JP2005311079A - Heat dissipation device of semiconductor element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve heat dissipation performance of a CPU 13 mounted on a mounting substrate 11 with a heat sink 14 fixed thereon. <P>SOLUTION: The heat dissipation device of a semiconductor element is mounted on the mounting substrate 11 and dissipates heat generated by the semiconductor element 13, by fixing a heat sink 14 thereon. In the device, a substantially cross-shaped carbon graphite sheet 18 is interposed or jointed in between the upper surface of the semiconductor element 13 and the lower surface of the heatsink 14, or in the prescribed portion of the outer surface of the heat sink 14 which is not in contact with the semiconductor element 13; and four strip-like projection pieces 19 formed in an outer part side to project to the side are bent aslant to be positioned in the side with respect to the heatsink 14. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a heat dissipation device for a semiconductor element, and more particularly to a heat dissipation device for a semiconductor element in which a heat sink is attached to a semiconductor element mounted on a substrate to dissipate heat.

  A central processing unit (CPU) is widely used as a computing means for personal computers and various electronic devices. Such a CPU is usually a semiconductor bare chip sealed with a resin or ceramic and packaged. An electrode or a lead is attached to a predetermined position on the outer surface of the CPU, and the CPU is mounted on a motherboard. The electrodes or leads are soldered and connected to the connection lands of the mother board.

  On the other hand, higher performance of the CPU and higher calculation speed are advanced, and accompanying this, Joule heat is generated inside during operation. Such heat is transferred through the package to the outer surface. Therefore, in order to cool the inside of the CPU, a heat sink made of a material having a high thermal conductivity such as pure aluminum, aluminum alloy, copper or the like is attached so as to be in contact with the outer surface of the CPU. Released.

  However, the heat dissipation of the CPU cannot be sufficiently performed only by the heat dissipation of the conventional heat sink, and the CPU is heated to an abnormally high temperature, for example, a temperature of 100 ° C. or more, thereby limiting the life of the CPU. There is a possibility of causing problems in processing operations. Therefore, it is necessary to provide a more effective heat dissipation device in the semiconductor element, particularly in the CPU.

  An object of the present invention is to provide a heat radiating device that can radiate heat from a semiconductor element such as a CPU more effectively.

  Another object of the present invention is to provide a heat dissipation device for a semiconductor element which can be improved at a low cost and can greatly improve the heat dissipation performance.

  Still another object of the present invention is to provide a heat dissipation device for a semiconductor element that can more reliably prevent the temperature rise of the semiconductor element constituting the CPU.

  The above-described problems and other problems of the present invention will be clarified by the technical idea of the present invention and the embodiments thereof described below.

The main invention of the present application is a heat dissipation device for a semiconductor element in which a heat sink is mounted on a semiconductor element mounted on a substrate to dissipate heat.
The present invention relates to a heat dissipation device for a semiconductor element, characterized in that a carbon graphite sheet is interposed or joined between the semiconductor element and the heat sink or on the outer surface of the heat sink.

  Here, the carbon graphite sheet may include a protruding piece protruding to one side or two or more sides of the heat sink. The carbon graphite sheet may be bonded to the surface of the semiconductor element via an adhesive sheet. Thermally conductive grease may be applied to a portion of the carbon graphite sheet that is bonded to the semiconductor element or a portion of the carbon graphite sheet that is bonded to the heat sink. Further, an opening may be formed at a predetermined position of the carbon graphite sheet, and the semiconductor element may escape through the opening, and the carbon graphite sheet may be joined to a peripheral portion of a joint surface of the heat sink with the semiconductor element. Further, a joined piece or a bent piece of the carbon graphite sheet may be joined to the projecting piece projecting to the side of the carbon graphite sheet. In addition, a plurality of carbon graphite sheets are provided, and carbon graphite pads thicker than the carbon graphite sheets are interposed between the portions of these carbon graphite sheets in contact with the semiconductor element or the heat sink and between the protruding pieces protruding sideways. You can do it. In addition, a cut may be formed in the protruding piece protruding to the side of the carbon graphite sheet. Moreover, the front-end | tip part of the said protrusion piece of the said carbon graphite sheet may be joined to the inner surface of a housing | casing. The semiconductor element may be a central processing unit (CPU).

  A main invention of the present application is a heat dissipation device for a semiconductor element in which a heat sink is mounted on a semiconductor element mounted on a substrate to dissipate heat. It is intended to be interposed or joined.

