Semiconductor package

Details Semiconductor package Semiconductor package

2002-01-02

2003-01-21

Clark, Jasmine J B (Department: 2815)

Active solid-state devices (e.g., transistors, solid-state diode

Housing or package

C257S704000, C257S783000, C257S710000

Reexamination Certificate

active

06509636

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to semiconductor packages, and more particularly, to a photosensitive semiconductor package with a lid.
BACKGROUND OF THE INVENTION
In a conventional semiconductor package, a semiconductor chip is encapsulated with an opaque encapsulant for preventing the chip from being damaged by external contaminant and moisture, as well as providing the chip with protection against damage from external impact. However, in respect of a photosensitive semiconductor chip for use in an electronic device such as CMOS image sensor, the chip can function properly only with its photosensitive side receiving external light. Therefore, it usually adopts a different method for packaging such a photosensitive semiconductor chip, as compared to the foregoing conventional semiconductor package.
Up to now, there have been several patents regarding the packaging of photosensitive semiconductor chips. A common semiconductor package
1
for accommodating a photosensitive semiconductor chip is illustrated in
FIG. 1
, comprising: a chip carrier
10
defined with a chip attach region
102
; an encapsulant
12
formed on the chip carrier
10
with a cavity for exposing the chip attach region
102
by using a particular encapsulating mold during a molding process; a photosensitive semiconductor chip
15
adhered onto the chip attach region
102
, and electrically connected to the chip carrier
10
by a plurality of conductive elements
16
; and a transparent lid
13
attached to a top
121
of the encapsulant
12
in a manner that, the transparent lid
13
is positioned right above the photosensitive chip
15
.
Generally, a commercially available transparent lid (such as a glass slice) is applied with an epoxy resin adhesive (such as b-stage glue) at positions to be attached to the top of the encapsulant. After heating and applying pressure, the adhesive melts and solidifies for firmly attaching the lid onto the top of the encapsulant.
However, due to variations of adhesive amount applied to the lid, and of dimensionally or structurally design of the encapsulant, the adhesive usually occurs to be positionally difficult in compliance with the top of the encapsulant. Referring again to
FIG. 1
, as the top
121
of the encapsulant
12
is flatly made, compression between the lid
13
and the top
121
of the encapsulant
12
easily results in the leakage or loss of the molten adhesive
14
, making the adherence between the lid
13
and the encapsulant
12
undesirably damaged. Moreover, if the top
121
of the adhesive wall
12
is insufficiently dimensioned in adhering area, or the adhesive
14
is excessively applied, the molten adhesive
14
tends to flash over side walls of the encapsulant
12
; this seriously damages the appearance of the semiconductor package
1
. A solution is to form a dam (not shown) at an outer edge of the top
121
of the encapsulant
12
. However, this can only eliminate the occurrence of adhesive flash over the outer side wall of the encapsulant
12
, whereas the molten adhesive
14
still possibly leaks to the inner side wall of the encapsulant
12
, and even contaminates the chip attach region
102
.
SUMMARY OF THE INVENTION
A primary objective of the present invention is to provide a photosensitive semiconductor package with a lid, in which a groove in association with at least a beveled portion are formed on a top of an encapsulant for temporarily retaining excess adhesive, so as to eliminate the adhesive loss and the occurrence of adhesive flash over side walls of the encapsulant, thereby making the appearance of the semiconductor package well maintained.
In accordance with the foregoing and other objectives, the present invention proposes a photosensitive semiconductor package, comprising: a chip carrier, on which an encapsulant is formed with a cavity for exposing a portion of the chip carrier to outside of the encapsulant, wherein a top of the encapsulant is structured with a groove and at least a beveled portion that descends toward the groove and is associated with the groove; at least a semiconductor chip mounted in the cavity and on the exposed portion of the chip carrier, and electrically connected to the chip carrier; and a lid attached to the top of the encapsulant by an adhesive, for hermetically covering the cavity of the encapsulant so as to isolate the semiconductor chip from external atmosphere.
The photosensitive semiconductor package of the invention is characterized of adopting the groove in association with the beveled portion that is used for directing the adhesive flow toward the groove. Thereby, after the adhesive for attaching the lid to the encapsulant is melted by heating, the groove can temporarily retain excessive adhesive with its flow being directed toward the groove by the beveled portion, so that undesirable adhesive loss and adhesive flash can be both prevented from occurrence, making the appearance of the semiconductor package well maintained. In addition, the beveled portion is provided with a relatively larger surface area for accommodating the adhesive, allowing contact area to be increased between the top of the encapsulant and the adhesive, thereby effectively improving the bonding between the lid and the encapsulant.


REFERENCES:
patent: 4917466 (1990-04-01), Nakamura et al.
patent: 5023461 (1991-06-01), Nakazawa et al.
patent: 64-57738 (1989-03-01), None
patent: 1-199458 (1999-08-01), None

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