JP2011119600A - Method of manufacturing heat sink and heat sink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a heat sink capable of manufacturing a thick heat sink having high thermal conductivity to the thickness direction and a low thermal expansion coefficient, and to provide the heat sink. <P>SOLUTION: The manufacturing method of the heat sink includes a step of forming a laminated body 12 by laminating a dimple plate 1 having dimples 2 on the surface and a heat conductive plate 14, a step of forming a molded body 13 by molding the laminated body 12 into a roll shape, a step of forming a billet 16 by inserting the molded body 13 into a tube 15, and a step of filling a part of the heat conductive plate 14 into the dimples 2 by extruding the billet 16. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  INDUSTRIAL APPLICABILITY The present invention is suitable as a semiconductor circuit member for mounting a semiconductor element, particularly as a semiconductor circuit member such as a substrate, a heat spreader, and a heat sink member for the purpose of heat dissipation when mounting a semiconductor element that is heated by applying a large current. The present invention relates to a heat sink manufacturing method and a heat sink.

The semiconductor element is a low thermal expansion material such as Si or SiC. For example, the thermal expansion coefficient (linear expansion coefficient) of Si is about 4 × 10 ⁻⁶ (1 / K). On the other hand, the thermal expansion coefficient (linear expansion coefficient) of pure Cu or pure Al generally used as a material for semiconductor circuit members such as heat sinks and heat spreaders is about 20 × 10 ⁻⁶ (1 / K). Therefore, when pure Cu or pure Al is used for a semiconductor circuit member such as a heat sink or a heat spreader, when a semiconductor element (chip material) is mounted on the semiconductor circuit member, heat based on a difference in linear expansion between the semiconductor element and the semiconductor circuit member. Due to the occurrence of stress, peeling may occur at the joint between the semiconductor element and the semiconductor circuit member by solder or brazing material.

Therefore, conventionally, heat sinks used for these semiconductor circuit members are made of sintered metal (Mo, W, Cu-Mo, Cu-W, etc.), non-patented for the purpose of matching the thermal expansion coefficient (linear expansion coefficient). clad material as disclosed in the literature 1 (Cu-Invar alloy -Cu (hereinafter, such as CIC material)), ceramics (AlN, etc. _{Al 2 O 3, Si 3 N} 4) has been used. Here, the Invar alloy is a Fe-36 mass% Ni alloy.

  Recently, heat sinks used for semiconductor circuit members are required not only to have a matching thermal expansion coefficient (linear expansion coefficient), but also to have excellent thermal conductivity, light weight, and low price for the purpose of improving heat dissipation. It has been.

However, in the above-mentioned low expansion sintered metal, there are problems of thermal conductivity, weight and price, and in a clad material such as a CIC material, heat insulation and weight problems of the Invar alloy part, AlN, Al ₂ O ₃ , Ceramics such as Si ₃ N ₄ have problems of mechanical toughness, thermal conductivity and price, respectively.

As an improvement of such problems, impregnating materials (Al—SiC, Al—C), sintered materials (Cu—Cu ₂ O (patent document 1), Al—Invar alloy (patent document 2), Al -al ₂ O ₃ (Patent Document 3)) radiating plate using a metal matrix composite material such as has been proposed. However, since these metal matrix composite materials are generally expensive and have poor workability, a heat sink material having low workability and good workability is desired.

  Patent Document 4 proposes a heat radiating plate in which a metal plate made of copper, copper-tungsten or copper-molybdenum and a metal net made of molybdenum or tungsten fine metal wires are overlapped and integrated. . However, with this heat sink, copper does not wrap around the fine metal wire, and good heat transfer characteristics (heat conductivity) cannot be obtained. There is.

  On the other hand, in order to utilize a low-cost CIC material such as a CIC material, many proposals have been made for a heat dissipation plate having improved heat conductivity in the thickness direction, which is a drawback thereof.

  As one of them, Patent Document 5 proposes that a low thermal expansion material such as a drilled Invar alloy is used, and that the upper and lower sides thereof are subjected to HOT press bonding with a high thermal conductive material or the like. However, in Patent Document 5, since the low thermal expansion material is perforated, it cannot be said that the material yield is sufficient, and the HOT press has a problem that the work efficiency is low and the cost becomes high.

  In Patent Document 6, it is proposed to break the Invar alloy layer and adjust the upper and lower Cu intermittently by adjusting the processing conditions when the CIC material is clad rolled. However, in Patent Document 6, it is difficult to increase the Cu / Cu penetration rate and to ensure improvement in the conductivity of a constant specification in the thickness direction.

  In Patent Document 7, an expanded metal made of an Invar alloy is used, and the expanded metal is formed smoothly by rolling, and Cu (or Al) is laminated on the upper and lower sides of the expanded metal to form Cu (or Al ) Heat sinks have been proposed in which they are joined together to improve the thermal conductivity in the thickness direction.

  However, expanded metal (see JIS-G3351 “Expanded Metals”) is generally a net-like porous plate whose hole size is 10 to 100 times larger than the plate thickness, and when expanded metal is used as a heat sink. The aperture ratio becomes a problem. In other words, in a general expanded metal manufacturing method, a porous perforated plate having a pore size 10 to 100 times larger than the plate thickness can be manufactured. Difficult to manufacture. Further, when Cu (or Al) is laminated on the upper and lower sides of the expanded metal and clad rolling, the expanded metal has a hole size that is twice or more larger, resulting in a variation in the characteristics of the heat sink and the problem remains.

