Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package – With contact or lead
Reexamination Certificate
1999-02-18
2001-06-19
Tran, Minh Loan (Department: 2811)
Active solid-state devices (e.g., transistors, solid-state diode
Housing or package
With contact or lead
C257S690000, C257S693000, C257S668000, C257S779000, C257S783000, C257S697000, C257S698000, C257S699000, C257S780000, C257S778000
Reexamination Certificate
active
06249046
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a semiconductor device for surface-mounting, a method of manufacture thereof, and a mounting method for the same and circuit board with the same mounted.
BACKGROUND ART
To pursue downsizing in semiconductor devices, bare chip mounting is the ideal. However, for bare chips, quality control and handling are difficult, and this problem is answered by processing in package form. Particularly in response to the need for high pin counts, in recent years BGA (ball grid array) packages have been developed. BGA packages have a number of different forms, depending on the material of the substrate, but in particular to meet the requirements for mounting fine pitch pad semiconductor elements, and to meet the demands of manufacturing efficiency that fabrication in tape form should be possible to enable continuity, BGA packages using flexible tape exist, in which a flexible material is used as the material of the substrate. Such a BGA package has the bumps which are the external terminals on the flexible substrate disposed in an a real array, to allow surface mounting
With this BGA package, the wiring pattern connecting from the chip electrodes to the bumps is formed exposed on the flexible substrate, and during the process of mounting onto a circuit board, careful handling is required to prevent impairment of the quality of the wiring pattern.
Moreover, with a BGA package, not only is checking and testing of the state of connection of the bumps and the circuit board pads impossible, but even if there is a faulty connection repair is impossible, and for this reason high precision is called for in the mounting.
The flexible substrate used for a BGA package, because of its lack of rigidity is liable to distort, thus to cause problems for mounting.
Such a conventional BGA package thus presents a variety of problems at mounting time.
The present invention solves these problems, and has as it object the provision of a semiconductor device for surface-mounting capable of easy mounting, a method of manufacture thereof, and a mounting method for the same and circuit board with the same mounted.
DISCLOSURE OF THE INVENTION
The semiconductor device of the present invention comprises:
a semiconductor element;
an insulating film having a through hole;
a wiring pattern formed on first surface of the insulating film so as to pass over the through hole, and connected to the semiconductor element;
an external terminal provided on a second surface of the insulating film, and electrically connected through the through hole to the wiring pattern; and
a support plate being electrically conductive and acting as a planarity maintaining member, and provided to cover at least part of the wiring pattern on the surface of the wiring pattern opposite to that on which the insulating film is provided; and
the support plate is adhered to the Insulating film with an insulating adhesive interposed therebetween, and is connected to a constant potential portion of the wiring pattern.
This semiconductor device has the surface for forming the wiring pattern different from the surface for forming the bumps, separated by the insulating film, and as a result, on the surface on which the wiring pattern is formed, there are no obstructions other than the wiring pattern. Therefore, a support plate can be used without special processing (patterning) to cover the wiring pattern, and as a result the process of fabrication is extremely simple. Not only can the surface of the wiring pattern be protected, but also, since a support plate of adequate strength to preserve planarity can cover the insulating film, distortion in the flexible insulating film is eliminated, the planar stability of the bumps is improved, and the yield for mounting onto the circuit board is increased.
The support plate is electrically conducting, and is connected to a constant potential portion of the wiring pattern. A constant potential portion raters to a portion whose potential which does not vary during operation of the semiconductor device. By means of insulating adhesive, short circuits between the conductive support plate and the wiring pattern can be prevented.
In this way, with the support plate at a constant potential, since a signal can be transmitted along the planar constant potential formed by the support plate to the wiring pattern, this forms an ideal transmission path, and transmission with the impedance and particularly the inductance low is possible. Thus delays and distortion of a high frequency signal can be reduced, the transmission characteristics can be improved, and a semiconductor device of high reliability can be obtained.
A protective layer may be provided between the support plate and the wiring pattern, covering the wiring pattern.
In other words, on the side of the wiring pattern on which the insulating film is not provided, a protective layer of resist or the like may be provided beforehand over the whole area of the position in which the support plate is adhered, and furthermore the support plate adhered thereon with the interposition of an adhesive. In this case also, since a protective layer is provided on the surface opposite to the surface of the external terminals on the wiring pattern, the application of the resist or the like is simple. When the support plate is provided, since the wiring pattern is already protected by the protective layer, the occurrence of faults such as wiring breaks in the wiring pattern is eliminated.
The constant potential portion may be at one of a power supply potential and a ground potential.
The wiring pattern may have at least partially an arced portion, and the arced portion may be connected to the support plate.
The support plate may be connected to the constant potential portion of the wiring pattern by at least either of solder and an electrically conducting adhesive.
By this means too, the transmission characteristics can be improved.
The semiconductor device of the present invention comprises: a semiconductor element; an insulating film; a wiring pattern formed on the insulating film and connected to the semiconductor element; an external terminal formed on the wiring pattern; and a support plate being electrically conductive and acting as a planarity maintaining member, and supporting a portion of the insulating film; and
the support plate is connected to a constant potential portion of the wiring pattern.
By the provision of the support plate, distortion of the flexible insulating film can be prevented, and reliable mounting is made possible.
The support plate is electrically conducting, and is connected to a constant potential portion of the wiring pattern. A constant potential portion refers to a portion whose potential which does not vary during operation of the semiconductor device.
In this way, with the support plate at a constant potential, since a signal can be transmitted along the planar constant potential formed by the support plate to the wiring pattern, this forms an ideal transmission path, and transmission with the impedance and particularly the inductance low is possible. This delays any distortion of a high frequency signal can be reduced, the transmission characteristics can be improved, and a semiconductor device of high reliability can be obtained.
For the support plate may be used a material having a coefficient of thermal expansion larger than the coefficient of thermal expansion of the insulating film.
In the above mentioned semiconductor device, the support plate may have a slit or groove, and an extremity of the insulating film may be inserted into the slit or groove supported by the support plate.
In the above mentioned semiconductor device, the insulating film may have a slit, and an extremity of the support plate may project through the slit to the opposite surface of the insulating film.,
The method of manufacturing a semiconductor device of the present invention comprises:
a step of forming a through mole in an insulating film
a step of forming on a first surface of the insulating film a wiring pattern passing
Oliff & Berridg,e PLC
Seiko Epson Corporation
Thai Luan
Tran Minh Loan
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