JPH11330747A - Cooling structure of electronic element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling structure, which is excellent in cooling capacity and is simple in structure, of an electronic element. SOLUTION: A CPU 4 is mounted on the upper surface of a substrate 1 via a bonding agent 3. A plurality of through holes are formed in the part, which is located under the side of the lower part of the CPU 4, of the substrate 1 and pins 9, which are metallic and are longer than the thickness of the substrate 1, are inserted in the through holes in such a way as to protrude from the lower surface of the substrate 1. Moreover, the protruding parts of the pins 9 are inserted in insertion holes 12 formed in a heat pipe 10 in such a way that heat can be transferred from the pins 9 to the heat pipe 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling structure for electronic devices such as microchips, and more particularly to a tape carrier package (hereinafter referred to as TCP) for a central processing unit (hereinafter referred to as CPU) mounted on a flexible film. This is related to a structure that promotes heat radiation from the above.

[0002]

2. Description of the Related Art In the field of personal use computers (hereinafter referred to as personal computers), notebook type and sub-notebook type so-called notebook type personal computers have become widespread recently. Since the main purpose of this type of personal computer is portability, reduction in size and weight is strongly desired.
The space that U can occupy is also limited. Therefore, it is preferable to package the CPU as small as possible. On the other hand, the output of the CPU is increasing year by year with the increase in the functions of the personal computer and the improvement of the processing speed. Therefore, a high cooling capacity is also required for the cooling device for the heating element.

Therefore, instead of a general QFP (Quad Flat Package) in which the outer peripheral portion of the CPU is resin-sealed, a cooling structure using TCP has been developed as an example of means for satisfying the above-mentioned conditions. FIG. 2 shows an example of this cooling structure. A CPU 24 is attached via an adhesive 23 to a substrate 22 having a printed wiring 21 formed on the upper surface. On the upper surface side of this CPU 24 in FIG.
A plurality of electrically conductive leads 25 are provided to extend. The tips of these lead wires 25 are electrically connected to the printed wiring 21 respectively. Also,
The base end of each lead wire 25 (side end of CPU 24) and CP
The side surface and the upper surface of U24 in FIG. Further, a flexible tape 27 made of synthetic resin is laid at the boundary between the upper surface side of the cover 26 in FIG.

A large number of small-diameter through-holes 28 are formed at positions on the substrate 21 where the CPU 24 is installed, and metal pins 29 are inserted into these through-holes 28, respectively. . That is, the heat of the CPU 24 is transferred to the lower surface (CP
(A surface on which U24 is not provided). This is to protect the tape 27 and the lead wire 25 from heat. On the lower surface of the substrate 21 in FIG. 2, that is, the surface opposite to the CPU 24, a metal foil 30 made of copper, aluminum, or the like having a high thermal conductivity is affixed to each pin 29 so as to be able to conduct heat. Further, a metal heat sink 33 having a plurality of fins 32 is provided on the surface of the metal foil 30 via a thermal joint 31.
Is attached.

Therefore, when heat is generated from the CPU 24, most of the heat is transmitted to one end of each pin 29 via the adhesive 23, and is conducted to the other end of each pin 29. Is transmitted to The heat is further transmitted to the heat sink 33 via the thermal joint 31 and is released from each fin 32. Part of the heat generated by the CPU 24 is also transmitted to the cover 26 and is released from the surface. As a result, the CPU 24 is cooled.

[0006]

However, since the contact area between each pin 29 and the metal foil 30 is relatively small, the CPU 2
There was a possibility that the heat of No. 4 could not be sufficiently transmitted to the metal foil 30 via the pin 29. Further, since the surface of the substrate 22 and the end face of each pin 29 are not completely flush with each other, a minute gap is generated between the pin and the metal foil 30, and the effective heat between the pin 29 and the metal foil 30 is increased. The exchange area could be small. As a result, in the above cooling structure, CP
Due to the large thermal resistance between the U24 and the heat sink 33, there is a possibility that the CPU 24 cannot be cooled sufficiently.

