JP2010129774A - Method for manufacturing integrated pin-fin heat sink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method capable of manufacturing an integrated pin-fin heat sink by surely and integrally forming a base section and a pin-like fin section even when a metal material having large deformation resistance at an ordinary temperature such as copper or a copper alloy is used. <P>SOLUTION: The method is provided with: a heating step of performing heat treatment to a metal material; a forging step of forging the metal material after the heat treatment by using a die to form the metal material into a desired shape; and an extruding step of extruding the metal material after the forming by ejector pins to an outside of the die. A recessed portion for forming the metal material into a flat plate-like shape by pressure in the forging step is provided on the inside of the die, and many holes for drawing the metal material by pressure in the forging step to form pin-like shapes are drilled on a lower surface of the recessed portion. In the forging step, the ejector pins are inserted in all holes of the die from an outside of the die, and an outer diameter of the ejector pins is made smaller than an inner diameter of the holes of the die so that a space is formed between an outer peripheral surface of each of the ejector pins and an inner peripheral surface of each of the holes of the die. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a heat sink that releases heat generated in a semiconductor used for a semiconductor element for a high-power motor control device of an automobile, for example.

  Although this kind of conventional heat sink is not specifically shown, it has a base part that is formed of a metal material and comes into contact with the semiconductor on the back side, and a fin part that stands on the front side of the base part, The fin portion expands the surface area of the entire heat sink and efficiently releases heat generated in the semiconductor.

  Conventionally, aluminum having a relatively high thermal conductivity, light weight, and good workability has been used as a metal material for the heat sink. However, in recent years, the amount of heat generated by semiconductors has increased with the increase in integration and capacity of semiconductor elements, and since heat is not easily transmitted to the entire heat sink and its efficiency is poor, aluminum has a higher thermal conductivity than aluminum. Is required. Gold / silver and copper are listed as metal materials having higher thermal conductivity than aluminum. However, since gold and silver have a high unit price, copper having a relatively low unit price has been used.

  In addition, there are plate-shaped (plate fins) and pin-shaped (pin fins) as the shape of the fin part, but the pin fin can take a larger surface area for its volume, so it is more efficient Can release heat well.

  Therefore, in recent years, in order to cope with an increase in the amount of heat generated by a semiconductor, a heat sink that uses copper or a copper alloy mainly composed of copper as a metal material and has a fin portion (pin fin heat sink) is desired. However, copper has a higher deformation resistance than aluminum and its workability is poor, so it is difficult to integrally form the base and fins, so the base and fins are molded separately. And the manufacturing method which integrates a base part and a fin part by a caulking method is proposed (for example, refer to patent documents 1).

  In addition, there is a manufacturing method in which the base part and the fin part are formed separately and the fin part is brazed to the base part side, or the fin part is bonded to the base part side with an adhesive. However, according to these manufacturing methods, since the base part and the fin part are formed separately, heat is transferred from the base part to the fin part more efficiently than when the base part and the fin part are integrally formed. There is a problem that can not be. In particular, when used as a water-cooled heat sink, the fin part may come off from the base part.

  Furthermore, as a manufacturing method for integrally forming the base portion and the fin portion, the base portion and the fin portion are integrally formed by passing an extrusion die in which a heat sink-shaped hole is formed by conform extrusion of copper or a copper alloy. A method has also been proposed (see, for example, Patent Document 2). However, according to this manufacturing method, the fin portion that is primarily formed can only be formed into a plate shape, and therefore, a further cutting step is required to make the fin portion into a pin shape. However, there was a problem that the manufacturing process became complicated.

