JPH07161881A - Heat conductor for semiconductor chip, and structure of mounting semiconductor chip - Google Patents

Abstract

PURPOSE:To provide a heat conductor for a semiconductor chip high in conductivity and a structure for mounting a semiconductor chip at a high mounting density. CONSTITUTION:Heat radiation pads are provided above and below a metallic plate, and the intervals between them are larger than the diameter of the heat radiation pads. The heat conductor 12 by this structure produces flexibility by the flexure 13 of the metallic plate. When the heat conductor 12 having flexibility in thickness is put between the semiconductor chip 3 and a heat sink 9, the abutment and contact property between the head radiation pads and the semiconductor chip and the heat sink 9 improve. So, even if variation occurs in the interval between the semiconductor chip 3 and the heat sink 9, the heat radiation pad can be stuck fast to the rear of the semiconductor chip 3 and the surface of the heat sink 9. Moreover, the heat conductor 12 is constituted of metal high in heat conductivity. Therefore, the heat generated in the semiconductor chip 3 can be conducted efficiently to the heat sink 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor element heat conductor and semiconductor capable of efficiently conducting heat from a back surface of a bump-connected semiconductor element to a radiator such as a heat sink or a cap. The mounting structure of the element.

[0002]

2. Description of the Related Art Conventionally, various proposals have been made regarding heat dissipation of bump-connected semiconductor elements. For example, the heat generated in a semiconductor element is radiated to a heat sink through a via hole for heat transfer, that is, a thermal via formed in a bump and a wiring board, or a metal piston with a spring is pressed against the back surface of the element. , A thermally conductive grease is used between the element back surface and the heat sink. Figure 7
Shows one conventional example, in which the semiconductor element 3 is the wiring board 1
To the back surface of the semiconductor element 3 by pressing the metal piston 35 connected to the spring 34,
It is a structure that allows heat to escape to the cold plate 36. Also,
FIG. 8 shows another conventional example, in which a grease 37 having excellent thermal conductivity is used to radiate heat between the back surface of the semiconductor element 3 and the heat sink 39 and the cap 38. Examples of documents in which these conventional techniques are published are described below.・ "RC Chu, UPHwang, and RESimons." Conductio
n Cooling for an LSI Package: A One Dimensional Ap
proach, "IBM J. Res. Develop., 26 (1): PP.45-55, Jan
uary 1982. "," S. Oktay, B. Dessauser, and JIHo
rvath. "New International and External Coolinng En
hancements for the Air Cooled IBM 4381 Module, "IE
EE International Conf. On Computer Design, PP.2-5,
November 1983. "

[0003]

However, in such a conventional structure, in the structure in which the thermal via for heat conduction different from the wiring is formed on the wiring substrate on which the semiconductor element is mounted, the problem occurs in the semiconductor element. Most of the generated heat must be conducted to the heat sink via bumps or thermal vias. For this reason, the cooling efficiency is significantly reduced as compared with the configuration in which heat is dissipated from the entire back surface of the semiconductor element.

In the structure shown in FIG. 7 in which heat is released to the cold plate 36 by using the spring 34 and the metal piston 35, variations in the shape of the bump 2 and the thickness of the wiring board 1 and the height of the semiconductor element 3 are caused. Although there is an advantage of being able to absorb the variation of the above, the influence of the pressure of the spring 34 on the bump 2 and
There is a problem in that the shape of the component required for heat dissipation becomes large and there is an obstacle in improving the mounting density.

Further, in the structure for radiating heat using the grease 37 of FIG. 8, since the thermal conductivity of the grease 37 is as small as 1/10 to 1/100 as compared with metal, the heat generated in the semiconductor element 3 can be efficiently used. There is a limit to how well it can be transmitted to the heat sink 39.

[0006] Such a conventional structure has many problems from the viewpoint of improving the mounting density of the board and improving the efficiency of heat dissipation because of its complicated structure and poor heat dissipation performance. There is.

An object of the present invention is to provide a heat conductor for a semiconductor element having high conduction efficiency and a mounting structure of the semiconductor element which enables high density mounting.

[0008]

To achieve the above object, a heat conductor for a semiconductor device according to the present invention is a sheet-shaped metal plate in which convex heat radiation pads are alternately arranged at intervals larger than the diameter of the heat radiation pads. It is characterized in that it is arranged on the front surface and the back surface of.

Further, the above-mentioned convex heat radiation pad is preferably a coin-shaped metal piece having a flat surface, or a convex portion integrally formed from a metal plate.

The semiconductor element mounting structure of the present invention is
A plurality of heat-dissipating pads having a convex shape of a predetermined size are alternately arranged at a pitch larger than the diameter of the heat-dissipating pads, and a heat conductor composed of a structure arranged on the front surface and the back surface of a sheet-shaped metal plate, a semiconductor element and a heat sink It is characterized in that it is sandwiched between a heat radiator such as a cap.