  Therefore, according to such a semiconductor element heat dissipation device, the carbon graphite sheet interposed or bonded between the semiconductor element and the heat sink or on the outer surface of the heat sink is more reliably generated inside the semiconductor element with respect to the heat sink. Since heat is transmitted or the carbon graphite sheet itself radiates heat, the heat radiating performance is improved as compared with heat radiating only by a heat sink. Therefore, an excessive temperature rise of the semiconductor element is reliably suppressed, and it is avoided that the semiconductor element is deteriorated by heat and its life is shortened.

  The present invention will be described below with reference to embodiments shown in the drawings. 1 to 3 show a first embodiment. Here, a socket 12 is mounted at a predetermined position on a mounting board 11 made of a motherboard, and a semiconductor element, for example, a CPU 13 is connected to the socket 12, and an electrode of the CPU 13 is connected to the motherboard 11 via the socket 12. Thus, an electrical connection with the circuit on the mother board 11 is established. A heat sink 14 is attached to the upper surface of the CPU 13. The heat sink 14 is made of an aluminum alloy, and is formed with a plurality of grooves parallel to each other, and fins 15 are formed between these grooves. Heat is released into the atmosphere by bringing a wide part into contact with the atmosphere.

  In such a mounting structure of the CPU 13, a carbon graphite sheet 18 is particularly used here. The graphite sheet 18 is formed by rolling natural graphite and insulatingly sealing the surface with a resin to form a sheet. Note that a number of streaks may be formed on the surface of the carbon graphite sheet 18 if necessary. Further, the direction of the formed line can be formed so as to substantially coincide with the heat transfer direction.

  As shown in FIG. 3, such a carbon graphite sheet 18 is provided with protruding pieces 19 on four sides on the outer side. The protruding piece 19 becomes a heat radiating part as will be described later. Such a carbon graphite sheet 18 is sandwiched and attached between the CPU 13 and the heat sink 14. In addition, as shown in FIG. 2, the projecting pieces 19 projecting in four directions of the carbon graphite sheet 18 are bent obliquely as necessary so as to be located on the side of the heat sink 14. When the heat sink 14 is fixed to the mounting substrate 11 by the fixing means, the carbon graphite sheet 18 is sandwiched between the semiconductor element 13 and the heat sink 14 and the surfaces on both sides thereof are the upper surface of the semiconductor element 13 and the heat sink 14. Each is crimped to the lower surface. It is preferable to apply thermal conductive grease between the semiconductor element 13 and the carbon graphite sheet 18 and / or between the carbon graphite sheet 18 and the bottom surface of the heat sink 14.

  According to such a heat dissipation device for the semiconductor element 13, when the CPU 13 constituting the semiconductor element performs an arithmetic operation, Joule heat generated therein is passed through the package of the semiconductor element 13, and the carbon graphite sheet 18, the heat sink 14, Will be communicated to. That is, since the heat generated here is transmitted from the carbon graphite sheet 18 to the heat sink 14, it is dissipated into the atmosphere in contact with the fins 15. Further, part of the heat is radiated by the heat radiation function of the carbon graphite sheet 18 itself. That is, the carbon graphite sheet 18 is more excellent in heat dissipation than the heat sink 14 made of an aluminum alloy, and the protruding pieces 19 protruding on the four sides perform a heat dissipation operation. Therefore, the heat radiation operation by the heat sink 14 and the heat radiation operation by the carbon graphite sheet 18 are superimposed. Therefore, the heat dissipation amount per unit time increases, the temperature rise of the semiconductor element 13 is prevented, and the heat dissipation effect is improved as compared with the conventional case.

  Next, another embodiment will be described with reference to FIGS. This embodiment employs a structure in which a cooling fan 23 for forced cooling is disposed on the heat sink 14 and the semiconductor element 13 and the carbon graphite sheet 18 are joined to each other by an adhesive sheet 26.

  Here, as shown in FIG. 5, the adhesive sheet 26 is obtained by dispersing a large number of conductive particles 27 in an adhesive layer. As shown in FIG. 6, the conductive particles 27 have a nickel layer 29 formed on the surface of a resin ball 28, and a gold layer 30 formed thereon. Such an adhesive sheet is called an anisotropic conductive film, and is supplied by, for example, Sony Chemical Corporation. Here, for example, CP7632K manufactured by the company is used.

  When the carbon graphite sheet 18 is bonded to the semiconductor element 13 and the adhesive sheet 26 interposed therebetween is compressed in the thickness direction, the conductive particles 27 come into contact with each other as shown in FIG. Heat transfer is reliably generated in the thickness direction. Therefore, the carbon graphite sheet 18 is reliably bonded to the surface of the semiconductor element 13 by such an adhesive sheet 26, and the heat generated in the semiconductor element 13 is reliably transmitted to the carbon graphite sheet 18 through the adhesive sheet 26. It becomes possible to communicate. Here, the cooling fan 23 is mounted on the heat sink 14 as described above. Therefore, by forcibly sending the air to the groove portion between the fins 15 of the heat sink 14 by the cooling fan 23, the heat dissipation performance of the heat sink 14 can be further enhanced, and higher heat dissipation is ensured.

