Active solid-state devices (e.g. – transistors – solid-state diode – Combined with electrical contact or lead – Wire contact – lead – or bond
Reexamination Certificate
1999-10-25
2003-07-01
Williams, Alexander O. (Department: 2826)
Active solid-state devices (e.g., transistors, solid-state diode
Combined with electrical contact or lead
Wire contact, lead, or bond
C257S685000, C257S712000, C257S723000, C257S730000, C257S704000, C257S710000, C257S786000, C257S686000, C257S717000
Reexamination Certificate
active
06586845
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device module and a semiconductor device module part and, more particularly, to such a module and a module part, including a plurality of semiconductor devices mounted on a mounting board, each device including a semiconductor element having one surface on which electrode terminals are formed, pads formed on the same surface, and wires provided at an intermediate portion thereof with a bent portion and connected by its one end to a terminal on the mounting board.
2. Description of the Related Art
A chip-sized semiconductor package (CSP), i.e., a semiconductor device which has a substantially same size as that of a semiconductor chip, has been known in the prior art, such as disclosed in U.S. Pat. No. 5,476,211. Such a known CSP is shown in
FIG. 12
, in which CPS
2
includes a semiconductor chip
10
having one surface, i.e., an electrode forming surface, on which are formed electrode terminals and re-wiring pads
12
to which first ends of respective wires
14
are connected. Each of the wires
14
is flexible, since it has a bent portion at an intermediate position, or portion, thereof. The other, second end
16
of the wire
14
is to be connected to a terminal on a mounting board.
FIG. 13
shows a semiconductor device module in which a plurality of CSPs
2
are mounted on the mounting board
18
. The semiconductor device module shown in
FIG. 13
includes a plurality of CSPs
2
each of which is connected to a pad
20
, as a terminal, on the mounting board
18
via a wire
14
. Connection between the wire
14
and the pad
20
is conducted by means of a solder
22
.
The bent portion of the wire
14
reduces the thermal stress exerted on both the semiconductor element
10
and the mounting board
18
, caused by the difference in thermal expansion coefficient therebetween. In order to allow the wire to be expanded or contracted, a space is kept between an electrode forming surface
10
a
of the semiconductor element
10
, facing the mounting board
18
, and the mounting board
18
.
On the other hand, since there is a space between the surface
10
a
of the semiconductor element
10
and the mounting board
18
, it is difficult to improve the efficiency of heat radiation from the electrode forming surface
10
a
of the semiconductor element
10
.
Thermal conductivity of the semiconductor device module shown in
FIG. 13
can be improved as compared with that of a semiconductor device module having only a space between the bottom of the recessed heat spreader
26
and the other surface
10
a
of the semiconductor element
10
.
However, the length of the wires for connecting the respective pads
20
of the mounting board
18
to the pads
12
of the semiconductor element
10
is variable among the respective CSPs
2
,
2
,
2
, . . . and among the same CSP
2
, since the respective wires have respective bent portions. Therefore, the positions of the other surfaces
10
b
of the semiconductor elements
10
of the CSPs
2
mounted on the mounting board
18
are different for the respective CSPs
2
and, therefore, the thickness of the thermal conductive resin
28
filled on the other surfaces
10
b
of the semiconductor element
10
is variable so that the level of the thermal conductivity is different for the respective CSPs
2
. Thus, a heat accumulated portion may be generated in the semiconductor device module shown in FIG.
13
and may cause error
In the CSP
2
shown in
FIG. 12
, the wires
14
extend upwardly from the pads
12
of the semiconductor elements
10
. Therefore, during assembling process of the semiconductor device module, wires
14
of CSP
2
may interfere with the other wires
14
or other parts and may thus be damaged. The wires could be transferred together but handing of the wires would then be troublesome.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a semiconductor device module and a semiconductor device module part, capable of absorbing the thermal stress caused by the difference in respective thermal expansion coefficients of a semiconductor device and a mounting board on which a semiconductor device is mounted, capable of obtaining a uniform heat radiation from the respective semiconductor devices, and affording easy assembling and handling of the semiconductor devices. To overcome the problem of improving efficiency of heat radiation addressed in paragraph 0005 above, the inventors have made an arrangement in which, in order to improve heat radiation from the other surface of the semiconductor element
10
, a peripheral edges of recessed portion of a heat spreader
26
is first adhered to a surface of the mounting board
18
by means of an adhesive layer
24
and, then, a bottom of the recessed portion of the heat spreader
26
are arranged to face to the other surfaces of the semiconductor elements
10
which constitute respective CSPs
2
,
2
,
2
, . . . , as shown in FIG.
12
. In addition, the inventors filled a thermal conductive resin
28
containing fillers of non-organic material, such as alumina, silica or the others, into a region between the bottom of the recessed heat spreader
26
and the other surface of the semiconductor element
10
, to improve the thermal conductivity.
According to the present invention, there is provided an apparatus for a semiconductor device module comprising: a plurality of semiconductor devices, each comprising a semiconductor element having first and second surfaces, pads formed on the first surface on which electrode terminals are also formed and curved, flexible wires having first ends fixed to the pads; a mounting board on which the semiconductor devices are mounted in such a manner that the other, second ends of the wires are connected to terminals on the mounting board; a heat spreader having a recessed inner wall provided with a peripheral edge thereof which is adhered to or engaged with the mounting board in such a manner that the second surfaces of the semiconductor elements faces to a bottom surface of the recessed inner wall; and a thermal conductive resin layer disposed between the second surface of the semiconductor element and the bottom surface of the recessed inner wall of the heat spreader, the thermal conductive resin layer having a substantially constant thickness.
The peripheral edge of the heat spreader is adhered to the mounting board by means of an elastic resin to absorb a difference in thermal expansion due to a difference in thermal expansion coefficient therebetween.
An inside region of the recessed inner wall of the heat spreader is filled with sealing resin in such a manner that the first surface of the semiconductor element is covered with the sealing resin and the wire protrudes from a surface of the sealing resin.
The thermal conductive resin layer is provided for the respective semiconductor element.
The thermal conductive resin layer is a film made of thermal conductive resin.
The thermal conductive resin layer is made of a resin containing therein fillers made of non-organic material, such as alumina, silica or the other, and/or fillers made of metallic material, such as aluminum, copper or the other.
The wire is provided at an intermediate position thereof with a bent portion.
According to another aspect of the present invention, there is provided an apparatus for a semiconductor device module comprising: a plurality of semiconductor devices, each comprising a semiconductor element having first and second surfaces, pads formed on the first surface on which electrode terminals are also formed and curved, flexible wires having one end fixed to the pads; a mounting board on which the semiconductor devices are mounted in such a manner that the other end of the wire is connected to terminals on the mounting board; a heat spreader having a recessed inner wall provided with a peripheral edge thereof which is adhered to or engaged with the mounting board in such a manner that the second surface of the semiconductor element faces to a bottom surface o
Higashi Mitsutoshi
Koike Hiroko
Shinko Electric Industries Co. Ltd.
Staas & Halsey , LLP
Williams Alexander O.
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