JP 2003-179191 A JP 2000-183234 A JP 2002-208660 A JP-A-6-77365 JP 2004-152970 A Japanese Patent Laid-Open No. 5-386 Japanese Patent No. 4062994 Japanese Patent Publication No. 7-026174

“Clad material for semiconductor substrates (heat countermeasure application): Hitachi Cable Hitachi Cable”, [online], Hitachi Cable, Ltd., [searched on November 30, 2009], Internet <URL: http: //www.hitachi- cable.co.jp/products/copper/clad/semi/index.html ＞

  As described above, a great number of proposals have been made for a heat sink as a semiconductor circuit member for the purpose of heat dissipation, but these conventional heat sinks are expensive as a result. The CIC material made cheaper has anisotropy in thermal conductivity, and further improvement is required, and another device is necessary for industrial use.

  In Patent Document 7, which uses expanded metal and improves the characteristics of the CIC material by clad rolling, the expanded metal (microporous plate) made of an Invar alloy having a fine pore size is used to improve the thermal conductivity anisotropy. ) Must be made thin, and as a result, only a thin heat sink (0.2 to 0.5 mm thick) can be produced. In addition, when using a heat sink as a heat sink material, the thickness of about 2-4 mm is desired practically.

  In addition, in the aspect of the manufacturing method, even if a multilayer clad material using expanded metal is manufactured, a plate material is sent out from individual rolls, and these are laminated and continuously manufactured by cold rolling. In this case, however, there is a limit to the number of laminated plate materials that can be manufactured.

  Therefore, in a heat sink as a semiconductor circuit member for the purpose of heat dissipation, the thermal expansion coefficient is low, as well as there is no anisotropy in thermal conductivity (that is, the thermal conductivity in the thickness direction is high), and In addition, a heat sink having a thickness that can be sufficiently used as a heat sink material or the like, and an inexpensive heat sink is desired.

  Accordingly, an object of the present invention is to solve the above-described problems, and to provide a heat dissipation plate manufacturing method and heat dissipation capable of manufacturing a heat sink having a high thermal conductivity in the thickness direction, a low coefficient of thermal expansion, and a thick heat sink. To provide a board.

  The present invention was devised to achieve the above object, and includes a step of laminating a dimple plate having a dimple on the surface and a heat transfer plate to form a laminate, and forming the laminate into a roll shape. Forming a molded body, and forming the billet by inserting the molded body into a tube and filling the dimple with a part of the heat transfer plate by extrusion molding the billet; The manufacturing method of the heat sink provided with these.

  The billet may be formed by inserting the molded body into the tube and then closing front and rear ends of the tube.

  The present invention also includes a step of laminating a dimple plate having a dimple on the surface and a heat transfer plate to form a laminated body, and housing the laminated body in a housing to form an ingot, and rolling the ingot And a step of filling a part of the heat transfer plate into the dimples.

  The dimple plate may further include dimples on the back surface.

  The laminated body may be formed by alternately laminating a plurality of the dimple plates and a plurality of the heat transfer plates.

  A hole penetrating the dimple plate may be formed in at least a part of the dimple, and the upper and lower heat transfer plates sandwiching the hole may be joined via the hole.

  The dimple plate may be made of a material having a smaller thermal expansion coefficient than the heat transfer plate, and the heat transfer plate may be made of a material having a higher thermal conductivity than the dimple plate.

  The tube may be made of a material having a higher thermal conductivity than the dimple plate.

  The casing may be made of a material having higher thermal conductivity than the dimple plate.

Furthermore, the present invention is a heat radiating plate comprising a dimple plate having dimples on the surface and a heat transfer plate that is bonded to the surface and fills the dimples, and has a thickness of 1 mm or more in the thickness direction. The heat dissipation plate has a thermal conductivity of 150 (W / ° C. · m) or more and a thermal expansion coefficient in the plate surface direction of 12 × 10 ⁻⁶ (1 / K) or less.

  According to the heat sink manufacturing method of the present invention, the number of stacks of plate materials that can be manufactured can be increased compared with the cold rolling method of the multilayer clad material. A heat radiating plate having a high thermal conductivity in the direction and a low thermal expansion coefficient in the plate surface direction can be manufactured.

  According to the heat sink of the present invention, since it is possible to achieve both the desired thermal expansion characteristics in the plate surface direction and the thermal conductivity in the thickness direction, it is assumed that a semiconductor element used for the application of a large current is mounted. Also, good heat dissipation characteristics and thermal expansion characteristics can be exhibited.

It is a perspective view of the dimple board used for the heat sink which concerns on one embodiment of this invention. It is sectional drawing of the dimple board used for the heat sink which concerns on one embodiment of this invention, (a) is a single-sided dimple board, (b) is a double-sided dimple board, (c) is a dimple board with a single-sided dimple hole, (d ) Is a cross-sectional view of a dimple plate with double-sided dimple holes. It is a photograph which shows the external appearance of the dimple board of FIG.2 (d). (A)-(d) is a figure explaining the manufacturing method of the dimple board 1 in this invention. In this invention, it is a perspective view at the time of manufacturing a billet. In this invention, it is sectional drawing at the time of extruding a billet. (A), (b) is a figure which shows the cross-sectional shape after extrusion of a heat sink in this invention. In this invention, it is a figure which shows the relationship between thermal conductivity (lambda) and thermal expansion coefficient (rho). It is a perspective view which shows the ingot used for the heat sink which concerns on one embodiment of this invention. It is sectional drawing at the time of rolling the ingot of FIG. It is sectional drawing after the rolling process of the ingot of FIG. It is the graph which compared the thermal expansion coefficient and thermal conductivity in the Example of this invention, and a comparative example. It is a figure which shows the position of the Example and comparative example in the relationship figure of thermal conductivity (lambda) of FIG. 8, and thermal expansion coefficient (rho).

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

  First, the dimple plate used for the heat sink according to the present embodiment will be described with reference to FIGS.

  As shown in FIG. 1, the dimple plate 1 is formed having a plurality of concave dimples (dents) 2.

