JPH05326767A - Heat dissipating board - Google Patents

Abstract

PURPOSE:To provide a heat dissipating board which is coincident with an LSI mounted on it in thermal expansion coefficient and excellent in bonding strength and heat dissipating properties by a method wherein a metal junction layer, a first and a second intermediate junction layer, a polycrystalline diamond, and a substrate material are set in material and thickness as prescribed. CONSTITUTION:A board mother material 2 installed inside a package 1 is formed of metal or ceramic, which is a sintered body whose main component is one out of Si, Mo, W, Cu-W, Cu-Mo, SiC, or AlN taking that a mounting surface of an LSI chip 5 is covered with a polycrystalline diamond 3 which is 10 to 500mum in thickness and 500 to 2000W/m.K in thermal conductivity at a room temperature of below 400 deg.C into consideration. It is preferable that the sintered body is as thick as 1 to 2mm. A first intermediate junction layer 8a is formed of one of 4a to 8a elements on a periodic table or one of oxides, carbides, and nitrides of them. Then, a second intermediate junction layer 8b is formed of one of Mo, Ni, Pd, Pt, and Au, and it is preferable that the first and the second intermediate junction layer are 0.01 to 5mum in thickness. A metal junction layer 4 on the second intermediate junction layer 8b is formed as thick as 1 to 50mum containing one or more elements selected from Au, Ag, Si, Ge, Sn, Pd, and In.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat dissipation board, and more particularly to a heat dissipation board on which a semiconductor element is mounted.

[0002]

2. Description of the Related Art Conventionally, an electronic component having a semiconductor element such as an LSI package mounted thereon is known. FIG. 3 is a cross-sectional view showing a conventional general LSI package. Figure 3
For the conventional LSI package, see Package 1
1, and a heat dissipation board 12 installed in the package 11,
An LSI chip 14 mounted on the surface of the heat dissipation substrate 12 via a bonding layer 13, a lead frame 15 formed inside and outside the package 11, a portion of the lead frame 15 inside the package 11 and the LSI chip. And a bonding wire 16 for electrically connecting 14 electrodes (not shown). As a material of the LSI chip 14, Si, GaAs or the like is used. Al ₂ O ₃ is often used as the material of the heat dissipation substrate 12.

However, recently, an increase in the amount of heat generated due to higher performance of LSIs and higher density mounting has become a problem, and as a countermeasure against this, a material having excellent heat conduction characteristics such as AlN or SiC is used as the heat dissipation substrate 12. The tendency to use it is increasing.

A paste-like resin is used as the bonding layer 13 for bonding the LSI chip 14 and the heat dissipation substrate 12. The paste resin contains dispersed powder of a material having good thermal conductivity such as Ag for the purpose of reducing thermal resistance.

[0005]

As described above, in the related art, since the thermal resistance of the bonding layer 13 for bonding the heat dissipation substrate 12 and the LSI chip 14 is reduced, a material having good heat conduction such as Ag is used. The paste-like resin in which the powder of No. 1 was dispersed and contained was used as the bonding layer 13.

However, the thermal resistance of the bonding layer 13 is considered to be the largest of the factors that determine the heat radiation characteristics of the package 11. Therefore, conventionally, in order to further improve the thermal resistance of the bonding layer 13, it has been proposed to use a metal bonding agent made of an Au—Sn alloy or a Pb—Sn alloy as the bonding layer 13.

However, when the above-mentioned alloy is used for the bonding layer 13, the thermal resistance of the bonding layer 13 is certainly improved, but with this, another new problem arises.

That is, by changing the material of the joining layer 13 from a resin to an alloy, the coefficient of thermal expansion of the joining layer 13 increases. Therefore, when the LSI chip 14 operates and its temperature rises, a large thermal strain occurs in the LSI chip 14, which is a disadvantage. When such thermal distortion occurs, there is a problem that the LSI chip 14 does not operate normally or the operating life is shortened.

As described above, conventionally, when an alloy or the like is used as the bonding layer 13 in order to improve the thermal resistance of the bonding layer 13, there is a disadvantage that the coefficient of thermal expansion of the bonding layer 13 increases, and as a result, the LSI chip 14 During operation, there were new problems such as defective operation due to thermal distortion and shortened operating life.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a thermal expansion coefficient matching the thermal expansion coefficient of an LSI chip to be mounted. It is an object of the present invention to provide a heat dissipation board having excellent heat dissipation characteristics and excellent bonding strength.