Accordingly, a manufacturing method using a forging method utilizing the plasticity of a metal material has attracted attention as a manufacturing method for integrally forming a pin fin heat sink. Forging methods include a so-called cold forging method in which metal material is forged at room temperature without heat treatment, and a so-called hot forging method in which metal material is forged by heat treatment. In the case of production, a metal material can be formed into a complicated shape by forging using a mold.
Japanese Patent No. 3453612 JP-A-2005-72180

  Therefore, in the manufacturing method using the forging method, it is possible to easily manufacture a pin fin heat sink in which the base portion and the fin portion are integrally formed. However, in a general cold forging method, a metal material is used at room temperature. In relation to forging, since the hardness of the metal material remains high and the deformation resistance is large, particularly when forging copper or copper alloy, a large molding pressure is required compared to the size of the metal material. In order to reduce the frictional resistance between the mold and the metal material, the metal material must be lubricated.

  Therefore, in order to obtain a large molding pressure, in addition to having to increase the size of the manufacturing apparatus, a lubrication processing line is also required, so the problem that the equipment necessary for the manufacturing process increases. There is.

  In addition, since the deformation resistance of the metal material is large, there is a risk of damage to the mold or cracking of the metal material, so the amount of deformation given at a time must be reduced. However, there is a problem that the forging process must be repeated.

  On the other hand, in the hot forging method, the metal material is heat-treated, so that even a metal material having a large deformation resistance at room temperature such as copper or copper alloy is forged with a small deformation resistance. Therefore, it is possible to solve the problems in the cold forging method described above, and it is also possible to reduce the pitch of the fin portions and to manufacture a large-sized integrated pin fin heat sink.

  However, in a general hot forging method, burrs generated on the outer periphery of the metal material in the forging process are pushed with an ejector pin, and the metal material is pushed out of the mold. Since the position of each fin part shifts from the position of the corresponding mold hole by cooling and shrinking, it is impossible to extrude metal material from the mold, especially when the number of fins is large Even if the metal material can be extruded from the mold, the metal material molded into the target shape may be distorted.

  The present invention was developed in order to effectively solve the problems of such a conventional method for manufacturing an integrated pin fin heat sink. The invention according to claim 1 comprises a base portion having a flat plate shape, and the base portion. A manufacturing method for manufacturing an integrated pin fin heat sink having a large number of fin portions erected on one surface side of a metal material, and heating the metal material; A forging process in which a metal material after heat treatment is forged using a mold and formed into a target shape, and an extrusion process in which the metal material after molding is pushed out of the mold with an ejector pin are provided. On the inside, there is a recess that molds the metal material into a flat plate shape by the pressure during the forging process, and a number of holes are formed on the bottom surface of the recess to squeeze the metal material and mold into a pin shape at the pressure during the forging process. During the forging process, Insert the ejector pin into the hole from the outside of the mold, make the outer diameter of the ejector pin smaller than the inner diameter of the hole of the mold, and the outer periphery of the ejector pin and the inner periphery of the hole of the mold. A gap is defined between the surface and the surface.

  The invention described in claim 2 is characterized in that, based on claim 1, the outer diameter of the ejector pin is made 0.05 mm smaller than the inner diameter of the hole of the mold.

  According to a third aspect of the present invention, on the premise of the first or second aspect, the hole edge of each hole portion of the mold is chamfered.

  Therefore, in the invention described in claim 1, since the heating process is performed before the forging process, even if it is a metal material having a large deformation resistance at room temperature, such as copper or a copper alloy, the deformation resistance. Forging can be performed with a small size, so that problems in the cold forging method can be eliminated, and the pitch of the fins can be made finer, and large integrated pin fin heat sinks can be manufactured. Needless to say, in addition to this, during the forging process, the ejector pins are inserted from the outside of the mold into all the holes of the mold, so that the mold is bent by the forging pressure. Therefore, it is possible to effectively prevent breakage due to repeated use of the mold, and at the time of extrusion after the forging process, the ejector pin ensures uniform distribution on the outer end surfaces of all the formed fins. It is possible to apply pressure started to, there is no probability distorted metallic material molded into the shape of interest.

  In addition, since a gap is defined between the outer peripheral surface of the ejector pin and the inner peripheral surface of the hole of the mold, it is possible to absorb the distortion even if the mold is distorted by heat during the forging process. In addition, during the extrusion process after the forging process, the ejector pin can be allowed to move smoothly.