  The dimple plate 1 is formed of a material having a thermal expansion coefficient (linear expansion coefficient) smaller than that of the material constituting the heat transfer plate described later, that is, a low thermal expansion material. Specifically, the dimple plate 1 is made of an Invar alloy (Invar alloy) and is composed of a super invar (Super Invar) made of Fe-36 mass% Ni, Fe-36.5 mass% Ni, Fe-32 mass% Ni-5 mass% Co. ) Material, Fe-54 mass% Co-9.5 mass% Cr, or the like.

  The dimple 2 is formed with a thickness that is thinner than the thickness of the dimple plate 1 on which the dimple 2 is formed. In the dimple plate 1, the portion where the dimple 2 is formed is a thin portion. The dimple plate 1 has a plurality of thin portions having a thickness smaller than the thickness of the dimple plate 1 and the pitch of the thin portions may be equal to or less than a predetermined pitch. The shape of the dimple 2 is concave ( That is, the present invention is not limited to a state in which there is no hole penetrating the dimple plate 1), a hole shape (that is, a form having a hole penetrating the dimple plate 1), and the like.

  Examples of the form of the dimple plate 1 include the following forms.

  The dimple plate 1a shown in FIG. 2A has a plurality of dimples 2 on the front surface S, and the back surface R is substantially flat. That is, the dimple plate 1a has a plurality of concave dimples 2 only on one surface (hereinafter, the dimple plate 1a as shown in FIG. 2A may be referred to as a “single-sided dimple plate 1a”).

  A dimple plate 1b shown in FIG. 2B has a plurality of dimples 2 on the front surface S and also has a plurality of dimples 2 on the back surface R. However, the dimple 2a formed on the front surface S and the dimple 2b formed on the back surface R are isolated by the material constituting the dimple plate 1b. That is, in the dimple plate 1b, the dimple 2a and the dimple 2b are kept separated from each other (hereinafter, the dimple plate 1b as shown in FIG. 2B may be referred to as “double-sided dimple plate 1b”). In FIG. 1, the double-sided dimple plate 1b is shown.

  A dimple plate 1 c shown in FIG. 2C has a plurality of dimples 2 on the surface S and a hole 3 at the bottom of each dimple 2. That is, in the dimple plate 1c, each dimple 2 is formed such that the width of the opening gradually decreases from the front surface S toward the back surface R when the cross section of the dimple plate 1c is observed. Are formed in the rear surface R (hereinafter, the dimple plate 1c as shown in FIG. 2C may be referred to as “dimple plate 1c with dimple holes on one side”).

  Further, the dimple plate 1 d shown in FIG. 2D has a plurality of dimples 2 on the front surface S and also has a plurality of dimples 2 on the back surface R. Further, in the dimple plate 1d, the dimple 2a provided on the front surface S and the dimple 2b provided on the back surface R are connected to each other through a hole 3 in the vicinity of the bottom. That is, the dimple 2a and the dimple 2b are connected via the air hole 3 penetrating the dimple plate 1d (hereinafter, the dimple plate 1d as shown in FIG. 2D is referred to as “dimple plate 1d with double-sided dimple holes”). Sometimes). When holes 3 are provided in the dimple 2 of the dimple plate 1, it is preferable that the holes 3 occupy an area that is less than half of the area that the dimple 2 occupies on the surface of the dimple plate 1 in plan view.

  FIG. 3 is a photograph showing the appearance of the dimple plate 1 (dimple plate with dimple holes on both sides 1d). As shown in FIG. 3, the shape of the dimple 2 in the dimple plate 1 in plan view (hereinafter simply referred to as “dimple plate surface shape”) is a substantially triangular shape. The dimple plate surface shape is not limited to a triangular shape, but may be a shape having an arc such as a circle or an ellipse, or a shape such as a polygon such as a quadrangle, a hexagon, or an octagon. The dimple plate surface shape is preferably triangular from the viewpoint of ease of manufacture.

  Further, for example, in the single-sided dimple plate 1a described above, all of the plurality of dimples 2 are formed in a concave shape having a predetermined depth from the surface of the dimple plate 1a. An opening (hole 3) penetrating the single-sided dimple plate 1a can also be formed in 2. The same applies to the double-sided dimple plate 1b.

  Further, in the dimple plate 1, for the purpose of ensuring the heat dissipation characteristics of the heat radiating plate, the ratio of the dimple 2 to the surface of the dimple plate 1, that is, the region where the dimple 2 is formed with respect to the surface area of the dimple plate 1. The area ratio (hereinafter sometimes referred to as “dimple occupancy ratio”) is, for example, preferably in the range of 20% to 80%, or 30% or less.

  By the way, for example, when a semiconductor element having a size of several millimeters is mounted on the heat sink, assuming that the pitch of the dimples 2 (or holes 3) is a predetermined value or more, the semiconductor element is mounted on the heat sink. Depending on the location, the heat generated in the semiconductor element may not be radiated appropriately. That is, unless the pitch of the dimples 2 (or the holes 3) is not fine to some extent, the thermal conductivity in the thickness direction of the heat sink is deteriorated. Therefore, in the present embodiment, each of the plurality of dimples 2 (or holes 3) is provided for the purpose of maintaining the heat transfer characteristics in the thickness direction of the heat sink substantially the same regardless of the portion of the heat sink. In the longitudinal direction and the width direction, for example, the pitch is 1 mm or less, preferably 0.7 mm or less, more preferably 0.5 mm or less, and the pitch is substantially uniform. In particular, in order to increase the ratio of the Invar alloy in the heat sink, it is desirable that the pitch in the width direction of the dimples 2 (or holes 3) be 0.5 mm or less.

  Here, the manufacturing method of the dimple plate 1 will be described with reference to FIG. Here, as an example, a case where a dimple plate 1d with double-sided dimple holes (see FIG. 2D) is manufactured will be described.

  When the dimple plate 1 is manufactured, it is desirable to use a multistage forming method that can form a mesh of a plurality of layers at once.

