JP2004200568A - Radiator and its producing process - 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 has a metallic main component 17 provided with a filler 18 having a low thermal expansion coefficient. The main component 17 is formed of a so-called high heat conducting material having a high thermal conductivity, e.g. Cu or a Cu alloy. The filler 18 is a linear body having an appropriate size formed of a metal, e.g. Invar alloy, having a thermal expansion coefficient smaller than that of the main component 17 integrally with the main component 17. The filler 18 is oriented to a specified direction on a plane when the radiator 16 is formed. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a radiator and a method of manufacturing the radiator, and more particularly to a technique used for a semiconductor device for controlling a large voltage and a large current and suitable for dissipating heat generated from a heating element such as a semiconductor chip.
[0002]
[Prior art]
Generally, in a power module as a semiconductor device, since a semiconductor chip is mounted on a power module substrate and heat of the semiconductor chip is transmitted to the power module substrate, it is necessary to radiate heat transmitted to the power module substrate.
Such a power module substrate as a heat radiating body is provided with a circuit layer on one surface of an insulating substrate made of a ceramic material and a heat radiating member on the other surface. In general, a cooling sink having cooling means such as cooling water is provided.
The radiator provided on such a power module substrate is required to have a low thermal expansion material in order to bond with the insulating substrate, while having a high thermal conductivity in order to radiate heat of the semiconductor chip mounted on the insulating substrate. 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-A-11-097593
[Problems to be solved by the invention]
By the way, in the conventional radiator, if the radiator is made of CuMo, Mo itself is heavy and hard, so that there is a problem that the workability is inferior and the weight is difficult to reduce. The thermal expansion coefficient of Mo is 5.5 × 10 ⁻⁶ (/ ° C.), which is larger than 4.6 × 10 ⁻⁶ (/ ° C.) of the insulating substrate. There is a problem in strength because it is difficult to obtain perfect bonding, and there is also a problem in that when bonded to an insulating substrate at a high temperature, a large warpage occurs due to a difference in thermal expansion coefficient.
[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. And a method for manufacturing the same.
[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 heat to be transmitted, wherein the radiator is formed on a metal main component made of a high heat conductive material and has a smaller thermal expansion coefficient than the main component. A metal linear body made of a low thermal expansion material is oriented in a desired direction and integrally formed.
According to the method for manufacturing a radiator according to the present invention, since the linear body having a low coefficient of thermal expansion is formed so as to be oriented in a specific direction with respect to the main component, the strength of the radiator in a certain direction is ensured. And the workability is good and the weight can be reduced.
[0008]
According to a second aspect of the present invention, in the method for manufacturing a radiator according to the first aspect, the linear body is mixed into the powder of the main structure, and the radiator is formed by powder rolling or powder extrusion. It is characterized by doing.
According to the method for manufacturing a heat radiator according to the present invention, since the linear body is mixed into the powder in the main structure, the direction of the linear body is not restricted, and the linear body can be surely moved in the desired direction. Can be formed.
[0009]
According to a third aspect of the present invention, in the method for manufacturing a radiator according to the first or second aspect, the linear body is oriented in a desired direction with respect to the main component by a magnetic field.
According to the method for manufacturing a heat radiator according to the present invention, the direction of the linear body can be controlled by utilizing the magnetic field, and thus the linear body can be reliably oriented in a desired direction.
[0010]
The invention according to claim 4 is a heat dissipating body for dissipating heat to be transmitted, wherein the heat dissipating member has a metal main component made of a high heat conductive material and a low thermal expansion coefficient smaller than the thermal expansion coefficient of the main component. Characterized in that a metal linear body made of is oriented in a desired direction.
According to the radiator according to the present invention, since the linear body having a low coefficient of thermal expansion is formed so as to be oriented in a specific direction with respect to the main component, the strength of the radiator in a certain direction can be reliably increased. In addition, the workability is good and the weight can be reduced.
[0011]
According to a fifth aspect of the present invention, in the radiator of the fourth aspect, the linear body has a volume content of 50% or more of the entire radiator.