  In the invention of claim 2, the outer diameter of the ejector pin is made 0.05 mm smaller than the inner diameter of the hole of the mold, and the outer peripheral surface of the ejector pin and the inner peripheral surface of the hole of the mold In the relationship that defines a gap between them, the gap can absorb the distortion caused by the heat of the mold during the forging process and allow the ejector pin to move smoothly during the extrusion process. Since the metal material flowing into the gap can be extremely reduced, there is no possibility that a large burr is generated on the outer end surface of the formed fin portion.

  In the invention according to claim 3, when the hole edge of each hole portion of the mold is chamfered, the metal material is squeezed by the pressure during the forging process and formed into a pin shape. Since the deformation resistance of the material can be suppressed, it is possible to effectively prevent the mold from being damaged.

  The present invention relates to a manufacturing method in which an integrated pin fin heat sink having a flat plate-like base portion and a large number of fin portions standing on one surface side of the base portion is integrally formed of a metal material. A heating process for heat-treating the metal material, a forging process for forging the heat-treated metal material into a desired shape by using a mold, and the metal material after the molding with the ejector pin An extrusion process for extruding the mold outward, and a recess for forming a metal material into a flat plate shape by pressure during the forging process is provided inside the mold, and the metal material is squeezed on the lower surface of the recess by the pressure during the forging process. A large number of holes to be stretched and formed into a pin shape are drilled. During the forging process, ejector pins are inserted into all the holes of the mold from the outside of the mold, and the outer diameter of the ejector pins is set to the hole of the mold. Make the ejector smaller than the inner diameter of the By defining a gap between the outer peripheral surface of the pin and the inner peripheral surface of the hole of the mold, it is possible to ensure that even a metal material having a large deformation resistance at room temperature such as copper or copper alloy can reliably And a pin-shaped fin portion are integrally formed to provide a manufacturing method capable of manufacturing an integrated pin fin heat sink.

  Hereinafter, the present invention will be described in detail based on a preferred embodiment shown in the drawings. First, an example of an integrated pin fin heat sink manufactured by the manufacturing method according to the embodiment will be described. As shown in FIG. 1 and FIG. 2, for example, a base part B that is integrally formed of a metal material such as copper or copper alloy and has a flat plate shape in contact with the semiconductor on the back side, and stands on the front side of the base part B It has a structure in which a large number of fin portions F having a cylindrical pin shape are formed, and the surface area of the entire heat sink is widened by the fin portions F to efficiently release heat generated in the semiconductor. Since the pin fins are cylindrical pin-shaped, the surface area can be made larger for the volume than the plate fins. Further, since the base portion B and the fin portions F are integrally formed, heat can be efficiently transferred from the base portion B to the fin portions F, and each fin is also used when used as a water-cooled heat sink. There is no possibility that the part F comes off the base part B. In addition, as a metal material, it is not limited to the copper or copper alloy mentioned above, It is arbitrary according to implementation to use aluminum, an aluminum alloy, a composite material, etc.

  Here, the base portion B has a length of 133 mm, a width of 77 mm, and a thickness of 5 mm, the fin portion F has an outer diameter of 1.5 mm and a height of 8 mm, and the pitch P of the fin portion F is 4 mm. The fin portions F arranged in a row are displaced by a half pitch for each row and are arranged in a staggered arrangement. In such an integrated pin fin heat sink H, the outer diameter of the fin portion F and the dimension of the pitch P are not limited to this, but the outer diameter of the fin portion F is preferably 1.5 to 2 mm, The pitch P of the fin portion F is desirably 4 to 5 mm. If this range is exceeded, the entire structure becomes unnecessarily large, and the number of fin portions F cannot be increased to increase the surface area. Is insufficient.

