Active solid-state devices (e.g. – transistors – solid-state diode – Combined with electrical contact or lead – Die bond
Reexamination Certificate
2000-03-03
2001-05-01
Clark, Sheila V. (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Combined with electrical contact or lead
Die bond
C257S706000, C257S707000, C257S677000
Reexamination Certificate
active
06225701
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-058749, filed Mar. 5, 1999, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor device provided with a heat-sink and a method of manufacturing the same, particularly, to a semiconductor device in which a lead-frame is fixed to a heat-sink and a method of manufacturing the same.
A semiconductor device in which a lead-frame is fixed to a heat-sink is disclosed in, for example, Japanese Utility Model Disclosure (Kokai) No. 7-10955.
In this prior art, a polyimide-based resin containing a crystalline silica having a high heat conductivity is printed on a heat-sink, followed by applying a heat treatment to the printed resin to form a polyimide-based resin layer. Then, an epoxy resin having a good adhesivity is printed on the polyimide-based resin, followed by adhering a lead-frame assembly to the heat-sink with the epoxy resin interposed therebetween. Further, the semiconductor device is sealed with a resin molding body except the tip of the outer lead by using a known transfer mold.
In this prior art, excellent heat dissipating properties can be obtained because a polyimide-based resin layer containing 30 to 60 wt % of crystalline silica having a good heat conductivity is interposed between the lead-frame assembly and the heat-sink.
In this prior art, however, the polyimide-based resin layer formed on the heat-sink is adhered to the lead-frame with an adhesive epoxy resin layer interposed therebetween. As the result, a heat dissipating efficiency is decreased by amount that the epoxy resin layer provided between the lead-frame assembly and the heat-sink.
What should also be noted is that, since an epoxy resin layer is formed on the polyimide-based resin layer, a difficulty arises if the sealed semiconductor device is used for an unexpectedly long period of time or a power semiconductor device generating a large amount of heat is sealed with the resin. Specifically, cracks tend to occur in the bonding interface between the polyimide-based resin layer and the epoxy resin layer because of the difference in thermal expansion coefficient between the two.
BRIEF SUMMARY OF THE INVENTION
An object of the present invention, which has been achieved in view of the situation described above, is to provide a semiconductor device provided with a heat-sink, which is constructed to be excellent in durability and to withstand sufficiently the mounting of a power semiconductor element generating a large amount of heat, and a method of manufacturing the particular semiconductor device.
According to an aspect of the present invention, there is provided a semiconductor device, comprising: a heat-sink; a lead-frame; a laminated insulating film interposed between the heat-sink and the lead-frame, the laminated insulating film including a first layer positioned on the side of the heat-sink and made of an insulating matrix containing a heat dissipating filler and a second layer positioned on the side of the lead-frame and made of the insulating matrix containing the heat dissipating filler; an electronic part mounted to the lead-frame; and a molding body which molds the electronic part with the outer lead portion of the lead-frame and the heat dissipating surface of the heat-sink exposed to the outside.
In the semiconductor device of the construction described above, the heat dissipating efficiency can be improved because a heat dissipating filler is contained in all the layers constituting the laminated insulating film. Also, all the layers of the laminated insulating film are formed of the same kind of the matrix, with the result that cracks derived from a difference in thermal expansion coefficient is unlikely to be generated within the laminated insulating film. It follows that it is possible to obtain a semiconductor device provided with a heat-sink, which is constructed to be excellent in durability and to withstand sufficiently the mounting of a power semiconductor element generating a large amount of heat.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
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Hori Tetsuji
Thai Cao Minh
Clark Sheila V.
Kabushiki Kaisha Toshiba
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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