  In this molding method, first, as shown in FIG. 4A, a flat plate 5 as a raw material is fed between upper and lower laminated blades 6 and 7 of a cutting device 4 by a raw material feed roller (not shown). The laminated blades 6 and 7 have a plurality of (five in FIG. 4) thin wave blades 6a to 6e and 7a to 7e each having a wave shape (uneven wave shape), and the wave shape has a predetermined pitch (1 / The flat plate 5 is laminated in the feeding direction so as to be shifted by 5 to 1/2 pitch). Each of the thin wave blades 6a to 6e and 7a to 7e can move up and down individually.

  After that, as shown in FIG. 4B, the cutting device 4 is operated to move the taper punch 8 in the inclined surface direction (direction in which the flat plate 5 is pressed against the multistage guide punch 9). Then, it is pushed by the taper punch 8, and the whole laminated blade 6 and the flat plate 5 move downward. The opposing lower laminated blade 7 also moves downward, but only the first thin-walled wave blade 7a is supported by the lower multi-stage guide punch 9, and therefore cannot move, and the wave of the thin-walled wave blade 7a. The eye-shaped convex portions are pushed into the flat plate 5 to form the dimples 2 and the holes 3.

  More specifically, when the first-stage thin wave blade 7a is pushed in, the flat plate 5 is bent and deformed between the upper first-stage thin wave blade 6a facing the first-stage thin wave blade 7a. In response, the dimple 2 is formed in a wave pattern. Further, since the first-stage thin wave blade 7a and the second-stage thin wave blade 6b are arranged with a predetermined pitch shift in the blade width direction (paper surface direction), the first-stage thin wave blade 7a. Between the thin-walled wave blades 6b of the second stage, shear holes are made at the protruding edge portions (wave-shaped convex portions) for each pitch in the blade width direction, and holes 3 are formed.

  Further, when the taper punch 8 moves on the inclined surface and becomes the second stage load, only the upper first stage thin wave blade 6a is detached from the horizontal portion of the taper punch 8 as shown in FIG. The other thin-walled wave blades 6b to 6e come into contact with the horizontal portion of the taper punch 8 and move downward, and the flat plate 5 also moves downward. On the other hand, the first-stage thin wave blade 7 a and the second-stage thin wave blade 7 b below are supported by the multistage guide punch 9 and pushed into the flat plate 5. At this time, the flat plate 5 is subjected to bending deformation between the second stage thin wave blades 6b and 7b by pressurization between the taper punch 8 and the multistage guide punch 9, and the dimple 2 is formed. Between the second-stage thin wave blade 7b and the third-stage thin wave blade 6c, a shear cut is made at the projecting edge portion (wave-shaped convex portion) for each pitch in the blade width direction. 3 is formed.

  Further, when the taper punch 8 moves on the inclined surface, as shown in FIG. 4D, the third to fifth steps are formed in the same manner as the second step described above, and the forming process for one stroke is completed. . In the state of FIG. 4 (d), the steps of the thin-walled wave blades 6 a to 6 e are generated in accordance with the inclination of the inclined portion of the taper punch 8, and the steps of the thin-walled wave blades 7 a to 7 e are those of the multistage guide punch 9. The inclination is the same as the taper punch 8 depending on the shape. In addition, the thin wave blades 7a to 7e arranged below are spring-supported on the side surfaces, and the flat plate 5 is formed while pressing the flat plate 5 with the thin wave blades 7a to 7e of the laminated blade 7 at a constant load. Is done. As a result, a dimple plate 1 in which a plurality of layers (here, five layers) of dimples 2 and holes 3 corresponding to the upper and lower thin wave blades 6a to 6e and 7a to 7e are formed is obtained.

  After completion of the first stroke molding, unloading and releasing are performed, and after feeding the flat plate 5 for one stroke, the second stroke molding is performed in the same manner. By repeating this, an infinite length dimple plate 1 is obtained.

  When forming the double-sided dimple plate 1b (see FIG. 2 (b)) that does not form the holes 3, the thin-walled wave blades 6a to 6e of the laminated blades 6 and 7 are made so that the flat plate 5 is not sheared. , 7a to 7e may be provided with gaps (intervals). When the dimple 2 is formed only on one surface such as the single-sided dimple plate 1a (see FIG. 2 (a)) and the single-sided dimple plate 1c (see FIG. 2 (c)), One of 7 may be formed with a flat blade instead of a wave blade.

  Next, the manufacturing method of the heat sink which concerns on this Embodiment is demonstrated using FIG.

  The heat sink manufacturing method according to the present embodiment includes a step of laminating the dimple plate 1 and the heat transfer plate to form a laminate, and a step of forming the laminate into a roll shape to form a compact. And forming the billet (composite billet) by inserting the molded body into the tube, and filling the dimple 2 with a part of the heat transfer plate by extrusion molding the billet.

  Hereinafter, each step will be described in detail. In the present embodiment, a case where a dimple plate 1d with double-sided dimple holes (see FIG. 2D) is used as the dimple plate 1 will be described.

  In the heat sink manufacturing method according to the present embodiment, first, a plurality of dimple plates 1 (dimple plates with double-sided dimple holes 1d) and a heat transfer plate to be bonded to the front surface S and back surface R of the dimple plate 1 are prepared. . Specifically, a plurality of dimple plate coils wound with a long dimple plate 1 on which dimples 2 are formed are prepared, and a plurality of heat transfer plate coils wound with a long heat transfer plate are prepared.

  The heat transfer plate is made of a material having a higher thermal conductivity than the material constituting the dimple plate 1. As the heat transfer plate, for example, copper or copper alloy, or aluminum or aluminum alloy can be used. Moreover, the material similar to a heat-transfer board can be used also about the high heat conductive core and pipe | tube mentioned later. In the present embodiment, the case where the heat transfer plate, the high thermal conductive core, and the tube are formed of copper will be described.