  Further, the thickness of the base portion B is desirably 5 mm, and if it is 5 mm or less, the metal material is not sufficiently expanded during the forging process described later, and it is difficult to form the fin portion F integrally with the base portion B. It becomes. Furthermore, the height of the fin portion F is desirably 6 to 8 mm. When the height is 8 mm or more, the thickness of the base portion B has to be increased, and the metal material is not sufficiently expanded during the forging process. It becomes difficult to mold the outer end surface of the fin portion F.

  Next, the manufacturing method according to the present embodiment will be described. The manufacturing method according to the present embodiment basically includes a heating process in which heat treatment is performed on a metal material cut as necessary, and a metal after the heat treatment. It includes a forging process in which a material is forged using a mold 1 to be described later and formed into a desired shape, and an extrusion process in which the molded metal material is pushed out of the mold 1 by an ejector pin 2 to be described later. Because of the heating process before the forging process, especially metal materials with large deformation resistance at room temperature, such as copper and copper alloys, can be forged with a small deformation resistance. The problem in the forging method can be solved, the pitch P of the fin portion F can be made fine, and a large integrated pin fin heat sink can be manufactured. Is Relative to the mold 1 and the ejector pin 2 used in forming process and the extrusion process, it lies in employing the following configuration.

  That is, first, the mold 1 will be described. In the present embodiment, as shown in FIGS. 3 and 4, the metal material is formed into the shape of the above-described base portion B inside the mold 1 by the pressure during the forging process. A concave portion 1a to be formed is provided, and a plurality of hole portions 1b are formed along the arrangement of the fin portions F by squeezing a metal material by the pressure during the forging process on the lower surface of the concave portion 1a to form the shape of the fin portion F described above. The hole edge 1c of each hole 1b is configured to be chamfered as shown in FIG. In this embodiment, each hole 1b has a circular cross section in order to obtain a cylindrical pin-shaped fin portion F. It is optional depending on the implementation to make the cross section rectangular such as rectangular or triangular. Further, in order to manufacture the integrated pin fin heat sink H having the above-described dimensions, it is desirable that the hole edge 1c of each hole 1b has a chamfered shape having a roundness of R0.5 mm.

  Next, the ejector pin 2 will be described. In this embodiment, the ejector pin 2 is formed in a columnar shape having a cross section similar to the cross sectional shape of the hole 1b of the mold 1, as shown in FIGS. The lower end side of the metal material is fixed to the knockout 3 and inserted into all the holes 1b of the mold 1 from the outside of the mold 1 during the forging process, and is expanded by the holes 1b of the mold 1. Is closed according to the length dimension of the fin portion F described above. Further, as shown in FIG. 7, the outer diameter of the ejector pin 2 is made 0.05 mm smaller than the inner diameter of the hole 1b of the mold 1 so that the outer periphery of the ejector pin 2 and the inner periphery of the hole 1b of the mold 1 It is the structure which defines the clearance gap 4 between surfaces.

  Therefore, during the forging process, as shown in FIG. 6, when the metal material M is put into the mold 1 and pressure is applied in one shot by a flexure press (not shown) from above, as shown in FIG. In this case, the metal material M is molded in the space defined by the mold 1 and the ejector pin 2. In this case, the hole edge 1 c of each hole 1 b of the mold 1 is chamfered. Therefore, when the metal material M is expanded and molded into a pin shape, the deformation resistance of the metal material M can be suppressed, so that the mold 1 can be effectively prevented from being damaged. Since the heating process is performed before the forging process, the metal material M can be formed into a target shape by simply applying a pressure with one shot by a flexion press, and there is no need to apply pressure many times.

  In addition, since the ejector pins 2 are inserted into all the holes 1b of the mold 1 from the outside of the mold 1, the mold 1 is prevented from being bent by the pressure of the flexure press. It is possible to effectively prevent damage due to repeated use.