[0011]

A heat dissipation board according to any one of claims 1 to 3 is a heat dissipation board on which a semiconductor element is mounted, the board base material being made of either metal or ceramic; A polycrystalline diamond formed on at least one surface of the material, and periodic table numbers 4a, 5a, 6 formed in a predetermined region on the surface of the polycrystalline diamond.
a first group consisting of at least one selected from group a elements, oxides, carbides, nitrides and carbonitrides thereof
And the M formed on the first intermediate joining layer
a second intermediate bonding layer made of at least one selected from o, Ni, Pd, Pt, and Au, and Au formed on the surface of the second intermediate bonding layer and having a semiconductor element mounted on the surface. , Ag, Si, Ge, Sn, Pb, and In, a metal bonding layer made of at least one kind of metal, and a metal bonding layer, a first intermediate bonding layer, a second intermediate bonding layer, By setting the material and the thickness of the polycrystalline diamond and the base material of the substrate to the predetermined material and thickness, respectively, the coefficient of thermal expansion of the whole is from room temperature to 400 ° C.
Is set to a predetermined value within the range of 4 × 10 ^{−6 to} 6 × 10 ⁻⁵ / ° C.

According to a fourth aspect of the present invention, there is provided a heat dissipation board in which a semiconductor element is mounted on the surface thereof, and the heat dissipation board is formed on at least one surface of the board base material made of metal or ceramic. And a polycrystalline diamond formed in a predetermined area on the surface of the polycrystalline diamond and having a semiconductor element mounted on the surface.
a metal bonding layer made of at least one metal selected from g, Si, Ge, Sn, Pb and In, and the material and thickness of the metal bonding layer, the polycrystalline diamond and the substrate base material are predetermined. By setting the material and the thickness of the above, the overall coefficient of thermal expansion is set to a predetermined value within the range of 4 × 10 ^{−6 to} 6 × 10 ⁻⁵ / ° C. in the range of room temperature to 400 ° C.

[0013]

In the heat dissipation substrate according to claims 1 to 3, polycrystalline diamond is formed on at least one surface of the substrate base material,
Periodic table elements 4a, 5a, 6a, their oxides, and carbides are formed in predetermined areas on the surface of the polycrystalline diamond.
At least one selected from nitrides and carbonitrides
A first intermediate bonding layer of different types is formed, and a second intermediate bonding layer of at least one selected from Mo, Ni, Pd, Pt, and Au is formed on the first intermediate bonding layer. Au, Ag, Si, Ge, Sn, on which the semiconductor element is mounted on the surface of the second intermediate bonding layer.
A metal bonding layer made of at least one metal selected from Pb and In is formed,
The materials and thicknesses of the first intermediate bonding layer, the second intermediate bonding layer, the polycrystalline diamond and the base material of the substrate are set to predetermined materials and thicknesses, respectively, so that the thermal expansion coefficient of the entire heat dissipation substrate is from room temperature to 400 ° C. Is set to a predetermined value within the range of 4 × 10 ^{−6 to} 6 × 10 ⁻⁵ / ° C., the thermal expansion coefficient of the entire heat dissipation substrate easily matches the thermal expansion coefficient of the semiconductor element. Is formed as. Further, the first and second intermediate bonding layers enhance the bonding strength between the polycrystalline diamond and the metal bonding layer.

According to a fourth aspect of the present invention, there is provided a heat dissipation substrate in which a polycrystalline diamond is formed on at least one surface of a substrate base material, and a semiconductor element is attached to a predetermined region on the surface of the polycrystalline diamond. Ag, Si,
A metal bonding layer made of at least one kind of metal selected from Ge, Sn, Pb, and In is formed, and the metal bonding layer, the polycrystalline diamond, and the base material of the metal have predetermined material and thickness. The thermal expansion coefficient of the entire heat dissipation board is set to 4 x within the range of room temperature to 400 ° C.
Since it is set to a predetermined value within the range of 10 ^{−6 to} 6 × 10 ⁻⁵ / ° C., the thermal expansion coefficient of the entire heat dissipation substrate is easily formed to match the thermal expansion coefficient of the semiconductor element.