  Thereafter, the plurality of dimple plates 1 drawn from the plurality of dimple plate coils are positioned between the plurality of heat transfer plates drawn from the plurality of heat transfer plate coils, that is, the plurality of dimple plates 1 and the plurality of heat transfer plates. The dimple plate coil and the heat transfer plate coil are arranged so as to be alternately stacked, and the dimple plate 1 and the heat transfer plate are drawn from each coil. Thereby, the laminated body which laminated | stacked the dimple board 1 and the heat exchanger plate is formed.

  After forming the laminated body, as shown in FIG. 5, the laminated body 12 is wound around the high thermal conductive core 11 to form a roll-shaped molded body 13. In FIG. 5, reference numeral 14 denotes a heat transfer plate.

  Thereafter, the roll-shaped molded body 13 is inserted and filled into a cylindrical tube (circular tube) 15, and the front and rear ends that are openings of the tube 15 are sealed with a sealing material (such as a copper plug) not shown. In addition, it is preferable that the bonding interface between the dimple plate 1 and the heat transfer plate 14 is sufficiently cleaned. Thereby, the billet (composite billet) 16 for extrusion is formed.

  After forming the billet 16, as shown in FIG. 6, when the billet 16 is extruded from the die 21 by hydrostatic extrusion, the heat radiating plate 100 is obtained. In the heat radiating plate 100, the heat transfer plate 14 is joined to the front and back surfaces of the dimple plate 1 by extrusion processing, and the material constituting the heat transfer plate 14 flows into the dimple 2 and is joined to the surface in the dimple 2. ing. Further, in the heat radiating plate 100, the material constituting the heat transfer plate 14 flowing into the dimple 2 a on the front surface S side and the material constituting the heat transfer plate 14 flowing into the dimple 2 b on the back surface R side through the holes 3. The heat transfer plates 14 are joined to each other through the air holes 3. In this way, by using the dimple plate 1d with double-sided dimple holes (see FIG. 2D) as the dimple plate 1, the heat transfer plate 14 is provided on both the front surface S side dimple 2a and the rear surface R side dimple 2b. Since the constituent material is filled, the bonding area between the dimple 2 and the heat transfer plate 14 can be increased and the bonding strength can be increased. The same effect can be obtained by using a double-sided dimple plate 1b (see FIG. 2B) as the dimple plate 1.

  Extrusion molding by isostatic pressing is preferably performed in a warm or hot state of 500 to 700 ° C., and thereby, the bonding state of the composite interface (the bonding interface between the dimple plate 1 and the heat transfer plate 14) is optimized and good. It exhibits excellent heat conduction and thermal expansion characteristics. The extrusion method is not limited to isostatic extrusion, and may be lubrication extrusion.

  The heat sink 100 is obtained by the above. The cross-sectional shape of the heat sink 100 after extrusion is not particularly limited. For example, a flat plate shape (rectangular cross section) as shown in FIG. 7A or a flat plate 101 to a fin as shown in FIG. It can be set as the shape with a fin which 102 protruded. The extruded heat radiating plate 100 has a thickness of 1 mm or more, and can be used as, for example, a heat sink material with low thermal expansion and high thermal conductivity having good cooling characteristics. 7A and 7B, only the cross-sectional shape is shown by omitting the dimple plate 1, the high heat conductive core 11, the heat transfer plate 14, and the tube 15 for simplification of the drawing.

  As described above, in the manufacturing method of the heat sink according to the present embodiment, the step of forming the laminate 12 by laminating the dimple plate 1 having the dimple 2 on the surface and the heat transfer plate 14, and the laminate 12 And forming the billet 16 by inserting the billet 16 into the tube 15 and extruding the billet 16 into the dimple 2. And a step of filling a part of the heat transfer plate 14.

  That is, in the manufacturing method of the heat sink according to the present embodiment, the low thermal expansion dimple plate 1 and the high heat conduction heat transfer plate 14 are arranged in a multi-layered form, and subjected to strong processing (here, extrusion processing) and joined. Thus, the heat sink 100 having a multi-composite structure is formed.

  The problem in manufacturing a heat sink with an Invar composite material structure, such as a conventional CIC material, is that the semiconductor element is a small one of about several millimeters. The material structure is also required to be submillimeter-order refinement (fine porosity or fine unevenness), and it is necessary to manufacture it at low cost.

  However, in the conventional heat sink made of CIC material using expanded metal, as described above, when sub-millimeter order miniaturization is attempted, the thickness of the expanded metal must be reduced. For example, a large current is applied. However, it is impossible to manufacture a heat sink having a thickness of 1 mm or more, which is suitable as a heat sink for the purpose of heat dissipation when mounting a semiconductor element that becomes high in use.

  In the present invention, the dimple plate 1 and the heat transfer plate 14 are multi-layered to form the multi-composite heat dissipation plate 100. Therefore, the ratio of the dimple plate 1 (Invar alloy) in the heat dissipation plate 100 is maintained, and heat dissipation is achieved. The coefficient of thermal expansion of the entire plate 100 can be kept low. In the present invention, since the dimple plate 1 and the heat transfer plate 14 are multilayered, it is possible to easily realize the heat radiating plate 100 having a thickness of 1 mm or more that can be sufficiently used as a heat sink material or the like.

  Furthermore, in the present invention, since the dimple plate 1 is formed by the multi-stage forming method described with reference to FIG. 4, it is possible to make the dimple plate 1 finely porous or finely uneven without reducing the thickness of the dimple plate 1. By manufacturing the heat radiating plate 100 using the dimple plate 1, the heat radiating plate 100 having no anisotropy in thermal conductivity (high thermal conductivity in the thickness direction) can be realized at low cost.

That is, according to the present invention, it is possible to manufacture a heat sink 100 that is thick enough to be used as a heat sink material and the like and that is homogeneous in terms of thermal expansion, heat conduction, and mechanical characteristics. In the above plate thickness, the thermal conductivity in the thickness direction is 150 (W / ° C. · m) or more and the coefficient of thermal expansion is 12 × 10 ⁻⁶ (1 / K) or less. The heat sink 100 can be realized.

