Metal fusion bonding – With control means responsive to sensed condition – Work-responsive
Reexamination Certificate
2001-02-05
2002-03-12
Dunn, Tom (Department: 1725)
Metal fusion bonding
With control means responsive to sensed condition
Work-responsive
C228S049500, C228S103000
Reexamination Certificate
active
06354480
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for positioning a thin plate and, more specifically, to an apparatus for detecting a mark provided at a predetermined position on a thin plate placed on a stage and positioning the thin plate in place.
2. Description of the Related Art
During the production of a semiconductor device, a flip-chip system can be adopted wherein electrode terminals of a semiconductor element are directly placed on a circuit board for forming a semiconductor device package. To adopt the flip-chip system, it is necessary to provide bumps on the respective electrode terminals to be in contact and connected with predetermined locations on the circuit board.
One method for forming such bumps is illustrated in FIG.
5
. According to the bump-formation system shown in
FIG. 5
, after a semiconductor element
10
has been placed on a table
200
adapted to be movable in the horizontal direction so that electrode terminals
12
thereof are directed upward (see FIG.
5
(
a
)), a gold bump
14
having a pointed distal end is formed on the respective electrode terminal
12
,
12
, . . . (see FIG.
5
(
b
)).
This gold bump
14
is formed on the electrode terminal
12
by using a bonding device
40
shown in FIG.
6
. In the bonding device
40
, a tip end of a gold wire
44
wound on a wire spool
42
is heated, after passing through a clamper
46
and a capillary
48
, to form a ball-like end
49
. Thereafter, the capillary
48
descends to pressingly bond the ball-like end
49
onto the electrode terminal
12
. Then, the gold wire
44
is stretchingly severed by means of the clamper
46
to form the gold bump
14
having a pointed tip end.
Such gold bumps
14
,
14
, . . . having the pointed ends are then subjected to a flattening treatment to be converted into bumps
16
,
16
, . . . having flat ends (see FIG.
5
(
c
)).
In the bonding device
40
shown in
FIG. 6
, the semiconductor element
10
placed on the table
200
is initially detected and located (fixed) at a predetermined position since it is necessary to form the ball-like ends
49
of the gold wire
44
exactly above the electrode terminals
12
,
12
, . . . of the semiconductor element
10
.
The electrode terminals
12
,
12
, . . . of the semiconductor element
10
detected and located on the table
200
are formed at predetermined positions on one surface of the semiconductor element
10
. For this purpose, the semiconductor element
10
is movable by, for example, a controller (not shown) for controlling a drive means such as a servo-motor (not shown) for moving the table
200
in the horizontal direction so that a selected electrode terminal
12
on which the gold bump
14
is to be formed is positioned exactly beneath the ball-like end
49
of the gold wire
44
.
In the prior art, the detection and positioning of the semiconductor element
10
placed on the table
200
are carried out by a positioning device shown in FIG.
7
.
The positioning device shown in
FIG. 7
includes the table
200
movable in the horizontal direction and having a suction hole
204
formed in a central region of the table
200
and fluidly connected to a vacuum generating means
202
such as a vacuum pump, four pusher members
100
provided so that a front end face of each thereof abuts to the respective side of the rectangular semiconductor element
10
and is movable to be away from and closer to the semiconductor element
10
to slide the semiconductor element
10
in the predetermined direction, a camera
50
such as a CCD for detecting marks provided at a selected position on the surface of the semiconductor element
10
placed on the table
200
, and an optical detection means having a controller
52
for controlling a drive means (not shown) such as a servo-motor for moving the camera
50
leftward and rightward.
In the above-mentioned positioning device, the camera
50
has a high magnification to accurately detect the marks formed on one surface of the semiconductor element
10
, which means that the camera
50
has a smaller field of view
54
. Accordingly, as shown in
FIG. 7
, it is impossible to cover all of one surface of the semiconductor element
10
by the field of view
54
of the camera
50
but only part of the semiconductor element
10
can be covered.
If the marks
18
,
18
provided on one surface of the semiconductor element
10
placed on the table
200
are out of the field of view
54
of the camera
50
, as shown in FIG.
8
(
a
), the respective pusher members
100
move to cause the front end faces thereof to abut to the four sides of the rectangular semiconductor element
10
, respectively, in four directions, to slide the semiconductor element
10
on the table
200
so that the mark
18
of the semiconductor element
10
is within the field of view
54
of the camera
50
located at a fixed position, as shown in FIG.
8
(
b
). Thus, the position of the semiconductor element
10
is easily detectable.
Then, the vacuum generating means
202
such as a vacuum pump is driven to secure the semiconductor element
10
thus detected on the table
200
through the suction hole
204
, after which the table moves to the subsequent process.
According to the positioning device shown in
FIG. 7
, the front end faces of the pusher members
100
abut to sides of the semiconductor element
10
, respectively, to slide the latter, as shown in FIGS.
7
and
8
(
b
). Therefore, a pushing force applied to the semiconductor element
10
by the two pusher members
100
opposite to each other is liable to bend the semiconductor element
10
.
Recently, the semiconductor element
10
has been made thinner; for example, in an extreme case, a thickness is less than 150 &mgr;m. Such a thin semiconductor element
10
may be bent due to a pushing force applied thereto while gripping the same between the front end faces of pusher members
100
disposed opposite to each other. In the semiconductor element
10
thus bent, even though the mark
18
is caught within the field of view of the camera
50
, the position of the mark cannot be correctly detected.
Since the pusher members
100
must be in contact with and away from the semiconductor element
10
placed on the table
200
, a predetermined gap is provided between the pusher member
100
and the table
200
. There is a risk in that the thin semiconductor element
10
may slide into the gap
102
.
Another prior art related to the present invention is disclosed in Japanese Examined Utility Model Publication No. 1-9168 wherein stopper portions are provided at opposite corners of a positioning stage, and position-restricting surfaces corresponding to outer sides of leads of a workpiece and contact surfaces to abut to the stopper portions are provided in pusher members, wherein the positional relationship between the position-restricting surfaces, the stopper portions and the contact surfaces is so selected that a sum of gaps between the position-restricting surfaces and the outer sides of the leads of the workpiece is equal to a predetermined value when the pusher members reach their foremost positions.
Also, in Japanese Unexamined Patent Publication No. 4-74443, a die-bonding device is disclosed, wherein a semiconductor chip is located on a positioning stage by a positioning member, then moves to a bonding position on a body to be bonded by means of a bonding head and is bonded onto the body. In this prior art, a protrusion is formed in a central region of the positioning stage, having a size smaller than the semiconductor chip. According to this device, any debris generated from the semiconductor chip during the positioning operation is not left on the stage surface on which the positioning of the semiconductor is carried out, whereby the positioning member can assuredly be brought into contact with the semiconductor chip every time to accurately locate the latter at a predetermined position.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide an apparatus for positioning a thin p
Higashi Mitsutoshi
Koike Hiroko
Dunn Tom
Paul & Paul
Shinko Electric Industries Co., Ltd
Stoner Kiley
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