Metal working – Barrier layer or semiconductor device making
Reexamination Certificate
2002-01-16
2003-02-25
Graybill, David E. (Department: 2827)
Metal working
Barrier layer or semiconductor device making
C269S021000
Reexamination Certificate
active
06524351
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device mounting jig and a method of mounting a semiconductor device, more particularly relates to a method of mounting a semiconductor device having a package form made to be compact and high density and a semiconductor device mounting jig used therefor.
2. Description of the Related Art
Demand for more compact, thinner, and lighter digital video cameras, digital cellular phones, laptop personal computers, and other portable electronic devices has been increasing steadily. To meet the demand, a 70% reduction in three years has been realized and smaller sizes and high performance have been achieved in recent VLSIs and other semiconductor devices.
Along with the higher performance of semiconductor devices, semiconductor device packages have been made smaller and higher in number of pins. There has been a shift from the conventionally broadly used dual inline packages (DIP) and other through hole mount devices (THD) inserting leads into through holes formed in a printed board to quad flat (L-leaded) packages (QFP) and other surface mount devices (SMD) mounted by soldering lead terminals on the surface of a board and further to ball grid array (BGA) packages with output terminals provided at areas on the bottom surface.
Further, a package called a chip size package (CSP), also called a fine-pitch BGA (FBGA), having terminals on its bottom surface, making the package size close to the size of the semiconductor chip, and realizing further compactness and higher density has been developed and put into broad use up to now.
As the method of mounting a semiconductor chip of the above CSP format, flip-chip mounting for directly mounting a bare LSI chip with the pad opening surface side facing to the mounting board or mounting an LSI chip to a buffer base called an “interposer” to make a CSP and mounting this on a mounting board has come into note.
In flip-chip mounting, the LSI chip is provided with projecting electrodes such as gold stud bumps and solder bumps.
Flip-chip mounting using solder bumps enables simultaneous mounting of a large number of LSI chips when using reflow of the solder bumps, so the productivity is extremely high. Also, compared with connection using gold stud bumps, there is the advantage that bonding with a low load is possible.
Generally, in flip-chip mounting using reflow of the solder bumps, a rigid substrate comprised of glass-epoxy etc. is used.
On the other hand, flip-chip mounting may also be conducted using a flexible tape substrate formed by processing polyimide or another insulating resin to a tape shape and having the advantage of being thin and light weight.
However, since a flexible tape substrate is more flexible than a rigid substrate, a flexible tape substrate easily flexes in the process of mounting an LSI chip by flip-chip mounting, therefore easily suffers from problems in connection of the solder bumps described below.
When, for example as shown in
FIG. 9
, mounting a semiconductor device
5
comprised of an LSI chip
50
, electrodes
51
connected to its pads, and solder bumps
52
formed on the electrodes, on to a flexible tape substrate
4
comprised of a highly flexible substrate
40
on which lands (electrodes)
41
a
are formed, if mounting by reflow of the solder bumps while the flexible tape substrate
4
is left flexed, unconnected portions U arise between the solder bumps
52
and lands
41
a
, and alternatively, in the case of a semiconductor
5
having a narrow pitch P between adjacent solder bumps
52
, bridges B occur between adjacent solder bumps
52
and other problems arise easily in solder bump connection.
To prevent the above disadvantages in solder bump connection, it is necessary to keep the flexible tape substrate
4
flat during especially narrow pitch P flip-chip soldering by reflow.
As a method of reflow while keeping the flexible tape substrate
4
flat, a method of affixing the flexible tape substrate
4
on a holding base using an adhesive tape (see Japanese Unexamined Patent Publication (Kokai) No. 8-222820) and a method of forming through holes in the flexible tape substrate
4
in advance and affixing the flexible tape substrate
4
by fitting them over projections formed on the holding base (see Japanese Unexamined Patent Publication (Kokai) No. 8-254996) have been proposed.
The above two methods, however, have disadvantages that the area for holding the flexible tape substrate
4
is small, the holding force is weak, and the flexible tape substrate
4
sometimes comes off from the holding base.
Also, a method of affixing the flexible tape substrate
4
on the holding base by an adhesive or two-sided adhesive tape may be considered.
In this case, however, at the time of release, that is, detaching the flexible tape substrate
4
from the holding base, stress ends up being imposed on the semiconductor device. The semiconductor device is liable to be damaged in some cases.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a semiconductor device mounting jig capable of stably holding a flexible tape substrate flat in a process of mounting a semiconductor device on the flexible tape substrate by flip-chip mounting and not applying stress to the semiconductor device at the time of release and a method of mounting a semiconductor device mounted on a flexible tape substrate by using the semiconductor device mounting jig.
To attain the above object, according to a first aspect of the present invention, there is provided a semiconductor device mounting jig for holding a mounting board flat when mounting a semiconductor device on the mounting board, comprising a holding plate having a flat mounting board holding surface; suction holes penetrating through the holding plate at the mounting board holding surface; and a suction means for applying suction at the suction holes from an opposite side to the mounting board holding surface; suction being applied at the suction holes while the mounting board is placed on the mounting board holding surface so as to hold the mounting board by suction.
Preferably, the holding plate is fit into an opening of a plate support having a hollow portion inside it and the opening communicated with the hollow portion and the suction means applies suction to the hollow portion to apply suction at the suction holes from the opposite side to the mounting board holding surface.
Preferably, a suction nozzle communicating with the hollow portion is provided at the plate support; and a suction pump is connected to the suction nozzle to apply suction to the hollow portion.
More preferably, a valve for opening and shutting the suction nozzle is provided at the suction nozzle; and the suction pump can be attached to or removed from the suction nozzle.
Preferably, the holding plate and the plate support are made as one body.
Preferably, the holding plate is fit into the opening of the plate support through an O-ring.
That is, the above semiconductor device mounting jig of the present invention comprises a holding plate having a flat mounting board holding surface integrally formed at an opening of a plate support having a hollow portion inside it and the opening communicated with the hollow portion or fitted in the opening of the plate support through an O-ring, suction holes in the mounting board holding surface penetrating through the holding plate, and a suction means for applying suction at the suction holes from the opposite side to the mounting board holding surface such as applying suction at the hollow portion of the plate support.
Accordingly, by placing a mounting board on the mounting base holding surface while applying suction from the suction holes, the flexible tape substrate is held by suction and kept flat and stable in the process of mounting a semiconductor device on a flexible tape substrate by flip-chip mounting etc. Further, the hold can be easily released by releasing suction to return to a normal pressure, so no stress is imposed on the semiconductor device
Graybill David E.
Sonnenschein Nath & Rosenthal
Sony Corporation
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