JP2013045782A - Cooler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooler having a cover plate bonded to a case by friction stir welding and fixing an article to be cooled onto the cover plate, in which burrs produced by friction stir welding are not required to be removed.SOLUTION: In a cooler 10, a cover plate 4 is welded to the upper surface 7 around the opening of a case 6 for feeding a cooling medium, and a base plate 2 having a heating element 90 fixed to the center of the upper surface is fixed onto the cover plate 4. In the central region of the upper surface of the cover plate 4, a terrace part 4a is formed to stretch for the peripheral region thereof. In the peripheral region, a gap Sp is formed between the base plate 2 and the cover plate 4. The friction stir bonding part W of the cover plate 4 and the upper surface 7 around the opening of a case is located below the gap Sp. The base plate 2 is fixed to the upper surface 7 around the opening of a case by means of a bolt 14 on the outside of the friction stir bonding part W.

Description

  The present invention relates to a cooler. In particular, the present invention relates to a cooler that cools a heating element by fixing a plate (base plate) to which a heating element (typically a semiconductor chip such as a power transistor) is fixed on an upper surface.

  In the cooler, when joining the cover plate to the case, it is necessary to join the cover plate without a slight gap so that the refrigerant does not leak. As a technique for joining the cover plate so that the refrigerant does not leak, Patent Document 1 proposes a technique for joining the cover plate to the upper surface around the case opening continuously by friction stir welding. Has been.

JP 2010-69503 A

  In friction stir welding, a rotating tool is pressed against a member, the member is softened and plastically flowed by frictional heat, and the two members are locally mixed and joined. For this reason, the area around the place where the rotating tool is pressed rises and becomes a so-called burr when solidified. Usually, an object to be cooled is often placed on the cover plate. Patent Document 1 discloses a process of removing burrs after friction stir welding. The present specification provides a cooler that eliminates burr removal in a cooler in which a cover plate is joined to a case by friction stir welding and a cooling target is fixed on the cover plate.

  In the cooler provided in this specification, the cover plate is welded to the upper surface around the opening of the case for flowing the refrigerant, and the base plate having the heating element fixed at the center of the upper surface is fixed on the cover plate. It is a vessel. That is, this cooler is suitable for cooling the heating element by fixing the plate (base plate) on which the heating element is fixed to the upper surface. In this cooler, the central region protrudes from the surrounding region surrounding the central region on one of the lower surface of the base plate and the upper surface of the cover plate. In other words, a terrace that is one step higher than the surface of the surrounding region is formed in the central region. Since there is a terrace, when the base plate is overlaid on the cover plate, the lower surface of the base plate and the upper surface of the cover plate are in contact with each other in the central region, but a gap is formed between the base plate and the cover plate in the peripheral region. And the friction stir welding site | part of a cover plate and case opening part surrounding upper surface is located under said clearance gap. Furthermore, the base plate is fixed to the upper surface around the case opening by a bolt outside the friction stir welding site. Although the friction stir welding site between the cover plate and the upper surface around the case opening is located below the gap, the manufacturing process does not require welding after forming the gap by placing the base plate. The base plate may be attached after welding the cover plate and the upper surface around the case opening.

  According to said structure, a clearance gap is ensured on a friction stirring site | part. For this reason, even if burrs generated by friction stir welding remain, they do not affect the contact between the central regions of the cover plate and the base plate, so it is not necessary to remove the burrs.

  In the cooler described above, the center area of the lower surface of the base plate and the center area of the upper surface of the cover plate may be in contact with each other via heat radiation grease. If the base plate and the cover plate are overlapped after applying heat dissipation grease, excess heat dissipation grease protrudes from the center to the gap, but there is a gap, so it does not spread further outside, and the bolt outside the friction stir welding site It is possible to prevent heat radiation grease from entering the fastening portion. That is, the bolts are not easily loosened by the heat dissipation grease. Here, “outside from the friction stir welding part” means “outside” when the case is viewed in plan.

It is a disassembled perspective view of the cooler of an Example. It is sectional drawing in the II-II line of FIG. 1 (finished product). It is sectional drawing of the cooler of a modification.

  A cooler 10 according to an embodiment will be described with reference to the drawings. FIG. 1 is an exploded perspective view of the cooler 10. 2 is a cross-sectional view taken along line II-II in FIG. However, FIG. 2 is a cross-sectional view of the finished product.

  The cooler 10 is a device for cooling the semiconductor chip 90 (heating element). The cooler 10 includes a case 6 through which a coolant flows, a cover plate 4 that seals the opening of the case, and a base plate 2 that fixes the semiconductor chip 90 on the upper surface and contacts the cover plate 4 on the lower surface. A refrigerant supply port 8 a and a discharge port 8 b are provided on a side surface of the case 6. As shown in FIG. 2, a plurality of fins 4 b that promote heat diffusion of the semiconductor chip 90 are provided on the back surface of the cover plate 4. The case 6, the cover plate 4, and the base plate 2 are made of a material having high thermal conductivity such as aluminum or copper.

  On the upper surface 7 around the opening of the case, there are double steps that make a round along the periphery of the opening. A first step 7b that is one step lower is formed inside the outermost plane 7a, and a second step 7c that is one step lower is formed further inside. The cover plate 4 is sized to fit in the second step 7c that makes a round along the innermost edge of the upper surface 7 around the opening of the case. After the cover plate 4 is fitted in the second step 7c, the periphery is joined by friction stir welding so as to make a round of the opening. The location indicated by the symbol W in FIG. 2 is the friction stir weld. Since FIG. 1 is an exploded view, the friction stir welding portion is not shown.

