JPH0445564A - Semiconductor package - Google Patents

Abstract

PURPOSE:To adjust the height of a semiconductor chip and also keep enough conductivity and relax stress by arranging a heat conductor between a heat radiating plate and a semiconductor chip, and letting the surplus of a binder in joining move to a binder escape. CONSTITUTION:High heat-conductive conductors 4, which have escapes for a binder and have functions of adjusting the height of a chip 2 to the height of a base 3, are arranged on the region for mounting a semiconductor 2 of a heat radiating plate 1. The chip 2 is placed on spherical heat conductors 4, and the binder 5 is dried while pressing down the semiconductor chip 2 as in this condition. When joining heat conductors 4 to a heat radiating plate 1, a binder 5 permeates into the under space between heat conductors 4, and the heat conductors 4 joins in point contact with the heat radiating plate 1 without causing the floating-up. Furthermore, as regards the joining between the heat conductors 4 and the chip 2, the binder 5 permeates into the upper space between the heat conductors 4. Hereby, the chip 2 is joined in point contact condition with the spherical heat conductors 4, without causing floating-up.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a technology for mounting a semiconductor chip on a heat diffusion plate, particularly a semiconductor chip that generates a large amount of heat and is mounted on a heat diffusion plate and on the same plane. The present invention relates to a technique that can be effectively used to bond semiconductor devices whose height is lower than that of the base.

[Conventional technology]

For example, one type of semiconductor device has a semiconductor chip mounted on a heat diffusion plate that functions as a heat sink, and a base with pins set up on the heat diffusion plate with the semiconductor chip exposed in the center. Some use a package structure.

By the way, the present inventor has studied various problems caused by temperature expansion when bonding a semiconductor chip to a thermal diffusion plate.

The following are the techniques studied by the present inventor, and the outline thereof is as follows.

That is, as the packaging density of semiconductor chips increases, the amount of heat generated increases, and some kind of heat dissipation measure is required. For this reason, a thermal diffusion plate is used to radiate heat from the semiconductor chip, but since the thermal expansion plate and the semiconductor chip have different coefficients of thermal expansion, solder connection cannot be performed.

Therefore, bonding is performed using a flexible adhesive such as silicone rubber. Thereby, even if the thermal expansion plate and the semiconductor chip have different coefficients of thermal expansion, it is possible to prevent the bonded portion from peeling off.

In this case, increasing the thickness of the adhesive layer makes it easier to absorb stress caused by thermal expansion, but conversely increases thermal resistance and impairs thermal diffusion. That is, if one is tried to improve, the other becomes worse, and it is necessary to determine the thickness of the adhesive layer by balancing thermal expansion and thermal resistance.

Also, if the height (thickness) of the base and the semiconductor chip mounted on the heat diffusion plate are different (for example, if the semiconductor chip is thin and the base is thick), a step will be created between them, and the bonding wire will become longer. Since this can cause short circuits or contacts, a protrusion is provided in the mounting area of the semiconductor chip to adjust the height.

[Problem to be solved by the invention]

However, in the package structure of a semiconductor device in which bonding is performed using an adhesive as described above, the bonding surface between the heat diffusion plate and the semiconductor chip is both flat, so the adhesive applied to this bonding surface tends to become thick. It is in. In order to make the semiconductor chips thinner, loads are sometimes applied to the semiconductor chips during bonding, but applying too much load can lead to accidents such as damage to the semiconductor chips, making it difficult to ensure an appropriate thickness. The present inventor discovered that there is a problem.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a technique that can adjust the height of a semiconductor chip and at the same time achieve sufficient thermal conductivity and stress relaxation while using an adhesive for bonding.

The above objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means to solve the problem]

A brief overview of typical inventions disclosed in this application is as follows.

That is, a semiconductor package in which a semiconductor chip having a height lower than that of the base is bonded to a heat diffusion plate on which a base is mounted using a resin adhesive, and the semiconductor chip is attached to a mounting area of the semiconductor chip of the heat diffusion plate using a resin adhesive. A highly thermally conductive heat transfer body having a resin adhesive relief part and a function of adjusting the height of the semiconductor chip to the base is disposed.

