JPH11214576A - Package for mounting semiconductor chip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide such a package for mounting semiconductor chip that its initial deformation (warp) and its deformation resulting from thermal stresses can be suppressed to the minimum. SOLUTION: In a package P for mounting semiconductor chip which has a plate-like metallic substrate and a resin substrate 2 put on and stuck to the metallic substrate and is mounted on a mother board by soldering using solder balls 8, solder deposited sections 9 having areas larger than the cross sections of the solder balls 8 are provided in at least part of the outer peripheral section of the package in the plan view. Therefore, the bonding strength of the package to the mother board can be increased at the outer peripheral section or four corners of the package where stresses are apt to be concentrated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a package for mounting a semiconductor chip, and more particularly to a package for mounting a semiconductor chip using a metal substrate.

[0002]

2. Description of the Related Art In recent years, packages that are smaller, lighter, less costly and more excellent in heat dissipation than substrates for semiconductor chips using ceramics (hereinafter simply referred to as packages) have been developed for substrates and heat sinks. A package using a metal plate such as aluminum or copper has attracted attention (see Japanese Patent Application No. 8-238612).

[0003]

However, packages of the above type have different coefficients of thermal expansion (for example,
23μ / ℃ for aluminum, 1 for glass epoxy composite
(5 μ / ° C.) Due to the structure in which the plate-like bodies are bonded to each other, warpage occurs when a thermal load is applied. For this reason,
There has been a problem that concentrated stress is generated at an outer peripheral portion or a corner portion of the solder joint portion between the package and the mother board where displacement is particularly large, and cracks and peeling of the joint portion are likely to occur. Particularly in an environment where temperature changes are severe, it has been experimentally confirmed that the durability and fatigue life become shorter as the package size is larger and the package warpage in the initial state is larger because the thermal shock is repeatedly applied.

Although it is possible to reduce the thermal load by using a radiation fin or a cooling fan, this hinders downsizing and is disadvantageous in terms of cost.

The applicant of the present application has already proposed a countermeasure to reduce the concentrated stress such as cutting a part of a metal substrate or an adhesive film (Japanese Patent Application No. 9-344591). However, the package tends to be reduced year by year. Taking such measures also tends to be difficult.

The present invention has been devised to solve the problems of the prior art as described above, and its main objects are as follows.
An object of the present invention is to provide a semiconductor chip mounting package capable of minimizing initial deformation (warpage) and deformation due to thermal stress.

[0007]

SUMMARY OF THE INVENTION According to the present invention, there is provided a semiconductor device comprising a flat metal substrate, a resin substrate which is superimposed on and adhered to the metal substrate, and has a solder ball.
In the semiconductor chip mounting package P mounted on the motherboard M by soldering, at least a part of the outer peripheral portion of the package viewed from the planar direction has a solder attachment portion 9 having an area larger than the cross-sectional area of the solder ball.
Is achieved by arranging. According to this, the bonding strength with the motherboard can be increased at the outer peripheral portion or at the four corners of the package where stress tends to concentrate.

[0008]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a bottom view of a package of a metal ball grid array showing a first embodiment to which the present invention is applied, and FIG. 2 is a side sectional view of a central portion thereof. This package P has a substantially square plate shape, and is formed by laminating a metal substrate 1 made of aluminum and a resin substrate 2 made of glass epoxy resin, and then forming an adhesive layer 3 made of a film or liquid resin adhesive. Further, the semiconductor chip 4 and the semiconductor chip 4 bonded by die bonding to the central portion of the metal substrate 1 via the opening 2a formed in the central portion of the resin substrate 2 are formed. It has a sealing resin 6 and a metal cap 7 for sealing in the opening 2a. Reference numeral 5 denotes an adhesive layer in which the semiconductor chip 4 is bonded to the metal substrate 1.

A large number of solder balls 8 are fixed to the lands on the bottom surface (the surface facing the motherboard) of the resin substrate 2 by reflow. And this package P
After being soldered to a motherboard (not shown) via the solder balls 8, it is connected to an external circuit.

At the four corners of the bottom surface of the resin substrate 2, as shown in FIG. Is formed. This solder attachment portion 9 is formed in the same process as the other solder balls 8 at the same time.
When mounted on the motherboard, it is fused to the motherboard M in the same manner as the other solder balls 8. According to this, since the bonding area to the motherboard M can be increased, a larger bonding strength can be obtained, or
Thus, the solder attachment portion 9 is formed at a time, so that the manufacturing cost does not need to be increased.

In a general package, it is rare that all pins are used as electrical connection terminals.
Above all, since wiring is difficult at the four corners, the solder-attached portion 9 can be used exclusively as a mechanical fixing means. However, it goes without saying that the solder-attached portion 9 can also be configured to also serve as an electrical connection terminal.

FIG. 4 shows a second embodiment of the present invention. In this embodiment, only the plating surfaces are provided at the four corners of the package P in place of the solder attachment portions 9 provided at the four corners of the package P. The package P is fixed to the motherboard M with a cream solder layer (or an adhesive layer) 10 formed in advance on a portion corresponding to the plating surface on the motherboard M.

