Semiconductor device manufacturing: process – Packaging or treatment of packaged semiconductor
Reexamination Certificate
2000-10-25
2004-09-07
Zarneke, David A. (Department: 2827)
Semiconductor device manufacturing: process
Packaging or treatment of packaged semiconductor
C438S110000, C438S111000, C438S127000
Reexamination Certificate
active
06787389
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a discrete semiconductor device. More particularly, it relates to a discrete semiconductor device for small signal operation having excellent high-frequency characteristics and heat dissipation performance.
2. Description of the Related Art
A discrete semiconductor device of the prior art is typically packaged in a DIP (dual inline package) shown in FIG.
25
.
FIG. 25A
is a cut-away view from above of a resin-sealed DIP, and
FIG. 25B
is a cut-away view of the side of the resin-sealed DIP. In the drawing, numeral
2
denotes a sealing resin,
8
denotes a discrete semiconductor element,
9
denotes a wire connecting an electrode of the discrete semiconductor element
8
and an inner lead
39
,
38
denotes an island for securing the discrete semiconductor element
8
,
39
denotes the inner lead and
40
denotes an outer lead.
In the case of such a resin-molded DIP, the discrete semiconductor element
8
is secured onto the island
38
of a lead frame
41
by die bonding and the electrode of the discrete semiconductor element
8
is connected to the inner lead
39
by means of the Au wire
9
, then the circuit is sealed with resin by using an independent die for each discrete semiconductor element
8
, with the lead being cut off the lead frame
41
thereby to fabricate the discrete semiconductor device (FIG.
27
).
When packaging the discrete semiconductor device on a mother board, there has been such a problem that a large packaging area is required to connect the device to the mother board by using the outer lead
40
which is installed on a side face of the package and extends outward.
Also because the discrete semiconductor element and the mother board are connected by means of a lead, wiring length becomes longer and causes a substantial loss in the discrete semiconductor element in high-frequency region which leads to unsatisfactory high frequency characteristics.
Moreover, because the discrete semiconductor element is sealed with a resin of low thermal conductivity, heat dissipation efficiency decreases and causes such a problem that it is impossible to package discrete semiconductor elements of high power.
For example, Japanese Patent Kokai Publication No. 8-236665 discloses a method of packaging electronic elements on a mother board by means of bumps provided on the back of a resin-sealed semiconductor device which carries an IC chip mounted thereon, without using leads.
However, because the discrete semiconductor element employs a high power element such as power MOS device compared to an IC which employs a low power element, heat transfer through the bumps is not enough to dissipate the heat generated by the semiconductor device and the like. Also when high-frequency elements are used, it has been necessary to improve the high-frequency characteristics by making the distance between the electrode of the high-frequency element and the mother board whereon the high-frequency element is mounted as short as possible.
Moreover, in the process of producing resin-sealed discrete semiconductor devices of the prior art, semiconductor elements are sealed with resin by using an independent die for each discrete semiconductor device and injecting the sealing resin in each die, although such a method requires it to fu fabricate a new die every time the external dimension or profile of the semiconductor divide is changed, thus making it difficult to reduce the period of time and cost of development of the semiconductor devices.
Also when a lead frame is used, peripheral portion of the frame except for the leads becomes unnecessary making it difficult to reduce the producing cost.
SUMMARY OF THE INVENTION
The present invention is intended to solve the problems with the discrete semiconductor elements described above, and an object of the present invention is to provide a discrete semiconductor device which requires a small packaging area and has excellent high-frequency characteristics and good heat dissipation performance, and a method of producing the same.
The present inventors have intensively studied. As a result, the present inventors have found that it is possible to connect the back faces of die bond pads and wire bond pads directly on a mother board and to achieve the object described above, by using a discrete semiconductor device made by mounting the discrete semiconductor elements on the die bond pads and the wire bond pads and sealing the packaging surface with a resin Thus, the present invention has been accomplished.
Hence the present invention provides a discrete semiconductor device comprising die bond pads and wire bond pads arranged at specified intervals, discrete semiconductor elements which are fastened on the back face thereof onto the die bond pads and have electrodes electrically connected to the wire bond pads, and a sealing resin provided on one side of the die bond pads and the wire bond pads thereby to seal the discrete semiconductor elements.
In the discrete semiconductor device as described above, one side of the discrete semiconductor device is not sealed with resin and the die bond pads and the wire bond pads on the back side which is not sealed with the resin allow direct connection with the mother board.
Therefore, firstly, packaging area can be reduced compared to the packaging technique of the prior art which uses leads, because the discrete semiconductor device has connecting points on the back. Also because the die bond pads and the wire bond pads provided on the back can be directly connected to the mother board by using solder or the like, packaging height can also be reduced compared to the configuration of the prior art which uses bumps.
Secondly, because the discrete semiconductor elements are directly fastened on the die bond pads while the die bond pads are connected directly to the mother board, efficiency of heat dissipation of the discrete semiconductor elements can be greatly improved compared to the configuration of the prior art which dissipates heat through the leads. This configuration makes it possible to use elements which generate much heat such as power MOS devices.
Thirdly, because the die bond pads and the wire bond pads are connected directly to the mother board, connection distance between the discrete semiconductor device and the mother board can be reduced, thereby making it possible to improve the high-frequency characteristics when the discrete semiconductor device is used in a high frequency band.
Also the present invention provides a discrete semiconductor device wherein the die bond pads and the wire bond pads are electrically conductive metal sheets which are fastened at specified positions on the back of an insulating sheet and have aperture in the insulating sheet on the metal sheets, and the sealing resin is provided on one side of the die bond pads and the wire bond pads thereby to seal the discrete semiconductor element.
This makes it easy to product a plurality of semiconductor devices at the same time.
Also the present invention provides a discrete. semiconductor device wherein the die bond pads and the wire bond pads are the metal sheets which are cut off as born by the sealing resin that is formed on an electrically conductive metal sheet, and the sealing resin is provided on one side of the die bond pads and the wire bond pads thereby to fasten the die bond pads and the wire bond pads at specified intervals and seal the discrete semiconductor element.
By using the metal sheets formed at the specified intervals as the die bond pad and the wire bond pads as described above, it is made possible to manufacture the discrete semiconductor device having a plurality of semiconductor elements connected in series or parallel, having such a configuration as the wire bond pads are used in common.
The discrete semiconductor device preferably has electrodes on the back thereof and is electrically connected with the wire bond pads.
This is because the efficiency of heat dissipation can be improved and the wiring can be made sh
Fujihara Teruhisa
Ohgiyama Kenji
Oohira Minoru
Mitsubishi Denki & Kabushiki Kaisha
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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