JP2010245496A - Heat conduction composite material and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce thermal expansion in a surface direction while securing high thermal conductivity in a thickness direction of a board. <P>SOLUTION: A heat conduction composite material includes: a core material 11 formed by a material with a comparatively small coefficient of thermal expansion and having a plurality of through holes 11a penetrating along a thickness direction of a board; a pair of surface layer materials 13, 14 formed by a material with a larger thermal conductivity as compared with the core material 11 and laminated on the two surfaces of the core material 11; and heat transfer materials 12 formed by a material with a larger thermal conductivity as compared with the core material 11 and arranged in each of the plurality of through holes 11a in contact with the pair of surface layer materials 13, 14, while securing a gap in at least a portion between an inner wall surface of each of the through holes 11a and each of the heat transfer materials. Between the core material 11 and the pair of surface layer materials 13, 14 and between the heat transfer materials 12 and the pair of surface layer materials 13, 14 are unified by diffusion joining. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a heat conductive composite material constituting a heat dissipating member such as a heat spreader or a heat sink mounted on a semiconductor element or the like, and a method for manufacturing the same.

  Integrated circuit chips (hereinafter referred to as “chips”) for semiconductor packages, especially LSl and ULSI for large computers, are progressing toward higher integration and higher calculation speed, which increases power consumption during operation. The accompanying calorific value is very large. The chip has a large capacity and a large calorific value, and the thermal expansion coefficient of the heat transfer substrate is greatly different from the thermal expansion coefficient of silicon (Si) or gallium arsenide (GaAs) which are chip materials, The chip will be peeled off or cracked. Along with this, the design of the semiconductor package also takes heat dissipation into consideration, and the heat transfer board mounted on the chip is required to have heat dissipation, and the heat conductivity of the heat transfer board is required to be increased. That is, the heat transfer substrate is required to have a thermal expansion coefficient close to that of the chip and to have a high thermal conductivity.

  On the other hand, in the field of power electronics, thyristors, bipolar transistors, MOSFETs, and the like have been put into practical use by various pn junction combination structures. Furthermore, an insulated gate bipolar transistor (IGBT) and a gate turn-off thyristor (GTO) having a turn-off function by a gate signal have been developed, and are widely spread as inverter devices for power control and motor control. In addition, as a measure for reducing the environmental load in recent years, these power semiconductor elements also play a major role in the hybridization of the engine and motor of an automobile power source.

  However, these power semiconductor elements generate heat when energized, and the amount of generated heat tends to increase with increasing capacity and speed. In order to prevent deterioration in characteristics and shortening of the life of the semiconductor element due to heat generation, it is necessary to provide a heat radiating member to suppress the temperature rise in the semiconductor element and its vicinity. Copper has a large thermal conductivity of 400 W / mK and is inexpensive, so it is generally used as a heat dissipation member. However, as a heat radiating member of a semiconductor device provided with a power semiconductor element, it is bonded to silicon (Si) having a thermal expansion coefficient of 3.5 to 4.2 ppm / K or gallium arsenide (GaAs) having 5.9 ppm / K. Therefore, the coefficient of thermal expansion needs to be close to these. Copper has a large coefficient of thermal expansion of 17 ppm / K and is not preferable for solder bonding with a semiconductor element. For this reason, conventionally, a material such as molybdenum (Mo) or tungsten (W) having a thermal expansion coefficient close to that of silicon (Si) is used as the heat radiating member or provided between the semiconductor element and the heat radiating member.

  FIG. 14 is a side view showing a known heat conducting composite material. This thermal conductive composite material 100 is formed by laminating a molybdenum (Mo) material 101 having a thermal expansion coefficient close to that of a semiconductor element and a copper (Cu) material 102 having a high thermal conductivity, and then diffusion-bonding to each other by equipment such as hot pressing. In this way, they are integrated to realize intermediate properties of these materials (see, for example, Patent Document 1). The basic technical concept is common to heat conductive composites that are integrated by brazing instead of diffusion bonding, and heat conductive composites (clad materials) that are joined by successively laminating and rolling different materials. To do.

  FIG. 15 shows the relationship between the thickness ratio, the thermal conductivity, and the thermal expansion coefficient of the heat conducting composite material 100 shown in FIG. In FIG. 15, the horizontal axis represents the thickness ratio of the molybdenum (Mo) material and the copper (Cu) material in the heat conductive composite material 100, the left thermal axis represents the apparent thermal conductivity, and the right vertical axis represents the apparent thermal expansion coefficient. Is shown. In this heat conducting composite material 100, the material thickness ratio of the molybdenum (Mo) material and the copper (Cu) material is uniquely determined in order to obtain a thermal expansion coefficient (5 to 6 ppm / K) equivalent to that of the semiconductor element. , Mo: Cu = 9: 1 or so. In addition, according to FIG. 15, in this heat conductive composite material 100, the same thermal expansion coefficient (around 4 ppm / K) as silicon (Si) cannot be implement | achieved. Clad materials having a copper (Cu) / invar (Fe—Ni alloy) / copper (Cu) structure using invar (Fe—Ni alloy) instead of molybdenum (Mo) or tungsten (W) are also commercially available. However, when the thermal expansion coefficient in the plane direction is set to 5 ppm / K depending on the material thickness configuration, only a very low characteristic of 15 W / mK in the plate thickness direction can be obtained.

  FIG. 16 is a perspective view showing a known heat conducting composite material. This heat conducting composite 110 is an iron-nickel-cobalt alloy (Fe-Ni-Co) or iron-nickel alloy (Fe-Ni) having a thermal expansion coefficient equivalent to that of silicon (Si), A through-hole 111a is filled with copper or aluminum by sandwiching and rolling a plate-like body 112 of copper (Cu) or aluminum (Al) between a pair of plate-like bodies 111 provided with a through-hole 111a. (For example, refer to Patent Document 2, Patent Document 3, and Patent Document 4).

  Since the heat conductive composite material 110 exposes a part of the plate-like body 112 having a large thermal conductivity in the plate thickness direction of the plate-like body 111 which is the main heat transfer direction, the heat conductive composite material 100 described above. If the stacked structure is a serial arrangement of thermal resistances, the stacked structure of the heat conducting composite material 110 can be a parallel arrangement of thermal resistances.

  In addition, the heat transfer characteristics of the above-described heat conductive composite material 100 change in a quadratic function as shown in FIG. Expected to show. For this reason, a low-cost material such as an iron-nickel (Fe—Ni) alloy can be used for the plate-like body 111. However, the method of filling copper or aluminum into the through-hole 111a is a method that applies plastic flow by strong processing such as rolling or hot isostatic pressing, and its flow range is naturally limited. Moreover, when filled by rolling, the structure of the obtained molded product is stretched by the rolling action, and the through-hole 111a of the plate-like body 111, which was circular before rolling, is deformed into an elliptical shape after rolling. . As a result, the characteristics of the thermal expansion coefficient and thermal conductivity in the planar direction of the finished material have anisotropy, which is not preferable when used as a heat radiating member.

  On the other hand, the heat conductive composites of copper-molybdenum (Cu-Mo) alloy and copper-tungsten (Cu-W) alloy, which have different structures from those of these heat conductive composites, are almost equal to the thermal expansion coefficient of the semiconductor element. Sintered molybdenum (Mo) powder or tungsten (W) powder to produce a sintered body having a large porosity, and then impregnated with molten copper (for example, Patent Document 5) See also), or molybdenum (Mo) powder, or a composite of molybdenum (Mo) or tungsten (W) and copper (Cu) obtained by sintering a powder of tungsten (W) and copper (Cu). Body (see, for example, Patent Document 6). The characteristics of these heat conductive composites are uniquely determined by the composition ratio of molybdenum (Mo) and tungsten (W), which are skeleton structures, and copper (Cu), which is a heat conductive material. If an example of a commercial item is raised, in the material of mass ratio 89% W-11% Cu, a coefficient of thermal expansion is 6.5 ppm / K, and thermal conductivity is 180-210 W / mK. Increasing the composition ratio of copper (Cu) increases the thermal conductivity, but also increases the thermal expansion coefficient. At 80% W-20% Cu, the thermal expansion coefficient is 8.3 ppm / K, and the thermal conductivity is In particular, when the thermal expansion coefficient is remarkably increased from 200 to 230 W / mK, and the importance of matching the thermal expansion coefficient with the semiconductor element is emphasized, there is no flexibility in the selection range of the constituent ratio. Molybdenum (Mo) and tungsten (W) are heavy because of their high density, and mechanical molding is required to obtain a predetermined dimension, which requires processing costs. Furthermore, molybdenum (Mo) and tungsten (W) are a rare metal, and there is concern about the depletion of resources. As a result, the material price is also expensive, so it is essential to meet the recent demands for reducing the cost of electronic devices. difficult.