[0015]

First, the essence of the present invention will be described before describing the embodiments. FIG. 1 illustrates an L according to one aspect of the present invention.
It is sectional drawing which showed the SI package. With reference to FIG. 1, an LSI package according to one aspect of the present invention includes a package 1, a substrate base material 2 fixedly installed in the package 1, and a polycrystalline diamond coated on the substrate base material 2. 3, the first intermediate bonding layer 8a, the second intermediate bonding layer 8b, and the metal bonding layer 4 on a predetermined region of the polycrystalline diamond 3.
LSI chip 5 attached via the package and package 1
Lead frame 6 formed to extend inside and outside the
And the portion of the lead frame 6 inside the package 1 and the LSI
A bonding wire 7 for electrically connecting to an electrode portion (not shown) of the chip 5 is provided. Although metal or ceramic can be used for the substrate base material 2,
In consideration of coating the surface on which the SI chip 5 is mounted with the polycrystalline diamond 3, a firing containing any one of Si, Mo, W, Cu-W alloy, Cu-Mo alloy, SiC and AlN as a main component. It is desirable to use a tie. The thickness of the substrate base material 2 is preferably 0.1 to 2 mm. That is, if the thickness is less than 0.1 mm, the strength may be lowered, which may cause a problem, and if the thickness is more than 2 mm, the heat dissipation characteristic may be deteriorated and the size of the LSI package may be increased.

As shown in FIG. 1, by covering the substrate base material 2 with the polycrystalline diamond 3, the substrate base material 2, the polycrystalline diamond 3, the first intermediate bonding layer 8a, and the second intermediate bonding layer. It is possible to improve the heat dissipation characteristics of the heat dissipation substrate composed of 8b and the metal bonding layer 4, and reduce the thermal strain of the LSI chip 5.

As a method for forming the polycrystalline diamond 3, any known low-pressure vapor phase such as a method of decomposing and exciting a source gas by utilizing thermoelectron radiation or plasma discharge, or a film forming method using a combustion flame is used. The law can be applied. As the source gas, for example, methane / ethane /
A mixed gas containing hydrogen as a main component and hydrocarbons such as propane, alcohols such as methanol and ethanol and organic carbon compounds such as esters, is generally used. However, in addition to these, an inert gas such as argon, oxygen, carbon monoxide, water or the like may be contained in the raw material as long as it does not impair the synthetic reaction of diamond and its characteristics.

Further, the polycrystalline diamond 3 has room temperature to 4
Thermal conductivity in the range of 00 ° C is 500 to 2000 W / m
-It must be within the range of K. This is a condition necessary to satisfy the performance exceeding the heat dissipation characteristics of the conventional heat dissipation board. The upper limit of the thermal conductivity is 2000 W
/ M · K only indicates the level that can be achieved by the current technology, and it is more desirable if a material having higher thermal conductivity can be obtained.

The thickness of the polycrystalline diamond 3 varies depending on the type of the LSI chip 5 to be mounted, the substrate base material 2, the first intermediate bonding layer 8a, the second intermediate bonding layer 8b and the metal bonding layer 4 specifications. It is generally in the range of 10 to 500 μm. That is, when it is thinner than 10 μm, it is too thin and the effects of improving heat dissipation characteristics and reducing thermal strain do not appear conspicuously, and when it is thicker than 500 μm, the adhesion strength with the substrate base material 2 decreases.

The first intermediate bonding layer 8a is formed of at least one element selected from elements of groups 4a, 5a and 6a of the periodic table, oxides, carbides, nitrides and carbonitrides thereof. ing. Then, the first intermediate bonding layer 8a
The second intermediate bonding layer 8b formed on the top surface is made of Mo, Ni, P.
It is formed of at least one selected from d, Pt, and Au. The thicknesses of the first intermediate bonding layer 8a and the second intermediate bonding layer 8b are both set to 0.01 to 5 μm in consideration of bonding strength.

The metal bonding layer 4 formed on the second intermediate bonding layer 8b is formed so as to contain at least one metal selected from Au, Ag, Si, Ge, Sn, Pb and In.
The metal bonding layer 4 made of a brazing material such as Au has a thickness of 1 to 50 because of both characteristics of thermal resistance and thermal expansion coefficient.
It is preferably formed to have a thickness of μm. That is, when the thickness is less than 1 μm, the bonding becomes insufficient when the LSI chip 5 is large, and when the thickness is more than 50 μm, the effect of improving the thermal resistance cannot be seen.