[0011]

Therefore, according to the heat conductor for a semiconductor element of the present invention, the convex heat radiation pads are alternately arranged on the front surface and the back surface of the sheet-shaped metal plate at intervals larger than the diameter of the heat radiation pads. Therefore, when a pressing force is applied between the heat radiating pads on the front surface and the back surface of the metal plate, the metal plate between the heat radiating pads has a flexing spring property, and the distance between the heat radiating pads on both sides of the metal plate is freely changed.

Further, according to the semiconductor element mounting structure of the present invention, the convex heat radiation pads are arranged alternately on the front surface and the back surface of the sheet-shaped metal plate with a gap larger than the diameter of the heat radiation pad. Since the conductor is configured, when this heat conductor is sandwiched and pressed between the semiconductor element and the heat radiator, the heat dissipation pad stably abuts the semiconductor element and the heat radiator, Improves thermal conductivity.

[0013]

Embodiments of the heat conductor for a semiconductor device and the mounting structure of the semiconductor device according to the present invention will now be described in detail with reference to the accompanying drawings. 1 to 6, there is shown an embodiment of a heat conductor for a semiconductor device and a semiconductor device mounting structure of the present invention. Hereinafter, the configuration of the present invention will be described in detail based on the embodiments shown in the drawings.

<First Embodiment> FIGS. 1 to 3 show a first embodiment of the present invention, in which a semiconductor chip mounted by pumping is mounted on a back surface of a semiconductor element through a heat conductor having heat radiating pads formed on both surfaces of a metal plate. The structure which radiates heat to the heat sink is shown.

The heat conductor for a semiconductor element and the mounting structure of the semiconductor element shown in FIGS. 1 to 3 have a wiring board 1, a bump 2, a semiconductor element 3, a heat sink 9 and a heat conductor 12.
It is composed of The heat conductor 12 is composed of the metal plate 10 and the heat radiation pad 11.

The wiring board 1 is a circuit network in which predetermined wiring is formed on an insulating plate such as glass epoxy. Bump 2
Is a material for making an electrical connection with an electronic component mounted on the wiring board 1. In this embodiment, general solder is used. The semiconductor element 3 is a component of an electronic component mounted on the wiring board 1. The heat sink 9 is a radiator, and in the embodiment, is a component for promoting heat dissipation of the semiconductor element 3. The metal plate 10 is a component for forming a heat conductor 12 together with a heat radiation pad 11 described later, and transferring the heat of the semiconductor element 3 to the heat sink 9. The heat dissipation pad 11 is
It is a convex body having a predetermined size. The heat dissipation pad 11 on one surface is joined to the semiconductor element 3 to absorb heat, and the absorbed heat is transmitted to the heat sink 9 via the metal plate 10 and the heat dissipation pad 11 on the other surface. The heat conductor 12 composed of the metal plate 10 and the heat radiation pad 11 is a component for transmitting the heat generated by the semiconductor element 3 to the heat sink 9 and promoting heat radiation.

FIG. 2 shows the structure of the heat conductor 12, in which circular button-shaped heat radiation pads 11 are arranged on both sides of a flexible sheet-shaped metal plate 10. The heat dissipation pads 11 are alternately arranged on the front surface and the back surface of the metal plate 10 at a pitch larger than the diameter of the heat dissipation pads.
Therefore, the plurality of heat dissipation pads 11 sandwiching the metal plate 10,
, 11 are not overlapped with each other. The size of the convex portion of the heat dissipation pad and the distance between the heat dissipation pads are the size of the heat conductor 12, the size of the semiconductor element, the thickness of the metal plate 10 and the flexibility required for the heat conductor 12. Etc. In addition, for example, solder having excellent thermal conductivity is used for connecting the heat radiation pad 11 and the metal plate 10.

According to the above construction, when a pressing force is applied between the heat radiation pads 11, ..., 11 on both sides of the metal plate 10, the metal plate 10 between the heat radiation pads is bent, and the heat radiation pads on both sides are bent. The distance between them is flexible. Therefore, even if the gap between the semiconductor element 3 and the heat sink 9 varies, the heat radiation pad 11 can be stably brought into close contact with the back surface of the semiconductor element 3 and the front surface of the heat sink 9. FIG. 3 shows a cross section taken along the line AA ′ of the heat conductor 12 shown in FIG. In addition, FIG.
Is conceptually shown in a cross-sectional structure when it is mounted by being inserted between the heat sink 9 and the back surface of the semiconductor element 3 connected to the wiring board 1 by the bump 2.

Thermal conductor 12 having flexibility in thickness
When is sandwiched between the semiconductor element 3 and the heat sink 9, the contact and contact between the heat dissipation pad 11 and the semiconductor element 3 and the heat sink 9 are improved. The heat conductor 12 is made of metal having high heat conductivity. Therefore, the heat generated in the semiconductor element 3 can be efficiently conducted to the heat sink 9.