FIG. 5 is a bottom view of a package similar to FIG. 1 showing a third embodiment of the present invention, and FIG. 6 is a partial side view of this embodiment. In this configuration, the resin substrate 2
Are provided at the four corners of the metal substrate 1 (see FIG. 7), and the resin substrate 2 is superposed on the metal substrate 1 avoiding the triangular thick portion 11. Have been. Further, similar to the first embodiment, the solder attachment portion 9 having a larger area than the cross-sectional area of the other solder balls 8 is provided in the thick portion 11. Also in the case of this package P, it is fused to the motherboard M with the solder balls 8 and the solder attachment portions 9.

FIG. 8 shows a fourth embodiment of the present invention, in which only a plating surface is formed on the bottom surface of a triangular thick portion 11 and a portion corresponding to the plating surface on the motherboard M. Package P with a pre-formed cream solder layer (or adhesive layer) 12 on motherboard M
Is fixed to the surface. In this case, it is preferable that the bottom surface of the thick portion 11 be located at a position substantially equal to the apex of the solder ball 8.

In recent years, it has been found that the mounting height (the shape of the solder terminals) of the package of the metal ball grid array affects the fatigue life, but the structure in which the thick portion 11 is provided on the metal substrate 2 as described above. According to this, the mounting height of the package P can be set precisely by the size of the thick portion 11. Moreover, since a large load cannot be applied to the package P because the solder balls 8 normally form a bridge or the like, according to this structure, since the thick portion 11 of the metal substrate 1 supports the load, the resin substrate 2 or the package P
Even if the package P itself is warped, distortion of the package P can be corrected by pressing the package P from the upper surface during mounting. In addition, since the metal substrate 1 is directly connected to the motherboard M, the amount of heat that is saturated by the package P alone can be diffused to the motherboard M, so that heat dissipation can be improved.

In each of the above embodiments, the solder-attached portion has a triangular shape provided at the four corners of the package P.
As shown in FIGS. 9 to 11, the ridge 13 may be provided so as to surround the entire periphery or four corners of the package P. Also in this case, the ridge-shaped solder attachment portion may be provided directly on the resin substrate 2 (FIGS. 9 and 10), or the outer peripheral portion of the metal substrate 1 is made thick to make the bottom surface of the resin substrate 2 bottom. Alternatively, it may be equal to the top of the solder ball 8 (FIG. 11). Needless to say, a cream solder layer or an adhesive layer may be provided on the motherboard side.

The present invention is not limited to a metal ball grid array package, but is effective for a package in which stress is concentrated on the outer peripheral portion. In such a case, an underfill is not required, so that the cost can be reduced.

[0019]

As described above, according to the present invention, the deformation of the package is prevented by providing a large-area solder-attached portion for increasing the bonding strength with the motherboard at the outer periphery or at the four corners of the package where stress tends to concentrate. The stress can be forcibly suppressed, and the stress in the solder ball portion serving as an electrical connection terminal can be relaxed. Thereby, the fatigue life against a thermal load can be greatly extended. In addition, when the solder-attached portion is used as an electrical connection terminal, if this large-area terminal is used as a power supply terminal, the current capacity increases (resistance value decreases) and inductance decreases, so that electrical characteristics are improved. Is advantageous. If the package is repaired in an extremely harsh environment, it is necessary to make an electrical connection failure judgment at this soldered part, which may affect other terminals and cause malfunction. Can be done.

[Brief description of the drawings]

FIG. 1 is a bottom view of a package of a metal ball grid array showing a first embodiment of the present invention.

FIG. 2 is a side sectional view of the center of the package of FIG. 1;

FIG. 3 is a side view of a main part of the package of FIG. 1;

FIG. 4 is a side view of a main part similar to FIG. 3, showing a second embodiment of the present invention;

FIG. 5 is a bottom view similar to FIG. 1, showing a third embodiment of the present invention;

FIG. 6 is a side view of a main part of the package of FIG. 5;

FIG. 7 is a schematic perspective view of a metal substrate.

FIG. 8 is a side view similar to FIG. 3, showing a fourth embodiment of the present invention.

FIG. 9 is a bottom view similar to FIG. 1, showing a fifth embodiment of the present invention;

FIG. 10 is a bottom view similar to FIG. 1, showing a sixth embodiment of the present invention;

FIG. 11 is a bottom view similar to FIG. 1, showing a seventh embodiment of the present invention;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal substrate 2 Resin substrate 2a Opening 3 Adhesive layer 4 Semiconductor chip 5 Adhesive layer 6 Sealing resin 7 Metal cap 8 Solder ball 9 Solder adhesion part 10 Cream solder layer (adhesive layer) 11 Thick part 12 Cream solder layer (Adhesive layer) 13 ridge M motherboard P package

Claims (4)

[Claims] 1. A package for mounting a semiconductor chip, comprising: a flat metal substrate; and a resin substrate superimposed on and bonded to the metal substrate, and mounted on a motherboard by soldering with solder balls, A package for mounting a semiconductor chip, wherein a solder adhering portion having an area larger than a cross-sectional area of the solder ball is provided on at least a part of an outer peripheral portion of the package as viewed in a plane direction. 2. The package for mounting a semiconductor chip according to claim 1, wherein the solder attachment portion is provided on the resin substrate. 3. The semiconductor chip mounting package according to claim 1, wherein said solder attachment portion is provided on said metal substrate. 4. A method according to claim 1, wherein only the plating surface for forming the solder-attached portion is provided, and the plating surface is soldered to a solder-adhering surface provided at a position corresponding to the plating surface on the motherboard. Claim 1.
Or the package for mounting a semiconductor chip according to 2.