The heat dissipating substrate composed of the five members of the substrate base material 2, the polycrystalline diamond 3, the first intermediate bonding layer 8a, the second intermediate bonding layer 8b, and the metal bonding layer 4 manufactured as described above is 5 By controlling the materials and the thicknesses of the two members respectively, in order to match the coefficient of thermal expansion of the entire heat dissipation board to the LSI chip 5 to be mounted, 4 × 1 in the range of room temperature to 400 ° C.
It can be set to any value within the range of 0 ^{−6 to} 6 × 10 ⁻⁶ / ° C.

Based on the essence of the present invention as described above, the following examples were carried out in order to confirm the effect. (Example 1) Polycrystalline diamond was synthesized on a 20 mm square W substrate having a thickness of 1.5 mm by a microwave plasma CVD method for 10 hours. This synthesis was performed under the following conditions.

Source gas (flow rate): H ₂ 300 sccm CH ₄ 8 sccm Gas pressure: 100 Torr Microwave oscillation output: 400 W After synthesizing the polycrystalline diamond under the above conditions,
The upper surface of the recovered W substrate could be covered with polycrystalline diamond having a thickness of 0.2 mm. First, Ti having a thickness of 0.06 μm and a second intermediate bonding layer were formed on the coated surface.
Pt having a thickness of 1.2 μm was sequentially coated as an intermediate bonding layer. Further, a metal bonding layer made of an Au—Sn alloy was coated on this to a thickness of 30 μm.

15 m on the heat dissipation board (A) with the bonding material
The performance was evaluated by mounting an m-square Si LSI chip.

As a comparative example, a bonding material was prepared by changing the heat dissipation substrate material to AlN having the same shape as the above with the above specifications (B). Furthermore, as another comparative example, a conventional structure having a bonding material made of silver paste was also prepared (C). The performance of these comparative examples was also evaluated.

For performance evaluation, a thermal shock test and thermal resistance measurement were performed. The respective evaluation conditions are shown below. (Thermal shock test) The heat dissipation board on which the above LSI chip is mounted is alternately and repeatedly immersed 100 times in an organic solvent (Fluorinert) whose temperature is set to 125 ° C and -55 ° C to obtain L
The damaged state of the SI chip was observed. (Measurement of thermal resistance) Applying 4W of power to the LSI chip,
The temperature of the LSI chip when it was in a steady state was measured by an infrared thermometer and compared.

The results are shown in Table 1 below.

[0029]

[Table 1]

With reference to Table 1 above, the present invention A is an LSI
It can be seen that the difference in thermal expansion from the chip is small, thermal distortion unlike in the prior art is unlikely to occur, and good heat dissipation characteristics are exhibited. (Example 2) Cu-W having a thickness of 1.5 mm and 25 mm square
-In the reaction tube placed on the Mo alloy substrate, H ₂ and C ₂ H ₆
Gas mixed with Ar and Ar at a ratio of 7: 2: 1, flow rate: 4
The pressure was adjusted to 120 Torr. Then, from the high frequency oscillator, the high frequency (13.56 MH
z) to excite the mixed gas to generate plasma 2
The synthesis was carried out for 8 hours. This high frequency output is 750W
Met.

After synthesizing the polycrystalline diamond as described above, the thickness of 0.04 m on the upper surface of the recovered substrate.
m of polycrystalline diamond could be coated. First, Ta having a thickness of 0.08 μm as a first intermediate bonding layer and Pd having a thickness of 2.0 μm as a second intermediate bonding layer were sequentially coated on the coated surface. Further, a bonding material made of Au-Si alloy was further coated thereon to a thickness of 38 μm.

17 m on the heat dissipation board (D) with this bonding material
The performance was evaluated by mounting an m-square GaAs LSI chip.

As comparative examples, combinations (EJ) of the bonding materials and heat dissipation substrate materials shown in Table 2 below were also evaluated. For performance evaluation, the same thermal shock test and thermal resistance measurement as in Example 1 were performed. The results are also shown in Table 2 below.

[0034]

[Table 2]

Referring to Table 2 above, the present invention D is an LSI
It was found that the difference in thermal expansion from the chip is small, the thermal strain that occurs in the conventional one is less likely to occur, and that good heat dissipation characteristics are exhibited.

Next, an LSI package according to another aspect of the present invention will be described. FIG. 2 is a sectional view showing an LSI package according to another aspect of the present invention. With reference to FIG. 2, an LSI package according to another aspect is similar to that shown in FIG.
Unlike the LSI package according to the first aspect shown in FIG. 3, the LSI chip 5 is mounted on the predetermined region of the polycrystalline diamond 3 only via the metal bonding layer 4. With this configuration, the same effect as that of the LSI package according to the one aspect shown in FIG. 1 can be obtained. The following examples were carried out to confirm the effect. (Example 3) Polycrystalline diamond was synthesized on a 20 mm square Si substrate having a thickness of 1.5 mm for 10 hours by a microwave plasma CVD method. This synthesis was performed under the following conditions.

