JP2006108247A - Liquid-cooled heat sink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide such a heat sink that can solve a problem included in a liquid-cooled heat sink made of polyethylene. <P>SOLUTION: A specified notch is made on one surface of a main body 1 made of polycarbonate, and communication ports 3 and 4 communicating from the notch to the outside are formed at least at two places. A thin film 2 made of polycarbonate is fitted to the surface in a manner to cover the notches, so as to form an internal space 5. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid-cooled heat sink that cools a semiconductor element.

  One heat sink that abuts against a semiconductor element that generates heat and cools the heat is a structure that circulates a liquid as a cooling medium inside. In this structure, a space is formed inside the heat sink body, and an inlet and an outlet communicating with the space are provided, and a cooling medium is introduced and circulated from the outside into the inner space, and heat is exchanged with the circulating cooling medium.

  Conventionally, a metal structure has been widely used as such a liquid-cooled heat sink. That is, another flat metal plate is brought into contact with and brazed to the notch surface of the metal plate in which the notch serving as an internal space is formed.

  However, this structure requires a brazing furnace because it requires brazing for manufacturing, and the flatness of the metal surface is out of the allowable range due to brazing (if it is severe, it may cause waves). Therefore, a process of smoothing by machining was required, and the cost was high. In addition, since it is made of metal, it is heavy and unpreferable as a liquid-cooled heat sink applied to a product that is reduced in weight.

  Therefore, a structure has been proposed in which a flexible film is bonded to form an internal space that can expand up and down, and a cooling medium is circulated therethrough, instead of brazing a metal plate (see Patent Document 1). Cooling pack, cooling body shown in Patent Document 2). With this structure, it is only necessary to bond the flexible film to form the internal space, so that the weight can be reduced and the manufacturing cost can be reduced.

  However, with this structure, the inlet and outlet of the cooling medium can only be formed at the side edges of the films, and the strength is not strong, so the shape of the internal space can be changed variously. It is difficult and the degree of freedom of the product form is small. Furthermore, since both the upper and lower surfaces are membranes, one side cannot be a fixed surface and cannot be screwed.

For this reason, as a form to improve the structure, a liquid-cooled heat sink in which a polyethylene plate-like body is formed by punching through the upper and lower surfaces and a polyethylene thin film is stretched on the upper and lower surfaces to form an internal space is put into practical use. Has been. With this structure, the plate-like main body serves as a frame for the internal space while retaining the advantages of the membrane bonding structure, so that the degree of freedom in the form of the internal space is increased, and the inlet and outlet can be provided at any location on the main body. In addition, the strength is sufficiently improved as compared with the laminated structure of the films.
JP 2002-111267 (0004 stages) JP-A-7-45763 (FIGS. 1 to 6)

  However, in the case of the one made of polyethylene, the main body and the thin film are fixed by heat welding, but the welded part is weak to pressure, and if the pressure of the liquid as the cooling medium is high, the flexible film will peel off and water leakage will occur There was a risk. Further, although the strength is improved as compared with the lamination of the films, the strength by itself is insufficient due to the restriction by the material of polyethylene. Furthermore, since the limit temperature of thermal deformation is around 50 ° C., if the heat transferred from the semiconductor element exceeds that temperature, the main body may be deformed, and the adhesion rate may be reduced and the heat dissipation efficiency may be reduced. It was. For this reason, in the mounted state, the heat sink body is used while being coated with a metal foil. However, there is a problem that a heat resistance is generated between the film and the metal foil, and a heat dissipation effect is lowered.

  Moreover, when using the main body with screws, screw holes cannot be machined with polyethylene. Therefore, it is necessary to prepare a metal tap as a separate part and screw it into the screw hole forming portion.

  Further, in a use state in which the semiconductor element is brought into contact with only one side and the other part is brought into contact with the other side, heat may be transmitted to the other parts, causing a problem.

  Further, since the internal space is sandwiched between the upper and lower thin films, it has not been possible to provide a protrusion or a wall in the space portion to freely form a cooling medium flow path.

  The present invention has been devised in view of the above-described problems of the prior art, and is intended to provide a heat sink that can solve the problems of a liquid-cooled heat sink made of polyethylene.

  For this reason, the liquid-cooled heat sink according to the present invention forms a predetermined notch on one surface of the polycarbonate body, and forms at least two communication ports communicating with the outside from the notch, and covers the notches. As described above, a polycarbonate thin film is fixed to one surface to form an internal space.

  In the present application, the notch refers to a recess that forms an internal space, and its shape is not particularly limited, but it always refers to a form having a bottom. Therefore, it does not include a form that penetrates through the other surface side.

  One of the communication ports is an inlet for the cooling medium, and the other is an outlet for the cooling medium. That is, a communication port serving as an inlet and a communication port serving as an outlet are formed at a minimum.