Japanese Patent No. 2860037 Japanese Patent Publication No. 63-3741 Japanese Patent Publication No. 7-80272 JP-A-9-312364 JP 59-141247 A JP 62-294147 A

  As described above, any semiconductor device on which a semiconductor element is mounted generates heat in its operation, and there is a risk of impairing the function of the semiconductor element when the heat is stored. For this reason, the heat radiating member excellent in thermal conductivity for dissipating generated heat to the outside is required. Since the heat dissipating member is joined to the semiconductor element directly or via an insulating layer, consistency with the semiconductor element is required not only in terms of thermal conductivity but also in terms of coefficient of thermal expansion. The above-described heat conductive composite material achieves a thermal expansion coefficient close to that of a semiconductor element and a heat conductivity of around 200 W / mK by combining two metal materials having different physical properties.

  However, if higher thermal conductivity is to be obtained, the component ratio of copper (Cu) in the constituent material must be increased, but this increases the thermal expansion coefficient of the entire heat dissipating member, resulting in low thermal expansion. A heat dissipation board with high thermal conductivity could not be realized.

  Considering the essential cause of this problem, the above-mentioned heat conduction composite material has a structure in which a material mainly composed of heat conduction and a material mainly composed of suppressing the coefficient of thermal expansion are coupled to each other. . Here, if the characteristics required for the heat radiating member of the semiconductor element are arranged, first, the consistency of the thermal expansion coefficient required for the heat radiating member is necessary in the surface direction in which the semiconductor element is in contact with the heat radiating member. It is not necessary in the thickness direction. The main heat transfer direction of the thermal conductivity is required in the plate thickness direction of the heat radiating member. Therefore, a high thermal conductivity material is arranged in the plate thickness direction where high thermal conductivity is required, and at the same time, it is a separation structure that does not transmit the effect of thermal expansion of the high thermal conductivity material in the plane direction, and the heat radiating member is integrated It is required to be a structure.

  The present invention has been made in view of the above, and suppresses thermal expansion in the plane direction and ensures high thermal conductivity in the plate thickness direction so as to match the semiconductor element to be mounted. An object of the present invention is to provide a heat conductive composite material and a method for producing the same.

  In order to achieve the above object, a heat conductive composite material according to the present invention is a heat conductive composite material formed by laminating a plurality of plate-like bodies having different thermal expansion coefficients and heat conductivity, and is relatively A first plate-like body formed by a material having a small expansion coefficient and having a plurality of through holes penetrating along the plate thickness direction, and a material having a larger thermal conductivity than the first plate-like body A pair of second plates that are molded and bonded to two surfaces of the first plate, respectively, and a material having a larger thermal conductivity than the first plate, A heat transfer body disposed in each of the plurality of through-holes in such a manner that a gap is secured in at least a part between the inner wall surfaces of the through-holes and is bonded to the pair of second plate-like bodies, respectively. It is provided with.

  The heat conductive composite material according to the present invention is a heat conductive composite material formed by laminating a plurality of plate-like bodies having different thermal expansion coefficients and thermal conductivity, and a material having a relatively low thermal expansion coefficient. And a first plate-like body having a plurality of through holes penetrating along the plate thickness direction, and a material having a larger thermal conductivity than the first plate-like body, A pair of second plate-like bodies laminated on the two surfaces of one plate-like body, and a material having a larger thermal conductivity than the first plate-like body, and the inner wall surface of the through hole A heat transfer body disposed in each of the plurality of through-holes in a manner of contacting each of the pair of second plate-shaped bodies, while ensuring a gap in at least a portion between Between the first plate and the pair of second plates, and the heat transfer body and the pair of second plates Characterized in that the integrated by diffusion bonding respectively between.

  Further, the present invention is the above-described heat conductive composite material, wherein the heat transfer body is a columnar shape having a cross-sectional shape that is similar to the internal cross-sectional shape of the through hole formed in the first plate-like body. It is a member.

  Further, the present invention is the above-described heat conductive composite material, wherein the first plate-like body has a through hole having a circular cross section, and the heat transfer body is a columnar member having a circular cross section. It is characterized by being.

  In addition, the method for manufacturing a heat conductive composite material according to the present invention is configured by laminating a plurality of plate-like bodies having different thermal expansion coefficients and thermal conductivities, and is formed using a material having a relatively small thermal expansion coefficient. The first plate-shaped body is formed by a first plate-shaped body having a plurality of through holes penetrating along the plate thickness direction, and a material having a larger thermal conductivity than the first plate-shaped body. Between a pair of second plate-like bodies joined to the two surfaces, and a material having a larger thermal conductivity than the first plate-like body, and between the inner wall surfaces of the through holes A heat conductive composite material comprising a heat transfer body disposed in each of the plurality of through-holes in a mode in which a gap is secured at least in part and is bonded to the pair of second plate-like bodies, respectively. The second plate on a surface located below the first plate-like body. Laminating the sheet-like body, placing the heat transfer body in the through holes of the first plate-like body, and laminating the second plate-like body on the surface located above the first plate-like body. And applying the pressure along the thickness direction of the laminated first plate and the pair of second plates to form the first plate and the pair of second plates. And a step of performing diffusion bonding between the heat transfer body and the pair of second plate-like bodies.

  In addition, the method for manufacturing a heat conductive composite material according to the present invention is configured by laminating a plurality of plate-like bodies having different thermal expansion coefficients and thermal conductivities, and is formed using a material having a relatively small thermal expansion coefficient. The first plate-shaped body is formed by a first plate-shaped body having a plurality of through holes penetrating along the plate thickness direction, and a material having a larger thermal conductivity than the first plate-shaped body. Between a pair of second plate-like bodies joined to the two surfaces, and a material having a larger thermal conductivity than the first plate-like body, and between the inner wall surfaces of the through holes A heat conductive composite material comprising a heat transfer body disposed in each of the plurality of through-holes in a mode in which a gap is secured at least in part and bonded to the pair of second plate-like bodies, respectively. A first plate-like body penetrating in one second plate-like body The step of preliminarily diffusing and bonding the heat transfer body to each of the parts corresponding to the above, and the step of laminating the first plate-like body on the one second plate-like body in a mode of disposing the heat transfer body in each of the through holes And a step of laminating the other second plate-like body on the first plate-like body in such a manner that the first plate-like body is sandwiched between the second plate-like body to which the heat transfer body is diffusion-bonded, By applying pressure along the thickness direction of the laminated first plate and the pair of second plates, between the first plate and the pair of second plates and the transmission. And a step of performing diffusion bonding between the thermal body and the other second plate-like body.

  In addition, the method for manufacturing a heat conductive composite material according to the present invention is configured by laminating a plurality of plate-like bodies having different thermal expansion coefficients and thermal conductivities, and is formed using a material having a relatively small thermal expansion coefficient. The first plate-shaped body is formed by a first plate-shaped body having a plurality of through holes penetrating along the plate thickness direction, and a material having a larger thermal conductivity than the first plate-shaped body. Between a pair of second plate-like bodies joined to the two surfaces, and a material having a larger thermal conductivity than the first plate-like body, and between the inner wall surfaces of the through holes A heat conductive composite material comprising a heat transfer body disposed in each of the plurality of through-holes in a mode in which a gap is secured at least in part and is bonded to the pair of second plate-like bodies, respectively. A first plate-like body penetrating in one second plate-like body A step of integrally forming the heat transfer body in a portion corresponding to the above, and a step of laminating the first plate-like body on the one second plate-like body in such a manner that the heat transfer body is disposed in each of the through holes. And a step of laminating the other second plate-like body on the first plate-like body in such a manner that the first plate-like body is sandwiched between the second plate-like body to which the heat transfer body is diffusion-bonded, By applying pressure along the thickness direction of the laminated first plate and the pair of second plates, between the first plate and the pair of second plates and the transmission. And a step of performing diffusion bonding between the thermal body and the other second plate-like body.

  Further, the present invention applies to the method for manufacturing a heat conductive composite described above, the heat transfer body is formed into a spherical shape having an outer diameter larger than the plate thickness of the first plate-like body. Features.

  In the method for manufacturing a heat conductive composite material described above, the present invention is such that a spherical concave portion is formed in advance in each of the portions corresponding to the through holes of the first plate-like body in the second plate-like body. Features.

  Further, the present invention is the above-described method for manufacturing a heat conducting composite material, wherein the first plate-like body has a through hole having a circular cross section, and the heat transfer body has a circular cross section. It is characterized by applying a columnar shape.

