LSI package structure

Details LSI package structure LSI package structure

2000-05-12

2001-10-16

Gaffin, Jeffrey (Department: 2841)

Electricity: conductors and insulators

Conduits, cables or conductors

Preformed panel circuit arrangement

C174S256000, C174S261000, C174S267000, C361S760000, C361S768000, C257S690000, C257S783000

Reexamination Certificate

active

06303876

ABSTRACT:

FIELD OF THE INVENTION
The Present invention relates to a structure for packaging an LSI and in particular to an LSI packaging structure in which an LSI is integral with a wiring board.
BACKGROUND OF THE INVENTION
In a computer device, an LSI is Packaged and is implemented (or mounted) on a circuit board. The LSIs have been mounted on wiring board while they are housed in a package. The structure of such a package is generally known from Japanese Patent Kokai Publication JP 11-17058A. The known package structures are provided in the form of BGA package in which the LSIs are sealed in a mould resin so that they will not be exposed. The BGA Package is bonded on a wiring board. The BGA board has a surface area which is smaller than that of the wiring board. The BGA board to be connected in a face-up manner will be connected to the wiring board by a wire bonding technique. In such a package structure, signals are fed out from the BGA board via solder balls provided on a reverse side of the BGA board.
SUMMARY OF THE DISCLOSURE
Since wire bonding is conducted in an outward direction from the LSI in the known structure, the wires in the BGA are elongated, so that operation at higher frequencies becomes impossible. The larger BGA requires a larger mounting area, which prevents reduction in size of devices. The generated heat is dissipated to the BGA board to increase its electric resistance, which largely deteriorates the reliability of the LSI.
The LSI packages having a smaller size enabling the wiring length to be shorter have been demanded. There is much to be desired in the heat dissipation structures in which the heat is substantially directly dissipated from the LSI having a smaller size.
It is an object of the present invention to provide an LSI package structure having such a smaller size such that the wiring length is shorter.
It is another object of the present invention to provide an LSI package structure which adopts a heat dissipation structure in which heat is substantially directly dissipated from a smaller size LSI.
The technical features in the following description, which correspond to the Claims are suffixed with reference numerals, symbols, etc. with parenthesis. Although the numerals, symbols, etc. make clear the correspondence and relation between the technical features relevant to the Claims and the technical feature of one of the plural embodiments, it is to be noted that the technical features relevant to the Claims are not limited to the technical features of the embodiments.
According to an aspect of the present invention, there is provided an LSI package structure comprising connecting the LSI (
2
) to the wiring board (
1
).
The wiring structure includes first connecting terminals (
3
) which are arrayed on the LSI (
2
), and second connecting terminals which are arrayed on the wiring board.
The first connecting terminal (
3
) are arrayed on an outer periphery (
5
) of a facing surface (
4
) which faces the wiring board (
1
). The second connecting terminals (
6
) are arrayed on an intersecting face (
7
) which intersects with the outer periphery (
5
). In such a structure, the wiring substrate (
1
) is substantially similar to the LSI (
2
) in size so that the area of the facing surface (
4
) of the wiring board (
1
) which faces the LSI (
2
) is smaller than that of the bonding surface of the LSI (
2
).
The facing surface (
4
) and the intersecting face (
7
) intersect with each other for forming an intersecting line (
8
) therebetween. The facing surface (
4
) substantially intersects with the intersecting surface (
7
) along the intersecting line (
8
). In such a structure, the wiring board (
1
) is smaller than the LSI (
2
) in size. The first connecting terminals (
3
) are preferably connected to the second connected terminals (
6
) by means of soldering. More preferably, the first connecting terminals (
3
) are connected to the second connected terminals (
6
) with an electrically conductive adhesive.
An adhesive layer (
13
) is sandwiched between the wiring board (
1
) and the LSI (
2
) on the facing surface (
4
). In this case, the intersecting line (
8
) is included in the adhesive layer (
13
). The wiring structure further includes third connecting terminals (
9
) which are arrayed on the wiring board (
1
) on the side (surface) opposite to the side (surface) on which the wiring board faces the LSI (
2
). The wiring structure further includes solder balls (
11
) which are connected to the third connecting terminals (
9
). The second terminals (
6
) are connected to the third connecting terminals (
9
) via conductors (
14
) which are formed in the wiring board (
1
). Such a wiring structure enables the package to be formed more compact.
The LSI (
2
) is positively formed with a heat dissipating face (
15
) on the side opposite to the facing surface (
4
). Such a heat dissipation effectively improves the electric characteristics.


REFERENCES:
patent: 5220486 (1993-06-01), Takubo et al.
patent: 5291375 (1994-03-01), Mukai
patent: 5471368 (1995-11-01), Downie et al.
patent: 5483421 (1996-01-01), Gedney et al.
patent: 5550406 (1996-08-01), McCormick
patent: 5574630 (1996-11-01), Kresge et al.
patent: 5586006 (1996-12-01), Seyama et al.
patent: 5717252 (1998-02-01), Nakashima et al.
patent: 5726861 (1998-03-01), Ostrem
patent: 5838064 (1998-11-01), Shimada et al.
patent: 5909010 (1999-06-01), Inoue
patent: 6052287 (2000-04-01), Palmer et al.
patent: 6084775 (2000-07-01), Bartley et al.
patent: 11-17058 (1999-01-01), None

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