Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package
Reexamination Certificate
2000-01-06
2001-11-20
Clark, Jhihan B (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Housing or package
C257S693000, C257S686000, C257S723000, C257S780000, C257S781000, C257S792000
Reexamination Certificate
active
06320250
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor package and a process for manufacturing the same, and, particularly, to a surface mounting semiconductor package and a process for manufacturing the same.
2. Description of the Related Art
As examples of conventional semiconductor packages having a ball grid array (hereinafter abbreviated as “BGA”) structure using a tape carrier, those having the structure shown in
FIG. 10
are given.
As shown in
FIG. 10A
, a semiconductor package
100
comprises a plurality of lands
17
(electrodes) formed in an array along four sides of the surface side of a substrate each land having a solder ball
20
(external connection terminal) mounted on the top face thereof; a base substrate
12
(polyimide film) to whose bottom face is adhered a patterned copper foil
16
using an insulating adhesive
14
; an adhesive sheet elastomer
26
(elastic body) adhered to the exposed portions of the bottom face of the insulating adhesive
14
and to the lands
17
; a semiconductor device
28
which is loosely secured to the bottom face of the elastomer
26
and bonded to a plurality of electrode pads
30
having an inner lead
18
, extending from the land
17
, on the peripheral portions of its upper face; and an insulating resin
32
protecting the inner lead
18
and the bonded portion.
Note that the base substrate
12
, the insulating adhesive
14
, the copper foil
16
, the lands
17
and the inner lead
18
there are generically called a tape carrier
25
.
SUMMARY OF THE INVENTION
In the aforementioned semiconductor package having the BGA structure, however, in the case where the assembly conditions are bad or an inadequate elastomer material is used, the elastomer
26
adhering to the bottom face of the base substrate
12
partially peels off around the circumference of the lands
17
with the result that, as shown in
FIG. 10B
, a space
102
enclosed by the bottom face of the insulating adhesive
14
, the side faces of the land
17
, and the elastomer
26
is produced. Therefore, water, air and the like collected in the space
102
expand on account of historical heat history and the like when the semiconductor device is mounted on a mother board, giving rise to the problem of a package deforming and cracks being produced.
In recent years, with the progress in the miniaturization of electronic equipment, there has been a demand for smaller semiconductor packages. The above semiconductor package, however, has the structure in which one semiconductor device is provided in one package. When there is a need, in equipment using this type of package semiconductor, for example, for a semiconductor device having a different function or for a plurality of semiconductor devices even if they are of the same type, then naturally, the necessary number of semiconductor devices are mounted and the space to be occupied by the packages of each semiconductor package and by the connection terminals thereof needs to be provided. Hence, it has been desired to reduce this space thereby improving the packaging density of semiconductor packages.
In consideration of the above, an object of the present invention is to provide a method for producing semiconductor package in which deformation of the package and cracking do not occur even when heat history is applied during the packaging, and which further provides an improved packaging density during packaging, compared to the conventional structure.
According to a first aspect of the present invention, there is provided a semiconductor package, the package comprising:
a base substrate having a perforation formed therein, the perforation including a bottom and the base substrate including a backface;
an electrode portion secured to the backface of the base substrate and disposed on the bottom of the perforation, wherein a gap exists between the base substrate and the electrode portion;
a semiconductor device electrically connected to the electrode portion and disposed on the backface of the base substrate;
a sheet elastic body interposed between the semiconductor device and the electrode portion; and
a leveling material filling the gap between the base substrate and the electrode portion.
Specifically, in the present invention, the leveling material for eliminating a step between the base substrate and the electrode portions is provided in the gap which is produced in the backface portion of the base substrate by the electrode portions, thereby eliminating a step which is formed on the backface portion of the base substrate. This makes the backface portion of the base substrate smooth and hence no gap is produced at the contact section of the sheet elastic body which is to be brought into surface contact with the smoothed surface. Also, even if this elastic body is adhesive, no partial peeling force is produced at the joint surface.
In the above structure, there is neither gap nor space produced by partial peeling at the contact surface or joint surface between the backface portion of the base substrate and the elastic body. Therefore, even if heat history is applied in the packaging, the package is not deformed and no cracks are produced.
In a second aspect of the semiconductor package according to the first aspect, preferably the base substrate is a polyimide film and the leveling material is an insulating coating agent.
Specifically, in the second aspect, since the leveling material is a coating agent, the gaps on the backface portion of the base substrate can be reliably filled. Accordingly, gaps are not left on the backface portion of the base substrate but are reliably filled and any step on the backface portion of the base substrate is eliminated. In addition, since the coating agent is insulated, short circuiting across the electrode portions through which current flows can be avoided.
In a third aspect of the semiconductor package according to the first aspect, preferably the semiconductor package comprises: the base substrate: electrode portions formed on the base substrate; and a plurality of semiconductor devices connected electrically to the electrode portions and connected to the base substrate.
In the third aspect, the semiconductor package is provided with a plurality of semiconductor devices, which are electrically connected to each other. In other words, the semiconductor package has a structure in which the plurality of semiconductor devices are arranged in the same package and share the package and the electrode portions.
Accordingly, the packaging space is reduced as compared with the case of packaging, within a given area, a plurality of semiconductor packages having the conventional structure in which one semiconductor device is stored in one package. Specifically, as compared with the semiconductor package having the conventional structure, the outside dimension is substantially reduced and the packaging density in packaging is thereby improved.
In a fourth aspect of the semiconductor package according to the third aspect, the plurality of semiconductor devices are connected to the base substrate in a stacked arrangement.
In the fourth aspect of the semiconductor package, when the plurality of semiconductor devices are stacked, each semiconductor device is stacked in the direction of the thickness thereof and hence the outside dimension in the direction of the packaged plane of the semiconductor package is reduced as compared with the case of placing each semiconductor device side by side on the same plane. Therefore, the packaged area is reduced to be less than in conventional arrangements in which semiconductor packages are placed side by side on a planar material such as a substrate.
In a fifth aspect of the semiconductor package according to the fourth aspect, the stacked arrangement includes a top semiconductor device on which the electrode portion is disposed, and each semiconductor device is electrically connected directly to the electrode portion.
In the fifth aspect of the semiconductor package, each of the plurality of stacked semiconduct
Clark Jhihan B
OKI Electric Industry Co., Ltd.
Volentine & Francos, PLLC
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