  According to the heat conductive composite material according to the present invention, a pair of heat transfer members is provided by joining the second plate member to the two surfaces of the first plate member and disposing the first plate member in the through holes. Since the second plate-like bodies are connected to each other, high thermal conductivity can be ensured in the thickness direction of the heat conductive composite material. In addition, since a gap is secured at least partially between the through hole of the first plate-like body and the heat transfer body, the influence of the thermal expansion of the heat transfer body on the first plate-like body is as much as possible. It is possible to reduce the coefficient of thermal expansion along the surface direction of the heat conducting composite material.

  Moreover, according to the manufacturing method of the heat conductive composite material which concerns on this invention, it is between a 1st plate-shaped body and a pair of 2nd plate-shaped body by diffusion bonding, and between a heat exchanger and a pair of 2nd plate-shaped body. Since the spaces are integrated, the gap between the inner wall surface of the through hole and the heat transfer body can be accurately managed as compared with other joining methods such as brazing and welding. That is, since there is no possibility that high heat at the time of brazing or welding that has flowed out during brazing will affect the above-mentioned gap, the influence on the first plate-like body due to the thermal expansion of the heat transfer body is further suppressed, It becomes possible to realize a heat conducting composite material with extremely high performance.

FIG. 1 is a cross-sectional side view of a heat conducting composite material according to Embodiment 1 of the present invention. FIG. 2 is a plan view of the heat conducting composite shown in FIG. FIG. 3A is a cross-sectional view illustrating a state where a jig is mounted on the second plate-like body in the process of manufacturing the heat conducting composite material illustrated in FIG. 1. FIG. 3-2 is a cross-sectional view illustrating a state in which a heat transfer member is disposed in the jig accommodation hole in the process of manufacturing the heat conductive composite material illustrated in FIG. 1. FIG. 3C is a cross-sectional view illustrating a state where the heat transfer body is temporarily joined to the second plate-like body in the process of manufacturing the heat conductive composite material illustrated in FIG. 1. 3-4 is a cross-sectional view illustrating a state in which the first plate-like body is stacked on the second plate-like body in the process of manufacturing the heat conductive composite material illustrated in FIG. 1. 3-5 is a cross-sectional view illustrating a state in which the second plate-like body is laminated and joined to the first plate-like body in the process of manufacturing the heat conductive composite material illustrated in FIG. 1. FIG. 4 is a graph showing the relationship between the plate thickness of the second plate-like body and the coefficient of thermal expansion along the surface direction in the heat conducting composite shown in FIG. FIG. 5 is an exploded perspective view showing a detailed shape of the heat conducting composite material used in FIG. FIG. 6 is a cross-sectional side view of the heat conducting composite material according to the second embodiment of the present invention. FIG. 7 is a plan view of the heat conducting composite shown in FIG. 8A is a cross-sectional view illustrating a state where a jig is mounted on the heat transfer body in the process of manufacturing the heat conductive composite material illustrated in FIG. 6. FIG. 8-2 is a cross-sectional view illustrating a state in which the heat transfer body is temporarily joined to the second plate-like body in the process of manufacturing the heat conductive composite material illustrated in FIG. 6. 8-3 is a cross-sectional view illustrating a state in which the first plate-like body is stacked on the second plate-like body in the process of manufacturing the heat conductive composite material illustrated in FIG. 6. FIG. 8-4 is a cross-sectional view illustrating a state in which the second plate-like body is laminated and bonded to the first plate-like body in the process of manufacturing the heat conductive composite material illustrated in FIG. 6. FIG. 9 is an enlarged cross-sectional view of the heat conducting composite shown in FIG. FIG. 10 is a cross-sectional side view of a heat conducting composite material according to Embodiment 3 of the present invention. FIG. 11 is a cross-sectional side view showing the shape of the second plate-like body shown in FIG. FIG. 12 is an exploded perspective view of the heat conducting composite material according to the fourth embodiment of the present invention. FIG. 13 is a cross-sectional side view showing the cross-sectional shape of the second plate-like body in the heat conducting composite shown in FIG. FIG. 14 is a side view showing a known heat conducting composite material. FIG. 15 is a graph showing the relationship between the thickness ratio, the thermal conductivity, and the thermal expansion coefficient of the heat conducting composite shown in FIG. FIG. 16 is a perspective view showing a known heat conducting composite material.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of a heat conductive composite material and a manufacturing method thereof according to the present invention will be described in detail with reference to the accompanying drawings.

(Embodiment 1)
1 and 2 show a heat conducting composite material according to Embodiment 1 of the present invention. The heat conductive composite material 10 includes a core material (first plate-like body) 11 provided with a large number of through holes 11 a, a heat transfer material (heat transfer body) 12 accommodated in the through holes 11 a, and a core material 11. A surface layer material (second plate-like body) 13 joined to the heat transfer material 12 on one surface and a surface layer material (second plate-like body) 14 joined to the heat transfer material 12 on the other surface of the core material 11. And is configured.

  The core material 11 is a flat body formed of a material having a smaller coefficient of thermal expansion than the heat transfer material 12 and the surface layer materials 13 and 14, for example, invar (Fe—Ni alloy). The core material 11 is provided with a number of through holes 11a along the thickness direction. The through-holes 11a penetrate from one surface of the core member 11 to the other surface so as to be located at lattice points of a square lattice with a square cross section, respectively, and are provided by, for example, an etching method. Here, the opening dimension of the through hole 11a formed by the etching method is generally limited to the same thickness as the plate thickness. Therefore, for example, when the core material 11 having a plate thickness of 1 mm and the through hole 11a of 0.45 mm × 0.45 mm is required, the core material 11 is configured by superposing at least a plurality of plate-like bodies. Will have to. Therefore, in the first embodiment, two thin plates having a plate thickness of 0.4 mm provided with through holes 11a of 0.45 × 0.45 mm are stacked by an etching method, and the plate thickness is 0.8 (0.4 A core material 11 having a size of × 2) mm and a through hole 11a of 0.45 mm × 0.45 mm was configured.

  The core material 11 described above is provided with the through hole 11a having a square cross section. However, the through hole 11a is not limited to the square cross section, and the cross section is circular, rectangular, and many. Any of a square shape may be sufficient. The plurality of through holes 11a do not have to have the same shape as each other, and those having a plurality of shapes may be combined.

  The heat transfer material 12 is a block-shaped member formed of a material having a larger thermal conductivity than the core material 11, for example, oxygen-free copper (pure copper). In the first embodiment, the cross section is a square cuboid whose cross section is similar to the cross section of the through hole 11a, and the through hole is in a state where at least two outer surfaces ensure a gap between the inner wall surface of the through hole 11a. It is comprised so that it may have a dimension smaller than the dimension of the through-hole 11a so that it may be accommodated in the inside of 11a. On the other hand, the height dimension of the heat transfer material 12 is required to be equal to or greater than the thickness of the core material 11. Therefore, as described above, when the dimension of the through hole 11a formed in the core material 11 is 0.45 mm × 0.45 mm, the planar dimension of the heat transfer material 12 is, for example, 0.42 mm × 0.42 mm, When the plate thickness of the core material 11 is 0.8 mm, the height of the heat transfer material 12 is set to 0.85 mm, for example. The heat transfer material 12 having such dimensions can be manufactured by, for example, an etching method.

  In addition, although the heat transfer material 12 mentioned above shall be manufactured by the etching method, it is not restricted to manufacture by an etching method, A cross section is square (in the above-mentioned example, 0.42 mm x 0.42 mm). The wire may be manufactured by cutting it at a predetermined length (0.85 mm in the above example), or a plate having a predetermined thickness (0.85 mm or 0.42 mm in the above example) is pressed. You may manufacture by punching with a machine etc.

  Further, although the heat transfer material 12 having a columnar shape with a square cross section is applied, the heat transfer material 12 may be any one of a circular shape, a rectangular shape, and a polygonal shape as with the through hole 11a of the core material 11. Even a columnar shape can be applied. However, the cross-sectional shape of the heat transfer material 12 is preferably similar to the through hole 11 a of the core material 11.

  Similar to the heat transfer material 12, the surface layer materials 13 and 14 are flat plates formed of a material having a higher thermal conductivity than the core material 11. In the first embodiment, a flat plate-like body having a thickness of 0.03 mm made of the same oxygen-free copper as the heat transfer material 12 is used. Further, the surface layer members 13 and 14 are formed to have the same vertical and horizontal dimensions as the core member 11 so as to cover the entire two surfaces of the core member 11. The surface layer materials 13 and 14 having such dimensions can be manufactured by, for example, an etching method.

  FIG. 3 shows a method of manufacturing the heat conducting composite material 10 using the core material 11, the heat transfer material 12 and the pair of surface layer materials 13 and 14 described above. Hereinafter, the manufacturing method of the heat conductive composite material 10 is demonstrated, referring this figure.