Raw material gas (flow rate): H ₂ 200 sccm CH ₄ 5 sccm Gas pressure: 80 Torr Microwave oscillation output: 600 W After synthesizing polycrystalline diamond under the above conditions,
The upper surface of the recovered Si substrate could be covered with polycrystalline diamond having a thickness of 0.1 mm. Further A on this coated surface
A u-Sn alloy bonding material was coated to a thickness of 30 μm.

15 m on the heat dissipation board (K) with this bonding material
The performance was evaluated by mounting an LSI chip made of m-square Si.

As a comparative example, a joining material was prepared by changing the heat dissipation substrate material to AlN having the same shape as the above with the above specifications (L). Further, as another comparative example, a conventional structure having a bonding material made of silver paste was also prepared (M). And
The performance of these comparative examples was also evaluated.

For the performance evaluation, a thermal shock test and a thermal resistance measurement were performed. The respective evaluation conditions are shown below. (Thermal shock test) The heat dissipation board on which the above LSI chip is mounted is alternately and repeatedly immersed 100 times in an organic solvent (Fluorinert) whose temperature is set to 125 ° C and -55 ° C to obtain L
The damaged state of the SI chip was observed. (Measurement of thermal resistance) Apply 3W of power to the LSI chip,
The temperature of the LSI chip when it was in a steady state was measured by an infrared thermometer and compared.

The results are shown in Table 3 below.

[0042]

[Table 3]

Referring to Table 3 above, the present invention K is an LSI
It can be seen that the difference in thermal expansion from the chip is small, thermal distortion unlike in the prior art is unlikely to occur, and good heat dissipation characteristics are exhibited. During the reaction tube which is placed a Cu-Mo alloy substrate 25mm angle (Example 4) thickness of 1 mm, H ₂ and C ₂ H ₆ and the Ar 8: 1: 1 of the mixed gas at a rate Flow rate: 500sc
The pressure was adjusted to 135 Torr. Then, a high frequency (13.56 MHz) was applied from a high frequency oscillator, the mixed gas was excited to generate plasma, and synthesis was performed for 30 hours. The output of this high frequency was 800W.

After synthesizing the polycrystalline diamond as described above, the upper surface of the recovered substrate has a thickness of 0.03 m.
m of polycrystalline diamond could be coated. A bonding material made of Au-Si alloy having a thickness of 40 μm is further formed on the coated surface.
It was coated so that it would be m.

The heat dissipation board (N) with the bonding material is
The performance was evaluated by mounting an LSI chip made of mm square GaAs.

As a comparative example, a combination (O to T) of the bonding material and the heat dissipation substrate material shown in Table 4 below was also evaluated. As the performance evaluation, the same thermal shock test and thermal resistance measurement as in Example 3 were performed. The results are also shown in Table 4 below.

[0047]

[Table 4]

Referring to Table 4 above, the present invention N is an LSI
It can be seen that the difference in thermal expansion from the chip is small, the thermal strain that occurs in the conventional one is unlikely to occur, and that good heat dissipation characteristics are exhibited.

[0049]

As described above, according to the invention described in claims 1 to 3, polycrystalline diamond is formed on at least one surface of a substrate base material made of either metal or ceramic, and the polycrystalline diamond is formed. A first intermediate bond made of at least one selected from elements of Groups 4a, 5a, and 6a of the periodic table, oxides, carbides, nitrides, and carbonitrides of the periodic table in a predetermined region on the surface of crystalline diamond. A second intermediate bonding layer formed by forming at least one layer selected from the group consisting of Mo, Ni, Pd, Pt and Au on the first intermediate bonding layer. Au, Ag, Si, G on which semiconductor elements are mounted on layers
Forming a metal bonding layer made of at least one metal selected from e, Sn, Pb and In, and forming the metal bonding layer, the first intermediate bonding layer, the second intermediate bonding layer, polycrystalline diamond and By setting the material and thickness of the substrate base material to the predetermined material and thickness, respectively, the coefficient of thermal expansion of the entire heat dissipation substrate is 4 × 10 ⁻⁶ in the range of room temperature to 400 ° C.
Since it is set to a predetermined value within the range of 6 × 10 ^-5 / ° C,
It is possible to form a heat dissipation board having a coefficient of thermal expansion that matches the coefficient of thermal expansion of an easily mounted LSI chip, and to provide a heat dissipation board having excellent heat dissipation characteristics. Furthermore, since the bonding strength between the metal bonding layer and the polycrystalline diamond is increased by the first intermediate bonding layer and the second intermediate bonding layer, it is possible to provide a heat dissipation substrate having excellent strength.

