JPH0521661A - Semiconductor chip module - Google Patents

Abstract

PURPOSE:To provide a semiconductor chip module which is small in number of parts and excellent in heat dissipating properties. CONSTITUTION:A board 2 where a wiring section is formed, a semiconductor chip 6 so mounted that its circuit surface faces the wiring section, a heat sink 3 whose one edge comes into contact with the surface of the semiconductor chip 6 opposite to its circuit surface, and a cap 4 which is provided with a hole through which the other edge of the heat sink 3 is exposed outside and envelops the semiconductor chip 6 are provided. An insulating film 9 is formed on a prescribed region of the board 2 located around the semiconductor chip 6, and at least, a metal film is formed both on the inner wall of the hole concerned and on the surface of the heat sink 3 inserted into the cap 4, and bonding agent is filled into the spaces between these metal films and also between the tip of the heat sink 3 and the semiconductor chip 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor chip module (multichip module, single chip module) applicable to a field requiring high speed signal processing such as computers and communications.

[0002]

2. Description of the Related Art With the demand for large-scale and high-speed functions of electronic devices, the delay time per gate of a logic LSI has been increased to several hundred ps. On the other hand, in the conventional mounting mode in which a large number of DIPs and plug-in packages are mounted on the printed circuit board, it has become difficult to sufficiently exert the performance of the accelerated LSI. For this reason, a multi-chip module system, in which many chips are mounted on one ceramic substrate and which has high-speed performance and high-density mounting, has been developed and put into practical use (LSI Handbook, 1st edition, pp.4).
15-416, IEICE, 1984).

As a conventional technique, a structure is known in which a piston is brought into contact with a semiconductor chip by a spring to radiate heat to a cooling plate (“Materials / Processing Approaches to P”).
haseStabilization of Thermally Conductive Pastes
Pp.713-717, IEEE TRANSACTIONS OF COMPONENTS, H
YBRIDS. AND MANUCFACTURING TECHNOLOGY, VOL.13, NO.4,
DECEMBER1990).

[0004]

However, the semiconductor chip module using the piston has a drawback that the number of parts is large and the cost is extremely high.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a semiconductor chip module capable of a good heat dissipation design with a small number of parts.

[0006]

In order to achieve the above object, a semiconductor chip module according to the present invention includes a substrate on which a wiring portion is formed, a semiconductor chip mounted on the wiring portion with its circuit surface facing, and a semiconductor. The semiconductor chip is provided with a heat sink whose one end is in contact with the side opposite to the circuit surface of the chip, and a cap which has a hole for exposing the other end of the heat sink to the outside and encloses the semiconductor chip. An insulating film is formed in a predetermined area near the peripheral part, a metal film is formed on at least the inner wall of the hole and the surface of the heat sink to be inserted inside the cap, and an adhesive is embedded between the metal films and the heat sink is formed. An adhesive is embedded between the tip of the semiconductor chip and the semiconductor chip.

[0007]

According to the semiconductor chip module of the present invention, the heat sink is firmly fixed to the inner wall of the cap hole, and the heat generated from the semiconductor chip, which generates a relatively large amount of heat, efficiently reaches one end of the heat sink through the adhesive. It is thermally conducted and is conducted from one end to the other end (low temperature portion). By this heat conduction, heat is guided to the outside of the cap and radiated outside the cap. Further, the overflowing adhesive drops on the insulating film, and thus does not contact the wiring portion of the substrate.

[0008]

An embodiment of the present invention will be described below with reference to the accompanying drawings. In the description, the same elements will be denoted by the same reference symbols, without redundant description. FIG. 1 is a perspective view showing an appearance of a multi-chip module as one embodiment of the present invention, and FIG. 2 is a vertical cross-sectional view of the multi-chip module according to the embodiment cut along a heat sink.

The multi-chip module according to this embodiment comprises a lower substrate 1, an upper substrate 2, a heat sink 3 and a cap 4. The lower substrate 1 is made of an alumina material, and a plurality of lead pins 7 connected to the electric circuit constituted by the upper substrate 2 extend from the side surface of the lower substrate 1. The upper substrate 2 is made of a low dielectric constant insulating material,
For example, 3 with thermal resistance of 3 ° C / W and thermal via
Inch-square polyimide multi-layer wiring structure can be used (“Copper-polyimide multi-layer wiring board”, HYBRIDS, Vol.
7, No.1, pp.10-12).

The lower substrate 1 is composed of a flat plate larger than the upper substrate 1, and the upper substrate 2 is fixed in a stacked state on the upper surface thereof. Lower substrate 1 where upper substrate 2 does not overlap
The edge of the cap 4 is covered on the upper surface of the. Therefore, with the cap 4 and the lower substrate 1, the upper substrate 2
Is in a contained state.