  First, in this manufacturing method, the heat transfer material 12 is joined to the part corresponding to the through-hole 11a of the core material 11 in one surface layer material 13, respectively. When joining the heat transfer material 12 and the surface layer material 13, as shown in FIG. 3A, a dedicated jig J 1 is applied, and the surface layer material 13 is mounted in advance with the jig J 1.

  The jig J1 has a plate shape that is the same shape as the core material 11 described above, and has a receiving hole JH1 at a portion corresponding to the through hole 11a of the core material 11. The accommodation hole JH1 is a square whose cross-sectional shape is similar to that of the through-hole 11a, and has a slightly small size. For example, when the through hole 11a of the core material 11 is 0.45 mm × 0.45 mm as described above, a 0.43 mm × 0.43 mm accommodation hole JH1 is provided in the jig J1. More specifically, a jig J1 having a plate thickness of 0.8 mm is configured by bonding two thin plates having a plate thickness of 0.4 mm having a receiving hole JH1 of 0.43 mm × 0.43 mm. Yes. The material of the jig J1 to be applied is preferably one having a thermal expansion coefficient equal to or lower than that of the core material 11.

  Moreover, it is preferable to provide the guide hole GH in the mutually corresponding site | part in each of the core material 11, the surface layer materials 13 and 14, and the jig | tool J1 mentioned above. If the alignment pins AP are inserted through the guide holes GH, the mutual positions can be easily and accurately defined. That is, in the step of mounting the jig J1 on the surface layer material 13 described above, the mutual position can be easily achieved by sequentially inserting the surface layer material 13 and the jig J1 through the alignment pins AP through the respective guide holes GH. And can be accurately defined. In addition, it is preferable to interpose a material that inhibits diffusion bonding between the jig J1 and the surface layer material 13.

  From this state, as shown in FIG. 3-2, if the heat transfer material 12 is inserted into the accommodation hole JH1 of the jig J1, a plurality of heat transfer materials 12 are arranged at correct positions with respect to the surface layer material 13. Can do.

  Next, as shown in FIG. 3C, after pressing the end face of the inserted heat transfer material 12 with a plate material B that inhibits diffusion bonding, such as quartz, an appropriate pressure is applied, and the surface layer material 13 and the heat transfer material 12 Is temporarily bonded by diffusion bonding. In addition, you may temporarily join between the surface layer material 13 and the heat-transfer material 12 by methods other than diffusion bonding.

  Thereafter, the jig J1 is removed in a state in which the heat transfer material 12 is cooled, and the core material 11 is inserted into the alignment pin AP through the guide hole GH so that the core material 11 is laminated on the surface layer material 13. As shown to 3-4, the heat-transfer material 12 will be arrange | positioned at each through-hole 11a of the core material 11, respectively.

  Further, from this state, as shown in FIG. 3-5, after the other surface layer material 14 is inserted through the alignment pin AP through the guide hole GH, it is placed in an inert gas atmosphere or in a vacuum, By heating and pressurizing with temperature and pressure, diffusion bonding between the pair of surface layer materials 13, 14 and the heat transfer material 12, and between the pair of surface layer materials 13, 14 and the core material 11, A heat conducting composite material 10 is configured in which a core material 11, a plurality of heat transfer materials 12, and a pair of surface layer materials 13 and 14 are integrated. However, as described above, since the size of the heat transfer material 12 is made smaller than the through hole 11a of the core material 11, the core material 11, the plurality of heat transfer materials 12, and a pair of surface layer materials are further provided. As shown in FIG. 1, gaps x and y are ensured between the outer surface of the heat transfer material 12 and the inner wall surface of the through hole 11a. Will be. In addition, after integrating the core material 11, the plurality of heat transfer materials 12, and the pair of surface layer materials 13 and 14 by diffusion bonding, it is preferable to close the guide hole GH used for positioning. .

  When the heat conductive composite material 10 configured as described above is used as a heat radiating member, any one surface layer material, for example, the surface layer material 13 may be bonded to a heat source such as a chip. The heat transferred to the surface layer material 13 is thermally transferred from the surface layer material 13 to the heat transfer material 12 and from the heat transfer material 12 to the surface layer material 14. The surface layer material 13, the heat transfer material 12 and the surface layer material 14 are all made of a material having a high thermal conductivity, and are in an integrated state by diffusion bonding. Therefore, it is possible to efficiently dissipate heat from a heat source such as a chip.

  During this time, the heat transfer material 12 and the pair of surface layer materials 13 and 14 thermally expand in the heat transfer direction, and also expand in the direction perpendicular to the heat transfer direction, that is, along the surface direction of the heat conductive composite material 10. Become. However, as described above, gaps x and y are secured at least partially between the inner wall surface of the through hole 11 a formed in the core material 11 and the outer surface of the heat transfer material 12. Therefore, even when the heat transfer material 12 is thermally expanded along the surface direction of the heat conducting composite material 10, the influence on the core material 11 can be suppressed as much as possible. Further, the pair of surface layer materials 13 and 14 are both joined to the core material 11 with a large area. As a result, according to the heat conductive composite material 10, the core material 11 having a smaller coefficient of thermal expansion than the pair of surface layer materials 13 and 14 and the heat transfer material 12 determines the coefficient of thermal expansion along the surface direction. Therefore, even when a large thermal conductivity is set in the plate thickness direction, the thermal expansion coefficient along the surface direction can be kept small, and heat can be efficiently radiated from the chip without causing peeling or cracking in the bonded chip. be able to.

  Specifically, in the heat conduction composite material 10 according to the first embodiment described above, when the area occupation ratio of the heat transfer material 12 to the core material 11 is 70%, the heat conductivity in the plate thickness direction is 250 to 280 W. / MK, and a coefficient of thermal expansion along the surface direction of 5.5 to 6.5 ppm / K could be obtained.

  When the completed heat conducting composite material 10 was cut and the flat cross section was confirmed, not all of the heat transfer materials 12 were located at the center of the through hole 11a of the core material 11, and the heat transfer material 12 was transferred to the inner wall surface of the through hole 11a. It was also confirmed that the outer surface of the heat material 12 was partially in contact. This is considered to be affected by thermal expansion during diffusion bonding and assembly accuracy. However, even if the outer surface of the heat transfer material 12 contacts the inner wall surface of the through hole 11a of the core material 11, the influence of thermal stress due to the thermal expansion of the heat transfer material 12 acting on the core material 11 is slight. It was confirmed. This is because if the dimension of the through hole 11a formed in the core material 11 and the outer dimension of the heat transfer material 12 are used, the entire outer surface of the heat transfer material 12 does not contact the inner wall surface of the through hole 11a. It is thought that. In addition, since a large number of heat transfer materials 12 are provided, the amount of individual deformation due to thermal expansion becomes small (in the above example, the amount of deformation of the heat transfer material 12 due to thermal expansion is about 2 μm), as well as the core material It is also considered that the contact point with 11 becomes random. Therefore, it is not necessary that the inner wall surface of the through hole 11a and the outer surface of the heat transfer material 12 are separated from each other over the entire circumference, and there is no difference between the inner wall surface of the through hole 11a and the outer surface of the heat transfer material 12. If a gap is ensured even in the portion, the influence of thermal stress due to the thermal expansion of the heat transfer material 12 acting on the core material 11 can be suppressed to a low level.

  The oxygen-free copper applied as the heat transfer material 12 in the first embodiment described above is appropriate from the viewpoint of cost and workability. However, the area occupation ratio of the heat transfer material 12 to the core material 11 is a dominant factor of the heat conductivity in the thickness direction of the entire heat conductive composite material 10, and a material having a higher heat conductivity is used for the heat transfer material 12. It is possible. For example, by using as a heat transfer material 12 a composite material in which diamond or cubic boron nitride (CBN) powder is dispersed in copper (Cu) at a high volume ratio, the thermal conductivity in the plate thickness direction is greatly improved. It is also possible. Therefore, the material of the heat transfer material 12 is not limited to a pure metal such as copper (Cu), and any composite material or nonmetal described above can be used as long as it can be joined to the surface layer materials 13 and 14. .

  FIG. 4 shows the relationship between the plate thickness of the surface layer materials 13 and 14 and the coefficient of thermal expansion along the surface direction of the heat conductive composite material 10 in the heat conductive composite material 10 having the same configuration as that of the first embodiment. Is. As the core material 11, a material having a plate thickness of 2.0 mm formed by Invar having a thermal expansion coefficient of 1.2 ppm / K is applied. As shown in FIG. 5, the core material 11 is formed with a through hole 11a having a circular shape with a cross section of φ = 2.1 mm. As the heat transfer material 12, a cylindrical material is used that is formed of oxygen-free copper having a thermal expansion coefficient of 17 ppm / K into a cylindrical shape having a cross section of φ = 2.0 mm. The area occupation ratio of the heat transfer material 12 to the core material 11 is 70%. As the surface layer materials 13 and 14, as with the heat transfer material 12, oxygen-free copper having a coefficient of thermal expansion of 17 ppm / K was applied. The plate | board thickness of the surface layer materials 13 and 14 was changed in 0.025-0.3 mm, and the change of the thermal expansion coefficient along the surface direction of the heat conductive composite material 10 was measured.