According to the heat dissipating body of the present invention, since the heat dissipating body is formed of a linear body having a volume content of 50% or more, the strength of the heat dissipating body can be reliably increased.
[0012]
According to a sixth aspect of the present invention, in the radiator according to the fourth or fifth aspect, a linear body having a low coefficient of thermal expansion arranged in a direction crossing the linear body is provided.
According to the heat dissipating body of the present invention, by arranging the linear members in the crossing direction, the strength of the heat dissipating body in the crossing direction can be increased, and good strength can be obtained.
[0013]
According to a seventh aspect of the present invention, in the heat radiator according to any one of the fourth to sixth aspects, the linear body has a high linear body density in the main component along a thickness direction of the heat radiator. And a low-density coarse-density layer.
According to the radiator according to the present invention, by providing the linear body with the high-density layer and the coarse-density layer, the strength is increased and the effect of preventing warpage can be favorably performed.
[0014]
According to an eighth aspect of the present invention, in the heat radiator according to any one of the fourth to seventh aspects, the main constituent body is any one of Cu, an alloy thereof, Al and an alloy thereof, and The expansion material is an iron-nickel alloy.
According to the radiator according to the present invention, the main constituent body is any one of Cu and its alloy, Al and its alloy, and the low thermal expansion material is an iron-nickel alloy. It is possible to firmly join each other, and it is possible to reliably obtain good jointability.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 3 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 and FIG. 3 is an explanatory view when a heat dissipator is formed by mixing a linear body into powder of a high heat conductive material by a powder rolling process.
As shown in FIG. 1, the power module 10 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 to a desired size with, for example, AlN, Al ₂ O ₃ , Si ₃ N ₄ , SiC or the like, and a circuit layer 12 and a metal layer 13 are provided on the upper and lower surfaces thereof. Each is laminated and joined. 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”.
[0016]
The semiconductor chip 30 is mounted on the circuit layer 12 of the insulating substrate 11 by the solder 14, while the radiator 16 is joined to the lower surface of the metal layer 13 by the solder 15 or by brazing or diffusion bonding. The body 16 is used by being attached to the cooling sink unit 20, and the heat transmitted to the radiator 16 is radiated to the outside by the cooling water (or cooling air) 21 in the cooling sink unit 20, so that the power module is 10 are configured. 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.
[0017]
In this embodiment, a filler 18 having a low thermal expansion coefficient is provided in a main component 17 in which a radiator 16 is made of metal. The main structure 17 is formed of a material having good thermal conductivity such as Cu or a Cu alloy, so-called high heat conductive material.
[0018]
On the other hand, the filler 18 is a linear body having an appropriate size, and is made of a metal having a thermal expansion coefficient smaller than that of the main component 17, for example, an invar alloy, and is formed integrally with the main component 17. Is done. 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.
[0019]
The filler 18 is oriented so as to face a specific direction on the surface when the heat radiator 16 is formed. For example, when the heat radiator 16 having a rectangular shape is formed as shown in FIG. It is oriented along the direction.
As shown in FIG. 3, such a radiator 16 is prepared by mixing a filler 18 into a powder 17 ′ constituting a main structural body 17 in a hopper A and sending it out by a rolling roller B in a powder rolling process. Thereby, the fillers 18 are arranged in the powder 17 ′, and in this state, the main component 17 and the fillers 18 are integrally formed. Alternatively, although not shown, the powder may be extruded by a powder extruder such as a conform and molded. Furthermore, a magnetic field may be configured so that the direction of the filler 18 can be controlled, and the direction of the filler 18 may be aligned by the magnetic force.
1 and 2, the fillers 18 are provided at substantially equal intervals in the surface direction and the thickness direction of the heat radiator 16, however, the intervals may be non-uniform. What is necessary is just to be oriented in 16 plane directions.
[0020]
The radiator 16 mixed with the filler 18 has 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 proportion of the filler 18 in the entire heat radiator 16 is such that the volume content (also referred to as a sectional area ratio) is at least 30% or more, and preferably 50% or more.
