Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1999-06-16
2001-11-06
Aftergut, Jeff H. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C029S832000
Reexamination Certificate
active
06312551
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for surface-mounting a semiconductor chip onto a circuit board in a reliable manner.
2. Description of the Related Art
As a process, as described above, there has been known a mounting process illustrated in
FIGS. 5 and 6
. In
FIG. 5
, a resinous ACF
30
having a larger width than a semiconductor chip
20
is prepared, and then the semiconductor chip
20
is mounted onto a surface of a circuit board
10
via the ACF
30
whilst the ACF
30
extends beyond of the periphery of the semiconductor chip
20
.
Next, as shown in
FIG. 6
, the ACF
30
and the peripheral region are heated while pressing the semiconductor chip
20
onto the circuit board
10
. Thereby, thermosetting resin of the ACF
30
may be heated to approximately 180° C. for approximately several tens of seconds to be cured, or thermoplastic resin of the ACF
30
may be cooled and hardened after the heating. Thus, the semiconductor chip
20
is bonded via the resin of the ACF
30
onto a surface of the circuit board
10
.
Electroconductive particles contained in the resin of the ACF
30
are interposed between conductive bumps
22
formed on electrodes of the semiconductor chip
20
and terminals
12
formed on the surface of the circuit board
10
, so that the electric connection is obtained between the conductive bumps
22
of the semiconductor chip
20
and the terminals
12
of the circuit board
10
via the electroconductive particles.
In this regard, “ACF” is an abridgement of “anisotropic conductive film” made, for example, of thermosetting resin such as epoxy resin or of thermoplastic resin such as polyethylene. The ACF has electroconductive particles in the resin forming the same. When the semiconductor chip is surface-mounted on the circuit board as described above, it is possible to interpose the electroconductive particles contained in the ACF resin between the conductive bumps formed on the electrodes of the semiconductor chip and the terminals formed on the surface of the circuit board. Also, it is possible for an area of the ACF interposed between the conductive bump of the semiconductor chip and the terminal of the circuit board to be electrically conductive. Thus the electric connection is obtainable between the conductive bump of the semiconductor chip and the terminal of the circuit board via the electroconductive particles contained in that portion of the ACF resin.
According to this mounting process, the semiconductor chip
20
is bonded onto the surface of the circuit board
10
via the resin of the ACF
30
. Together therewith, it is possible to electrically connect the conductive bump
22
formed on the electrode of the semiconductor chip
20
with the terminal
12
on the surface of the circuit board
10
. Thus, the semiconductor chip
20
can be surface-mounted, without being stripped off, on the circuit board
10
in a reliable manner.
When the semiconductor chip
20
is surface-mounted onto the circuit board
10
in a manner as described above, however, it is impossible to assuredly adhere the resin of the ACF
30
extended out of the periphery of the semiconductor chip
20
to the upright lateral surface
24
thereof while raising the resin upward.
Therefore, when the semiconductor chip
20
has been surface-mounted onto the circuit board
10
by the above-mentioned process, the resin of the ACF
30
is liable to be stripped off in use from the peripheral portion of the semiconductor chip
20
, whereby it is impossible to continue the favorable connection of the conductive bump
22
formed on the electrode of the semiconductor chip
20
with the terminal
12
formed on the surface of the circuit board
10
. This causes the desirable electrical connection of the conductive bump
22
formed on the electrode of the semiconductor chip
20
with the terminal
12
formed on the surface of the circuit board
10
to be damaged.
Also, when semiconductor chip
20
is surface-mounted onto the circuit board
10
via the ACF resin by the above-mentioned process, gas generated from the resin of the ACF
30
during the heating or air dwelling in the inside of the ACF
30
and expanding during the heating is expelled to the outer air encircling the semiconductor chip
20
through the ACF
30
interposed between the semiconductor chip
20
and the circuit board
10
, which is softened during the heating.
However, when the semiconductor chip
20
is surface-mounted to the circuit board
10
by the above-mentioned process, all the gas or air in the interior of the ACF
30
is not suitably expelled to the outer air encircling the semiconductor chip
20
through the softened ACF
30
, but tends to dwell in the inside of a portion of the ACF
30
in the peripheral region of the semiconductor chip
20
which is free from the pressure from the semiconductor chip
20
, forming voids
32
therein, as shown in FIG.
6
.
Therefore, the reliable bonding is not obtainable between the semiconductor chip
20
and the surface of the circuit board
10
via the resin of the portion of the ACF
30
wherein the void
32
is formed.
As a result, if the semiconductor chip
20
is surface-mounted onto the circuit board
10
by the above-mentioned process, the semiconductor chip
20
bonded to the circuit board
10
via the resin of the ACF
30
has been liable to be stripped off from the surface of the circuit board
10
during use, whereby the electrical connection between the conductive bump
22
formed on the electrode of the semiconductor chip
20
and the terminal
12
formed on the surface of the circuit board
10
is damaged.
The same is true of a semiconductor chip
20
surface-mounted onto a circuit board
10
by bonding the semiconductor chip
20
with the surface of the circuit board
10
via an electro-insulating film of thermosetting or thermoplastic resin, in the same manner as described above, wherein conductive bumps
22
formed on the semiconductor chip
20
are electrically connected to terminals
12
formed on the surface of the circuit board
10
.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a process for surface-mounting a semiconductor chip onto a circuit board, hereinafter referred merely to as a “mounting process”, in which the above-mentioned problems in the prior art can be solved.
Another object of the present invention is to provide a process for surface-mounting a semiconductor chip onto a circuit, capable of reliably and firmly surface-mounting the semiconductor chip onto the circuit board via a film-like resin, such as ACF, wherein part of the film-like resin such as the ACF extending out of the periphery of the semiconductor chip is raised upward along the peripheral lateral surface of semiconductor chip.
According to the present invention, there is provided a process for surface-mounting a semiconductor chip having electrodes onto a circuit board providing with terminals, the process comprising:
mounting a semiconductor chip onto a circuit board by interposing a resin film therebetween, in such a manner that a periphery of the resin film extends out of a periphery of the semiconductor chip, and placing a frame-shaped load member for enclosing the periphery of the semiconductor chip with a gap therebetween; and
adhering the semiconductor chip to a surface of the circuit board by means of the resin film by pressing the semiconductor chip and the load member toward the circuit board and heating at least the periphery of the resin film, so that the electrodes of the semiconductor chip come into electrical contact with the terminals on the circuit board, and resin of the resin film is softened so as to be urged into the gap and attached to a side wall of the semiconductor chip.
The semiconductor chip may have a rectangular shape and the frame-shaped load member also has a rectangular shape, so that the gap defines a constant width between a side wall of the semiconductor chip and an inner wall of the frame-shaped load member.
In this mounting process, the film portion ex
Higashi Mitsutoshi
Murayama Kei
Aftergut Jeff H.
Haran John T.
Shinko Electric Industries Co. Ltd.
Staas & Halsey , LLP
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