JP2004200566A - Radiator and its producing process, substrate for power module, and power module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the weight while enhancing machinability and to attain a sufficient strength while preventing warp. <P>SOLUTION: The radiator 16 is formed by impregnating a low density molding 17 formed of a material having characteristics of low thermal expansion coefficient with a metal high heat conduction material 18. The low thermal expansion material composing the low density molding 17 is an iron-nickel based alloy, e.g. Invar alloy. The high heat conduction material 18 is formed of a material having a high thermal conductivity, e.g. Cu or its alloy, or Al or its alloy. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a heat radiator and a method for manufacturing the same, a power module substrate, and a power module, and is particularly used for a semiconductor device for controlling a large voltage and a large current, and generates heat from a heating element such as a semiconductor chip. The present invention relates to a technique suitable for dissipating heat.
[0002]
[Prior art]
In this type of power module substrate, a circuit layer is provided on one surface of an insulating substrate made of a ceramic material, and a radiator is provided on the other surface, and a cooling layer is provided on a surface of the radiator facing the insulating substrate. A configuration having a cooling sink portion provided with a cooling means such as water is generally used.
A radiator provided on such a power module substrate is required to have a characteristic of a low coefficient of thermal expansion in order to be bonded to the insulating substrate, while in order to radiate heat of the semiconductor chip mounted on the insulating substrate. High thermal conductivity is also required.
[0003]
In order to satisfy these requirements, AlSiC or AlSiC in which Al is impregnated with Cu or CuSiC in which Al is impregnated with Cu, and AlC or CuC in which carbon is impregnated with Al or Cu are known as radiators. Conventionally, as a metal material, CuMo or CuW in which a temporary sintered body of molybdenum (Mo) or tungsten (W) is impregnated with Cu has been proposed (for example, see Patent Document 1).
[0004]
[Patent Document 1]
JP 2001-358266 A
[Problems to be solved by the invention]
By the way, in the conventional power module substrate, if the heat radiator is made of AlSiC or CuSiC, it is composed of metal and ceramics, so that there is a problem of poor workability. In addition, in the case of Al and C, or in the case of Cu and C, that is, a bonded body of metal and carbon, it is difficult to obtain perfect bonding, and there is a problem in strength. When joined at high temperatures, there is also a problem that a large warpage is generated due to a difference in thermal expansion coefficient.
On the other hand, in the case of CuMo or CuW, there is also a problem that the weight increases.
[0006]
SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has as its object to provide a heat radiator that has good workability, can be reduced in weight, can have sufficient strength, and can prevent warpage. Another object of the present invention is to provide a power module substrate and a power module having the heat radiator.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention proposes the following means.
The invention according to claim 1 is a method of manufacturing a radiator for radiating transmitted heat, wherein the low-density molded body formed of an iron-nickel alloy is impregnated with a molten metal of a high heat conductive material made of metal. Is formed.
[0008]
According to the method for manufacturing a heat radiator according to the present invention, the heat radiator is formed by impregnating a low-density molded body made of an iron-nickel alloy with a molten metal of a high heat conductive material made of metal. Since the body can be formed reliably, and therefore all the constituent materials are made of metal, the workability is improved, the bonding between the constituent materials is improved, and the weight of the radiator itself can be reduced. it can.
[0009]
According to a second aspect of the present invention, in the method for manufacturing a radiator for dissipating the transmitted heat, a low-density compact formed of an iron-nickel alloy is impregnated with a molten metal of a high thermal conductive material made of metal. Then, the core body is sandwiched between metal plates made of a high thermal conductive material to form a radiator.
[0010]
According to the method for manufacturing a radiator according to the present invention, a low-density molded body is impregnated with a molten metal of a high thermal conductive material to form a core body, and this is sandwiched between metal plates made of a high thermal conductive material to form a radiator. Since it is formed, a radiator in which all the constituent materials are made of metal can be reliably formed. Therefore, since all of the constituent materials are made of metal, the workability is improved and the bonding between the constituent materials is also improved. And the radiator itself can be reduced in weight.
[0011]
According to a third aspect of the present invention, in the method for manufacturing a radiator according to the second aspect, the metal plate sandwiches the core body by hot rolling or cold rolling.
ADVANTAGE OF THE INVENTION According to the manufacturing method of the radiator which concerns on this invention, since a metal plate clamps a core body by hot rolling or cold rolling, a radiator can be formed firmly and a favorable radiator can be formed. .