  According to the heat sink 100 of the present invention, it is possible to achieve both desired thermal expansion characteristics and thermal conductivity in the thickness direction. Therefore, even if a small semiconductor element that is heated to a high temperature by applying a large current is mounted, heat dissipation is achieved. It is possible to exhibit an effect that thermal stress based on a difference in linear expansion between the semiconductor element and the semiconductor element can be relaxed.

  In the present embodiment, the dimple plate 1 that has been made microporous or finely uneven without reducing the plate thickness by the multistage forming method described with reference to FIG. 4 is used. However, the present invention is not limited to this, and any molding method may be used as long as it can be microporous or finely uneven and can secure a certain thickness. In the molding method, even if the thickness of the dimple plate 1 is small and thin, the thin dimple plate 1 and the thin heat transfer plate are alternately formed, for example, several tens of times. By laminating a large number of layers, it is possible to obtain a thick heat sink 100 while maintaining the ratio of the dimple plate 1 (Invar alloy) in the heat sink 100 and keeping the coefficient of thermal expansion low. However, a commercially available expanded metal cannot be used as the dimple plate 1. This is because expanded metal essentially has a large hole pitch with respect to the plate thickness and a large hole area ratio, so that the Invar ratio becomes small as a result even when the number of layers is increased. This is because the thermal expansion coefficient is also increased.

  Here, the thermal conductivity and the thermal expansion coefficient in the heat sink 100 of the present invention will be examined.

  In general, the thermal conductivity and thermal expansion coefficient of an Invar composite material such as a CIC material can be calculated from the characteristic values of the constituent materials.

First, in the case of a single-layer CIC material whose core (Invar alloy layer) is not porous, the thermal conductivity λ in the plate surface direction is expressed by the following equation (1), and the thermal conductivity λ _{m in the} plate thickness direction is expressed by the following equation (2 ).
λ = λ ₁ · f ₁ + λ ₂ · f ₂ (1)
λ _m = (λ ₁・ λ ₂・ (Л ₁ + Л ₂ )) / (λ ₁・ Л ₂ + λ ₂・ Л ₁ ) (2)
Where λ ₁ : thermal conductivity of Invar alloy
λ ₂ : thermal conductivity of Cu
f ₁ : Section ratio of Invar alloy
f ₂ : Cu cross-sectional ratio
Л ₁ : Invar perforated plate thickness
Л _2/2: surface Cu layer thickness

  In the heat sink 100 of the present invention, the dimple plate 1d having double-sided dimple holes is used as the dimple plate 1. The dimple plate 1 made of Invar alloy is arranged in layers, and the heat transfer plate 14 made of Cu is the dimple plate 1. Therefore, the Invar alloy and Cu are homogeneously dispersed. Therefore, the thermal conductivity of the heat sink 100 is expressed by the formula (1) in both the plate surface direction and the plate thickness direction.

Regarding the thermal expansion coefficient (coefficient of thermal expansion), the direction of the plate surface is a problem, but the Young's modulus is close to the weighted average value because Invar alloy is close to 142 GPa and Cu is 136 GPa, and CIC material (single layer clad), dimple Both the heat sink 100 which has arrange | positioned the board 1 and the heat exchanger plate 14 in the multilayer are represented by the following Formula (3).
ρ = ρ ₁ · f ₁ + ρ ₂ · f ₂ (3)
Where ρ ₁ : thermal expansion coefficient of Invar alloy
ρ ₂ : Coefficient of thermal expansion of Cu

  Based on the above relational expressions (1) to (3), the result of calculating the relational expression between the thermal conductivity λ of the heat sink 100 and the CIC material and the thermal expansion coefficient ρ is shown in FIG.

As shown in FIG. 8, the thermal expansion coefficient ρ on the horizontal axis substantially corresponds to the cross-sectional composition ratio of the Invar alloy, and the thermal conductivity λ on the vertical axis varies greatly depending on the cross-sectional composition ratio of the Invar alloy. You can see that In the case of the CIC material, the thermal conductivity λ in the plate surface direction is expressed by the equation (1) and is a linear change corresponding to the cross-sectional composition ratio of the Invar alloy as shown by the solid line in FIG. The thermal conductivity λ _m becomes a low value close to the thermal conductivity λ ₁ of the Invar alloy regardless of the cross-sectional configuration ratio of the Invar alloy, as indicated by a broken line in FIG. This is a problem of the CIC material.

  In the case of the heat radiating plate 100 of the present invention, both the thermal conductivity in the plate surface direction and the thermal conductivity in the plate thickness direction are established by equation (1), and a straight line corresponding to the cross-sectional composition ratio of the Invar alloy as shown by the solid line in FIG. Since it becomes a change, it can be seen that the thermal conductivity in the thickness direction is greatly improved as compared with the CIC material. Specifically, according to the heat sink 100, the thermal conductivity in the plate thickness direction is improved by an order of magnitude compared to the CIC material. Since the shortcomings of the CIC material is concentrated in this respect, the range of the heat radiating plate 100 which has improved the disadvantage of the CIC material could be applied is believed to be increased remarkably.

  Moreover, since the heat sink 100 of the present invention is formed from Invar alloy and copper (or aluminum), it is less expensive than conventionally used Cu—Mo, Cu—W, etc., and has an economic advantage. large.

  As for the use of the heat sink 100, it can be used for the application of a conventional power module and the like, and further, it can be expected to provide an inexpensive use requiring low expansion and heat dissipation. Moreover, since the heat sink 100 with a large size can be manufactured, it can be applied particularly to high power applications.

  Another embodiment of the present invention will be described.

  In the said embodiment, although the case where an extrusion process was used was demonstrated as a method of performing the strong process in the case of multi-layering of the heat sink 100, it is not restricted to this but a rolling process is used as a method of performing a strong process. It may be.