Electrodes are exposed on the surface of the upper substrate 2, and semiconductor chips 5 and 6 connected to these electrodes are mounted. The semiconductor chips 5 and 6 are, for example, 10 mm square IC chips, and are connected to the electrodes formed on the surface of the upper substrate 2 by a wire bonding method or a face-down mounting method (flip chip mounting method). 1 and 2, the semiconductor chip 5 is an IC chip mounted by the wire bonding method, and the semiconductor chip 6 is an IC chip mounted by the face-down mounting method. Therefore, the circuit surface of the semiconductor chip 5 has the cap 4
, The circuit surface of the semiconductor chip 6 faces the upper substrate 2. A wiring portion 8 made of Cu is formed on the upper surface of the upper substrate 2, and the semiconductor chip 6 is bumped on the wiring portion 8 by the bump b.
Has been implemented through. What is important here is that the insulating film 9 is formed in a predetermined region of the upper substrate 2 located near the peripheral portion of the semiconductor chip 6. Details will be described later.

The cap 4 is formed, for example, in the shape of a lid of kovar having a thickness of 1 mm, and is provided at a position corresponding to the mounting position of the semiconductor chip 6 which generates a relatively large amount of heat.
For example, a hole 4a having an inner diameter of 6 to 8 mm is formed.
One end of the heat sink 3 is inserted into this hole 4a. Normally, the hole 4a has the same diameter at the inlet and the outlet, but the diameters of the outlet and the inlet may be changed.

The heat sink 3 is made of a material (A
1, CuW, AlN, CBN, diamond, etc.) and is composed of an insertion part and a heat dissipation part. The insertion portion has a shape that facilitates insertion into the hole 4a described above, and has, for example, a rod shape. Further, since the heat radiating portion is exposed to the outside of the cap 4, it has a structure having a large surface area so as to be easily cooled naturally, and has a disk shape, for example.
Therefore, the insertion into the inside of the cap 4 is easy, the upper surface of the semiconductor chip 6 can be easily contacted, and the heat from the semiconductor chip 6 can be efficiently dissipated to the outside of the cap 4. Heat sink 3 cap 4
A metal film is coated on the surface at one end inserted into the substrate, and solder is attached to the surface and between the semiconductor chip 6 and the tip of the heat sink 3 (see FIG. 2).

Next, an example of a heat sink mounting structure will be described with reference to FIG. FIG. 3 shows a mounting structure of a semiconductor chip and a heat sink mounted on an upper substrate on which an insulating film is formed. The figure (a) is a longitudinal sectional view cut along the insertion direction of the heat sink, and the figure (b) is the section A of the figure (a).
FIG. 6 is a plan view of the semiconductor chip taken along the line A ′. The insulating film 9 is arranged in a rectangular shape along the peripheral portion of the semiconductor chip 6. The material of the insulating film 9 can be formed of a polyimide material or SiO ₂ when the upper substrate 2 is formed of copper polyimide, and its film thickness can be formed when the thickness of the copper polyimide material forming the upper substrate 2 is small. It is desirable that the thickness is about 3 μm or more. By setting the film thickness to about 3 μm or more, it is possible to prevent the occurrence of pinholes or enlargement due to the heat of the solder and the short circuit of the wiring.

The inner wall of the hole 4a of the cap is coated with metal m, and the surface of one end of the heat sink 3 inserted into this hole 4a is also coated with metal m. Since the metal m coated on the heat sink 3 and the cap 4 has a property of being easily wettable with respect to the solder s, it is possible to perform soldering without voids (air bubbles), and the cap 4 is hermetically sealed. can do. For example, when Sb / Pb-based solder is used, it is preferable to use a metal such as AgSn or AgPd.

The embedding of the solder s between the semiconductor chip 6 and the tip of the heat sink 3 can be achieved by pouring liquid solder s from between the heat sink 3 and the inner wall of the hole 4a. The material of the solder s is B
A low temperature solder added with i, Cd and In can be used. In this case, the heat sink 3 may be heated to facilitate the flow of the solder s.

As described above, according to the multi-chip module of the embodiment, since the heat sink is mounted only on the semiconductor chip that requires heat dissipation (large heat generation amount),
Selectively and efficiently, it is possible to dissipate heat from the multi-chip module.

In this case, one heat sink is attached to one semiconductor chip, and the length of one end of the heat sink is adjustable in the insertion direction, so that the height from the substrate surface is different. Even when a plurality of semiconductor chips are mounted on the substrate, the heat sink is surely attached to each semiconductor chip.

Further, since the heat sink is individually attached to each semiconductor chip, it is applied to a multi-chip module in which semiconductor chips mounted by the face-down method and semiconductor chips mounted by the wire bonding method are mixed. It is possible and highly practical.

