Active solid-state devices (e.g. – transistors – solid-state diode – Encapsulated
Reexamination Certificate
2001-03-16
2004-09-14
Flynn, Nathan J. (Department: 2826)
Active solid-state devices (e.g., transistors, solid-state diode
Encapsulated
C257S778000, C257S779000
Reexamination Certificate
active
06791199
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device and a method of manufacturing the same, particularly a semiconductor device radiating excellently heat from the semiconductor device and a method of manufacturing the same.
2. Description of the Related Art
In recent years, use of IC package for portable equipment or small, hi-density mounting equipment progresses, and the conventional IC package and its concept of mounting are largely changing. These details are described in CSP technology, and mounting material and device supporting the technology-special issue of DENSHI ZAIRYO (p.22, September 1998).
FIG. 11
is a structure adopting a flexible sheet
50
as an interposer board, a copper foil pattern
51
is put on the flexible sheet through adhesive, and an IC chip is fixed. There is a pad for bonding
53
formed at periphery of the IC chip as the conductive pattern
51
. A pad for connecting solder ball
54
is formed through a conductive path
51
B formed in one body (integrally) with the pad for bonding
53
.
At backside of the pad for connecting solder ball
54
, an opening
56
where the flexible sheet is opened, and through the opening
56
, a solder ball
55
is formed. The entire body is sealed with an insulating resin
58
using the flexible sheet
50
as a board. Symbol
57
is a thin metal wire.
On the other hand,
FIG. 12
show a semiconductor device mounting an IC chips
52
with facedown method. Adopting a solder ball
60
instead of the thin metal wire
57
, thickness of the entire IC chip
52
is made thin.
However the flexible sheet
50
provided below of IC chip is very expensive, and there are problems that cost rises, thickness of the package becomes thick, and weight increases.
There is a problem that heat resistance from a back face of the IC chip to a back face of the package becomes large in a supporting board because the supporting board comprises material other than metal. For said supporting board, there is a flexible sheet, a ceramic board, or a printed board. A heat conduction path comprising material good in heat conduction is the thin metal wire
57
, the copper foil
51
, and the solder ball
55
, the above supporting board has a structure not to radiate fully at driving. Therefore there is a problem that driving current does not flow fully because of temperature rise of IC chip at driving.
In the facedown type semiconductor device shown in
FIG. 12
, the solder ball
60
flows to direction of an arrow
61
, so that there is a problem that gap between the IC chip
52
and the flexible sheet
50
is not arranged horizontally.
Because of the problems, the gap between the IC chip
52
and the flexible sheet
50
becomes narrow, washing liquid does not fill in the gap, bad quality appears, and under-filling material is not filled.
SUMMARY OF THE INVENTION
The invention is carried out in view of the above problems, and intends to solve the above problems and obtain a reliable semiconductor device having a small package and a good radiation characteristics.
The problems are solved by surrounding an arranged area of said electrical connection means on a pad and providing a flow-prevention film resisting flow.
For example, by forming a flow-prevention film so as to surround an arranged area of solder, melted solder does not flow, the solder is fixed with designated thickness, and gap of a semiconductor and a pad is substantially defined.
The problem is solved by providing a flow-prevention film resisting flow of said electrical connection means on the pad and/or said conductive path.
By forming the flow-prevention film on Cu pattern comprising the pad, the conductive path, and the external connection electrode in one body so that brazing material does not form from the conductive path to the pad, solder gets wet only at the pad. Therefore by making sizes of plural pads substantially same, thickness of wet solder is unified.
By preparing a conductive foil, forming a conductive pattern in projection shape by half-etching, and forming a flow-prevention film of an electrical connection means on the projection shape conductive pattern, and by facing a semiconductor chip down on said conductive pattern and electrically connecting the semiconductor chip and said conductive pattern with electrical connection means, the electrical connection means is formed in desired shape and thickness by the flow-prevention film.
By arranging an electrode for radiation below the semiconductor chip, heat generating from the semiconductor chip is radiated to outside through the electrode for radiation.
REFERENCES:
patent: 5391924 (1995-02-01), Uchida et al.
patent: 6011694 (2000-01-01), Hirakawa
patent: 6054652 (2000-04-01), Moriizumi et al.
Harper, Electronic Packaging and Interconnection Handbook, 1991,McGraw-Hill, pp. 6.71-6.73.*
CSP Technology, and Mounting Material and Device Supporting the Technology-Special Issue of Denshi Zairyo.
Igarashi Yusuke
Kobayashi Yoshiyuki
Maehara Eiju
Okada Yukio
Sakamoto Junji
Andújar Leonardo
Fish & Richardson P.C.
Flynn Nathan J.
Sanyo Electric Co,. Ltd.
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