Active solid-state devices (e.g. – transistors – solid-state diode – Encapsulated
Reexamination Certificate
1999-03-05
2002-04-02
Clark, Jhihan B (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Encapsulated
C257S794000, C257S793000, C257S693000
Reexamination Certificate
active
06365979
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
Present invention relates to semiconductor devices and manufacturing methods thereof, in particular, relates to thin and small resin encapsulated semiconductor devices suitable for portable devices such as cellular phones and video cameras, and manufacturing methods thereof.
2. Description of Related Art
Recently, as thin and small semiconductor devices, chip size packages (CSP) of which the external form are formed in conformity with the size of a semiconductor element (semiconductor chip) have been developed. Among them, a fine pitch area package, the pitch between terminals of which is narrow, is seen as a promising candidate.
A thin area package of fine pitch is broadly divided into one that employs an insulating resin film as a matrix, and the other one that employs a resin impregnated glass cloth substrate of rigid frame as a matrix. In particular, from a reliability point of view, the use of the latter one is being studied.
However, in the CSP in which a substrate of a resin impregnated glass cloth is employed as a matrix, it is difficult to cut off the substrate in the neighborhood of the external form line (mold line) of the molded resin layer. Accordingly, there is such a problem that the external form of a package becomes greatly larger than the external form of the molded resin layer.
That is, when manufacturing a CSP, die bonding and the electrical connection wire bonding of a semiconductor chip is carried out in this order to a wiring substrate having wiring patterns and holes for continuity. Thereafter, a metal mold is put on outside of the semiconductor chip and an epoxy-resin or the like is transfer molded in the metal mold. Thereby, a resin sealed layer (molded resin layer) is formed. Then, after solder bumps or the like are formed as external connecting terminals, in the last, along the mold line, the wiring substrate is cut.
However, in the step of forming the molded resin layer, from a gap between a pushing face of the metal mold and the wiring substrate, the mold resin is forced outside to stick firmly on the wiring substrate, resulting in a burr. The length of the burr reaches even 0.3 to 1.2 mm. That makes difficult to separate the wiring substrate at a portion of the burr. Accordingly, it is required to cut at a position more than the length of the burr apart from the mold line, resulting in a problem that the external form of the package becomes larger by 0.6 to 2.4 mm than that of the molded resin layer.
Further, upon cutting a wiring substrate, though different according to the thickness of the substrate, cutting accuracy of a tool or the like, a large excising margin (cutting margin) is required. Consequently, the demand for smaller size can not be fully satisfied. Further, since the cutting tools wear down rapidly to make necessary complicated management of the tools, in addition, to tend to lead to the poor cutting, the cost reduction was difficult.
SUMMARY OF THE INVENTION
The present invention was carried out to solve these problems. An object of the present invention is to provide a semiconductor device that is molded by a molded resin layer, thin, small and highly reliable, and a method of manufacturing efficiently such a semiconductor device.
This invention is disclosed in Japanese Patent Application No. 10-055563 on Mar. 6, 1998, and the entire disclosure thereof is incorporated herein by reference.
The first aspect of the present invention relates to a semiconductor device.
The semiconductor device comprises a wiring substrate having a wiring layer on at least one main face of a substrate composed of a resin impregnated glass cloth, a semiconductor element mounted and assembled on the main face of the wiring substrate, a molded resin layer covering and molding an outside of the semiconductor element, and a plurality of external connecting terminals disposed on the other main face of the wiring substrate. Here, below an external form line of the molded resin layer and between the molded resin layer and the wiring substrate, a protrusion comprising an insulating resin is formed.
The second aspect of the present invention relates to a manufacturing method of a semiconductor device.
The manufacturing method comprises a step of forming a wiring layer on at least one main face of a substrate composed of a resin impregnated glass cloth, a step of forming a protrusion mainly consisting of an insulating resin on a first area on the wiring substrate thereon the wiring layer is formed, a step of mounting and assembling a semiconductor element on an area inside of the first area of the wiring substrate, a step of pressurizing a pushing face of a metal mold against the protrusion formed on the wiring substrate to carry out molding of an insulating resin, thereby forming a molded resin layer outside of the semiconductor element, and a step of forming an external connecting terminal on the other main face of the wiring substrate.
The third aspect of the present invention relates to a manufacturing method of a semiconductor device.
The manufacturing method comprises a step of forming a wiring layer on at least one main face of a substrate composed of a resin impregnated glass cloth, a step of forming a protrusion consisting of an insulating resin on a first area on a wiring substrate thereon the wiring layer is formed, a step of, in the first area of the wiring substrate, cutting leaving a part of the protrusion to form a slit hole, a step of mounting and assembling a semiconductor element on an area inside of the first area of the wiring substrate, a step of pressurizing a pushing face of a metal mold against the protrusion left on the wiring substrate to carry out molding of an insulating resin, thereby forming a molded resin layer outside of the semiconductor element, a step of forming an external connecting terminal on the other main face of the wiring substrate; and a step of, in the wiring substrate thereon the external connecting terminal is formed, cutting between the slit holes to separate an inside molded body.
In the semiconductor device and the manufacturing method thereof of the present invention, as the substrate of the resin impregnated glass cloth, one that is obtained by stacking a prepreg, in which an insulating resin such as an epoxy resin, a BT resin or the like is impregnated, into a glass cloth, and by heating/pressing the same, can be employed. The thickness of such an insulating substrate is preferable to be in the range of from 0.08 to 0.30 mm. Incidentally, the BT resin is an addition polymerized thermosetting resin mainly consisting of bismaleimid and triazine. This resin impregnated substrate is excellent in heat resistance and insulating characteristic, and has a good processing characteristic.
In the present invention, on at least one main face of said resin impregnated substrate, a wiring layer of such as inner leads, a signal line or the like is formed, further, on a predetermined position, via holes for extracting the wiring layer to the other main face is bored. Thus, a wiring substrate is obtained.
Here, the pitch and arrangement of the inner leads are designated according to the pitch and arrangement of electrode terminals of the semiconductor element being assembled. Then, the wiring layer including the inner leads is formed by photo-patterning (photo-etching) a conductive metallic layer such as a copper foil or the like disposed on one surface or both surfaces of the substrate of the resin impregnated substrate. Further, the boring of the via holes can be carried out by boring, with a drill of fine diameter or the like, one in which a plurality of the wiring substrates are stacked.
In the present invention, immediate below the external form line (mold line) of the molded resin layer on the wiring substrate, a protrusion consisting of an insulating resin is formed. Thereby, in the step of forming the molded resin layer, the protrusion is pressed against a pushing face of a metal mold to make an intimate contact and seal a gap between the metal mold and the wiring s
Clark Jhihan B
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Kabushiki Kaisha Toshiba
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