  As is apparent from FIG. 4, when the plate thickness of the surface material 13, 14 is increased, the coefficient of thermal expansion along the surface direction of the heat conducting composite material 10 also tends to increase. During this time, the thermal conductivity in the plate thickness direction did not change at 284 W / mk because the area occupation ratio of the heat transfer material 12 to the core material 11 was not changed. That is, according to the heat conductive composite material 10 of Embodiment 1, by appropriately changing the plate thickness of the surface layer materials 13 and 14, the coefficient of thermal expansion along the surface direction can be adjusted to a desired value, In addition, by appropriately changing the area occupation ratio of the heat transfer material 12 to the core material 11, the thermal conductivity in the thickness direction can be adjusted to a desired value, and performance according to various requirements can be exhibited. It becomes.

  In the heat conductive composite material 10 described above, diffusion bonding is performed between the surface layer material 13 and the heat transfer material 12 and between the heat transfer material 12 and the surface layer material 14, but is limited to diffusion bonding. Instead, other metallurgical joining methods such as brazing including solder, laser welding, and electron beam welding can be applied.

  If the core material 11 is replaced with a material having high thermal conductivity such as molybdenum (Mo), the thermal conductivity of the thermal conductive composite material 10 can be set to 320 W / mK. Accordingly, various materials can be selected for the core material 11 in accordance with the overall thermal expansion coefficient and thermal conductivity which are targeted, and the material is not limited to the first embodiment.

(Embodiment 2)
In the first embodiment described above, when the heat transfer material 12 is inserted into the jig receiving hole in the manufacturing process, the direction of the heat transfer material 12 needs to be adjusted, and the number of the heat transfer materials 12 is large, so that the operation is easy. For this purpose, a special device for arranging the heat transfer material 12 is required. Therefore, in the second embodiment, a heat conductive composite material and a method for manufacturing the heat conductive composite material that can facilitate the manufacturing operation without separately preparing a special device will be described.

  6 and 7 show the heat conductive composite material according to the second embodiment of the present invention, and FIGS. 8-1 to 8-4 show the manufacture of the heat conductive composite material according to the second embodiment. The method is shown. As shown in FIG. 8A, in the heat conduction composite material 20, a material having a higher thermal conductivity than the core material (first plate-like body) 21 as the heat transfer material (heat transfer body) 22, for example, copper ( A product formed into a spherical shape by Cu) is applied. Specifically, a copper spherical body having an outer diameter of 0.5 mm is used as the heat transfer material 22. This copper sphere is widely distributed as a core material of a solder sphere used in a BGA (Ball Grid Array) package which is a semiconductor mounting means, and can be easily obtained. In addition, the copper spherical body used in the BGA package as described above is suitable as the heat transfer material 22 of the second embodiment because accuracy such as sphericity is guaranteed.

  The core material 21 is a flat plate formed of a material having a smaller coefficient of thermal expansion than the heat transfer material 22 and the surface layer materials (second plate bodies) 23, 24, for example, invar (Fe—Ni alloy). The core member 21 is provided with a number of through holes 21a along the thickness direction. Each of the through holes 21a has a circular shape similar to the projected shape of the heat transfer material 22 in plan view, and penetrates from one surface of the core material 21 to the other surface so as to be positioned at a lattice point of the triangular lattice. For example, it is provided by an etching method. In the second embodiment, when the 0.5 mm heat transfer material 22 is used, the core material 21 having a plate thickness of 0.45 mm and an inner diameter of the through hole 21a of 0.6 mm is applied. That is, as the core material 21, a spherical body used as the heat transfer material 22 is set so that the plate thickness is smaller than the outer diameter and the inner diameter of the through hole 21 a is slightly larger than the outer diameter. is doing.

  In addition, the surface layer materials 23 and 24 used for the heat conductive composite material 20 which is Embodiment 2 are the same as the surface layer materials 13 and 14 applied by the heat conductive composite material 10 of Embodiment 1 mentioned above with respect to the core material 21. Therefore, the detailed description is omitted.

  When the heat conductive composite material 20 is manufactured using the core material 21, the heat transfer material 22, and the pair of surface layer materials 23, 24 described above, first, one surface layer material 23 corresponds to the through hole 21 a of the core material 21. The heat transfer material 22 is joined to each part to be performed. When joining the heat transfer material 22 and the surface layer material 23, as shown in FIG. 8A, a dedicated jig J2 is applied, and the heat transfer material 22 is mounted on the surface layer material 23 in advance. The position with the surface material 23 is defined.

  The jig J2 has a plate shape having the same shape as that of the core material 21 described above, and has a receiving hole JH2 at a portion corresponding to the through hole 21a of the core material 21. The accommodation hole JH2 has a circular shape whose cross-sectional shape is similar to that of the through hole 21a, and is slightly smaller than the through hole 21a. For example, when the through hole 21a of the core member 21 has an inner diameter of 0.6 mm, the jig J2 is provided with a housing hole JH2 of 0.51 mm. More specifically, the jig J2 is constituted by a thin plate having a plate thickness of 0.45 mm having a housing hole JH2 of 0.51 mm. It is preferable that the material of the jig J2 to be applied has a thermal expansion coefficient equal to or lower than that of the core material 21.

  Further, although not clearly shown in the drawing, as in the first embodiment, each of the core material 21, the surface layer materials 23 and 24, and the jig J2 is provided with a guide hole at a corresponding portion and laminated. It is preferable that the alignment pins are sequentially inserted through the guide holes in order. From this state, as shown in FIG. 8A, if the heat transfer material 22 is inserted into the accommodation hole JH2 of the jig J2, a plurality of heat transfer materials 22 are arranged at correct positions with respect to the surface layer material 23. Can do.

  Here, in the second embodiment in which a spherical shape is applied as the heat transfer material 22, it can be moved by rolling on the upper surface of the jig J2. In addition, the heat transfer material 22 that is a spherical body does not need to define the direction or direction when it is disposed in the accommodation hole JH2 of the jig J2. Therefore, when the heat transfer material 22 is disposed in the accommodation hole JH2 of the jig J2, a plurality of heat transfer materials 22 may be poured into the upper surface of the jig J2. The heat transfer material 22 poured into the upper surface of the jig J2 is accommodated inside the accommodation hole JH2 (when the heat transfer material 22 is not accommodated), while the accommodation hole JH2 is already filled. If the heat transfer material 22 is housed, it flows toward the next housing hole JH2 and is sequentially housed in the housing hole JH2. Due to the relationship between the inner diameter of the accommodation hole JH2 and the outer diameter of the heat transfer material 22, the two heat transfer materials 22 are not accommodated in one accommodation hole JH2. Therefore, by repeating this process, the heat transfer material 22 can be individually accommodated in all the accommodation holes JH2 without requiring a special device.

  Next, as shown in FIG. 8-2, after the inserted heat transfer material 22 is pressed with a plate material B that inhibits diffusion bonding, such as quartz, an appropriate pressure is applied, and the surface layer material 23 and the heat transfer material 22 are interposed. Are temporarily bonded by diffusion bonding. Thereafter, the jig J2 is removed in a state in which the heat transfer material 22 is cooled, and the core material 21 is inserted into an alignment pin (not shown) through a guide hole (not shown), whereby the core material is placed on the surface material 23. If 21 is laminated | stacked, as shown to FIGS. 8-3, the heat-transfer material 22 will be each arrange | positioned to each through-hole 21a of the core material 21. FIG.

  From this state, the other surface layer material 24 is inserted through an alignment pin (not shown) through a guide hole (not shown), and then placed in an inert gas atmosphere or in a vacuum. 4, by heating and pressurizing at a desired temperature and pressure, between the pair of surface layer materials 23 and 24 and the heat transfer material 22 and between the pair of surface layer materials 23 and 24 and the core material 21. If they are diffusion-bonded together, the heat conductive composite material 20 in which the core material 21, the plurality of heat transfer materials 22, and the pair of surface layer materials 23 and 24 are integrated is configured. At this time, since the heat transfer material 22 receives force in the load direction, the heat transfer material 22 is crushed along the thickness direction of the core material 21 and bites into the surface layer materials 23 and 24 by diffusion bonding, while in the surface direction of the core material 21. Swell along the radial direction. However, as described above, since the outer diameter of the heat transfer material 22 is smaller than the through hole 21a of the core material 21, the core material 21, the plurality of heat transfer materials 22, and a pair of surface layers are further provided. Since the members 23 and 24 are integrated by diffusion bonding, as shown in FIG. 9, the outer surface of the heat transfer material 22 and the inner wall surface of the through-hole 21a are almost entirely covered. The gap d is secured.