  Further, the outer diameter of the ejector pin 2 is made 0.05 mm smaller than the inner diameter of the hole 1b of the mold 1, and a gap is formed between the outer peripheral surface of the ejector pin 2 and the inner peripheral surface of the hole 1b of the mold 1. 4, the gap 4 allows the mold 1 to absorb the distortion even if the mold 1 is distorted by heat, absorbs the distortion caused by the heat of the mold 1, and an extrusion process described later. The metal material M flowing into the gap 4 can be extremely reduced while allowing the ejector pin 2 to be smoothly moved at the time, so that a large burr is generated on the outer end surface of the formed fin portion F. This makes it possible to obtain a clean outer end surface.

  At the time of the extrusion process after the forging process, as shown in FIG. 9, the molded metal material M is pushed out of the mold 1 by the ejector pins 2 pushed up by the knockout 3. Since the ejector pins 2 are inserted into all the holes 1b of the mold 1 from the outside of the mold 1, the ejector pins 2 apply a uniform extrusion pressure to the outer end surfaces of all the formed fin portions F. Therefore, there is no possibility that the metal material M molded into the target shape is distorted. In addition, since the gap 4 is defined between the outer peripheral surface of the ejector pin 2 and the inner peripheral surface of the hole 1b of the mold 1, the ejector pin 2 can be allowed to move smoothly.

  Therefore, the integrated pin fin heat sink H shown in FIGS. 1 and 2 can be finally manufactured by performing chemical polishing or trimming on the extruded metal material M after molding. .

  The manufacturing method of an integrated pin fin heat sink according to the present invention is a highly integrated and large-capacity high-capacity system for controlling complex systems of these vehicles in the field of hybrid cars and electric vehicles, where demand is expected to increase in the future. When used for manufacturing a heat sink that releases heat generated in a semiconductor used for a semiconductor element or the like for an output motor control device, it is very convenient.

It is a perspective view which shows an example of the integrated pin fin heat sink manufactured by the manufacturing method of this invention. It is a top view which shows an example of the integrated pin fin heat sink manufactured by the manufacturing method of this invention. It is a perspective view which shows the relationship between the metal mold | die used for the manufacturing method which concerns on the Example of this invention, and an ejector pin. FIG. 4 is a sectional view taken along line AA in FIG. 3. It is an expanded sectional view which shows the hole edge of the hole part of a metal mold | die. It is explanatory drawing which shows the state at the time of the forge process of the manufacturing method which concerns on the Example of this invention. It is explanatory drawing which shows the clearance gap defined between the outer peripheral surface of an ejector pin, and the internal peripheral surface of the hole of a metal mold | die. It is explanatory drawing which shows the state immediately after the forge process of the manufacturing method which concerns on the Example of this invention. It is explanatory drawing which shows the state at the time of the extrusion process of the manufacturing method which concerns on the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mold 1a Concave part 1b Hole part 1c Hole edge 2 Ejector pin 3 Knockout 4 Crevice M Metal material H Integrated type pin fin heat sink B Base part F Fin part P Pitch

Claims (3)

  A manufacturing method in which an integrated pin fin heat sink having a flat plate-like base portion and a large number of fin portions standing on one side of the base portion is integrally formed of a metal material, and manufactured. Heating process to heat-treat the metal material, forging process to forge the heat-treated metal material to the desired shape using a mold, and the metal material after molding to the outside of the mold with an ejector pin An extrusion process that extrudes the metal material, and a recess is formed on the inner side of the mold to form the metal material into a flat plate shape by the pressure during the forging process. A large number of holes to be molded are drilled, and during the forging process, ejector pins are inserted into all the holes of the mold from the outside of the mold, and the outer diameter of the ejector pins is made larger than the inner diameter of the mold hole. And make it smaller outside the ejector pin Method of manufacturing integral pin fin heat sink, characterized in that to define a gap between the surface and the inner surface of the mold hole.   2. The method of manufacturing an integrated pin fin heat sink according to claim 1, wherein an outer diameter of the ejector pin is made 0.05 mm smaller than an inner diameter of the hole of the mold.   3. The method of manufacturing an integrated pin fin heat sink according to claim 1, wherein a hole edge of the hole portion of the mold has a chamfered shape.

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