Next, a method of manufacturing the multichip module according to this embodiment will be described. The multi-chip module having the mounting structure shown in FIG. 3 includes a substrate 2 on which semiconductor chips 5 and 6 are mounted, an insulating film 9 is formed, a cap 4 in which the inner wall of the hole 4a is previously coated with metal m, and one end portion is previously formed. After preparing the heat sink 3 coated with the metal m, the process of encapsulating the upper surface of the upper substrate 2 fixed to the lower substrate 1 with the cap 4,
A step of inserting one end of the heat sink 3 into the hole 4 of the cap and bringing the tip thereof into contact with the upper surface of the semiconductor chip 6, in a state where the heat sink 3 and the semiconductor chip 6 are in contact with each other, a gap between the inner wall of the hole 4a of the cap and the heat sink 3 By injecting a large amount of liquid solder s, the solder s is attached to one end of the heat sink 3 so as to reach the semiconductor chip 6, the heat sink 3 is fixed to the cap 4, and the cap 4 is hermetically sealed. Be converted.

In this case, when pouring liquid solder s,
Since one end of the heat sink 3 is automatically in contact with the semiconductor chip 6 due to its own weight, the heat sink 3 can be easily fixed to the cap 4.

Further, since the liquid solder s is embedded in the heat sink 3 and the inner wall of the hole 4a of the cap without a gap,
The cap 4 can be hermetically sealed. Particularly, when a thin film multilayer substrate such as polyimide / Cu is used as the upper substrate 2, since the polyimide itself has a hygroscopic property, hermetic sealing becomes important.

Further, since the tip of the heat sink 3 is also metal-coated, the weight of the solder s fills the gap between the tip of the heat sink 3 and the semiconductor chip 6 with the weight of the solder s. The contact area can be increased and the thermal resistance can be reduced.

In this case, the contact area between the semiconductor chip 6 and the heat sink 3 can be increased and the thermal resistance can be reduced without applying a metal coating to the tip of the heat sink 3, and a multi-chip excellent in heat dissipation is obtained. The module can be manufactured.

Further, when the solder s is injected, the solder spilled from the upper surface of the semiconductor chip 6 due to an excessive amount is received by the insulating film 9 of the upper substrate 2, so that the wiring portion 8 of the upper substrate 2 is covered. Wiring does not cause defective wiring.

The present invention is not limited to the above embodiment. In this embodiment, the multi-chip module including the semiconductor chip mounted by the wire bonding method and the semiconductor chip mounted by the face-down method, and the heat sink mounted on the semiconductor chip mounted by the face-down method has been described as an example. The present invention can be applied to a semiconductor chip module mounting a single semiconductor chip, and may include a flip chip to which a heat sink is not mounted. Further, the shape of the hole of the cap is not limited to the circular shape, and may be a square shape or a polygonal shape as long as it is substantially the same as one end of the heat sink.

[0027]

Since the present invention is configured as described above, it can be applied to a multi-chip module and a single-chip module, has a small number of parts, and is excellent in heat dissipation capable of good heat dissipation design. A semiconductor chip module can be provided.

Further, when the present invention is applied to a multi-chip module, variations due to the height of face-down bonding can be allowed, and reliability is improved.

Further, since the insulating film is formed on the substrate in the vicinity of the peripheral portion of the semiconductor chip, wiring failure due to injection of a large amount of adhesive can be prevented.

[Brief description of drawings]

FIG. 1 is a perspective view showing an appearance of a multi-chip module according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of a multi-chip module according to an embodiment of the present invention cut along a heat sink.

FIG. 3 is a vertical cross-sectional view showing a mounting structure example of a heat sink that can be used in a multi-chip module according to an embodiment of the present invention.

[Explanation of symbols]

1 ... Lower substrate, 2 ... Upper substrate, 3 ... Heat sink, 4 ...
Cap, 5, 6 ... Semiconductor chip, 7 ... Lead pin, 8
... Wiring part, 9 ... Insulating film, b ... Bump, m ... Metal, s ...
Solder.

Claims (1)

Claim: What is claimed is: 1. A substrate on which a wiring portion is formed, a semiconductor chip mounted on the wiring portion with a circuit surface facing, and one end of the semiconductor chip on the side opposite to the circuit surface. And a cap that encloses the semiconductor chip and has a hole that exposes the other end of the heat sink to the outside, and the substrate is insulated in a predetermined region located near the periphery of the semiconductor chip. A film is formed, a metal film is formed on at least the inner wall of the hole and the surface of the heat sink to be inserted inside the cap, and an adhesive is embedded between the metal films, and the tip of the heat sink and the semiconductor are formed. A semiconductor chip module in which an adhesive is embedded between chips.