[0012]
According to a fourth aspect of the present invention, the heat radiator of the first aspect or the core body of the second aspect is characterized in that a molten metal of the high thermal conductive material is cast at a high pressure on the low density molded body.
According to the method for manufacturing a heat radiator according to the present invention, the heat radiator is formed by high-pressure casting of the high-thermal-conductivity material on the low-density compact, so that the low-density compact and the high-thermal-conductivity material are reliably formed integrally. can do.
[0013]
According to a fifth aspect of the present invention, there is provided a radiator for dissipating the transmitted heat, wherein a low-density molded body formed of an iron-nickel alloy and a metal high-heat formed integrally by impregnation of the low-density molded body. It is characterized by being formed of a conductive material.
[0014]
According to the heat dissipating body of the present invention, since the heat dissipating body is formed of the low density molded body and the high thermal conductive material integrally formed by impregnation, the heat dissipating body in which the constituent materials are all metal can be reliably formed. Therefore, since all the constituent materials are made of metal, workability is improved, bondability between the constituent materials is improved, and the heat radiator itself can be reduced in weight.
[0015]
According to a sixth aspect of the present invention, there is provided a heat dissipating body for dissipating heat to be transmitted, comprising: a low-density molded body formed of an iron-nickel alloy; It is characterized by being formed by a metal plate sandwiching the body and made of a high thermal conductive material.
[0016]
According to the radiator according to the present invention, since the core body and the metal plate sandwiching the core body are formed by the low-density molded body and the high thermal conductive material integrally formed with the low-density molded body, all the constituent materials are made of metal. Radiator can be reliably formed, and therefore all the constituent materials are made of metal, so that the workability is improved, the bonding property between the constituent materials is improved, and the radiator itself is reduced in weight. can do.
[0017]
The invention according to claim 7 is characterized in that, in the heat radiator according to claim 5 or 6, the low-density molded body is provided with a pore portion having a desired porosity.
According to the heat radiator according to the present invention, when impregnated with the high thermal conductive material, the molten metal of the high thermal conductive material enters the pores of the low density molded body, thereby increasing the thermal conductivity in the low density molded body, Thereby, good heat conduction can be obtained even if the material is formed of a material having a low coefficient of thermal expansion.
[0018]
The invention according to claim 8 is the radiator according to any one of claims 5 to 7, wherein the high thermal conductive material is any of Cu, an alloy thereof, Al, and an alloy thereof. I do.
ADVANTAGE OF THE INVENTION According to the radiator of this invention, since a high thermal conductive material consists of either Cu and its alloy, and Al and its alloy, it can join reliably with an iron-nickel alloy and form a favorable radiator. can do.
[0019]
According to a ninth aspect of the present invention, a heat radiator according to any one of the fifth to eighth aspects is attached to an insulating substrate.
ADVANTAGE OF THE INVENTION According to the board | substrate for power modules which concerns on this invention, workability is favorable and it can aim at weight reduction, and also since it has the radiator which the joining property between component members becomes favorable, reliability is so much. Increase.
[0020]
The invention according to claim 10 is characterized in that a chip is mounted on the insulating substrate of the power module substrate according to claim 9.
ADVANTAGE OF THE INVENTION According to the power module which concerns on this invention, since workability is favorable and weight reduction can be attained, and since it has the heat radiator which the joining property between component members becomes favorable, reliability improves correspondingly.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 4 are views showing a heat radiator according to a first embodiment of the present invention. FIG. 1 is an overall view showing a power module to which the heat radiator is applied, and FIG. 2 is an explanatory diagram showing the heat radiator. FIG. 3 is a perspective view, FIG. 3 is an explanatory view when manufacturing a radiator, and FIG. 4 is an explanatory view of clamping a low density molded body.
The power module 10 shown in FIG. 1 is configured by joining a heat radiator 16 to a power module substrate 11 as a heat radiator.
The power module substrate 11 is an insulating substrate formed in a desired size with, for example, AlN, Al ₂ O ₃ , Si ₃ N ₄ , SiC, etc., and a circuit layer 12 is laminated and joined on the upper surface thereof. The metal layer 13 is laminated and joined to its lower surface. The circuit layer 12 and the metal layer 13 are formed of Al, Cu, or the like. Hereinafter, the power module substrate 11 is abbreviated as “insulating substrate 11”.