The present invention has been made in view of the above circumstances, and has as its object to provide a cooling structure for an electronic element which has an excellent cooling capacity and a simple structure.

[0008]

In order to achieve the above object, according to the first aspect of the present invention, a heating member serving as a heat source is mounted on one surface of a substrate on which an electric circuit is formed. And a heat transfer member penetrating the substrate in a thickness direction thereof, wherein heat generated from the heat generation member is transmitted to the other surface side of the substrate. The heat pipe is connected to the heat transfer member so that the heat member protrudes from the other surface of the substrate and the projecting portion of the heat transfer member is inserted into the recess of the heat pipe so as to be able to transfer heat. And at least one of the above.

Therefore, according to the first aspect of the present invention, since the heat transfer member is inserted into the recess of the heat pipe, the contact area between the heat transfer member and the container of the heat pipe increases. As a result, heat can be sufficiently transmitted from the heat transfer member to the heat pipe. In addition, since the heat transport capability of the heat pipe is large, the heat transmitted from the heat transfer member can be sufficiently transported. As a result, the heat generating member can be sufficiently cooled.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to specific examples. FIG. 1 shows the present invention using C for a notebook computer.
It is sectional drawing which shows the example applied to PU. A printed wiring 2 corresponding to an electric circuit is formed on the upper surface of the substrate 1 shown in FIG. On the upper surface thereof, a CPU as a heat-generating member is provided via an adhesive 3 having thermal conductivity.
4 is attached. A plurality of electrically conductive leads 5 are provided extending from the upper surface of the CPU 4 in FIG. The tips of these lead wires 5 are electrically connected to the printed wiring 2 respectively. The base end of each lead wire 5 (side end of CPU 4)
The side and top surfaces of the CPU 4 are covered with a cover 6. Further, a flexible tape 7 made of synthetic resin is laid at the boundary between the upper surface side of the cover 6 in FIG. 1 and each lead wire 5.

A plurality of small-diameter through holes 8 are formed in the substrate 1 at positions where the CPU 4 is installed. Metal pins 9, which are heat transfer members and have a length longer than the thickness of the substrate 1, are inserted into these through holes 8. In addition, on the surface of the substrate 1 on which the CPU 4 is provided (the upper surface in FIG. 1), the pins 9 are inserted so that the pins 9 and the substrate 1 are flush with each other. On the surface of the substrate 1 (the lower surface in FIG. 1), the pins 9 are inserted so as to protrude. These pins 9 are provided to transport the heat of the CPU 4 toward the surface on the opposite side of the substrate 1 and to protect the tape 7 and the lead wires 5 from the heat.

A heat pipe 10 is mounted on the surface of the substrate 1 on which the CPU 4 is not provided (the lower surface in FIG. 1) at a position directly below the CPU 4 in FIG. The container 11 of the heat pipe 10 is formed in a hollow, closed rectangular parallelepiped, and a plurality of insertion holes 12 each having a circular cross section are provided in a substantially upper half of FIG. These insertion holes 12
Has a depth reaching the middle part of the heat pipe 10 in the vertical direction in FIG. 1, and a pin 9 can be inserted into each of them, and the surface of the pin 9 transfers heat to the surface of the insertion hole 12. It is formed so that it can make contact. The heat pipe 10 is formed by encapsulating a condensable fluid such as water or alcohol as a working fluid (not shown) in a hollow metal rectangular parallelepiped container (container) that has been degassed under vacuum. Further, a wick (not shown) such as a mesh or a groove is provided inside the container 11 to allow the liquid-phase working fluid to flow by capillary force. The heat pipe 10 starts operating when a partial temperature difference occurs in the container 11. Then, the working fluid input and evaporated in the high-temperature portion flows to the low-temperature portion and radiates and condenses, so that the heat pipe 10 performs heat transport as latent heat of the working fluid.

