Metal working – Means to assemble or disassemble – Means to assemble electrical device
Reexamination Certificate
1996-06-05
2001-08-28
Rosenbaum, I Cuda (Department: 3729)
Metal working
Means to assemble or disassemble
Means to assemble electrical device
C029S743000, C029S762000, C029SDIG004, C029S832000, C294S002000, C294S064200, C901S040000, C414S737000, C414S752100
Reexamination Certificate
active
06279225
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to methods and apparatus for handling of packaged integrated circuits.
2. The Prior Art
Production of integrated circuit (IC) chips involves considerable handling, particularly of packaged IC's during the burn-in and test phases. Efficient production requires fully automatic transfer of IC's, for example, from carrying-tray bins to burn-in-board sockets and, after burn-in, back to carrying-tray bins. Transfer must be fast, avoid damage to the IC's and the sockets, assure correct placement of the IC's in the sockets so that device functionality can be checked, and permit sorting of the IC's based on results of the burn-in operation.
An example of a system for loading and unloading IC's on burn-in boards is the BLU300 Burn-In Board Loader/Unloader, commercially available from Schlumberger ATE Automated Systems, Westerville, Ohio, USA. Such a system can be adapted for use with bum-in boards of various sizes, can be fitted with component tooling to handle IC's having various package types, and can be programmed for automated operation in various modes.
Burn-in boards (BIB's) used in such a system typically have an array of sockets, each of which receives a single packaged IC.
FIGS. 1A
,
1
B and
1
C show one type of commercially-available “Zero Insertion Force” (ZIF) socket
100
used on BIB's, in respective top, side elevation and end views.
FIGS. 2A
,
2
B and
2
C show a type of IC package
200
intended to be inserted in such a socket, in respective top, side elevation and end views. ZIF socket
100
has a body
105
opposed rows of spring contacts
110
and
115
, a cover
120
, and rows of connector pins
125
and
130
. Cover
120
is resiliently biased upwardly as shown. When cover
120
is pressed downwardly, spring contacts
110
and
115
are retracted so that an IC package
200
can be dropped into the well area of socket
100
without resistance. When IC package
200
is in place and cover
120
is allowed to return to its upward position, spring contacts
110
and
115
extend toward the center of socket
100
to make electrical contact with respective rows
205
and
210
of pins of IC package
200
.
While generally effective, the use of such ZIF sockets has drawbacks. The cost of the sockets is higher than for “Low Insertion Force” (LIF) sockets of the type described below with reference to
FIGS. 3A-3C
. The BIB area required for ZIF sockets is greater than that for LIF sockets, primarily because of the area required for the cover surrounding the well area of the ZIF socket, such as cover
120
. Thus, fewer IC's can be loaded on each BIB with ZIF sockets than might be possible with LIF sockets. The tooling required to load IC's into ZIF sockets is complicated by the need for an actuator to depress the cover before an IC can be inserted or removed and to release the cover after an IC is dropped into or picked out of the socket. The need to move the cover down and then up again adds to the time needed each time an IC is inserted in or removed from the ZIF socket. When the IC is dropped into the ZIF socket, gravity and chamfered walls in the upper portion of the chip well are all that can guide the IC into correct position. If the IC is not sufficiently aligned with the well before being dropped in, it may not seat properly and may have to be removed for another try. Because there is little or no sliding contact between the ZIF socket's spring contacts and the IC's pins, surface corrosion and impurities which may interfere with electrical conductivity are not displaced during the insertion process.
FIGS. 3A
,
3
B and
3
C are sectional views showing one type of commercially-available “Low Insertion Force” (LIF) socket
300
.
FIGS. 3A and 3B
are a sectional views taken along centerline
3
A/
3
B—
3
A/
3
B of FIG.
3
C.
FIG. 3C
is a sectional view taken along centerline
3
C—
3
C in
FIGS. 3A and 3B
. Socket
300
has a socket body
305
with a well
310
for receiving an IC, horizontally-opposed rows of contact springs
315
and
320
, and horizontally-opposed rows of connector pins
325
and
330
. Precise alignment of an IC package in the horizontal (x- and y-directions) is required before the package can be inserted vertically (in the z-direction) into well
310
and into contact with contact springs
315
and
320
.
The left side of each of
FIGS. 3A and 3C
shows in phantom lines at
335
a packaged IC in a first position just prior to insertion in socket
300
. The IC package is mis-aligned to the left by an amount
340
which would cause the end pin of the package to hit the end wall
345
of socket body
305
and thus to prevent further insertion into well
310
. The right side of each of
FIGS. 3A and 3C
shows in phantom lines at
350
a packaged IC in a second position just as contact is being made between contact springs
320
of the socket and pins
355
of the IC package. In the second position, the IC package is mis-aligned to the right by an amount
360
which would cause the end
365
of the IC package to hit the end wall of socket body
305
and thus to prevent further insertion into well
310
.
The left side of
FIG. 3B
shows in phantom lines at
370
a packaged IC in a third position just prior to insertion in socket
300
. The IC package is mis-aligned to the left by a maximum amount
375
which would still permit insertion into well
310
of a socket without locator pins. The right side of
FIG. 3B
shows in phantom lines at
380
a packaged IC in a fourth position just prior to insertion in socket
300
. The IC package is mis-aligned to the left by a maximum amount
385
which would still permit insertion into well
310
of a socket having locator pins.
Precise alignment of the IC package with the socket is difficult to achieve in a high-speed, automated, production environment. BIB's can be slightly misaligned in the burn-in board loader/unloader due to manufacturing tolerances and wear. Positioning of sockets on the BIB's can vary within some tolerance. The automated handler which positions the IC package over the socket can have some small positioning error from operation to operation due to manufacturing tolerances and wear. LIF sockets are in general less forgiving of mis-alignments than are ZIF sockets.
Beside the requirement to precisely align the IC package with the LIF socket, insertion of the IC package into well
310
requires a force which will cause pins of the IC package to deflect contact springs
315
and
320
outwardly. Removal of the IC package from the LIF socket also requires a force. The amount of force depends upon the particular design of the IC package and the socket, but is significant enough that it does not allow use of the package-handler tooling designed for dropping packaged IC's into and vacuuming packaged IC's out of ZIF sockets. To use LIF sockets in an automated setting such as on burn-in boards, tooling is required which will apply the needed insertion and removal forces, but without damage to the IC or the socket even when the two are mis-aligned. Bent IC pins, broken sockets and the like are not acceptable.
A new type of handler is needed to allow use of LIF sockets in such applications.
SUMMARY OF THE INVENTION
Preferred embodiments of the invention offer apparatus and methods for handling packaged integrated circuits (IC's), particularly for inserting packaged IC's in and removing packaged IC's from low-insertion-force (LIF) sockets. The apparatus preferably includes a precisor having a chip precisor feature for receiving an IC package and a socket precisor feature for receiving a socket in a predetermined alignment relative to the chip precisor feature. One or more releasable chip retainers is provided, such as a vacuum nozzle for pulling the packaged IC into a seated position within the chip precisor feature and a pair of gripper fingers for holding the packaged IC within the chip precisor feature during extractio
Martin Jeffery
Searfoss Dave
Zeune Raymond E.
Chang Rick Kiltae
Cuda Rosenbaum I
Foley & Lardner
Schlumberger Technologies Inc.
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