周を通電メッキ処理することにより、炭素が落下することなく、かつ、 天然鱗片状黒鉛等との密着性が高いため、より冷却性及び通電性を高めてなる。1) A sintered body obtained by laminating a composite material of natural flake graphite and copper powder in layers is cut vertically or horizontally to form natural flakes on the upper and lower surfaces of a heat sink main body with a wire brush. After the graphite is removed, copper powder is applied and sintered, so that the scale-like graphite is less likely to peel off, and the risk of short-circuiting in joining IGBTs can be minimized.
2) By providing thin copper plates on the upper and lower surfaces of the heat sink (tilted 90°) cut from the sintered body, especially in joining IGBTs, etc., brazing can be performed with thin copper plates, and the current flow is good.

In addition, the heat dissipation function and the conductive function are highly functional.
3) By wrapping the upper, lower, and outer peripheral surfaces of the heat sink with thin copper plates, natural flake-like graphite, etc., will not fall from the sides, and the heat sink can be used safely and securely.
4) By electroplating the entire periphery of the heat sink, the carbon does not fall off and the adhesion to natural flake graphite is high, so the cooling and electrical conductivity are improved.

FIG. 1 is a longitudinal front view of a radiator showing a first embodiment of the present invention; A longitudinal front view of a radiator showing a second embodiment of the present invention. A longitudinal front view of a radiator showing a third embodiment of the present invention. A longitudinal front view of a radiator showing a fourth embodiment of the present invention. FIG. 4 is a processing diagram of a heat sink main body used in each embodiment of the present invention; FIG. 2 is a vertically cut perspective view of a heat sink main body used in each embodiment of the present invention; FIG. 2 is a side cut perspective view of a heat sink main body used in each embodiment of the present invention. FIG. 1 is a partially longitudinal front view of a power semiconductor radiator showing an embodiment of the present invention;

First, the heat sink main body of the present invention will be described.
FIG. 6 shows a block-shaped vertical heat sink main body SH obtained by vertically cutting a sintered body S (FIG. 5) obtained by laminating a composite material of natural flake graphite TK and copper powder DF in layers (in the Z direction). show.
FIG. 7 shows a block-shaped horizontal heat sink main body HH cut in the horizontal direction.

The sintered body S exhibits anisotropy in thermal conductivity, strength, electrical conductivity, and thermal expansion.
The method of effectively using this anisotropy depends on the cutting direction of the sintered body S.
For example, when the vertical heat sink body SH and the horizontal heat sink body HH are used in the Y direction and the X direction, the thermal conductivity is 800 w/mK or more, and is considerably low at 60 w/mK in the Z direction.
The bending strength is strong in the Z direction and weak in the Y and X directions.
Therefore, the cutting direction is selected according to the purpose of use.

In the vertical heat sink body SH (block shape) and horizontal heat sink body HH (block shape) of the present invention, the natural flake graphite and the copper powder do not react with each other (the state of crimping), and the natural flake graphite is formed by the copper powder. Since it is wrapped (coated), the outer peripheral natural flake graphite and copper powder may peel off (miss).

Ｎに取り付けてパワー半導体用放熱体として使用するものである。In order to prevent this, the following invention was made.
As shown in FIG. 1, the vertical radiator plate main body SH is used in a state of being tilted at an angle of 90°. In other words, the thermal conductivity in the Y direction is good.
1 removes the natural scale-like graphite from the side surface SM of the block-shaped vertical heat sink main body SH with a wire brush, then coats the side surface SM with copper powder, and sinters SK (processed by electrical sintering). (See, for example, Japanese Patent Application Laid-Open No. 9-53103) (a thin plate-like vertical heat sink main body SH1 cut horizontally as necessary), and is used as a heat sink for power semiconductors. (Fig. 1)
Next, the radiator 21 is a radiator in which a thin copper plate 2 having a thickness of 0.05 mm to 0.1 mm is provided (in close contact with) on the upper and lower surfaces of the radiator 1 . (Figure 2)
This heat radiator 21 is soldered to the lower surface of the power semiconductor (IGBT) I as shown in FIG.

It is attached to N and used as a heat sink for power semiconductors.

つまり、従来のように銅板のみであれば、熱膨張率に大きな差があり、変形する危険性がある。
これに対して、本発明の放熱体２１は薄銅板２のため熱膨張に対する応力が少なく、かつ垂直放熱板本体ＳＨ１は絶縁材Ｓと熱膨張が近いため変形が少ない。
かつ、銅板は熱を持ちやすいが、放熱体２１は熱伝導率が高く放熱効果が高い。Incidentally, the coefficient of thermal expansion of a general copper plate is 17.7×10 ⁻⁶ /K, and the radiator 1 of the present invention is 4 to 1

In other words, if there is only a copper plate as in the conventional case, there is a large difference in coefficient of thermal expansion, and there is a risk of deformation.
On the other hand, since the radiator 21 of the present invention is the thin copper plate 2, it has less stress due to thermal expansion, and the vertical radiator plate main body SH1 has a thermal expansion similar to that of the insulating material S, so that deformation is small.
In addition, although the copper plate tends to retain heat, the radiator 21 has high thermal conductivity and a high heat dissipation effect.

Next, the radiator 31 will be explained.
The vertical heat sink main body SH2 is similar to the vertical heat sink main body SH1. In order to wrap (adhere) the entire outer circumference of the vertical heat sink main body SH2, the outer edge of the same thin copper plate 22 as described above is bent to form lids on the upper and lower sides. It is a thing. (Fig. 3)

This radiator 31 can also perform efficient electrical conduction, thermal expansion, and heat dissipation by using it in the same manner as described above.
In addition, since the entire circumference is wrapped with the thin copper plate 22, natural flake graphite and copper powder do not drop.

Next, the radiator 41 will be explained.
The heat sink 41 is a vertical heat sink main body SH3 similar to the one described above, and the outer periphery (which may not be polished if necessary) is plated 32 to allow current to pass through, such as Ni plating, Au plating, or Ag plating.・Cu plating, etc., with a thickness of several microns. (Fig. 4)
This is also used for IGBTs, and since the entire outer periphery is plated, natural flake graphite does not fall off, and materials with different thermal conductivity and thermal expansion coefficient can be used as required.

In each of the above embodiments, the size, thickness, etc. of the main body of the vertical heat sink may be determined according to need.
Also, the size and shape of the thin copper plate may be determined as required, and the electroplating may also be determined as required.

1---Heat radiator 2---Thin copper plate SH1-Main body of vertical heat sink I---Power semiconductor S---Insulator

Claims (5)

A sintered body obtained by vertically laminating a composite material of natural flake graphite and copper powder is cut in the vertical or horizontal direction. A method of manufacturing a radiator, characterized in that after removing the copper powder, the copper powder is applied and sintered. 2. A method of manufacturing a radiator according to claim 1, wherein thin copper plates are provided on the upper and lower surfaces of said radiator plate main body which is tilted at an angle of 90 degrees. 2. A method of manufacturing a heat radiator according to claim 1, wherein lid-shaped lids are provided at two locations by bending the outer edge of the thin copper plate so as to wrap the entire outer circumference of the heat radiator plate body. 2. A method of manufacturing a radiator according to claim 1, wherein the entire surface of said radiator plate body is electroplated. 5. A method for manufacturing a heat radiator for a power semiconductor, comprising attaching a heat radiator manufactured by the method for manufacturing a heat radiator according to any one of claims 1 to 4 to a power semiconductor.

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