A heat sink 13 made of metal is attached to the lower surface of the heat pipe 10 in FIG. The heat sink 13 is provided on the base 1.
4 and a plurality of fin portions 15 projecting from the base portion 14 and formed in a plate shape. The heat sink 13 is for dissipating the heat transmitted from the heat pipe 10 into the air flowing near the heat sink 13.

Next, the operation of the cooling structure for an arithmetic element configured as described above will be described. When heat is generated from the CPU 4 with use of the personal computer, most of the heat is transmitted to the plurality of pins 9 via the adhesive 3. Then, the transmitted heat is transmitted from the pin 9 to the portion of the container 11 of the heat pipe 10 in which the insertion hole 12 is provided. Then, the working fluid (not shown) inside the container 11 existing at that position is evaporated by the transmitted heat, and the vapor flows to the bottom of the container 11 in FIG. Further, at the bottom of the container 11, the working fluid radiates heat to the bottom of the container 11 and condenses. Then, the condensed working fluid flows upward of the container 11 in FIG. 1 by a wick (not shown), and the same cycle is repeated. The portion of the container 11 where the insertion hole 12 exists is the heating portion 16 of the heat pipe 10, and the bottom of the container 11 in FIG.
It becomes 7.

The heat transmitted to the bottom of the container 11 in FIG. 1 is transmitted to the base portion 14 of the heat sink 13 and also to the fin portion 15, where it is radiated to the air flowing near the heat sink 13. You. As a result, the CPU 4 is cooled.

As described above, the length of the pin 9 is made longer than the thickness of the substrate 1, the pin 9 is made to protrude from the substrate 1, and the protruding portion is inserted into the insertion hole 12 of the container 11 of the heat pipe 10. By transmitting and inserting, the contact area between the pin 9 and the heat pipe 11 can be increased. Therefore, heat from the CPU 4 can be sufficiently transmitted from the pins 9 to the heating section 16 of the heat pipe 10. Further, since the heat transfer capability of the heat pipe 10 is large, the heat transmitted from the pins 9 can be sufficiently transferred to the heat radiating portion 17 side of the heat pipe 10. as a result,
The CPU 4 can be sufficiently cooled.

In the embodiment of the present invention, the CPU is used as the heat generating member. However, the present invention is not limited to this, and can be applied to a heat generating member such as a memory.

[0018]

As described above, according to the first aspect of the present invention, since the heat transfer member is inserted into the concave portion of the heat pipe, the contact area between the heat transfer member and the container of the heat pipe is increased. Increase. As a result, heat can be sufficiently transmitted from the heat transfer member to the heat pipe. In addition, since the heat transport capability of the heat pipe is large, the heat transmitted from the heat transfer member can be sufficiently transported. As a result, the heat generating member can be sufficiently cooled.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a specific example of a cooling structure for an electronic element of the present invention.

FIG. 2 is a sectional view showing a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Board, 4 ... CPU, 9 ... Pin, 10 ... Heat pipe, 12 ... Insertion hole.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H01L 23/04 H01L 23/04 C 23/467 23/46 C (72) Inventor Katsuo Eguchi 1-5 Kiba, Kiba, Koto-ku, Tokyo No. 1 Inside Fujikura Co., Ltd. (72) Inventor Tan Nuen 1-5-1, Kiba, Koto-ku, Tokyo Inside Fujikura Co., Ltd.

Claims (1)

[Claims] 1. A substrate on which an electric circuit is formed,
A heat-generating member serving as a heat source is mounted, and the heat-transfer member penetrating the substrate in a thickness direction thereof is configured to transmit heat generated from the heat-generating member to the other surface side of the substrate. In the cooling structure of the element, the heat pipe is formed such that the heat transfer member protrudes from the other surface of the substrate, and a protruding portion of the heat transfer member is inserted into a recess of the heat pipe so as to be able to transfer heat. Is attached to at least one of the substrate and the heat transfer member.