  When using the rolling process, instead of the billet 16 in the extrusion process, as shown in FIG. 9, first, the dimple plate 1 and the heat transfer plate 14 are laminated to form the laminated body 12, and the formed laminated body 12 is An ingot (composite ingot) 23 is formed in a housing (case) 22.

  As the case 22, similarly to the heat transfer plate 14, a high thermal conductive material made of copper or copper alloy, or aluminum or aluminum alloy may be used. The shape of the housing 22 is not particularly limited, but a rectangular tube is used so that the ingot 23 can be easily rolled, and the front and rear ends thereof are sealed with a sealing material (such as a Cu cap) not shown. That's fine.

  Thereafter, as shown in FIG. 10, the ingot 23 is fed between two rolling rolls 24 arranged at a predetermined interval, and the ingot 23 is hot-rolled with both rolling rolls 24, thereby transferring heat into the dimple 2. A part of the plate 14 is filled. What is necessary is just to set it as the temperature range between 400-700 degreeC when performing a rolling process. As described above, as shown in FIG. 11, a heat sink 100 having a multi-composite structure formed into a rectangular cross section is obtained.

  In order to improve the homogeneity of the material for both extrusion and rolling, it is necessary to form the dimple 2 (or hole 3) of the dimple plate 1 finely, but the heat conduction characteristics in the thickness direction are improved. For this purpose, it is only necessary to achieve miniaturization in the width direction, and the width direction pitch of the dimples 2 (or holes 3) may be set to 0.5 mm or less. In the extrusion method and rolling method of the present invention, compared to the CIC material (single-layer clad), the total degree of processing until the heat sink 100 as a product is completed is large, and the dimple 2 in the longitudinal direction (or Although the pitch of the holes 3) tends to increase, as described above, this point does not become a problem, and a constant heat conduction characteristic in the thickness direction is promised.

  In the said embodiment, although the heat-transfer plate 14, the high heat conductive core 11, and the pipe | tube 15 were comprised with the same material (copper), you may make it mutually differ. For example, in the above embodiment, the tube 15 is made of copper, but by forming the tube 15 from aluminum, a heat sink 100 having a rectangular cross section with high fins can be manufactured. It can be suitably used as a high heat conduction cooling material. Further, by forming the tube 15 with copper and forming the heat transfer plate 14 and the high thermal conductive core 11 with aluminum, it is possible to manufacture a heat dissipation plate 100 that is inexpensive and in particular has a low thermal expansion with a high Invar ratio. This is applicable to both the extrusion method and the rolling method.

Example 1
In carrying out the present invention, Fe-36 mass% Ni was used as the Invar alloy, and the dimple plate 1 (double-sided dimple plate 1b) of FIG. 1 was used.

  Specifically, the dimple plate 1 has a thickness of 0.22 mm and a width of 50 mm, the pitch of the dimples 2 in the 45 degree direction is 0.5 mm, and the pitch in the width direction is 0.35 mm. The dimple plate 1 is a concavo-convex plate in which a depression (dimple 2) is inserted from the upper and lower surfaces, and is characterized in that the bottom wall thickness is thin, and there are some having a through hole of about 10%.

  The dimple plate 1 and a heat transfer plate 14 made of a Cu plate having a thickness of 0.2 mm or 0.15 mm are overlapped and wound to form a roll-shaped molded body 13 having an outer diameter of 60.5 mm as shown in FIG. Then, it was inserted into a pipe 15 made of copper of φ65 mm / φ61 mm and the front and rear ends were sealed with a sealing material (copper plug) to produce a billet 16 for extrusion.

  The dimple plate 1 made of an Invar alloy and the heat transfer plate 14 made of a Cu plate used for the raw material were cleaned and brightly annealed to obtain a clean surface state.

  As shown in FIG. 6, the billet 16 was extrusion molded at a temperature of 600 ° C. by a hydrostatic extrusion apparatus. The uniform heat sink 100 which does not change in the longitudinal direction is obtained by the hydrostatic extrusion. As the extrusion shape, a multilayer laminated heat sink 100 having a required size was used as a rectangular cross-section material (50 mm × 3 mm) shown in FIG. By this high-temperature and high-reduction processing in the extrusion, the interface of Invar alloy (dimple plate 1) / Cu (heat transfer plate 14) is satisfactorily bonded, and through the holes 3 or through the thin portion of the dimple 2. The upper and lower heat transfer plates 14 are joined, and the heat conductivity in the thickness direction of the heat radiating plate 100 is also improved. Further, in the width direction, since the slightly reduced (50mm from 65 mm), uneven hole pitch in the width direction, further reduced than the initial 0.35 mm, the uniformity of the thermal conductivity and thermal expansion coefficient characteristic improves.

(Example 2)
The manufacturing method of the heat sink 100 is not limited to the extrusion method, and there is a manufacturing method by rolling.

  FIG. 9 shows a multi-layer composite ingot 23 of porous dimples Invar / Cu for rolling. A housing 22 made of a 0.4 mm thick highly heat conductive Cu case was prepared, a dimple plate 1 (double-sided dimple plate 1b) having a width of 50 mm, a length of 100 mm and a thickness of 0.22 mm, and a heat transfer plate made of the same size Cu plate. Ten layers of 14 were alternately stacked, and a Cu cap was stacked to seal the periphery, thereby forming an ingot 23 for rolling.

  The uneven hole shape and pretreatment of the dimple plate 1 and the heat transfer plate 14 used for the material were the same as in Example 1.

  Then, as shown in FIG. 10, the ingot 23 was rolled. The temperature was 400 ° C., joint rolling was performed with 40% reduction, and then a heat sink 100 having a rectangular cross section with a thickness of 3 mm was formed by cold rolling.

