Multi-station rotary die handling device

Details Multi-station rotary die handling device Multi-station rotary die handling device

1999-12-10

2002-04-02

Bidwell, James R. (Department: 3651)

Conveyors: power-driven

Conveyor for changing attitude of item relative to conveyed...

For changing both the elevation and the posture of...

C198S406000, C198S403000

Reexamination Certificate

active

06364089

ABSTRACT:

FIELD OF THE INVENTION
The present invention pertains to apparatus and methods used in handling semiconductor devices and the like.
BACKGROUND OF THE INVENTION
Semiconductor Integrated Circuits (ICs) are typically fabricated in wafer form. After fabrication, the individual chips are scribed from the wafer and then undergo numerous processing and handling steps before they are tested and packaged. A tape and reel assembly is typically used to transport the scribed chips to the individual processing stations. The tape and reel assembly includes a tape with a plurality of cavities spaced at regular intervals. Once a chip has been placed inside a cavity, the cavity is sealed with an adhesive tape so the chip can be safely transported from station to station by the tape and. reel assembly. Special devices, known as device transfer machines, are used to transfer chips scribed from a wafer into the cavities of the tape and reel assembly.
FIG. 1A
illustrates a diagrammatic side view of a device transfer machine
100
. The device transfer machine
100
is responsible for transferring a semiconductor device, such as a flip chip die
102
, from a stretched wafer
104
to a cavity
105
. The cavity
105
is included in a tape
106
of a tape and reel
108
. The transfer to the cavity
105
is complicated by the small size, delicacy and orientation of the die
102
. An exemplary flip chip die may be about
35
mils square, which limits the applicable handling techniques. In addition, after sawing, the die
102
is oriented with its solder bumps
110
facing up, however, the die
102
is to be placed in the cavity
105
with the solder bumps
110
facing down.
The device transfer machine
100
performs the transfer from the stretched wafer
104
to the cavity
105
in five steps. The first step involves attaining the die
102
from the stretched wafer
104
. Typically, the die
102
is picked up by a loader arm
112
. The loader arm
112
may a robotic arm or another suitable pick and place mechanism.
FIG. 1B
illustrates a closer diagrammatic view of a head
114
of the loader arm
112
. The head
114
includes a vacuum tube
116
. To hold the die
102
, the vacuum tube
116
applies a vacuum pressure on the surface
118
of the die
102
between the solder bumps
110
. In addition, a vision apparatus
130
determines if the right die is being picked up.
To flip the die
102
, a flipper
122
is used. The flipper
122
includes two platforms
126
and
128
on either end of a flipper arm
124
. In the second step, the loader arm
114
places the die
102
onto the platform
126
. In the third step, an actuator
132
rotates the flipper arm
124
to flip the die
102
. In the fourth step, a placing mechanism
136
takes the die
102
from the platform
126
on the flipper
122
and moves it to the vicinity of the cavity
105
.
In the fifth step, the die
102
is placed within the cavity
105
of the tape
106
by the placing mechanism
136
. A second vision apparatus
138
is used to determine the correct position of the die
102
in the cavity
105
. The die
102
and cavity
105
may then be indexed. Subsequently, a cover tape
140
is applied over cavity
105
to contain and protect the die
102
during shipping.
The device transfer machine
100
is problematic for a number of reasons. The handling rate of the flipper
122
is typically less than a thousand units per hour. This represents a significant bottleneck in the overall IC testing and packaging sequence. Attempts have been made to increase the rotational speed of the elongated mechanical arm. However, the increased speed creates excessive rotational torque, causing the chip to move or even fall off the platform.
In view of the foregoing, a device transfer machine with improved throughput would be desirable.
SUMMARY OF THE INVENTION
To achieve the foregoing, the invention provides to a rotary flipper including a wheel having a plurality of stations. A semiconductor device is placed within a first station in a first orientation. While the semiconductor device is held, the wheel portion of the rotary flipper rotates and the next station receives another semiconductor device. When the first station reaches an unloading position, the semiconductor device is released. At this point, the semiconductor device is in a second orientation. The wheel also includes an intermittent position between the loading and unloading position in which another semiconductor device may be loaded into another station on the wheel.
In another aspect, to facilitate continuous transfer to a tape and reel, the size of the wheel and the spatial arrangement of the stations on the circumference of the wheel are proportional to the spacing of the cavities on the tape and reel. Advantageously, this permits continuous and synchronous motion between the rotary flipper and the tape and reel. In another aspect, the number of stations on the wheel is maximized to restrict the motion of the wheel to small steps, thus eliminating high torque movements required for high speed movement over a larger distance.
In one aspect, a vacuum pressure is applied within the station to hold the semiconductor device. The vacuum pressure for a station may be independently controlled or automatically upon positioning of the wheel. In one embodiment, the vacuum pressure is not used and a shield is used to contain the semiconductor device in the station during movement.
In another embodiment, the invention relates to a semiconductor device transfer machine including a rotary flipper.


REFERENCES:
patent: 4128174 (1978-12-01), Frisbie et al.
patent: 4308942 (1982-01-01), Ackley
patent: 5110255 (1992-05-01), Le Ban et al.
patent: 5865292 (1999-02-01), Aguilar et al.
patent: 2670191 (1992-06-01), None

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