<Second Embodiment> FIGS. 4 to 6 show a second embodiment of the heat conductor. FIG. 5 shows the structure of the heat conductor 22, in which convex heat dissipation pads 21 are formed on both sides of the metal plate 20 by pressing.
FIG. 6 shows a cross section taken along the line BB ′ of the heat conductor 22 shown in FIG. FIG. 4 shows a cross-sectional structure when the heat conductor 22 is inserted between the back surface of the semiconductor element 3 connected to the wiring board 1 by the bump 2 and the heat sink 9 and mounted. The metal plate 20 bends 23 due to the pressing force, and can absorb the variation in the distance between the back surface of the semiconductor element 3 and the heat sink 9. Therefore, the heat dissipation pad 21 can be brought into close contact with the back surface of the semiconductor element and the front surface of the heat sink 9 even if the spacing varies.

The heat conductor 22 of this embodiment has a high heat conductivity because it is composed of one continuous metal plate 10.
In addition, the heat dissipation pads 21 formed on both sides of the metal plate 10,
The dimension of the gap between the two in the thickness direction has flexibility and elasticity. Therefore, the contact of the heat conductor 22 between the semiconductor element 3 and the heat sink 9 is stabilized, and the heat generated in the semiconductor element 3 can be efficiently transferred to the heat sink 9.

In the above two embodiments, the size of the heat radiation pads, the distance between the heat radiation pads, the thickness of the metal plate, etc. affect the heat conduction characteristics and flexibility of the heat conductor. That is, the size and spacing of the heat radiation pads affect the contact area between the semiconductor element and the heat sink, and the plate thickness dimension affects the thermal conductivity. It also affects the heat transfer characteristics and flexibility of the heat conductor. These specific numerical values are determined by the size of the semiconductor element, the material of the metal plate, the processing method, and the like.

In the above-mentioned embodiment, the example of the heat sink is described, but the mounting structure using the cap is also applicable. Further, in the present embodiment, an example of a single semiconductor element has been shown, but even when the intervals between a plurality of semiconductor elements are varied, the heat conductor integrally configured can be applied.

The above embodiment is an example of the preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention. For example, although the heat dissipation pad of this embodiment has a columnar shape or a rectangular shape, it is not limited to this shape.

[0025]

As is apparent from the above description, in the heat conductor for a semiconductor element and the mounting structure of the semiconductor element of the present invention, the convex heat radiation pad has an interval larger than the diameter of the heat radiation pad. Are alternately arranged on the front surface and the back surface of the sheet-shaped metal plate. Therefore, a spring property is generated in the intermediate plate portion between the heat radiation pads on the front surface and the back surface of the metal plate, and the distance between the heat radiation pads on both surfaces of the metal plate is freely changed.
When a heat conductor having this structure is installed between a semiconductor element and a heat sink or a radiator such as a cap, the contact and contact between the heat dissipation pad and the semiconductor element and the radiator are stable, and the heat conductivity is improved. The heat dissipation efficiency can be kept high. By consolidating the mounting structure of the semiconductor element and the heat conductor and improving the heat dissipation effect, it is possible to increase the mounting density of components such as the semiconductor element on the substrate.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a first embodiment of a heat conductor for a semiconductor element and a mounting structure of the semiconductor element of the present invention.

FIG. 2 is an external perspective view of the heat conductor of FIG.

3 is a cross-sectional view taken along the line A-A ′ of FIG.

FIG. 4 is a longitudinal sectional view showing a second embodiment of the heat conductor for a semiconductor element and the mounting structure of the semiconductor element of the present invention.

FIG. 5 is an external perspective view of the heat conductor of FIG.

6 is a cross-sectional view taken along the line B-B ′ of FIG.

FIG. 7 is a longitudinal sectional view showing an example of a heat conductor for a semiconductor element and a mounting structure of the semiconductor element based on a conventional technique.

FIG. 8 is a vertical cross-sectional view showing another example of a heat conductor for a semiconductor element and a mounting structure of the semiconductor element based on a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 wiring board, 2 bumps, 3 semiconductor element, 9 heat sink, 10, 20 metal plate, 11, 21 heat dissipation pad, 12, 22 heat conductor, 13, 23 bending.

Claims (2)

[Claims] 1. A heat conductor for a semiconductor element, characterized in that the convex heat radiation pads are alternately arranged on the front surface and the back surface of a sheet-shaped metal plate at intervals larger than the diameter of the heat radiation pad. 2. A heat conductor having a structure in which a plurality of heat-dissipating pads having a predetermined size and having a convex shape are alternately arranged on the front surface and the back surface of a sheet-shaped metal plate at a pitch larger than the diameter of the heat-dissipating pads. A mounting structure of a semiconductor element, which is sandwiched between a semiconductor element and a heat sink, a heat radiator such as a cap, or the like.