  It is not always necessary to temporarily bond the surface layer material 23 and the heat transfer material 22 using the jig J2 described above. For example, the heat transfer material 22 is poured into the through-hole 21a in a state where the core material 21 is laminated on the surface layer material 23, and after the surface layer material 24 is laminated, the heat conduction material 22 is integrated at once by diffusion bonding. The composite material 20 can be obtained. However, in this manufacturing method, there may be a case where the gap d cannot be secured over the entire circumference between the inner wall surface of the through hole 21 a formed in the core member 21 and the outer surface of the heat transfer material 22.

  However, according to the dimension of the through hole 21a and the outer diameter of the heat transfer material 22, the entire outer surface of the heat transfer material 22 does not contact the inner wall surface of the through hole 21a. The influence of thermal stress due to the thermal expansion acting on the core material 21 is slight. In addition, since a large number of heat transfer materials 22 are provided, not only the amount of individual deformation due to thermal expansion is reduced, but also that the contact point with the core material 21 is random is considered as the above-mentioned factor. That is, the inner wall surface of the through hole 21a and the outer surface of the heat transfer material 22 do not need to be separated from each other over the entire circumference, and there is no difference between the inner wall surface of the through hole 21a and the outer surface of the heat transfer material 22. If the gap d is secured even at the portion, the influence of thermal stress due to the thermal expansion of the heat transfer material 22 acting on the core material 21 can be suppressed to a small level.

  When the heat conductive composite material 20 configured as described above is used as a heat radiating member, any one surface layer material, for example, the surface layer material 23 may be bonded to a heat source such as a chip. The heat transferred to the surface layer material 23 is thermally transferred from the surface layer material 23 to the heat transfer material 22 and from the heat transfer material 22 to the surface layer material 24. The surface layer material 23, the heat transfer material 22 and the surface layer material 24 are all made of a material having a high thermal conductivity, and are in an integrated state by diffusion bonding. Therefore, it is possible to efficiently dissipate heat from a heat source such as a chip.

  During this time, the heat transfer material 22 and the pair of surface layer materials 23 and 24 thermally expand in the heat transfer direction, and also expand in the direction orthogonal to the heat transfer direction, that is, along the surface direction of the heat conducting composite material 20. Become. However, as described above, a gap d is secured at least partially between the inner wall surface of the through hole 21 a formed in the core member 21 and the outer surface of the heat transfer material 22. Therefore, even when the heat transfer material 22 is thermally expanded along the surface direction of the heat conducting composite material 20, the influence on the core material 21 can be suppressed as much as possible. The pair of surface layer materials 23 and 24 are both joined to the core material 21 with a large area. As a result, according to the heat conductive composite material 20, the core material 21 having a smaller coefficient of thermal expansion than the pair of surface layer materials 23, 24 and the heat transfer material 22 determines the coefficient of thermal expansion along the surface direction. Therefore, even when a large thermal conductivity is set in the plate thickness direction, the thermal expansion coefficient along the surface direction can be kept small, and the bonded chip can be efficiently removed from the chip without causing peeling or cracking. It becomes possible to dissipate heat.

  In the second embodiment described above, since the copper spherical body is used for the heat transfer material 22, it can be easily poured into the accommodation hole JH2 of the jig J2. For this reason, the operation | work which inserts the heat-transfer material 22 in the accommodation hole JH2 of the jig | tool J2 becomes easy, and the special apparatus for inserting the heat-transfer material 22 in the accommodation hole JH2 of the jig | tool J2 becomes unnecessary.

  Moreover, since the copper spherical body is widely distributed as a core material of a solder sphere used for the BGA package and can be obtained at a low price, the material cost of the heat conducting composite material 20 can be reduced.

  The heat transfer material 22 is not limited to copper (Cu), and a metal material such as silver (Ag) or a material in which diamond or CBN powder is dispersed in copper (Cu) at a high volume ratio is used. Thus, it is possible to greatly improve the thermal conductivity in the thickness direction.

  In addition, diffusion bonding is performed between the surface layer material 23 and the heat transfer material 22 described above, and between the heat transfer material 22 and the surface layer material 24. However, the bonding is not limited to diffusion bonding, and brazing including solder. Metallic metallurgical joining such as laser welding and electron beam welding can be applied.

(Embodiment 3)
In the second embodiment described above, the flat surface layer materials 23 and 24 are used. However, the effect of the bonding area between the spherical heat transfer material 22 and the surface layer materials 23 and 24 on the thermal conductivity is great. In the third embodiment, the junction area between them is increased.

  FIG. 10 shows a heat conductive composite material according to Embodiment 3 of the present invention. As in the second embodiment, the heat conductive composite material 30 exemplified here uses a sphere-shaped material as the heat transfer material (heat transfer body) 32, and the surface layer material (second plate-like body) to be applied. ) Only the configuration of 33 and 34 is different. That is, the pair of surface layer materials 33 and 34 applied in the third embodiment is made of a material having a higher thermal conductivity than the core material (first plate-like body) 31, for example, oxygen-free copper, and has a thickness of 0.15 mm. This is formed into a plate-like body. As shown in FIG. 11, concave portions 33 a and 34 a are provided in advance in positions corresponding to the through holes 31 a of the core material 31 in the respective surface layer materials 33 and 34. The recesses 33a and 34a have a spherical shape formed so as to have a curvature equivalent to the outer diameter of the heat transfer material 32. These concave portions 33a and 34a can be formed by, for example, half etching.

  The heat transfer material 32 applied in the third embodiment is formed by a material having a larger thermal conductivity than the core material 31, as with the surface layer materials 33 and 34. The point that it is formed of a material having a smaller coefficient of thermal expansion than those of the surface layer materials 33 and 34 and the heat transfer material 32 is the same as in the second embodiment. The point that the through hole 31a formed in the core material 31 has an inner diameter slightly larger than the outer diameter of the heat transfer material 32 is the same as that of the second embodiment.

  The method for manufacturing the heat conductive composite material 30 using the core material 31, the heat transfer material 32, and the pair of surface layer materials 33 and 34 described above is also the same as that described in the second embodiment. However, since the recessed portions 33a and 34a formed in advance when the heat transfer material 32 is disposed on the surface layer materials 33 and 34 function as positioning of the heat transfer material 32, it is necessary to use the jig J2 used in the second embodiment. Absent. That is, the surface layer material 33 and the core material 31 are sequentially inserted into the alignment pins through the guide holes and stacked, and the heat transfer material 32 is poured directly into the through holes 31a of the core material 31. In a state in which the heat transfer material 32 is accommodated in all the through holes 31a, the surface layer material 34 is inserted into the alignment pins and the surface layer material 34 is laminated on the core material 31, and then in an inert gas atmosphere or in a vacuum. By arranging and heating and pressurizing at a desired temperature and pressure, diffusion between the pair of surface layer materials 33 and 34 and the heat transfer material 32 and between the pair of surface layer materials 33 and 34 and the core material 31 is performed. If joined, the heat conductive composite material 30 in which the core material 31, the plurality of heat transfer materials 32, and the pair of surface layer materials 33 and 34 are integrated is configured.

  At this time, in the third embodiment, since the concave portions 33a and 34a are formed in the surface layer materials 33 and 34 in advance, the heat transfer material 32 can be applied without applying a large pressing force as compared with the second embodiment. A large bonding area can be ensured between and the thermal conductivity along the thickness direction can be further increased. However, as described above, since the outer diameter of the heat transfer material 32 is smaller than the through hole 31a of the core material 31, the core material 31, the plurality of heat transfer materials 32, and a pair of surface layers are further provided. Since the members 33 and 34 are integrated by diffusion bonding, a gap is ensured over the entire circumference between the outer surface of the heat transfer material 32 and the inner wall surface of the through hole 31a. Become.

  In the case where the heat conducting composite material 30 configured as described above is used as a heat radiating member, any one surface layer material, for example, the surface layer material 33 may be bonded to a heat source such as a chip. The heat transferred to the surface layer material 33 is thermally transferred from the surface layer material 33 to the heat transfer material 32 and from the heat transfer material 32 to the surface layer material 34. The surface layer material 33, the heat transfer material 32, and the surface layer material 34 are all made of a material having a high thermal conductivity, and are integrated with each other by diffusion bonding. Therefore, it is possible to efficiently dissipate heat from a heat source such as a chip.

