Package making – With means responsive to a sensed condition – Of individual contents or group feed or delivery
Reexamination Certificate
2003-04-04
2004-08-31
Gerrity, Stephen F. (Department: 3721)
Package making
With means responsive to a sensed condition
Of individual contents or group feed or delivery
C053S498000, C053S560000, C053S900000, C033S501600
Reexamination Certificate
active
06782677
ABSTRACT:
BACKGROUND OF THE INVENTION
This application relies for priority upon Korean Patent Application No. 2001-18557, filed on Apr. 4, 2002, the contents of which are herein incorporated by reference in their entirety.
1. Field of the Invention
The present invention relates to a semiconductor package manufacturing apparatus and, more particularly, to a tablet detecting system for a molding tablet supplying apparatus.
2. Description of the Related Art
Semiconductor products are manufactured in general through many processes, i.e., wafer fabrication, EDS (electrical die-sorting), package assembly and test processes. The package assembly process includes a wafer sawing process, a die attaching process, a wire bonding process, a molding process, and a lead trimming/forming process.
In the molding process, wire-bonded semiconductor chips are encapsulated with molding resin such as epoxy compound. The molding resin is supplied to a molding apparatus in the form of solid tablets. The tablets are heated, melted and injected into the mold dies of the molding apparatus, and then hardened to form a package body.
An automated apparatus supplies the molding tablets to the molding apparatus. A conventional tablet supplying apparatus is shown in FIG.
1
. As shown in
FIG. 1
, the conventional tablet supplying apparatus
10
includes a storing unit
20
, an aligning unit
30
, a transfer unit
40
and a loader unit
50
.
The storing unit
20
stores the tablets
12
and discharges the tablets
12
through an exit slide
22
. Typically, the tablet
12
has a cylindrical shape. The aligning unit
30
arranges the tablets
12
in an upright posture. The tablet
12
discharged from the storing unit
20
drops to a conical plane
32
of the aligning unit
30
. The peripheral edge of the conical plane
32
connects with a curved road
34
a
. The tablets
12
on the conical plane
32
gather around the peripheral edge of the conical plane
32
and then move along the curved road
34
a
by a vibrating act of the aligning unit
30
. On the curved road
34
a
, a height sorter
36
a
and a diameter sorter
36
b
are positioned to sort out bigger tablets
12
. That is, the sorters
36
a
and
36
b
stop tablets
12
larger than standard height and diameter. Only tablets
12
of standard size or smaller can move to a straight road
34
b.
The transfer unit
40
transfers one by one the tablets
12
from the end of the straight road
34
b
to the loader unit
50
. The transfer unit
40
has a transfer rod
42
, an air cylinder
44
and a transfer plate
46
. The transfer rod
42
has a grasp groove
42
a
and the transfer plate
46
has a drop hole
46
a
. After the tablet
12
discharged from the straight road
34
b
is caught in the grasp groove
42
a
, the air cylinder
44
pushes the transfer rod
42
toward the drop hole
46
a
. When the grasp groove
42
a
reaches the drop hole
46
a
, the tablet
12
in the grasp groove
42
a
falls through the drop hole
46
a
to the loader unit
50
under the transfer plate
46
.
A loader block
51
of the loader unit
50
has a lateral hollow
51
a
and plural receiving holes
51
b
. A lifting plate
52
is placed in the lateral hollow
51
a
and plural lifting pins
53
are formed on the lifting plate
52
. Each lifting pin
53
is inserted into the receiving hole
51
b
. The lifting plate
52
can move up and down by the rotation of a screw rod
55
driven by a motor
54
. The tablet
12
supplied through the drop hole
46
a
stays in the receiving hole
51
b
, while the lifting pin
53
supports the bottom of the tablet
12
. Thereafter, the loader unit
50
moves to the molding apparatus (not shown) and the lifting pin
53
pushes up the tablet
12
in the receiving hole
51
b
by the rising of the lifting plate
52
.
As described above, tablets
12
exceeding the standard size are unacceptable and sorted out by both the height sorter
36
a
and the diameter sorter
36
b
. However, another unacceptable tablets
12
below the standard size pass through the sorters
36
a
and
36
b
. Unfortunately, when the smaller tablets
12
are used for the molding process, the package body is incompletely filled. In these situations, the package bodies include voids after cooling because the culls are thinner than the standard thickness. Additionally, poor packages formed from unacceptable tablets are more common in small packages like the ball grid array (BGA) packages.
For the above reasons, the conventional tablet supplying apparatus
10
further uses a tablet detecting system
60
to discover the existence of unacceptable tablets before supplying the tablets
12
to the molding apparatus. As illustrated in
FIGS. 1 and 2
, the conventional detecting system
60
includes movable rods
62
and a sensor
64
. When the loader unit
50
is positioned under the detecting system
60
, the movable rods
62
are inserted into the receiving holes
51
b
of the loader unit
50
. The movable rods
62
can freely move up and down. As depicted in
FIG. 2
, if the tablet
12
exists in the receiving hole
51
b
, the movable rod
62
moves upward just as high as the tablet
12
. Further, the sensor
64
senses the existence of the movable rod
62
at a position equivalent to the height of the standard-sized tablet
12
. Therefore, if no tablet or a smaller tablet exists in the receiving hole
51
b
, the movable rod
62
does not reach the position of the sensor
64
and the tablets are determined to be unacceptable.
The conventional tablet detecting system has a difficulty in precisely distinguishing unacceptable tablets that are very similar in size to the standard tablets. Considering a tendency toward smaller packages, a minute difference in size of the tablet is becoming a more important factor in reliable molding process. Therefore, a precise detection system for ascertaining minute size differences of the tablets is required. Furthermore, a sensor of the conventional detecting system often operates erroneously due to impurities such as tablet particles.
SUMMARY OF THE INVENTION
The present invention provides a tablet detecting system, which can ascertain whether a tablet exists in a receiving hole of a loader unit used for a molding tablet supplying apparatus or, if exists, whether the tablet has a standard size, by using a mechanical contact manner.
The tablet detecting system of the present invention comprises a push rod, a contact head, an insulation plate, a conductive assembly and a control unit. The push rod is inserted into the receiving hole and moves upward just as high as the tablet. The contact head is formed on a top of the push rod and made of electrically conductive material. The insulation plate is located over the contact head. The conductive assembly is formed in the insulation plate and made of electrically conductive material. The control unit is electrically connected to the conductive assembly. In particular, when the tablet in the receiving hole has a standard size, the contact head mechanically touches the conductive assembly and gives electrical connection to the conductive assembly, and the control unit senses the electrical connection.
In the tablet detecting system of the present invention, the conductive assembly may include a pair of conductive pads formed separately on a bottom surface of the insulation plate. Alternatively, the conductive assembly may include a pair of cylindrical bodies each formed in the insulation plate and spaced apart from each other, a pair of plungers each inserted into the cylindrical body, and a pair of springs each interposed between the cylindrical body and the plunger so that the plunger protrudes downward from the insulation plate. The contact head may have a size enough to simultaneously touch the pair of conductive pads or the pair of plungers.
REFERENCES:
patent: 07270128 (1994-03-01), None
patent: 2003174050 (2001-12-01), None
Cho Kyoung-Rae
Choi Ju-Hwan
Park Kyung-Soo
Gerrity Stephen F.
Marger & Johnson & McCollom, P.C.
Truong Thanh
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