Conveyors: power-driven – Conveyor system for moving a specific load as a separate unit – System includes an oscillating or reciprocating load...
Reexamination Certificate
1998-01-27
2001-01-09
Underwood, Donald W. (Department: 3652)
Conveyors: power-driven
Conveyor system for moving a specific load as a separate unit
System includes an oscillating or reciprocating load...
C198S468600, C414S416060, C414S415000, C414S753100
Reexamination Certificate
active
06170640
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a carrying system and a carrying method for positioning and carrying a frame of a semiconductor device or the like.
In fabricating a semiconductor device, a carrying system for carrying the frame of an IC is employed. The carrying system is used with a processing unit such as a laser marker for marking the package of a semiconductor device. In recent years, the integration degree of semiconductor devices has increased. In addition, many types of semiconductor devices are now fabricated. Thus, a carrying system for carrying semiconductor devices must not only cope with various types of semiconductor devices, but also control the positional deviation of a lead frame being carried.
FIG. 1
shows a schematic top view of a conventional carrying system.
As shown in
FIG. 1
, a carrying system
11
is provided with a pair of carriers
12
a
and
12
b
. The carriers
12
a
and
12
b
are set at the same height. The carriers
12
a
and
12
b
are provided with holders
18
a
and
18
b
, respectively. In addition, the carriers
12
a
and
12
b
are provided with motors
19
a
and
19
b
for moving the holders
18
a
and
18
b
, respectively. Magazines
15
and
16
are provided between the carriers
12
a
and
12
b
. One magazine
15
accommodates a lead frame
17
.
The carrying operation of the frame
17
of the semiconductor device is controlled by a controller (not illustrated) as described below. First, the controller moves one holder
18
a
from a standby position (position shown in
FIG. 1
) toward the lead frame
17
disposed in the magazine
15
, to hold one side of the lead frame
17
. At this time, the holder
18
a
holds the left side of the lead frame
17
with respect to the moving direction. The controller moves the holder
18
a
by driving the motor
19
a
to carry the lead frame
17
to a processing position
14
along a carrying line L. At the processing position
14
, a processing unit (not illustrated) processes the frame
17
. After processing of the frame
17
is completed, the controller moves the holder
18
a
to thereby carry the frame
17
to the magazine
16
. After moving of the frame
17
to the magazine
16
is completed, the controller moves the holder
18
a
on the carrying line L to a standby position.
While the holder
18
a
moves the magazine
16
from the processing position
14
, the other holder
18
b
moves another frame
17
in the magazine
15
to the processing position
14
. At this time, the holder
18
b
holds the right side of the frame
17
with respect to the moving direction. After the frame
17
is processed by the processing unit, the holder
18
b
moves the frame
17
to the magazine
16
. At this time, the holder
18
a
returns to the initial position to hold the next frame
17
in the magazine
15
. Thus, the carrying system
11
carries the frames
17
alternately using the two holders
18
a
and
18
b
. The alternate carrying decreases the time between processing of one frame
17
and processing of the next frame
17
, thereby improving the throughput of frame carrying.
However, the following problem occurs when a clamping operation of the lead frame
17
is performed. As shown in
FIGS. 2A
to
2
C, the holder
18
a
rotates a movable damper
21
against a fixed damper
20
to hold the lead frame
17
. When the lead frame
17
is deflected, the position of the lead frame
17
is deviated leftward in
FIG. 1
(direction perpendicularly intersecting the carrying line L) because the movable damper
21
pushes the lead frame
17
. Thus, the lead frame
17
is moved to the processing position
14
while having a positional deviation.
Similarly, when the holder
18
b
holds the lead frame
17
, the position of the lead frame
17
deviates rightward. The directions of the positional deviations of the lead frame
17
caused by the holders
18
a
and
18
b
are opposite to each other. Therefore, the range in which the lead frame
17
is position-deviated from the processing position
14
is equal to a value obtained by adding the positional-deviation value due to the carrier
12
a
and the positional-deviation value due to the carrier
12
b
. For example, when assuming that the positional-deviation values due to the carriers
12
a
and
12
b
are roughly the same, the range in which the lead frame
17
can be position-deviated at the processing position
14
is twice as large as the positional-deviation values due to each carrier
12
a
and
12
b
. As the range in which the lead frame
17
can be position-deviated increases, it is necessary to further expand the range for detecting the position of the frame
17
to perform an alignment of the lead frame
17
at the processing position
14
. Such expansion of the detection range lowers the accuracy for performing alignment of the lead frame
17
at the processing position
14
.
Referring to
FIG. 3
, a stream mark
22
of resin used for sealing a semiconductor chip or a part of a runner may be left on the lead frame
17
. Therefore, the position for clamping the frame
17
is further deviated or the frame
17
cannot be securely held due to the resin.
It is an object of the present invention to provide a carrying system and a carrying method capable of reducing a positional deviation value without decreasing the throughput of frame carrying.
SUMMARY OF THE INVENTION
To achieve the above objective, the present invention provides a carrying system for carrying a frame of a semiconductor device provided at a start point of a carrying line to an end point of the carrying line, the carrying system comprising: a first carrier movable along the carrying line to carry the frame; and a second carrier movable along the carrying line to carry the frame, the second carrier located below the first carrier; wherein the first and second carriers are located on the same side of the carrying line and hold a specific end of the frame when carrying the frame.
The present invention further provides a carrying system for carrying a frame of a semiconductor device from a start point of a carrying line to an end point of the carrying line, comprising: a first carrier movable along the carrying line for carrying the frame; and a second carrier movable along the carrying line and located below the first carrier, for carrying the frame, each carrier including; a holding member for holding a specific end of the frame, a first stage for moving the holding member along the carrying line, and a second stage for moving the holding member in a direction perpendicular to the carrying line, wherein the first and second carriers are located on the same side of the carrying line to alternately carry and hold the specific end of the frame, when carrying the frame.
The present invention provides a carrying method for carrying a frame of a semiconductor device provided at a start point of a carrying line, comprising the steps of: providing a first carrier for carrying the frame; providing a second carrier on the same side of the carrying line as the first carrier and at a position below the first carrier; holding a specific end of the frame with the first carrier; moving the first carrier to an end point of the carrying line; holding the specific end of the frame with the second carrier; and moving the second carrier to the end point of the carrying line.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.
REFERENCES:
patent: 4638904 (1987-01-01), Randar
patent: 4875824 (1989-10-01), Moe et al.
patent: 5564889 (1996-10-01), Araki
Armstrong, Westerman Hattori, McLeland & Naughton
Fujitsu Limited
Underwood Donald W.
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