  During this time, the heat transfer material 32 and the pair of surface layer materials 33 and 34 thermally expand in the heat transfer direction, and also expand in the direction perpendicular to the heat transfer direction, that is, along the surface direction of the heat conductive composite 30. Become. However, a gap is secured at least partially between the inner wall surface of the through hole 31 a formed in the core material 31 and the outer surface of the heat transfer material 32. Therefore, even when the heat transfer material 32 is thermally expanded along the surface direction of the heat conducting composite material 30, the influence on the core material 31 can be suppressed as much as possible. Further, the pair of surface layer materials 33 and 34 are both joined to the core material 31 with a large area. As a result, according to the heat conductive composite 30, the core material 31 having a smaller coefficient of thermal expansion than the pair of surface layer materials 33 and 34 and the heat transfer material 32 determines the coefficient of thermal expansion along the surface direction. Therefore, even when a large thermal conductivity is set in the plate thickness direction, the thermal expansion coefficient along the surface direction can be kept small, and the bonded chip can be efficiently removed from the chip without causing peeling or cracking. It becomes possible to dissipate heat.

  As described above, according to the heat conduction composite material 30 of the third embodiment, the heat transfer material 32 that is a spherical body is accommodated between the concave portion 33 a of the surface layer material 33 and the concave portion 34 a of the surface layer material 34. For this reason, the jigs J1 and J2 shown in the first and second embodiments are not applied or temporarily joined in the manufacturing stage, and positioned between the surface layer materials 33 and 34 and the heat transfer material 32. Diffusion bonding, which is direct main bonding, can be performed. For this reason, the operation | work at the time of manufacturing the heat conductive composite material 30 becomes efficient, and it becomes possible to reduce manufacturing cost.

  In the heat conduction composite material 30 according to the third embodiment described above, the ratio of the heat transfer area of the heat transfer material 32 to the contact surface height between the core material 31 and the surface layer materials 33 and 34 is the total area of the core material 31. The ratio is 60%.

  In addition, after diffusion bonding between the surface layer material 33 and the heat transfer material 32 and between the heat transfer material 32 and the surface layer material 34, the surface layer materials 33 and 34 are removed to process the heat conduction composite material 30 as a whole. The coefficient of thermal expansion can be adjusted. Specifically, lapping was performed until the surface layer materials 33 and 34 had a thickness of 0.03 mm. The thermal conductivity of the thermal conductive composite 30 thus lapped was 200 to 240 W / mK, and the thermal expansion coefficient in the plane direction was 5 to 6.6 ppm / K. Therefore, equivalent characteristics can be realized without using expensive materials such as tungsten (W) and molybdenum (Mo).

(Embodiment 4)
In the first to third embodiments described above, the surface layer materials 13, 23, 33 and the heat transfer materials 12, 22, 32 are independent members. However, in the fourth embodiment, as shown in FIG. The surface layer material (second plate-like body) 43 and the heat transfer material (heat transfer body) 42 are integrally formed in advance with a heat conduction composite material 40, which is a core material provided with a large number of through holes 41a ( (First plate-like body) 41, a heat transfer material 42 accommodated in the through hole 41 a are integrally formed, a surface layer body 45 disposed on one surface of the core material 41, and the other surface of the core material 41 And a surface layer material (second plate-like body) 44 joined to the heat transfer material.

  The core material 41 is a flat body formed of invar (Fe—Ni alloy) having a smaller coefficient of thermal expansion than the surface layer material 44 and the surface layer body 45. A large number of through holes 41a having a circular shape in plan view are provided in the core member 41 so as to be positioned at lattice points of a square lattice. The through hole 41a penetrates from one surface of the core material 41 to the other surface, and is provided by, for example, an etching method. For example, the core material 41 used in Embodiment 4 has a plate thickness of 0.3 mm and the inner diameter of the through hole 41a is 0.32 mm.

  As shown in FIG. 13, the surface layer body 45 has a surface layer material 43 having a thickness of 0.02 mm, and a diameter provided at a position corresponding to the through hole 41 a of the core material 41 on one surface of the surface layer material 43 is 0.3 mm. The heat transfer material 42 is formed integrally with a heat transfer material 42 having a height of 0.3 mm and a circular cross-sectional shape in a plan view. The heat transfer material 42 has a cross section similar to the through hole 41a.

  Thus, the surface layer body 45 in which the plurality of heat transfer materials 42 are integrally formed on the surface layer material 43 is manufactured by, for example, an electroforming method. Specifically, first, a pattern in which the outer shape of the surface layer material 43 is exposed on a metal plate such as stainless steel is formed by a resist process and a process similar to photolithography in manufacturing a semiconductor element. Next, the stainless steel plate is immersed in a copper (Cu) field deposition bath, and copper (Cu) is deposited until the plate thickness becomes 0.02 mm. Then, the stainless steel plate is taken out, the surface is washed and dried, and a cylindrical pattern having a diameter of 0.3 mm constituting the heat transfer material 42 is formed on the deposited copper (Cu) with a resist. In the electrolytic deposition bath, copper (Cu) is deposited until the plate thickness becomes 0.3 mm. When the deposition is completed, an unnecessary resist is removed, and the molded product is peeled off from the stainless steel plate, whereby the surface layer body 45 in which the heat transfer material 42 is integrally formed can be obtained.

  The surface layer material 44 is preferably made of a material having a larger thermal conductivity than the core material 41, and here, a flat plate-like body made of oxygen-free copper and having a thickness of 0.02 mm is used. Further, the surface layer material 44 has the same area as the core material 41 so as to cover the other surface of the core material 41. The surface layer material 44 having such dimensions is manufactured by, for example, an etching method.

  When manufacturing the above-described heat conductive composite material 40, first, the core material 41 and the surface layer material 44 are sequentially laminated on the surface layer body 45 arranged so that the heat transfer material 42 is on top. Although not clearly shown in the drawing, as in the first embodiment, each of the core material 41, the surface layer material 44, and the surface layer body 45 is provided with a guide hole in a corresponding part, and the guide holes are stacked in the order of stacking. It is preferable that the alignment pins are sequentially inserted through.

  From this state, it is placed in an inert gas atmosphere or in vacuum, and heated / pressurized at a desired temperature and pressure, so that the surface layer material 44 and the heat transfer material 42 of the surface layer body 45 and the surface layer material 44 When the surface layer body 45 and the core material 41 are diffusion-bonded, the heat conductive composite material 40 in which the core material 41, the surface layer material 44, and the surface layer body 45 are integrated is configured. However, as described above, since the size of the heat transfer material 42 is smaller than the through hole 41a of the core material 41, diffusion bonding is further performed between the core material 41, the surface layer material 44, and the surface layer body 45. Therefore, a gap is secured between the outer peripheral surface of the heat transfer material 42 and the inner wall surface of the through hole 41a.

  When the heat conductive composite material 40 configured as described above is used as a heat radiating member, any one surface layer material, for example, the surface layer material 43 may be bonded to a heat source such as a chip. The heat transferred to the surface layer material 43 is thermally transferred from the surface layer material 43 to the heat transfer material 42 and from the heat transfer material 42 to the surface layer material 44. The surface layer material 43, the heat transfer material 42, and the surface layer material 44 are all made of a material having a high thermal conductivity, and are integrated with each other by diffusion bonding. Therefore, it is possible to efficiently dissipate heat from a heat source such as a chip.

  During this time, the heat transfer material 42 and the pair of surface layer materials 43 and 44 thermally expand in the heat transfer direction, and also expand in the direction orthogonal to the heat transfer direction, that is, along the surface direction of the heat conductive composite 40. Become. However, a gap is secured at least partially between the inner wall surface of the through hole 41 a formed in the core member 41 and the outer surface of the heat transfer material 42. Therefore, even when the heat transfer material 42 is thermally expanded along the surface direction of the heat conducting composite material 40, the influence on the core material 41 can be suppressed as much as possible. The pair of surface layer materials 43 and 44 are both joined to the core material 41 with a large area. As a result, according to the heat conductive composite material 40, the core material 41 having a smaller coefficient of thermal expansion than the pair of surface layer materials 43 and 44 and the heat transfer material 42 determines the coefficient of thermal expansion along the surface direction. Therefore, even when a large thermal conductivity is set in the plate thickness direction, the thermal expansion coefficient along the surface direction can be kept small, and the bonded chip can be efficiently removed from the chip without causing peeling or cracking. It becomes possible to dissipate heat.