  Further, since the cutout is covered with the polycarbonate thin film, it becomes an internal space. The surface on the polycarbonate thin film side is a mounting surface of the semiconductor element, and the semiconductor element is mounted thereon. In this state, when the cooling medium is fed from the communication port serving as the inlet, the cooling medium flows into the internal space formed by the notches, and the thin film expands. Although the thin film expands, it is flexible so that it adheres closely to the attached semiconductor element. When the cooling medium is filled into the internal space (or while being filled), the cooling medium is sent to the outside from the communication port serving as the outlet. Through the circulation of the cooling medium from the inlet communication port to the internal space and the outlet communication port, the heat of the attached semiconductor element is exchanged by the cooling medium through the thin film.

  According to the liquid-cooled heat sink according to the present invention, both the main body and the thin film constituting the heat sink are polycarbonate. Therefore, in the form in which both are welded, even when a high pressure is applied to the welded portion due to the inflow of the cooling medium, the adhesive is bonded. Part will not peel off. Moreover, since the limit temperature of heat deformation of polycarbonate is around 130 ° C., there is no fear of heat deformation. In addition, since it is strong, there is no need to cover the metal foil like a liquid-cooled heat sink made of polyethylene. For this reason, a heat sink can be mounted alone and the heat dissipation effect can be maintained satisfactorily.

  Further, since polycarbonate has a predetermined hardness, tapping for screw holes can be directly applied to the main body. Therefore, since the metal foil and other metal taps are not required at all, the cost required for manufacture and use can be reduced.

  In addition, since the thin film is covered only on the surface where the cutout of the main body is formed, heat is transmitted only to the surface on the thin film side, for example, even when other parts that are not semiconductor elements are in contact with the opposite surface Since no heat is transmitted to other parts, no problems occur.

  In addition, since the internal space has a bottom portion, a projection, a wall, or the like can be provided on the bottom portion, and a cooling medium flow path that can be circulated efficiently can be freely formed.

  Of course, compared to conventional metal liquid-cooled heat sinks, the weight can be significantly reduced, the accuracy of the contact with the surface that contacts the semiconductor element is improved, and the thickness and weight can be further reduced. In comparison, the corrosion resistance and water resistance are improved.

  An example of a specific embodiment of the present invention will be described with reference to the drawings. It should be noted that the following embodiment is merely an example embodying the present invention, and the present invention is naturally not limited thereto.

  FIG. 1 shows the structure of this embodiment, where (a) is a plan view and (b) is an XX cross-sectional view. In the figure, 1 is a heat sink body, 2 is a sheet, 3 is a cooling medium inlet, 4 is a cooling medium outlet, and 5 is an internal space.

  In this embodiment, all members are made of polycarbonate. Next, the configuration of this embodiment will be described with reference to FIG.

  The main body 1 is a rectangular plate material, and a notch (a portion that becomes the internal space 5) is formed at the center of one side. The notch may be formed integrally when the body 1 is formed (a nose and communication holes 30 and 40 described later may be formed simultaneously), or after the body 1 is once formed and cut. What is necessary is just to form by appropriate methods, such as processing. A nose that serves as an inlet 3 and an outlet 4 for the cooling medium is fixed to one side surface of the main body 1, respectively. The holes in each nose are connected to communication holes 30 and 40 that communicate with the notches. Since the main body 1 is made of polycarbonate, it is not particularly shown, but when a fixing screw hole is required, it may be tapped directly. Needless to say, the shape and size of the main body 1 and the cutout may be appropriately changed.

  As shown in FIG. 2, a thin sheet is fixed to the surface of the body 1 where the cutout is formed so as to cover the cutout. The sheet is a thin film of 500 μm or less, and is flexible because the material is polycarbonate. The fixing method may be heat welding or bonding with an adhesive.

  Next, a method of using this embodiment will be described with reference to FIG. As shown in the drawing, the semiconductor element 6 is placed on the sheet 2, and a liquid cooling medium is sent from the inlet 3 to the internal space 5. As the internal space 5 is filled with the cooling medium, the sheet 2 expands as shown in FIG. In this state, the cooling medium flows in from the inlet 3 without interruption, and flows out from the outlet 4 and circulates. Therefore, the heat generated from the semiconductor element 6 is transmitted from the sheet 2 that is in close contact with the cooling medium in the internal space 5, and the cooling medium circulates, whereby the semiconductor element 6 is efficiently cooled.

  The present invention can be applied as a heat sink for cooling a semiconductor element.

It is explanatory drawing of this example of a form, (a) is a top view, (b) of (a) is XX sectional drawing. It is explanatory drawing of the manufacturing process of this example, (a) shows the state before adhering a sheet | seat, (b) shows the state which adhering the sheet | seat, respectively. It is explanatory drawing of the usage method of this example, (a) shows the state with which the cooling medium is not filled, (b) shows the state with which the cooling medium was filled, respectively.

Explanation of symbols

1 Heat sink body
2 sheet (thin film)
3 Entrance (nose)
4 Exit (nose)
5 Internal space (notch)
6 Semiconductor elements

Claims (1)

  A predetermined notch is formed on one side of the polycarbonate main body, and at least two communication ports communicating from the notch to the outside are formed, and a polycarbonate thin film is fixed to the one side so as to cover the notch. A liquid-cooled heat sink characterized by forming an internal space.

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