  Also in the case of the rolling method of Example 2, the interface of Invar alloy (dimple plate 1) / Cu (heat transfer plate 14) is satisfactorily bonded at high temperature and high pressure, and through the holes 3 or the dimple 2 The upper and lower heat transfer plates 14 are joined via the thin portion, and the heat conductivity in the thickness direction of the heat radiating plate 100 is also improved. Further, in the rolling method, the dimension is not changed in the width direction but also a pitch in the width direction of the dimple 2 (the holes 3) remained the initial 0.35 mm. Pitch of the dimples 2 (hole 3) is made to extend largely in the longitudinal direction, that is multilayered, the uniformity of the thermal conductivity and thermal expansion coefficient characteristic becomes good.

  For the purpose of producing a thick 3 mm plate, the structural dimensions of the heat sink 100 produced by the extrusion method (Examples 1-1 and 1-2) and the rolling method (Example 2) of the present invention manufactured as described above, and The performance measurement results are compared with other production examples (Comparative Examples 1 to 3), and are shown in Table 1. In addition, in FIG. 12, the heat-transfer characteristic (thermal conductivity) of Table 1 and a thermal expansion coefficient are compared and shown. Further, FIG. 13 shows positions of the example and the comparative example in the relationship diagram between the thermal conductivity λ and the thermal expansion coefficient ρ of FIG.

Examples 1-1 and 1-2 are data of the heat dissipation plate 100 made of a multilayer composite material of fine porous dimples Invar / Cu by an extrusion method in which the Cu layer thickness (thickness of the heat transfer plate 14) is changed. The coefficient of expansion ρ is also significantly lower than 1.7 × 10 ^-5 (1 / K) of the Cu material, and the thermal conductivity λ in the thickness direction is also significantly higher than the 9.4 (W / ° C. · m) of the Invar material. Is obtained. Example 2 is an example of the heat sink 100 by the rolling method, but the dimple 2 shape has substantially the same characteristics as Example 1-2 of the same extrusion method.

Further, the conventional CIC material (Cu / Invar alloy / Cu) of Comparative Examples 2 and 3 can directly produce a 3 mm thick material, but the coefficient of thermal expansion in the plate surface direction is 0.91. × 10 ⁻⁵ (1 / K) and 1.2 × 10 ⁻⁵ (1 / K) are sufficiently small and exhibit low thermal expansion, but the thermal conductivity in the thickness direction is 24 (W / ° C. · m), 31 Compared with (W / ° C. · m) and thermal conductivity 200 (W / ° C. · m) and 260 (W / ° C. · m) in the plate surface direction, it is one digit smaller. This is a problem of the CIC material.

  Moreover, although the comparative example 1 shows the example which made the heat sink which consists of a multilayer composite material by the extrusion method using the fine expanded metal which consists of a commercially available Invar alloy, an expanded metal is essentially with respect to plate | board thickness. large hole pitch can only intended porosity greater, have become even result in Invar ratios multilayered small, the thickness direction of the thermal conductivity is large but good, even larger thermal expansion coefficient It turns out that it is not suitable for making a low thermal expansion material.

Thus, according to the present invention, the thermal conductivity in the thickness direction is 150 (W / ° C. · m) or more even in a relatively thick application having a thickness of 1 mm or more, and the plate A heat sink 100 having a thermal expansion coefficient in the plane direction of 1.2 × 10 ⁻⁵ (1 / K) or less can be realized, and the heat sink 100 is used as a semiconductor circuit member for mounting a semiconductor element that becomes high in use. As a result, an effect of realizing a heat sink material having good heat dissipation characteristics and thermal expansion characteristics can be obtained.

DESCRIPTION OF SYMBOLS 1 Dimple board 2 Dimple 3 Hole 12 Laminate body 13 Molded body 14 Heat transfer plate 15 Tube 16 Billet

Claims (10)

A step of laminating a dimple plate having a dimple on the surface and a heat transfer plate to form a laminate;
Forming the molded body by forming the laminate into a roll, and
Inserting the molded body into a tube to form a billet, and extruding the billet to fill a part of the heat transfer plate into the dimple; and
The manufacturing method of the heat sink characterized by the above-mentioned.   The said billet is a manufacturing method of the heat sink of Claim 1 which closes the front-and-rear end of this pipe | tube after inserting the said molded object in the said pipe | tube. A step of laminating a dimple plate having a dimple on the surface and a heat transfer plate to form a laminate;
Forming the ingot by housing the laminate in a housing, and rolling the ingot to fill a part of the heat transfer plate in the dimple; and
The manufacturing method of the heat sink characterized by the above-mentioned.   The said dimple board is a manufacturing method of the heat sink in any one of Claims 1-3 which further have a dimple on a back surface.   The said laminated body is a manufacturing method of the heat sink in any one of Claims 1-4 formed by laminating | stacking several said dimple boards and several said heat-transfer board alternately.   At least a portion of the dimples, the dimples plate to form pores extending through the or one of claims 1 to 5 as the heat transfer plates of the upper and lower sandwiching the spatial hole joined through the holes The manufacturing method of the heat sink of description. The dimple plate is made of a material having a smaller thermal expansion coefficient than the heat transfer plate,
The said heat exchanger plate is a manufacturing method of the heat sink in any one of Claims 1-6 which consist of material which has a higher heat conductivity than the said dimple plate.   The said pipe | tube is a manufacturing method of the heat sink of Claim 1 which consists of material which has higher thermal conductivity than the said dimple board.   The method of manufacturing a heat sink according to claim 3, wherein the casing is made of a material having a higher thermal conductivity than the dimple plate. A dimple plate having dimples on the surface;
A heat radiating plate comprising a heat transfer plate joined to the surface and filling the dimples;
The thickness is 1 mm or more, the thermal conductivity in the thickness direction is 150 (W / ° C. · m) or more, and the thermal expansion coefficient in the plate surface direction is 12 × 10 ⁻⁶ (1 / K) or less. A heat sink characterized by.

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