Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package – Insulating material
Reexamination Certificate
2002-01-24
2004-11-16
Thai, Luan (Department: 2827)
Active solid-state devices (e.g., transistors, solid-state diode
Housing or package
Insulating material
C257S706000, C257S719000, C438S122000, C438S123000
Reexamination Certificate
active
06818982
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a semiconductor package that is most widely used to package semiconductor chips, and more particularly, to a semiconductor package by which an improved heat dissipation efficiency required due to an increase in the power consumption of a semiconductor chip can be obtained, the speed of a high frequency semiconductor chip can be increased, and improvement of the characteristics and stability of the qualities of semiconductor chips used in RF products can be achieved.
BACKGROUND ART
In general, a semiconductor package is formed by providing a semiconductor chip such as a single device, an integrated circuit device, and a hybrid circuit device, in which various electronic circuits are formed and electric wiring is made, with terminals constructed by a lead frame or the like for transmitting signals to a main board, and by subsequently molding the semiconductor chip in molding materials or the like, in order to protect the semiconductor chip from various external environments including dust, moisture, and electrical and mechanical loads and to optimize and maximize the performance of the semiconductor chip. At this time, the lead frame means a structure that serves as leads for connecting input/output pads on the semiconductor chip and electrical circuits formed in the main board, as well as a support for fixing the semiconductor package to the main board.
Packages for packaging the semiconductor chip can be classified into those of using plastic material and those of using ceramic material.
FIG. 1
illustrates an internal structure of a conventional semiconductor package using plastic material. A process of fabricating the semiconductor package shown in
FIG. 1
will be described below:
(1) In a semiconductor chip attaching step, a semiconductor chip
130
is attached to a die paddle
110
of a lead frame by means of an adhesive
180
;
(2) In a wiring step, bond pads
120
on the semiconductor chip
130
and inner leads
150
of the lead frame are connected by fine gold wires
170
;
(3) In a molding step, the semiconductor chip
130
and the fine gold wires
170
are overmolded with an epoxy molding compound
140
in order to protect them; and
(4) In a lead forming step, outer I/O terminals
160
of a semiconductor package obtained after completion of the molding step are trimmed and formed to form out leads.
FIG. 2
illustrates an internal structure of a conventional semiconductor package using ceramic material. A process of fabricating the semiconductor package shown in
FIG. 2
will be described below:
(1) In a semiconductor chip attaching step, a semiconductor chip
230
is attached to a ceramic body
290
having a cavity
292
by means of an adhesive
280
;
(2) In a wiring step, bond pads
220
on the semiconductor chip
230
and inner leads
250
of the ceramic body
290
are connected by fine gold wires
270
; and
(3) In a sealing step, the cavity of the ceramic body is sealed with a metallic lid
291
in order to protect the semiconductor chip
230
and the fine gold wires
270
.
FIG. 3
shows a conventional semiconductor package in which the internal structure is modified in order to improve the heat dissipation efficiency of the semiconductor package using plastic material as shown in
FIG. 1. A
process of fabricating the semiconductor package shown in
FIG. 3
will be described below:
(1) In a down-set step, a die paddle
310
of a lead frame is deeply downset;
(2) In a semiconductor chip attaching step, a semiconductor chip
330
is attached to the die paddle
310
by means of an adhesive
380
;
(3) In a wiring step, bond pads
320
on the semiconductor chip
330
and inner leads
350
of the lead frame are connected by fine gold wires
370
;
(4) In a molding step, the semiconductor chip
330
and the fine gold wires
370
are overmolded with an epoxy molding compound
340
in order to protect them; and
(5) In an out lead forming step, outer I/O terminals
360
of a semiconductor package obtained after completion of the molding step are trimmed and formed to form the out leads.
FIG. 4
shows another conventional semiconductor package in which the internal structure is modified in order to improve the heat dissipation efficiency of the semiconductor package using plastic material. A process of fabricating the semiconductor package shown in
FIG. 4
will be described below:
(1) In a heat slug forming step, an additional heat slug
495
instead of a die paddle of a lead frame is attached to the lead frame;
(2) In a semiconductor chip attaching step, a semiconductor chip
430
is attached to the heat slug
495
in the lead frame by means of an adhesive
480
;
(3) In a wiring step, bond pads
420
on the semiconductor chip
430
and inner leads
450
of the lead frame are connected by fine gold wires
470
;
(4) In a molding step, the semiconductor chip
430
and the fine gold wires
470
are overmolded with an epoxy molding compound
440
in order to protect them; and
(5) In an out lead forming step, outer I/O terminals
460
of a semiconductor package obtained after completion of the molding step are trimmed and formed to form the out leads.
However, in a case where these conventional semiconductor packages are used to package a semiconductor chip having high power consumption, there is a problem in that heat generated in the semiconductor chip cannot be efficiently dissipated to the exterior thereof.
Further, in a case where the die paddle to which the semiconductor chip is attached is exposed or the heat slug attached to serve the function of the die paddle is exposed, the package is repeatedly expanded and contracted due to the heat generated from the semiconductor chip, which causes warpage of the package due to unbalance of upper and lower structures of the material constructing the package. Accordingly, there is a problem that minute delamination is formed between the exposed die paddle or heat slug and the molding material, the reliability of package is deteriorated in the long run due to infiltration of moisture and the like.
DISCLOSURE OF INVENTION
The present invention is conceived to solve the aforementioned problems in the prior art. An object of the present invention is to provide a semiconductor package with a heat-radiating canopy molded thereon and a method of fabricating the same, by which efficient heat dissipation required due to an increase in the power consumption of a semiconductor chip can be obtained, a smooth operation thereof can be made in a high frequency band to increase the speed of the semiconductor chip, and improvement of the characteristics and stability of the qualities of semiconductor chips used in RF products can be achieved.
According to the present invention, there is provided a heat dissipation type semiconductor package including a die paddle, a semiconductor chip mounted on the die paddle and a lead frame, comprising: a plurality of wires electrically connecting bond pads formed on the semiconductor chip and inner leads in the lead frame; a heat-radiating canopy attached to a top surface of the semiconductor chip; and a molding material surrounding all of the die paddle, the semiconductor chip, the inner leads and a bottom surface of the heat-radiating canopy; wherein the top surface of the heat-radiating canopy is is exposed to the exterior, and a portion of the bottom surface of the heat-radiating canopy being in contact with the semiconductor chip is recessed.
According to the present invention, there is also provided a heat dissipation type semiconductor package including a substrate, a die paddle formed on the substrate, a semiconductor chip mounted on the die paddle, and inner leads attached to the substrate and serving as electrical contacts, comprising: a plurality of wires electrically connecting bond pads formed on the semiconductor chip and the inner leads; a heat-radiating canopy attached to a top surface of the semiconductor chip; a molding material surrounding all of the die paddle, the semiconductor chip, the inner lead and a bottom surface of the heat-radiating ca
Burns Doane Swecker & Mathis L.L.P.
Thai Luan
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