Active solid-state devices (e.g. – transistors – solid-state diode – Lead frame – With bumps on ends of lead fingers to connect to semiconductor
Reexamination Certificate
2002-10-28
2004-09-21
Clark, Jasmine (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Lead frame
With bumps on ends of lead fingers to connect to semiconductor
C257S693000, C257S737000, C257S738000, C257S780000, C257S781000, C257S782000, C257S784000
Reexamination Certificate
active
06794739
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a semiconductor device, a process for production thereof, and electronic equipment.
BACKGROUND ART
CSP (chip size package) to cope with increase in the number of electrodes in recent semiconductor chips has been usually accomplished by pellet-bonding the semiconductor chip and wire-bonding the semiconductor chip to the wiring of the wiring substrate side.
FIG. 14
is a sectional view showing an example of the semiconductor device of wiring bonding type. In this figure, a is a polyimide resin base, b is a wiring film, c is an electrode forming hole, d is a micro ball electrode of solder formed in said electrode forming hole c,
1
is, for example, a silver paste film, f is a semiconductor chip which is bonded to the surface of the base a through the silver paste film
1
, i is a resin reinforcement and a ring to dam up resin, m is a wire to electrically connect the electrode of the semiconductor chip f and the wiring film b, and n is a sealing resin supplied by potting.
However, CSP (chip size package) of the type in which the semiconductor chip is flip-chip-connected has recently appeared.
FIG. 15
is a sectional view showing one of conventional examples of CSP of flip chip connection type which employs FPC (flexible printed circuit board). In this figure, a is a polyimide resin base, b is a wiring film of copper formed on the surface of said base a, c is an electrode forming hole formed in said base a, d is a micro ball electrode of solder formed in said electrode forming hole c, e is an anisotropic conducting film, i is a film-reinforcing ring of, for example, copper or nickel, j is an adhesive to bond the film-reinforcing ring i to the base a, and k is a plating film of gold that coats the surface of said wiring film b. The anisotropic conducting film e bonds the semiconductor chip f to the base a surface and it also connects the external lead electrode of said semiconductor chip f to the wiring film b through the metal bump g on said electrode surface.
By the way, since CSP of the type shown in
FIG. 14
is constructed such that the semiconductor chip f is mounted on the base a with its electrodes upward and the electrodes are connected to the wiring film b by means of the wire m, the bent part of the wire m is above the top of the semiconductor chip f and there was the problem that it is difficult to reduce the thickness of the sealing resin and in turn to reduce the thickness of the package.
By contrast, CSP of the type shown in
FIG. 15
, which does not use the wire m, has no such a problem. However, there is an increasing demand for high integration and miniaturization of semiconductor devices, and there was a problem that it is difficult to meet the requirement for further smaller and thinner packages. One reason for this is that the package of the type shown in
FIG. 15
has the wiring film b which is formed on the surface of the resin base a. In other words, the wiring film b makes the resulting package thicker by its thickness, and hence it is difficult to meet the requirement for further thickness reduction.
Moreover, since the wiring film is formed convex on the film surface, the resin hardly enters the gap between the wiring film and the wiring film, and voids are liable to occur. These voids absorb moisture and absorbed moisture explodes at the time of reflowing, thereby peeling the connection between the wiring film on the film and the bump.
The present invention was completed in order to solve such problems. It is intended to facilitate the production of a semiconductor device of CSP or BGA type, in which the chip is mounted in flip chip type, to reduce cost, to reduce the package thickness, and to improve reliability.
DISCLOSURE OF INVENTION
The semiconductor device of the first claim is characterized in that it includes a wiring substrate and a semiconductor chip, said wiring substrate having a wiring film and an insulating resin formed thereon such that the former is embedded in one surface of the latter, with one surface of the former being flush with said one surface of the latter, said wiring substrate further having a hole at the position where at least part of said wiring film overlaps with said insulating resin, said semiconductor chip having at least part of its external lead electrodes connected to said wiring film on said wiring substrate through bumps.
Therefore, according to the semiconductor device of the first claim, since the wiring film is embedded in one surface of the base, it is possible to eliminate steps on the surface, and further since the semiconductor chip is mounted by flip chip on such base surface, it is possible to reduce the thickness of the semiconductor device.
And, since it is possible to form the electrode forming hole by exposure and development, it is possible to contrive miniaturization and higher integration density, and in turn it is possible to increase integration of the semiconductor device and to increase the number of electrodes.
The production process of the semiconductor device of the thirteenth claim is characterized in that it includes the steps of providing a wiring substrate which is so formed as to permit a plurality of semiconductor chips to be mounted thereon and a plurality of semiconductor chips each having bumps formed on the external lead electrode, connecting the gap between said bump of said each semiconductor chip and the wiring film of said wiring substrate by ultrasonic wave or heating under pressure, casting a resin into the vicinity of said bumps, thereby sealing it, and finally separating said wiring substrate to give a plurality of semiconductor devices.
Therefore, according to the production process of the semiconductor device of the thirteenth claim, the semiconductor chip is flip-chip-connected to the wiring substrate by ultrasonic wave or by heating under pressure and sealed with a resin, and subsequently it is divided; therefore, it is possible to obtain simultaneously a plurality of semiconductor devices which have been made thin.
The production process of the semiconductor device of the fourteenth claim is characterized in that it includes the steps of providing a wiring substrate and a plurality of semiconductor chips mounted thereon, each having bumps formed on the external lead electrode, pasting an anisotropic conducting film to the wiring film forming plane of said wiring substrate, placing the semiconductor chip on said anisotropic conducting film on said wiring substrate, electrically connecting the gap between the bump of said semiconductor chip and said wiring film by heating under pressure, and casting a resin into the vicinity of said semiconductor chip for its sealing.
Therefore, according to the production process of the semiconductor device of the fourteenth claim, the semiconductor chip is flip-chip-connected to the wiring substrate by using the anisotropic conducting film, and sealing with a resin, thereby it is possible to obtain the semiconductor device which has been made thin. Also, since the substrate is flat, voids hardly occur and it hardly suffers breakage due to moisture absorption at the time of reflowing.
The semiconductor device of the fifteenth claim is characterized in that a plurality of wiring films are placed on one side of an insulating resin base such that the surface of said wiring film is approximately flush with the surface of said base and at least part of said wiring film is so formed as to overlap with the electrode forming hole in said base, said electrode forming holes are filled with a conducting material, external electrodes projecting toward the opposite side of the wiring film are formed, and the semiconductor chip is flip-chip-bonded to said one surface of said base.
Therefore, according to the semiconductor device of the fifteenth claim, since the wiring film is embedded in one surface part of the base, it is possible to eliminate surface steps; since the semiconductor chip is mounted on such a surface, the mounting of the semiconductor chip becomes easy, and it is possible to increase t
Kobayashi Hirotaka
Koyama Toshiki
Clark Jasmine
Kananen Ronald P.
Rader & Fishman & Grauer, PLLC
Sony Corporation
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