[0021]
In this way, when the heat radiator 16 is formed such that the filler 18 having a low thermal expansion coefficient such as invar is oriented in a specific direction with respect to the main component 17, the strength of the heat radiator 16 in a certain direction is surely increased. be able to. Therefore, even if the heat radiator 16 is joined to the insulating substrate 11 by a high temperature such as the solder 14 or brazing, it is possible to suppress the warping of the heat radiator 16 due to the heat. Moreover, since the filler 18 is mixed with the main component 17, the thermal expansion coefficient of the heat radiator 16 as a whole can be reliably reduced, so that the effect of preventing the heat radiator 16 from warping is further enhanced.
[0022]
In addition, since the filler 18 does not have the weight and hardness unlike Mo, the workability is improved, and further, the heat radiator 16 itself can be reduced in weight, so that the entire substrate 11 can be reduced in weight. In addition, the bonding property with the main component 17 of a high thermal conductive material made of Cu or Cu alloy is good, and almost perfect matching can be obtained.
[0023]
When the heat radiator 16 is formed, the filler 18 mixed in the powder 17 ′ of the main component 17 is moved in a specific direction by a powder rolling process or a powder extrusion process shown in FIG. 3 or by using a magnetic field. It can be easily oriented. As a result, it is possible to reliably manufacture the heat radiator 16 which has good workability, can be reduced in weight, can obtain sufficient strength, and can prevent warpage.
[0024]
FIG. 4 shows a radiator according to a second embodiment of the present invention.
The heat radiator 16 shown in FIG. 4 is configured by joining a first main component 17A in which the filler 18A is oriented and a second component 17B in which the filler 18B is oriented. The filler 18B of the second main component 17B is provided in a direction orthogonal to the filler 18A of the first main component 17A, and therefore, the fillers 18A and 18B are arranged in the direction intersecting each other.
[0025]
According to this embodiment, since the fillers 18A and 18B are provided in the main components 17A and 17B, respectively, basically the same operation and effects as those of the first embodiment can be obtained. In addition, since the fillers 18A and 18B are arranged in the cross direction, the strength of the heat radiator 16 increases in the cross direction, and the heat radiator 16 having a high warp prevention effect can be obtained.
[0026]
FIG. 5 shows a radiator according to a third embodiment of the present invention.
The radiator 16 of this embodiment is joined to each other by first to third main components 17A to 17C, and the filler 18 made of Invar is provided in each of the main components 17A to 17C in an oriented manner. In each of the main components 17A to 17C, the filler 18 is formed in the high-density layer 18a by being relatively densely oriented on the upper surface side near the insulating substrate 11, and on the lower surface side thereof, It is composed of a coarse density layer 18b which is more densely oriented than the layer 18a. Therefore, the filler 18 is composed of the high density layer 18a and the coarse density layer 18b.
As described above, by changing the density of the filler 18 oriented in each of the main components 17A to 17C, the strength of the heat radiator 16 can be increased, and the effect of reducing the warpage can be increased.
[0027]
In the illustrated embodiment, an example in which Cu or an alloy thereof is used as the main component of the radiator has been described. However, as described above, if the radiator 16 is formed by powder rolling or powder extrusion, For example, since an oxide film formed on the surface of Al or an alloy thereof can be destroyed, a radiator serving as a main component can be formed, and the present invention is not limited to the illustrated example.
Further, by mixing a metal powder having a low coefficient of thermal expansion other than the filler 18, the coefficient of thermal expansion and the thermal conductivity of the entire radiator 16 can be further adjusted, and the metal in the radiator can be more firmly joined to each other. You can also. In any case, not only the filler 18 but also another low thermal expansion material, for example, 42 alloy, Cu invar, super invar, or the like can be used.
Further, the configuration in which the cooling sink portion 20 is provided on the heat radiator 16 has been described. However, the present invention is not limited to this, and a configuration in which corrugated fins are provided on the surface of the heat radiator 16 via a brazing material may be used.