According to the invention as set forth in claim 4, polycrystalline diamond is formed on at least one surface of a substrate base material made of either metal or ceramic, and the polycrystalline diamond is formed in a predetermined region on the surface of the polycrystalline diamond. Au, Ag, Si, Ge, Sn, on which the semiconductor element is mounted,
Forming a metal bonding layer made of at least one kind of metal selected from Pb and In, and setting the material and thickness of the metal bonding layer, the polycrystalline diamond and the substrate base material to a predetermined material and thickness, respectively. By doing so, the thermal expansion coefficient of the entire heat dissipation substrate is 4 × 10 within the range of room temperature to 400 ° C.
Since it is set to a predetermined value within the range of ^{−6 to} 6 × 10 ⁻⁵ / ° C., the heat dissipation board can be formed to have a coefficient of thermal expansion that matches the coefficient of thermal expansion of an easily mounted LSI chip, and the heat dissipation characteristics It is also possible to provide an excellent heat dissipation substrate.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an LSI package according to one aspect of the present invention.

FIG. 2 is a sectional view showing an LSI package according to another aspect of the present invention.

FIG. 3 is a cross-sectional view showing a conventional general LSI package.

[Explanation of symbols]

 1: Package 2: Substrate Base Material 3: Polycrystalline Diamond 4: Metal Bonding Layer 5: LSI Chip 6: Lead Frame 7: Bonding Wire 8a: First Intermediate Bonding Layer 8b: Second Intermediate Bonding Layer

Claims (4)

[Claims] 1. A heat dissipation substrate on which a semiconductor element is mounted on its main surface, wherein the substrate base material is made of any one of metal and ceramic, and a polycrystal formed on at least one surface of the substrate base material. Diamond and at least one selected from the group consisting of elements of Groups 4a, 5a, 6a of the periodic table, oxides, carbides, nitrides, and carbonitrides of diamond formed in a predetermined region on the surface of the polycrystalline diamond. A first intermediate bonding layer of a kind, and Mo, Ni, P formed on the first intermediate bonding layer
a second intermediate bonding layer made of at least one selected from d, Pt, and Au, and formed on the surface of the second intermediate bonding layer, and the semiconductor element is mounted on the surface. , Ag, Si,
A metal bonding layer made of at least one metal selected from Ge, Sn, Pb and In, the metal bonding layer, the first intermediate bonding layer, the second intermediate bonding layer, polycrystalline diamond and By setting the material and thickness of the substrate base material to the predetermined material and thickness, respectively,
The overall coefficient of thermal expansion is 4 × 10 in the range of room temperature to 400 ° C.
^A heat dissipation board set to a predetermined value within the range of ^{-6 to} 6 x 10 ^-5 / ° C. 2. The substrate base material is Si, Mo, W, Cu
-W alloy, Cu-Mo alloy, Cu-Mo-W alloy, Si
The heat dissipation board according to claim 1, which is formed of a sintered body containing one of C and AlN as a main component. 3. The polycrystalline diamond has a thermal conductivity of 500 to 2000 W / m in the range of room temperature to 400 ° C.
The heat dissipation board according to claim 1 or 2, which has a predetermined value within the range of K. 4. A heat dissipation substrate on which a semiconductor element is mounted, the substrate base material made of any one of metal and ceramic, and polycrystalline diamond formed on at least one surface of the substrate base material. A is formed in a predetermined region on the surface of the polycrystalline diamond, and the semiconductor element is mounted on the surface, A
a metal bonding layer made of at least one metal selected from u, Ag, Si, Ge, Sn, Pb and In, and the material and thickness of the metal bonding layer, the polycrystalline diamond and the base material of the substrate. By setting each to a predetermined material and thickness, the thermal expansion coefficient of the whole is set to a predetermined value within the range of 4 × 10 ^{−6 to} 6 × 10 ⁻⁵ / ° C. in the range of room temperature to 400 ° C. The heat dissipation board.