  A terrace 4 a that is one step higher than the surroundings is formed in the center of the upper surface of the cover plate 4. Hereinafter, the region where the terrace 4a is formed is referred to as a central region, and the periphery of the terrace 4a is referred to as a surrounding region. In other words, the central region of the upper surface of the cover plate 4 protrudes from the surrounding region. The surrounding area makes a round around the central area. The term “surrounding area” is used not only for the cover plate 4 but also for the base plate 2. That is, when the cover plate 4 and the base plate 2 are overlapped, the inner side than the edge of the terrace 4a is referred to as a “central region” and the outer side is referred to as a “surrounding region”.

  When the base plate 2 is overlaid on the cover plate 4 by the terrace 4a, both come into contact with each other in the central region, but in the surrounding region (however, in the first step 7b on the upper surface 7 around the opening), there is a gap Sp between them. Secured. As shown in FIG. 2, the friction stir welding portion W is located below the gap Sp. Although the burrs B generated during welding remain on both sides of the friction stir joint W, since there is a gap Sp, the burrs B do not reach the back surface of the base plate 2, and the burrs B are the performance of the cooler 10. Will not be affected. Therefore, it is not necessary to delete the burrs B. In addition, the height D of the gap Sp is set to be equal to or higher than the assumed height of the burr B. The height D of the gap Sp is approximately equal to the height of the terrace 4a. However, strictly speaking, the height D of the gap Sp is a value obtained by adding a desirable thickness of the heat radiation grease G (described later) to the height of the terrace 4a.

  The size of the base plate 2 is substantially the same as the outer shape of the case 6. Further, the outermost plane 7a of the upper surface 7 around the opening of the case is one step higher than the first step 7b that forms the lower boundary of the gap Sp. The height of the step is the same as the height of the terrace 4 a provided on the cover plate 4. That is, the outermost plane 7a and the lower surface of the base plate 2 are also in contact. The base plate 2 is fixed to the case 6 with bolts 14 on the upper surface 7 (outermost plane 7a) around the opening. 1 indicates a bolt through hole provided in the base plate 2, and 6 a indicates a bolt screw hole provided in the outermost plane 7 a of the upper surface 7 around the opening of the case 6. . In this embodiment, the base plate 2 is bolted at six locations on the upper surface around the opening. As shown in FIG. 2 and as is apparent from FIG. 1, the base plate 2 is fixed to the case 6 by bolts 14 outside the friction stir welding portion W.

  The center area of the lower surface of the base plate 2 and the center area of the upper surface of the cover plate 4 are in contact with each other through heat radiation grease G. When the base plate 2 and the cover plate 4 are overlapped after the heat radiation grease G is applied, excess heat radiation grease G protrudes from the side. At this time, since there is a gap Sp outside the central region, the heat dissipation grease G accumulates in the gap Sp and does not spread outward. As shown in FIG. 2, the heat radiation grease G stays inside the gap Sp and does not reach the outside, that is, the bolt 14. The grease makes it easy to loosen the screw, but since the heat dissipating grease G does not reach the bolt 14, the screw 14 that fixes the cover plate 4 is not easily screwed. In particular, since the flat surface 7a on which the screw hole 6a is formed is higher than the second step 7b that forms the lower boundary of the gap Sp, even if the heat radiation grease G reaches the outside of the gap Sp. Unless the heat dissipation grease G is so large that the entire gap Sp is filled, the heat dissipation grease G does not reach the bolt 14.

  A modification of the above embodiment will be described. FIG. 3 is a cross-sectional view of a cooler 110 according to a modification. The cross section of FIG. 3 corresponds to the cross section of FIG. In the cooler 10 of the said Example, the terrace part 4a was formed in the upper surface center area | region of the cover plate 4, and the lower surface of the baseplate 2 was flat. On the contrary, in the cooler 110 of the modified example, the terrace 102a is formed on the lower surface of the base plate 102, and the upper surface of the cover plate 104 is flat. Other parts are the same as those of the cooler 10. Obviously, the combination of the base plate 102 and the cover plate 104 can achieve the same effects as the cooler 10. That is, in the technique disclosed in this specification, it is only necessary that the central region protrudes from the surrounding region on either the lower surface of the base plate or the upper surface of the cover plate. In other words, it is only necessary to provide a terrace portion that is one step higher than the surrounding area on either the lower surface of the base plate or the upper surface of the cover plate. Of course, terraces may be provided in both the base plate lower surface center region and the cover plate upper surface Ryuo region.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

2: Base plate 4: Cover plate 6: Case 7: Upper surface around opening 14: Bolt W: Friction stir joint G: Heat radiation grease

Claims (2)

A cover plate is welded to the upper surface around the opening of the case for flowing the refrigerant, and a base plate with a heating element fixed to the center of the upper surface is a cooler that is fixed on the cover plate.
One of the lower surface of the base plate and the upper surface of the cover plate has a central area protruding from the surrounding area surrounding the central area, and a gap is formed between the base plate and the cover plate in the surrounding area. The friction stir welding site with the upper surface around the case opening is located under the gap, and the base plate is fixed to the upper surface around the case opening with a bolt outside the friction stir welding site,
A cooler characterized by that.   2. The cooler according to claim 1, wherein the lower surface center region of the base plate and the cover plate upper surface center region are in contact with each other through heat radiation grease.

Images