[Effect]

According to the above-mentioned means, a heat transfer body having excellent thermal conductivity and an adhesive relief part is disposed between the heat diffusion plate and the semiconductor chip, and the excess amount of adhesive during bonding is transferred to the adhesive relief part. By allowing the adhesive to escape, only the minimum necessary amount of adhesive remains at the joint, and the thickness of the joint adhesive layer can be reduced. Therefore, heat conduction is not inhibited, and stress absorption against thermal expansion and height adjustment can be achieved.

[Embodiment 1] FIG. 1 is a sectional view showing an embodiment of a semiconductor package according to the present invention.

A semiconductor chip 2 is disposed in the center of a rectangular heat diffusion plate 1 made of a metal material with excellent thermal conductivity such as copper. An opening corresponding to the size of the semiconductor chip 2 is provided in the center of the diffusion plate 1.

Among these, the base 3 is directly bonded to the heat diffusion plate 1 via a bonding material, but the semiconductor chip 2 is bonded via a spherical heat transfer body 4 (cube).

That is, a large number of spherical heat transfer bodies 4 having the same diameter and small diameter (for example, 0.7 to 0.8 uφ) and made of the same material (metal or highly thermally conductive ceramic) are arranged in the chip mounting area on the heat diffusion plate 1. The semiconductor chip 2 is bonded onto the spherical heat transfer body 4.

When assembling the embodiment shown in FIG. 9J1, first, the base 3 is joined to the heat diffusion plate 1. Next, a flexible adhesive 5 such as silicone rubber or silver base (a mixture of silver powder and epoxy resin) is applied inside the opening of the base 3. The spherical heat transfer bodies 4 are spread uniformly on this adhesive-applied surface and pressed so that the spherical heat transfer bodies 4 do not float.

In this case, the amount of adhesive 5 applied to the heat diffusion plate 1 is set to such an extent that it does not protrude above half of the spherical heat transfer body 40.

After the spherical heat transfer body 4 is fixed to the heat diffusion plate 1, the adhesive 5 is applied again to the surface of the spherical heat transfer body 4, and then the semiconductor chip 2 is placed on the spherical heat transfer body 4. The adhesive 5 is dried while the semiconductor chip 2 is pressed down. Thereafter, the electrode pattern formed on the base 3 and the electrode pattern formed on the semiconductor chip 2 are connected with bonding wires 6.

According to the above configuration, when bonding the spherical heat transfer bodies 4 to the heat diffusion plate 1, the adhesive 5 penetrates into the lower gap between the spherical heat transfer bodies 4, and the spherical heat transfer bodies 4 are lifted up. It is joined to the heat diffusion plate 1 in a point contact state without any contact. Furthermore, when bonding the spherical heat transfer bodies 4 and the semiconductor chip 2, the adhesive 5 penetrates into the upper gap between the spherical heat transfer bodies 4. This results in
The semiconductor chip 2 is bonded to the spherical heat transfer body 4 in point contact without lifting.

In this way, the surplus of the adhesive 5 penetrates into the gap between the spherical heat transfer bodies 4, and only the necessary minimum amount of adhesive 5 remains at the joint between the heat diffusion plate 1 and the semiconductor chip 2, and the The thickness of the adhesive 5 can be made extremely thin. Therefore, the thermal resistance of the joint can be reduced, and the heat generated in the semiconductor chip 2 can be quickly released to the heat diffusion plate 1. On the other hand, since the spherical heat transfer bodies 4 are only bound by the adhesive 5 in the direction in which they are arranged (horizontal direction), they can move according to the expansion and contraction of the adhesive 5, and can be moved due to thermal expansion. The accompanying stress can be absorbed.

The spherical heat transfer body 4 may be rectangular, polyhedral, semicircular, or
Alternatively, it may be a spherical body with a plurality of thorn-like protrusions protruding from the surface.

[Embodiment 2] FIG. 2 is a perspective view showing a second embodiment of the present invention. In addition, in FIG. 9J2, the same reference numerals are used for the same parts as in FIG. 1, so duplicate explanations will be omitted below.

In this embodiment, a plurality of cylindrical heat transfer bodies 7 (columnar bodies) are arranged in parallel in place of the spherical heat transfer bodies 4 of the previous embodiments.

In this embodiment, although the escape portion of the adhesive 5 is reduced, it is in line contact with each of the heat diffusion plate 1 and the semiconductor chip 2, so that thermal conductivity can be improved. In this case, the expansion and contraction of the adhesive 5 is restricted in the longitudinal direction of the cylindrical heat transfer body 7, so that the stress applied to the semiconductor chip 2 increases.

