Geometrical instruments – Gauge – Surface plate or gauge block
Reexamination Certificate
2000-08-31
2002-10-01
Fulton, Christopher W. (Department: 2859)
Geometrical instruments
Gauge
Surface plate or gauge block
C033S502000, C073S001790
Reexamination Certificate
active
06457251
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to automated test equipment for testing integrated circuits (ICs), and more particularly to apparatus and methods for calibrating the device pick-up heads used in IC handler systems.
RELATED ART
Packaged integrated circuits (ICs) are typically tested prior to sale. Testing is typically carried out using automatic test equipment (ATE) that includes an IC test signal generator (IC tester), a test fixture (e.g., a socket) for transmitting electrical signals from the IC test signal generator to an IC device-under-test (DUT), and a handler system that moves the DUTs between a shipping tray and the test fixture. This testing process is typically used to identify non-functional ICs.
FIG. 1
is a block diagram showing a handler system
100
used to move packaged IC DUTs between shipping trays
50
and an IC tester
70
. Handler system
100
is consistent with pick-and-place handler systems produced by, for example, Seiko Epson Corp. and sold under model number HM3000 (Hummingbird).
Handler system
100
includes an input arm
110
that moves DUTs between shipping tray
50
and a shuttle
120
, and a test arm
130
that moves DUTs between shuttle
120
and a test fixture
140
. An optional soaking tray
150
is provided between shipping tray
50
and shuttle
120
to facilitate heating or cooling of the DUTs before testing.
Input arm
110
is driven by a positioning mechanism (not shown) to move horizontally over shipping tray
50
, soaking tray
150
, and shuttle
120
, and includes one or more vertically movable frames (referred to as “hands”)
115
, each hand
115
supports one device pick-up head
200
. Each device pick-up head
200
includes a base structure
210
held by an associated hand
115
, and a movable portion
220
that transmits a vacuum pressure used to secure and pick-up DUTs during movement from one location to another. Specifically, to moved DUTs between shipping tray
50
and soaking tray
150
, input arm
110
is moved horizontally over shipping tray
50
, and then hands
115
are lowered until movable portions
220
of each device pick-up head
200
contact the upper surface of the DUTs stored on shipping tray
50
. Next, vacuum pressure is transmitted to device pick-up heads
200
to secure the DUTs, and the hands are moved upward from shipping tray
50
, thereby lifting the DUTs. Input arm
110
is then moved horizontally over soaking tray
150
, and hands
115
are lowered until the DUTs contact soaking tray
150
. The vacuum pressure is then released, and a brief positive pressure (puff) is transmitted to each device pick-up head
200
, thereby separating the DUTs from device pick-up heads
200
. Finally, device pick-up heads
200
are moved upward from soaking tray
150
. A similar sequence of steps is used to move the DUTs from soaking tray
150
to shuttle
120
, and from shuttle
120
back to shipping tray
50
after testing is completed.
Shuttle
120
is driven by a horizontal positioning mechanism (not shown) to move between a first position accessible by input arm
110
, and a second position accessible by test arm
130
. As depicted in
FIG. 1
, shuttle
120
moves between a staging/soaking (upper) area from which the DUTs are loaded and unloaded by input arm
110
, and a test (lower) area where the DUTs are loaded and unloaded by test arm
130
.
Similar to input arm
110
, test arm
130
is driven by a positioning mechanism (not shown) to move horizontally between shuttle
120
(when located in the test (lower) area) and test fixture
140
. Test arm
130
includes one or more vertical movable hands
135
, each supporting a device pick-up head
200
that includes a base structure
210
and a movable portion
220
. Test arm
130
uses a sequence of movements similar to that described above for input arm
110
to move DUTs between shuttle
120
and test fixture
140
. After tests are performed using test signals transmitted from IC tester
70
, the DUTs are picked up by device pick-up heads
200
, and returned to shuttle
120
, which in turn returns the tested DUTs to the staging/soaking (upper) area (see
FIG. 1
) for replacement onto shipping tray
50
.
FIG. 2
is a cross-sectional side view showing a simplified device pick-up head
200
-
1
that is similar to device pick-up heads mounted on both input arm
110
and test arm
130
when handler system
100
is used to test BGA packaged DUTs.
Device pick-up head
200
-
1
includes a rigid (e.g., aluminum) base structure
210
, a movable portion
220
, an adjustment collar
230
, and a spring
240
for biasing movable portion
220
away from base structure
210
. Base structure
210
defines an opening
212
and a hole
214
for slidably receiving movable portion
220
, and a spring mounting structure
216
for holding an upper portion of spring
240
. Movable portion
220
includes a base
222
that is slidably received in opening
212
of base structure
210
such that its lower surface
223
faces away from opening
212
, a shaft
224
extending upward from base
222
through hole
214
, and a narrow connection tube
226
extending from the upper end of shaft
224
. A central passage
228
extends through base
222
, shaft
224
, and connection tube
226
to facilitate the transmission of vacuum pressure from a source (not shown) to lower surface
223
of base
222
for purposes of securing BGA DUTs. Finally, collar
230
includes a central opening
232
for receiving connection tube
228
of movable portion
220
, and a set screw
234
for securing collar to connection tube
228
.
As described above, during operation, device pick-up head
200
-
1
is moved by an arm (e.g., input arm
110
or test arm
130
) horizontally over a BGA DUT, and then moved by a hand (e.g., hand
115
or hand
135
) vertically down onto the BGA DUT, which is located in a first location (e.g., shipping tray
50
; see FIG.
1
). Vacuum pressure is then transmitted from a source (not shown) through central passage
228
to pull the BGA DUT against lower surface
223
of base
222
. Head structure
200
-
1
is then lifted with the BGA DUT and moved over a second position (e.g., shuttle
120
). Head structure
200
-
1
is then lowered onto the second position, and then the vacuum pressure is released. More specifically, a puff of relatively high pressure air is transmitted down central passage
228
to push the BGA DUT away from base
222
.
FIG. 3
is a cross-sectional side view showing a simplified device pick-up head
200
-
2
that is similar to device pick-up heads mounted on both input arm
110
and test arm
130
when handler system
100
is used to test DUTs that have leads extending from their package (e.g., dual-inline package (DIP) DUTs, quad-flat-pack (QFP) DUTS, or plastic leaded chip carrier (PLCC) packaged DUTS).
Device pick-up head
200
-
2
includes a movable portion
320
, a collar
330
, and a spring
340
that are essentially identical to pick-up portion
220
, collar
230
, and spring
240
, respectively, of device pick-up head
200
-
1
, and function in a similar manner. However, a base structure
310
of device pick-up head
200
-
2
differs from base structure
210
in that it includes a metal (e.g., aluminum) base
311
that is fixedly mounted to a plastic blade pack
312
. Metal base
311
defines a hole
314
for slidably supporting movable portion
320
. Blade pack
312
includes a set of box-like outer walls
313
that extend down from metal base
311
, and includes a narrow ridge (protrusion)
314
extending from a lower edge of outer walls
313
that is used to push the leads of a QFP DUT onto a test fixture (such as test fixture
140
; see FIG.
1
). Lower surface
323
of movable portion
320
and the lower portion of blade pack
312
combine to form an opening
316
into which, for example, a QFP DUT is received during handler operation.
FIG. 4
illustrates a conventional method used to calibrate device pick-up head
200
-
1
using a caliper
410
according to conventional methods. Referring briefly to
FIG. 2
, the conventional method involves
Feltner Thomas A.
Marley John C.
Bever Patrick T.
Fulton Christopher W.
Xilinx , Inc.
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