  Next, still another embodiment will be described with reference to FIG. In this embodiment, a rectangular opening 34 is formed in a portion of the carbon graphite sheet 18 interposed between the semiconductor element 13 and the heat sink 14, particularly in a portion corresponding to the upper surface of the semiconductor element 13. The rectangular opening 34 has a size slightly larger than the size of the package of the semiconductor element 13 so that the opening 34 can escape the semiconductor element 13. Then, such a carbon graphite sheet 18 is bonded to the peripheral portion of the bottom surface of the heat sink 14 as shown in FIG. At this time, the semiconductor element 13 is positioned in the opening 34, whereby the semiconductor element 13 comes into direct contact with the bottom surface of the heat sink 14.

  Therefore, according to such a configuration, the heat generated in the semiconductor element 13 is directly transmitted to the bottom surface of the heat sink 14, and the heat transmitted to the bottom surface of the heat sink 14 is merely dissipated by the fins 15 of the heat sink 14. Instead, it is transmitted to the carbon graphite sheet 18 joined to the bottom surface of the heat sink 14 and is radiated by the projecting piece 19. Therefore, according to such a configuration, a heat dissipation device for a semiconductor element with further improved heat dissipation can be obtained.

  FIG. 10 shows a configuration obtained by further modifying the heat radiating device. The carbon graphite sheet joining piece 46 is also formed on the surface of the protruding piece 19 projecting to the side of the carbon graphite sheet 18 joined to the bottom surface of the heat sink 14. , And the tip end portion of the protruding piece 19 has a three-layer structure. Accordingly, this further improves the heat dissipation in the protruding piece 19 portion.

  FIG. 11 shows still another modification. In this modified example, a bent piece that is bonded to the bottom surface of the heat sink 14 and that is bent in an L-shaped cross section on a protruding piece 19 that protrudes to the side of the carbon graphite sheet 18 that escapes the semiconductor element 13 through the opening 34. 47 is joined. By joining such a bent piece 47, the heat dissipation of the protruding piece 19 protruding to the side is further improved.

  Next, still another modification will be described with reference to FIGS. This modification is provided with two carbon graphite sheets 18 as shown in FIG. These carbon graphite sheets 18 are made of a very thin carbon graphite sheet having a thickness of, for example, 20 μm, and projecting pieces 19 are integrally formed on the four sides so as to project sideways. . Five rectangular pads 48 are arranged between the carbon graphite sheets 18. That is, a carbon graphite sheet 48 having a thickness of, for example, 2.0 mm is interposed between a portion of the carbon graphite sheet 18 in contact with the semiconductor element 13 or the bottom of the heat sink 14 and a protruding piece 19 protruding sideways. . These pads 48 are bonded to corresponding portions of the upper and lower carbon graphite sheets 18 via an adhesive layer.

  FIG. 13 shows a state where the CPU 13 dissipates heat by such a heat dissipating device composed of a combination of the carbon graphite sheet 18 and the pad 48, and the two carbon graphite sheets 18 are disposed on the bottom surface of the heat sink 14 including the fins 15. In the center portion, a portion where the pad 48 is joined is arranged, and the pad 48 is joined between the four projecting pieces 19 projecting sideways. Therefore, according to such a configuration, heat from the semiconductor element 13 such as a CPU is transmitted to the heat sink 14 by the carbon graphite sheet 18, and also at the protruding piece 19 that protrudes to the side of the carbon graphite sheet 18. It is possible to effectively dissipate heat at the portion where the pad 48 is sandwiched and thickened. In addition, since the bent portion outside the side edge of the heat sink 14 of the carbon graphite sheet 18 does not include the pad 48, it can be easily bent.

  FIG. 14 shows a modification of the carbon graphite sheet 18. A plurality of triangular projecting pieces 51 divided by cutting are formed at the front end portions of the four projecting pieces 19 projecting sideways of the carbon graphite sheet 18 according to this modification. As a result of this tip effect, the heat dissipation from the tip of the protruding piece 19 is further improved. The attachment structure of the carbon graphite sheet 18 may be the same as that shown in FIG.