The assembly process of this embodiment is the same as that of the previous embodiment, so the explanation will be omitted.

Note that the cylindrical heat transfer body 7 may have a cylindrical shape as well as a cylindrical shape.

[Embodiment 3] FIG. 3 is a sectional view showing the main part of a third embodiment of the present invention.

The present embodiment is characterized in that, unlike the previous embodiments in which the heat transfer body was constructed by arranging small parts, an adhesive escape portion was formed in the plate-shaped body. That is, a plurality of disc-shaped protrusions 9 are formed on a heat transfer body 8 made of a copper plate or the like using press working or the like, and the gaps created between the protrusions 9 are used as adhesive escape parts.

During assembly, after the base 3 is mounted on the heat diffusion plate 1, adhesive 5 is applied inside the opening of the base 3, and then the heat transfer body 8 is set and bonded. Thereafter, an adhesive is applied to the surface of the heat transfer body 80 and the semiconductor chip 2 is bonded to complete the assembly.

[Embodiment 3] FIG. 4 is a sectional view showing the main part of a fourth embodiment of the present invention.

This embodiment is characterized in that a plurality of grooves 10 are provided in parallel, whereas the embodiment shown in FIG. 3 has protrusions 9 on the heat transfer body 8.

This embodiment has characteristics similar to the embodiment shown in FIG. 2, and although there are fewer adhesive escaping areas, the second embodiment has strip-like contact with each of the heat diffusion plate 1 and the semiconductor chip 2. Thermal conductivity can be further improved than the embodiment shown in the figure. Note that since expansion and contraction of the adhesive 5 is restricted in the longitudinal direction of the groove 10, the stress applied to the semiconductor chip 2 tends to increase.

The assembly process of this embodiment is the same as that of the previous embodiment, so the explanation will be omitted.

Above, the invention made by the present inventor has been specifically explained based on Examples, but it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. stomach.

For example, in the embodiment shown in FIG. 3, the protrusion 9 is circular, but it may also be rectangular, polygonal, cross-shaped, etc.

Further, in the embodiment shown in FIG. 4, the grooves 10 are provided parallel to each other in one direction, but they may also be provided to intersect vertically and horizontally. In this way, stress relaxation can be performed in both the vertical and horizontal directions.

〔Effect of the invention〕

Among the inventions disclosed in this application, the effects obtained by typical ones are as follows.

That is, a semiconductor package in which a semiconductor chip having a height lower than the base is bonded to a heat diffusion plate on which a base is mounted using a resin adhesive, and the resin is bonded to a mounting area of the semiconductor chip of the heat diffusion plate using a resin adhesive. Since a highly thermally conductive heat transfer body is provided which has an adhesive relief part and has a function of aligning the height of the semiconductor chip with the base, it does not impede heat conduction and also prevents heat transfer. Stress absorption and height alignment against expansion can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of a semiconductor package according to the present invention, FIG. 2 is a perspective view showing the main parts of the second embodiment of the invention, and FIG. 3 is a main part of the jlK3 embodiment of the invention. FIG. 4 is a sectional view showing the main parts of 14th embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Heat diffusion plate, 2... Semiconductor chip, 3... Base, 4... Spherical heat transfer body, 5... Adhesive, 6...
・Bonding wire, 7... Cylindrical heat transfer body, 8...
- Heat transfer body, 9... protrusion, lO... groove. Representative Patent Attorney Katsuhiro Ogawa Figure 1: Circular heat transfer body

Claims (1)

[Scope of Claims] 1. A semiconductor package in which a semiconductor chip having a height lower than that of the base is bonded to a heat diffusion plate on which a base is mounted using a resin adhesive, wherein the semiconductor chip of the heat diffusion plate is A semiconductor package characterized in that a highly thermally conductive heat transfer body having a relief part for the resin adhesive and having a function of aligning the height of the semiconductor chip with the base is disposed in a mounting area of the semiconductor package. 2. The semiconductor package according to claim 1, wherein the heat transfer body is a columnar body or a small-diameter cube laid out. 3. The semiconductor package according to claim 1, wherein the heat transfer body is a highly thermally conductive plate-like body with protrusions or grooves provided on both sides. 4. The semiconductor package according to claim 1, wherein the heat transfer body is a metal or a highly thermally conductive ceramic.