[0022]
As shown in FIG. 1, the semiconductor chip 30 is mounted on the circuit layer 12 of the insulating substrate 11 by solder 14, while the radiator is mounted on the lower surface of the metal layer 13 by solder 15 or by brazing or diffusion bonding. Further, the radiator 16 is used by being attached to the cooling sink portion 20, and the heat transmitted to the radiator 16 is cooled by the cooling water (or cooling air) 21 in the cooling sink portion 20. The power module 10 is configured by radiating heat. The radiator 16 is attached to the cooling sink unit 20 in a state in which the radiator 16 is in close contact with the attachment screw 22.
[0023]
As shown in FIG. 2, the heat radiator 16 of this embodiment is made of a low-density molded body 17 formed of a material having a low coefficient of thermal expansion and a characteristic of a low coefficient of thermal expansion, and is made of a material having a larger coefficient of thermal expansion. It is formed by impregnating a high heat conductive material 18 made of metal.
[0024]
That is, the low thermal expansion material forming the low density molded body 17 is a so-called iron-nickel alloy, for example, an invar alloy. An invar alloy (hereinafter, abbreviated as invar) is an alloy that hardly undergoes thermal expansion near room temperature, and has a composition ratio of 64.6 mol% of Fe and 35.4 mol% of Ni. However, Fe containing other unavoidable impurities is also called an Invar alloy. The high thermal conductive material 18 is formed of a material having a good thermal conductivity, such as Cu or an alloy thereof, or Al or an alloy thereof.
[0025]
The low-density molded body 17 is formed in a low-density state by molding Invar powder with a mold, and has pores 17a inside and outside as shown in FIG. For example, as shown in FIG. 4, when the low density molded body 17 is formed by clamping the Invar powder 19 with the sintering mold 31, the pores 17 a are formed in the low density molded body 17. It is necessarily formed. The molding is not limited to the sintering mold 31 and may be performed using a normal molding die. In the case of the powder 19 of Invar, such a pore portion 17a has a porosity of about 40 to 70%.
In the sintered mold 31 shown in FIG. 4, when the core 33 is set in the cavity of the die 32, the powder 19 of the low-thermal-expansion material is filled, and the punch 34 is lowered in this state. Such a low-density molded body 17 is formed.
[0026]
When molding the low-density compact 17, not only the Invar powder 19 but also other metal low-thermal-expansion materials may be mixed therein. For example, a linear filler or the like may be mixed. What is essential is that the ferro-nickel alloy is a low thermal expansion material smaller than the high thermal conductive material to be subsequently impregnated, and has good bondability with the high thermal conductive material.
[0027]
Then, after the low-density molded body 17 is formed, the low-density molded body 17 is put into a radiator molding die, and then the molten metal of the high thermal conductive material 18 is impregnated in the die. By filling the inside and curing in that state, the heat dissipating body 16 is formed by the low-density molded body 17 and the high thermal conductive material 18 cast into the molded body 17, as shown in FIGS. It has become. In this case, the molten metal of the high thermal conductive material 18 is cast at a high pressure, so that the pores 17 a in the low density molded body 17 are reliably filled. Note that the highly heat conductive material 18 shown in FIGS. 1 and 2 and the pore portion 17a shown in FIG. 3 are drawn extremely for convenience of explanation.
[0028]
The radiator 16 thus formed has, for example, a thermal conductivity of 100 W / mK or more and a thermal expansion coefficient of about ± 40% of the thermal expansion coefficient α of the insulating substrate 11, that is, 4 × 10 ⁻⁶ / K <. α <10 × 10 ⁻⁶ / K. In this case, the low-density molded body occupies at least 30% or more, and preferably 50% or more, as a proportion of the low-density molded body in the entire radiator 16.
[0029]
As described above, when the radiator 16 is formed by casting the molten metal of the high thermal conductive material 18 into the low density molded body 17 formed of a low thermal expansion material such as Invar, the heat of the radiator 16 as a whole is Since the coefficient of expansion can be reliably reduced, the difference in the coefficient of thermal expansion between the heat radiator 16 and the insulating substrate 11 can be reduced so as to be closer to the insulating substrate 11. Therefore, when the two members 16 and 11 are joined by the solder 15 (or brazing, diffusion bonding, or the like), it is possible to prevent the radiator 16 from warping toward the insulating substrate 11 and to prevent the insulating substrate 11 from being warped. The heat transfer from the radiator to the heat radiator 16 is performed favorably.