  In the heat conduction composite material 40 according to the fourth embodiment described above, the heat transfer material 42 and one surface layer material 43 are integrally formed in advance, so that the assembly accuracy is improved, and as a result, the heat transfer material in the plate thickness direction is increased. A large heat area was obtained. In addition, assembly man-hours were reduced, and assembly costs could be reduced.

  The heat transfer material 42 is not limited to a circular cylindrical shape in plan view, and may be a rectangular or polygonal column including a square in plan view.

  Further, not only the one surface layer material 43 and the heat transfer material 42 are integrally formed, but also the other surface layer material 44 and the heat transfer material 42 are integrally formed, and the heat transfer materials 42 are opposed to each other and diffusion bonded. May be. If comprised in this way, the plate | board thickness of the completed heat conductive composite material 40 can be doubled, and the ratio of the thickness direction of the core material 41 in the heat conductive composite material 40 can be increased. And if the ratio of the plate | board thickness direction of the core material 41 is increased, the heat conductivity of the surface direction of the heat conductive composite material 40 can further be reduced. For example, in the example mentioned above, the plate | board thickness of the core material 41 can be 0.6 mm.

  In electroforming, it is also possible to disperse high thermal conductive materials such as diamond or CBN as fine particles in copper (Cu) by applying the eutectoid plating technique. It is possible to further increase the thermal conductivity of the heat conductive composite 40.

  Moreover, although the manufacturing method by the electroforming method is shown in the present embodiment, a precision casting method or a metal powder is kneaded into a resin binder, injection molding is performed, and then a MIM (Metal Injection Molding) method is used. Then, the molded product may be sintered to form a surface layer material.

  In the first to fourth embodiments described above, the heat transfer body has a cross-sectional shape that is similar to the internal cross-sectional shape of the through hole formed in the first plate-like body. However, it is not always necessary to have a similar shape. For example, the internal cross-sectional shape of the through-hole may be a hexagon, and the cross-section of the heat transfer body may be a square or a circle.

  Moreover, in Embodiment 1-4 mentioned above, the manufacturing method which positions by making a guide hole in the plate-shaped body and jig | tool laminated | stacked mutually and inserting an alignment pin in these guide holes is illustrated. However, it is not always necessary to manufacture by applying the guide hole and the alignment pin.

DESCRIPTION OF SYMBOLS 10 Heat conductive composite material 11 Core material 11a Through-hole 12 Heat transfer material 13, 14 Surface layer material 20 Heat conductive composite material 21 Core material 21a Through hole 22 Heat transfer material 23, 24 Surface layer material 30 Heat conductive composite material 31 Core material 31a Through Hole 32 Heat transfer material 33, 34 Surface layer material 33a, 34a Recess 40 Heat conduction composite material 41 Core material 41a Through hole 42 Heat transfer material 43, 44 Surface layer material

Claims (10)

A heat conduction composite material formed by laminating a plurality of plate-like bodies having different thermal expansion coefficients and thermal conductivity,
A first plate-like body formed of a material having a relatively low coefficient of thermal expansion and having a plurality of through holes penetrating along the plate thickness direction;
A pair of second plate-like bodies formed by a material having a large thermal conductivity compared to the first plate-like body and bonded to the two surfaces of the first plate-like body;
The pair of second plate-shaped bodies are formed of a material having a higher thermal conductivity than the first plate-shaped body, and a gap is secured at least in part between the inner wall surfaces of the through holes. And a heat transfer member disposed in each of the plurality of through-holes in a mode of being joined to each other. A heat conduction composite material formed by laminating a plurality of plate-like bodies having different thermal expansion coefficients and thermal conductivity,
A first plate-like body formed of a material having a relatively low coefficient of thermal expansion and having a plurality of through holes penetrating along the plate thickness direction;
A pair of second plate-like bodies formed by a material having a larger thermal conductivity than that of the first plate-like body and laminated on the two surfaces of the first plate-like body;
The pair of second plate-shaped bodies are formed of a material having a higher thermal conductivity than the first plate-shaped body, and a gap is secured at least in part between the inner wall surfaces of the through holes. A heat transfer body disposed in each of the plurality of through-holes in a manner in contact with each other, and between the first plate-like body and the pair of second plate-like bodies and between the heat-transfer body and the pair. A heat conductive composite material characterized in that the second plate-like body is integrated by diffusion bonding.   The heat transfer body is a columnar member having a cross-sectional shape that is similar to an internal cross-sectional shape of a through-hole formed in the first plate-like body. 2. The heat conducting composite material according to 2. The first plate-like body has a through-hole having a circular cross section,
The heat transfer composite according to claim 1, wherein the heat transfer body is a columnar member having a circular cross section. It is constituted by laminating a plurality of plate-like bodies having different thermal expansion coefficients and thermal conductivities,
A first plate-like body formed of a material having a relatively low coefficient of thermal expansion and having a plurality of through holes penetrating along the plate thickness direction;
A pair of second plate-like bodies formed by a material having a large thermal conductivity compared to the first plate-like body and bonded to the two surfaces of the first plate-like body;
The pair of second plate-shaped bodies are formed of a material having a higher thermal conductivity than the first plate-shaped body, and a gap is secured at least in part between the inner wall surfaces of the through holes. Each of the plurality of through-holes in a manner of being joined to each other, and a method of manufacturing a heat conductive composite material comprising:
Laminating the second plate-like body on the surface located below the first plate-like body;
Disposing the heat transfer bodies in the through holes of the first plate-like body,
Laminating the second plate-like body on the surface located above the first plate-like body;
By applying pressure along the thickness direction of the laminated first plate and the pair of second plates, between the first plate and the pair of second plates and the transmission. And a step of performing diffusion bonding between the heat body and the pair of second plate-like bodies, respectively. It is constituted by laminating a plurality of plate-like bodies having different thermal expansion coefficients and thermal conductivities,
A first plate-like body formed of a material having a relatively low coefficient of thermal expansion and having a plurality of through holes penetrating along the plate thickness direction;
A pair of second plate-like bodies formed by a material having a large thermal conductivity compared to the first plate-like body and bonded to the two surfaces of the first plate-like body;
The pair of second plate-shaped bodies are formed of a material having a higher thermal conductivity than the first plate-shaped body, and a gap is secured at least in part between the inner wall surfaces of the through holes. Each of the plurality of through-holes in a manner of being joined to each other, and a method of manufacturing a heat conductive composite material comprising:
A step of preliminarily diffusing and bonding the heat transfer body respectively to a portion corresponding to the through hole of the first plate-like body in one second plate-like body;
Laminating the first plate-like body on the one second plate-like body in a manner in which a heat transfer body is disposed in each of the through holes;
A step of laminating the other second plate-like body on the first plate-like body in such a manner that the first plate-like body is sandwiched between one heat-transfer body and the second plate-like body joined by diffusion bonding;
By applying pressure along the thickness direction of the laminated first plate and the pair of second plates, between the first plate and the pair of second plates and the transmission. And a step of performing diffusion bonding between the thermal body and the other second plate-like body, respectively. It is constituted by laminating a plurality of plate-like bodies having different thermal expansion coefficients and thermal conductivities,
A first plate-like body formed of a material having a relatively low coefficient of thermal expansion and having a plurality of through holes penetrating along the plate thickness direction;
A pair of second plate-like bodies formed by a material having a large thermal conductivity compared to the first plate-like body and bonded to the two surfaces of the first plate-like body;
The pair of second plate-shaped bodies are formed of a material having a higher thermal conductivity than the first plate-shaped body, and a gap is secured at least in part between the inner wall surfaces of the through holes. Each of the plurality of through-holes in a manner of being joined to each other, and a method of manufacturing a heat conductive composite material comprising:
A step of integrally molding the heat transfer body in advance in a portion corresponding to the through hole of the first plate-like body in one second plate-like body;
Laminating the first plate-like body on the one second plate-like body in a manner in which a heat transfer body is disposed in each of the through holes;
A step of laminating the other second plate-like body on the first plate-like body in such a manner that the first plate-like body is sandwiched between one heat-transfer body and the second plate-like body joined by diffusion bonding;
By applying pressure along the thickness direction of the laminated first plate and the pair of second plates, between the first plate and the pair of second plates and the transmission. And a step of performing diffusion bonding between the thermal body and the other second plate-like body, respectively.   The heat conductive composite material according to claim 5 or 6, wherein a spherical shape having an outer diameter larger than a plate thickness of the first plate-like body is applied as the heat transfer body. Manufacturing method.   9. The method of manufacturing a heat conducting composite material according to claim 8, wherein a spherical concave portion is formed in advance in each of the portions corresponding to the through holes of the first plate-like body in the second plate-like body. As the first plate-like body, one having a through hole with a circular cross section is applied,
The method for manufacturing a heat-conducting composite material according to claim 5, wherein the heat transfer body is a column having a circular cross section.

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