[0028]
【The invention's effect】
As described above, according to the first aspect of the present invention, since the linear body having a low thermal expansion coefficient is oriented to the main component to form the heat radiator, the strength of the heat radiator is surely increased, and the warpage is increased. This has the effect of producing a heat radiator that can prevent this, has good workability and can be reduced in weight, and is particularly useful for a heat radiator that is joined to an insulating substrate made of alumina nitride at a high temperature such as brazing.
[0029]
According to the second aspect of the present invention, there is obtained an effect that the direction of the linear body is not restricted and the linear body can be formed in the powder in the main structure in a state in which the linear body is surely directed in a desired direction. Can be
[0030]
According to the invention according to claim 3, it is possible to control the direction of the linear body by using the magnetic field, and to obtain an effect that the linear body can be surely oriented in a desired direction.
[0031]
According to the invention according to claim 4, since the linear body having a low coefficient of thermal expansion is oriented so as to face a specific direction with respect to the main component and the radiator is formed, the strength of the radiator is reliably increased, The effect of preventing warpage, good workability and reduction in weight can be obtained.
[0032]
According to the fifth aspect of the present invention, the effect of reliably increasing the strength of the heat radiator can be obtained.
[0033]
According to the sixth aspect of the present invention, by arranging the linear bodies in the cross direction, it is possible to obtain an effect that the strength of the heat radiator in the cross direction can be increased and the overall strength can be further increased.
[0034]
According to the seventh aspect of the present invention, by appropriately providing the linear body with the high-density layer and the coarse-density layer, it is possible to obtain the effect of increasing the strength and excellently preventing the warpage.
[0035]
According to the invention according to claim 8, there is obtained an effect that the metal in the heat dissipating body can be firmly joined to each other, and good jointability can be reliably 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 diagram when a heat dissipator is formed by mixing a linear body into a powder of a high thermal conductive material by a powder rolling process.
FIG. 4 shows a radiator according to a second embodiment of the present invention.
FIG. 5 shows a radiator according to a third embodiment of the present invention.
[Explanation of symbols]
10 Power module 11 Power module substrate (insulating substrate)
Reference Signs List 16 heat radiator 17 main component 17 'main component powder 18, 18A, 18B filler 18a high density layer 18b coarse density layer 30 semiconductor chip

Claims (8)

In a method of manufacturing a radiator that dissipates the transmitted heat,
The heat radiator is formed integrally with a metal main body made of a high thermal conductive material by orienting a metal linear body made of a low thermal expansion material having a smaller thermal expansion coefficient than that of the main body in a desired direction. A method for manufacturing a radiator, comprising: The method for manufacturing a radiator according to claim 1,
A method of manufacturing a heat radiator, comprising mixing the linear body into the powder of the main constituent body and forming the heat radiator by powder rolling or powder extrusion. The method for manufacturing a heat radiator according to claim 1 or 2,
A method for manufacturing a radiator, comprising: orienting the linear body in a desired direction with a magnetic field with respect to the main constituent body. In a radiator that dissipates the transmitted heat,
The radiator is characterized in that a metal main body made of a high thermal conductive material and a metal linear body having a low coefficient of thermal expansion smaller than that of the main constituent are oriented in a desired direction. And the radiator. The radiator according to claim 4,
The radiator, wherein the linear body has a volume content of 50% or more of the entire radiator. The radiator according to claim 4 or 5,
A heat radiator comprising a linear body having a low coefficient of thermal expansion arranged in a direction intersecting with the linear body. The radiator according to any one of claims 4 to 6,
The heat radiator according to claim 1, wherein the linear body has a high-density layer having a high linear body density and a low-density coarse-density layer in the main structure along the thickness direction of the radiator. The radiator according to any one of claims 4 to 7,
The heat radiator is characterized in that the main component is one of Cu, an alloy thereof, Al and an alloy thereof, and the low thermal expansion material is an iron-nickel alloy.

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