[0030]
The radiator 16 of this embodiment is formed by impregnating a low-density molded body 17 made of a low-thermal-expansion material such as Invar with a molten metal of a high-thermal-conductivity material 18 as described above. Is not used, and since all the constituent materials are made of metal, the workability is improved and the bondability between the constituent members is improved. Further, since neither Mo nor W is used, the heat radiator 16 itself can be reduced in weight, and thus the entire insulating substrate 11 can be reduced in weight, and the power module 10 can be reduced accordingly.
[0031]
Also, when the high thermal conductive material 18 is cast into the low density molded body 17 by high pressure casting, the high thermal conductive material 18 flows into every corner of the pores 17a in the low density molded body, and the low density molded body 17 and the high thermal conductive material 18 and the low-density molded body 17 can be strengthened, and a strong joint can be obtained.
In addition, the low-density molded body 17 has a lower heat transfer coefficient than the high heat conductive material 18, but avoids a decrease in heat transfer as the heat radiator 16 due to the high heat conductive material 18 entering the pores 17 a. And heat conduction in the low-density molded body 17 can be favorably performed.
[0032]
Therefore, according to this embodiment, since the constituent members are all metal and a heavy material is not used, the workability is good and the weight can be reduced. It is possible to reliably form a heat radiator having good performance, thereby improving the reliability of the insulating substrate 11 and the power module 10.
[0033]
FIG. 5 shows a radiator according to a second embodiment of the present invention.
In this embodiment, after the core body 24 is formed by impregnating the low-density molded body 17 with the molten metal of the high thermal conductive material 18, the metal plate 25 made of the same high thermal conductive material as the high thermal conductive material 18 is then formed. Are prepared, and the heat radiator 16 is configured by sandwiching the core body 24 between these metal plates 25, 25. The metal plate 25 is preferably the same as the high heat conductive material 18 in consideration of the bonding property with the high heat conductive material 18 in the core body 24, but may be different.
[0034]
Therefore, after forming the core body 24 in the same manner as in the case of the heat radiator of the above-described embodiment, the heat radiator 16 is formed by sandwiching the core body 24 with the metal plate 25. In this case, the metal plate 25 can securely and firmly hold the core body 20 by hot rolling or cold rolling. The thermal conductivity and the thermal expansion coefficient of the radiator 16 formed in this way are configured to be substantially the same as those of the above-described embodiment.
[0035]
According to this embodiment, since the core body 24 formed by impregnating the low-density molded body 17 with the high thermal conductive material 18 is used, basically the same functions and effects as those of the first embodiment can be obtained. Moreover, since the core body 24 is sandwiched between the metal plates 25, the heat conduction between the insulating substrate 11 and the heat radiator 16 is further improved and the heat radiating action is further improved as compared with the first embodiment. is there.
[0036]
In the above-described embodiment, an example is shown in which invar is used as the low-density molded body 17 or the core body 24. However, another low-thermal-expansion material may be used, for example, a low-thermal-expansion material such as 42 alloy. May be formed. In the case of a low-density compact formed of 42 alloy, the porosity is about 50% or lower, but in the case of Invar, a porosity of 30 to 70% is obtained. The magnitude of the porosity may be appropriately selected depending on the material of the low thermal expansion material to be used, the material of the high thermal conductive material 19 to be impregnated, and the target values of the thermal conductivity and the thermal expansion coefficient. In addition to the above materials, Super Invar or the like may be used. In any case, the low thermal expansion material may be an iron-nickel alloy, and is not limited to the illustrated embodiment.
Further, the configuration in which the cooling sink portion 20 is provided on the heat radiator 16 has been described. However, the configuration is not limited to this, and a corrugated fin may be provided on the surface of the heat radiator 16 via a brazing material.
[0037]
【The invention's effect】
As described above, according to the first aspect of the present invention, a low-density formed body made of an iron-nickel alloy is impregnated with a high-thermal-conductivity material made of metal to form a radiator in which all constituent materials are metal. As a result, the workability is improved, the bonding property between the constituent materials is also improved, and the heat radiator itself can be reduced in weight, and the effect of producing a good heat radiator excellent in heat conduction and heat radiation characteristics can be obtained. .
[0038]
According to the second aspect of the present invention, a low-density molded body is impregnated with a molten metal of a high thermal conductive material to form a core body, and this is sandwiched between metal plates to form a radiator. Since all the constituent materials are made of metal in the same manner as described above, the workability is good, the bonding property between the constituent materials is good, and the heat radiator itself can be reduced in weight, resulting in a good heat radiator with excellent heat conduction and heat radiation characteristics. Can be obtained.