  FIG. 15 shows still another embodiment. In this embodiment, the projecting piece 19 formed on the outer side of the carbon graphite sheet 18 is made longer, and the tip side portion of the projecting piece 19 is folded to form a folded piece 40. The surface is bonded to the inner surface of the housing 42 via the adhesive sheet 41. Therefore, according to such a configuration, the heat flowing through the protruding piece 19 of the carbon graphite sheet 18 is further transmitted to the casing 42, and the casing 42 constitutes a heat radiating means. Therefore, the heat dissipation performance of the carbon graphite sheet 18 can be further enhanced by using the heat dissipation of the housing 42.

  Although the present invention has been described above with reference to the illustrated embodiments, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the technical idea of the invention included in the present application. For example, each of the above embodiments shows an example in which a CPU is used as the semiconductor element 13. However, the present invention is not necessarily limited to the CPU, and can be widely used for heat dissipation devices of various other semiconductor elements. Further, the form of the package and the form of mounting on the mounting substrate 11 are not limited to the above embodiment.

  The present invention can be widely used to dissipate heat generated by a semiconductor element such as a CPU.

It is a disassembled perspective view of the thermal radiation apparatus of 1st Embodiment. It is a longitudinal cross-sectional view of the same heat radiating device. It is a development top view of a carbon graphite sheet. It is a longitudinal cross-sectional view of the thermal radiation apparatus of 2nd Embodiment. It is an expanded sectional view of an adhesive sheet. It is an expansion longitudinal cross-sectional view of the electroconductive particle contained in an adhesive sheet. It is an expanded sectional view which shows the joining structure by an adhesive sheet. It is an expanded top view of the carbon graphite sheet of another embodiment. It is a longitudinal cross-sectional view of the heat radiating device using this carbon graphite sheet. It is a longitudinal cross-sectional view of the heat radiator which concerns on a modification. It is a longitudinal cross-sectional view of the thermal radiation apparatus which concerns on another modification. It is a disassembled perspective view of the carbon graphite sheet of the heat radiating device concerning another modification. It is a longitudinal cross-sectional view of the same heat radiating device. It is a development top view of the carbon graphite sheet of a modification. It is a longitudinal cross-sectional view which shows the thermal radiation apparatus of another embodiment.

Explanation of symbols

11 Mounting board (motherboard)
12 Socket 13 Semiconductor element (CPU)
14 Heat sink 15 Fin 18 Carbon graphite sheet 19 Projection piece 23 Cooling fan 26 Adhesive sheet 27 Conductive particle 28 Resin ball 29 Nickel layer 30 Gold layer 34 Opening 35 Small hole 36 Small hole 40 Folding piece 41 Adhesive sheet 42 Housing 46 Bonding piece 47 Folded piece 48 Pad (carbon graphite sheet)
51 Triangular protrusion

Claims (10)

In a heat dissipation device for a semiconductor element in which a heat sink is mounted on a semiconductor element mounted on a substrate to dissipate heat,
A heat dissipation device for a semiconductor element, wherein a carbon graphite sheet is interposed or bonded between the semiconductor element and the heat sink or on the outer surface of the heat sink.   The heat dissipating device for a semiconductor element according to claim 1, wherein the carbon graphite sheet includes a protruding piece protruding to one side or two or more sides of the heat sink.   The heat dissipating device for a semiconductor element according to claim 1, wherein the carbon graphite sheet is bonded to a surface of the semiconductor element via an adhesive sheet.   3. The thermal conductive grease is applied to a portion of the carbon graphite sheet that is bonded to the semiconductor element or a portion of the carbon graphite sheet that is bonded to the heat sink. Semiconductor device heat dissipation device.   An opening is formed at a predetermined position of the carbon graphite sheet, the semiconductor element is escaped by the opening, and the carbon graphite sheet is bonded to a peripheral portion of a bonding surface of the heat sink with the semiconductor element. The heat dissipation device for a semiconductor element according to claim 1.   The heat dissipating device for a semiconductor element according to claim 2, wherein a joining piece or a bent piece of the carbon graphite sheet is further joined to the projecting piece projecting to the side of the carbon graphite sheet.   A plurality of carbon graphite sheets were provided, and carbon graphite pads thicker than the carbon graphite sheets were interposed between the portions of these carbon graphite sheets in contact with the semiconductor element or the heat sink and between the protruding pieces protruding sideways. The heat dissipating device for a semiconductor element according to claim 2.   The heat dissipating device for a semiconductor device according to claim 2, wherein a notch is formed in a protruding piece protruding sideways of the carbon graphite sheet.   The heat dissipating device for a semiconductor element according to claim 2, wherein a tip end portion of the protruding piece of the carbon graphite sheet is joined to an inner surface of the housing. The said semiconductor element is a central processing unit (CPU), The heat radiating device of the semiconductor element in any one of Claims 1-9 characterized by the above-mentioned.

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