[0039]
According to the third aspect of the invention, there is obtained an effect that the heat radiator can be firmly formed.
[0040]
According to the fourth aspect of the present invention, since the heat radiator is formed by casting the high thermal conductive material into the low density molded body at a high pressure, the low density molded body and the high thermal conductive material can be surely integrally formed. Is obtained.
[0041]
According to the invention according to claim 5, since the low-density molded body and the high-thermal-conductivity material integrally formed by impregnation with the low-density molded body, the workability is good and the joining property between the constituent materials is good. In addition, as a result of reducing the weight of the heat radiator itself, an effect that is excellent in heat conduction and heat radiation characteristics can be obtained.
[0042]
According to the invention as set forth in claim 6, since all the constituent materials are metal, workability is improved, bonding properties between the constituent materials are improved, and the heat radiator itself can be reduced in weight. The effect of excellent conduction and heat dissipation characteristics can be obtained.
[0043]
According to the invention according to claim 7, the thermal conductivity in the low-density molded body can be increased, and even if it is formed of a low-thermal-expansion material, an effect of obtaining good thermal conductivity can be obtained.
[0044]
According to the invention according to claim 8, since the high thermal conductive material is made of any one of Cu and its alloy and Al and its alloy, it can be securely bonded to the iron-nickel alloy and forms a good heat radiator. can do.
[0045]
According to the ninth aspect of the present invention, since the heat radiator having good workability and light weight and good jointability between constituent members is provided, an effect of increasing reliability as a power module substrate is obtained. This is particularly useful for bonding a heat radiator to a substrate such as aluminum nitride at a high temperature such as brazing.
[0046]
According to the tenth aspect of the present invention, since there is provided a heat radiator having good workability and light weight, and having good bonding between constituent members, an effect of increasing reliability as a power module can be obtained.
[Brief description of the drawings]
FIG. 1 is an overall view showing a power module to which a heat radiator according to a first embodiment of the present invention is applied.
FIG. 2 is an explanatory perspective view showing a radiator.
FIG. 3 is an explanatory view when manufacturing the radiator shown in FIGS. 1 and 2;
FIG. 4 is an explanatory diagram for clamping a low density molded body.
FIG. 5 is a sectional view of a main part showing a radiator according to a second embodiment of the present invention.
[Explanation of symbols]
10 Power module 11 Power module substrate (insulating substrate)
Reference Signs List 16 Heat radiator 17 Low density molded body 18 High thermal conductive material 19 Invar powder 24 Core body 25 Metal plate 30 Semiconductor chip

Claims (10)

In a method of manufacturing a radiator that dissipates the transmitted heat,
A method for manufacturing a radiator, comprising: forming a radiator by impregnating a low-density formed body made of an iron-nickel alloy with a molten metal of a high thermal conductive material made of metal. In a method of manufacturing a radiator that dissipates the transmitted heat,
A low-density compact formed of an iron-nickel alloy is impregnated with a molten metal of a high thermal conductive material to form a core body,
Next, a method for manufacturing a heat radiator, comprising forming the heat radiator by sandwiching the core body with a metal plate made of a high thermal conductive material. The method for manufacturing a radiator according to claim 2,
A method for manufacturing a heat radiator, wherein the metal plate sandwiches a core body by hot rolling or cold rolling. The method for manufacturing a heat radiator according to claim 1, wherein the heat radiator according to claim 1 or the core body according to claim 2, wherein the molten metal of the high thermal conductive material is cast at a high pressure on the low density molded body. In a radiator that dissipates the transmitted heat,
A heat radiator, comprising: a low-density formed body formed of an iron-nickel alloy; and a metal high-thermal-conductivity material integrally formed by impregnating the low-density formed body. In a radiator that dissipates the transmitted heat,
A low-density molded body formed of an iron-nickel alloy is impregnated with a metal high-thermal-conductivity material and integrally formed by a core body, and a metal plate sandwiching the core body and made of a high-thermal-conductivity material. A heat radiator characterized by being formed. The radiator according to claim 5 or 6,
The heat radiator according to claim 1, wherein the low-density molded body has a pore portion having a desired porosity. The radiator according to any one of claims 5 to 7,
The heat radiator according to claim 1, wherein the high thermal conductive material is one of Cu, an alloy thereof, Al, and an alloy thereof. A power module substrate, wherein the heat radiator according to any one of claims 5 to 8 is attached to an insulating substrate. A power module comprising a chip mounted on an insulating substrate of the power module substrate according to claim 9.

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