U.S. patent number 3,695,414 [Application Number 05/092,973] was granted by the patent office on 1972-10-03 for die sorting system.
This patent grant is currently assigned to Teledyne Incorporated. Invention is credited to John S. MacIntyre, Virgil Martinonis, Mordechai Wiesler.
United States Patent |
3,695,414 |
Wiesler , et al. |
October 3, 1972 |
DIE SORTING SYSTEM
Abstract
A wafer of semiconductor devices is tested to determine the
quality of each device. The test data with respect to each die is
electro-optically encoded and photographically recorded in a
pattern corresponding to the die pattern on the wafer. Upon
completion of the testing and recording operations the wafer is
scored, mounted on a flexible pressure sensitive adhesive web and
broken so as to separate the dies from one another while
maintaining their original orientation. The dice and their
respective test record are then mounted on a common frame, side by
side, so that each die and its test data are readily matched. The
frame is then mounted on a die sorting mechanism comprised of an XY
indexing table which indexes through an electrooptical reader where
the test data is read out to designate the die to a selected
delivery station.
Inventors: |
Wiesler; Mordechai (Lexington,
MA), Martinonis; Virgil (Gloucester, MA), MacIntyre; John
S. (Lynnfield, MA) |
Assignee: |
Teledyne Incorporated (Woburn,
MA)
|
Family
ID: |
22236046 |
Appl.
No.: |
05/092,973 |
Filed: |
November 27, 1970 |
Current U.S.
Class: |
242/528;
198/688.1; 198/834; 206/460; 242/538.1; 206/710 |
Current CPC
Class: |
B07C
5/344 (20130101); H05K 13/003 (20130101) |
Current International
Class: |
B07C
5/344 (20060101); B07C 5/34 (20060101); H05K
13/00 (20060101); B65g 035/00 () |
Field of
Search: |
;242/76,187,188,205,202
;226/76 ;198/108 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Forlenza; Gerald M.
Assistant Examiner: Oresky; Lawrence J.
Parent Case Text
RELATED APPLICATION
The present application is a division of application Ser. No.
785,209, filed Dec. 19, 1968 for Die Sorting System in the names of
the applicants hereof, which has matured into Pat. No. 3,583,561
granted June 8, 1971.
Claims
What is claimed is:
1. An apparatus for handling a flexible tape:
a. a frame;
b. a first reel rotatably mounted to said frame;
c. A flexible tape formed with sprocket holes along a margin
thereof, said tape formed also with spaced storage holes centrally
thereof;
d. an adhesive web bonded to one side of said tape, each said
storage hole and one face of said adhesive web defining a storage
compartment adapted for reception of a semiconductor device, said
semiconductor device adhering to said adhesive web in said storage
compartment, said flexible tape and adhesive web wound on said
first reel;
e. a sprocket drive having radially extending fingers which operate
to engage successive ones of said sprocket holes, said sprocket
drive rotatably mounted to said frame;
f. first means operatively connected to said sprocket drive for
selectively rotating said sprocket drive and selectively advancing
said flexible tape and adhesive web;
g. a first contoured guide plate connected to said frame and
adapted to guide said flexible tape and adhesive web form said
sprocket drive to a first position;
h. a second contoured guide plate connected to said frame and
adapted to guide said flexible tape and adhesive web from said
first position to a second position;
i. a second reel rotatably mounted to said frame and adapted to
receive said flexible tape and adhesive web from said second
position; and
j. second means operatively connected to said first and second
reels for rotating said first and second reels in unison;
k. said first reel defining a feed reel and said second reel
defining a take-up reel, said flexible tape and adhesive web on
said feed reel threaded in said apparatus in such a manner so as to
successively engage said sprocket drive, said first and second
contoured guide plates for reception by said take-up reel.
2. A semiconductor device indexing apparatus comprising:
a. a flexible strip formed with indexing holes along one edge and
storage holes near the other edge;
b. a pressure sensitive adhesive tape laminated to said flexible
strip on a bottom side thereof, said adhesive tape operating as an
adhesive floor for said storage holes, said adhesive floor and each
said storage hole defining a storage compartment adapted for
reception of a semiconductor device, each said semiconductor device
received in each said storage compartment adhering to said adhesive
floor, said flexible strip and adhesive tape defining a laminated
strip;
c. a frame;
d. a feed reel rotatably mounted to said frame, said laminated
strip wound on said feed reel;
e. a sprocket having radially extending fingers which operate to
engage successive ones of said indexing holes, said sprocket
rotatably mounted to said frame;
f. first means drivingly connected to said sprocket for selectively
rotating said sprocket and selectively indexing said laminated
strip;
g. a take-up reel rotatably mounted to said frame and adapted to
receive said laminated strip;
h. second means operatively connected to said feed reel and take-up
reel for rotating said reels in unison; and
i. track means mounted to said frame for guiding said laminated
strip from said sprocket to said take-up reel, said laminated strip
on said feed reel threaded in said apparatus in such a manner as to
successively engage said sprocket and track means for reception by
said take-up reel.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to the classification and sorting
of individual semiconductive devices from monolithic wafers and
more particularly is directed towards a new and improved method and
associated apparatus for testing, sorting and packaging
semiconductive dice from monolithic wafers.
2. History of the Prior Art
In the production of semiconductive devices from a monolithic wafer
it has been necessary, by reason of the imperfect state of the art,
to test and divide the dies from one wafer into categories of
varying qualities and characteristics. While all devices on a given
wafer are designed and intended to be identical, in practice a
rather wide variation appears in the quality of the when tested.
Heretofore, the sorting of the dies according to their
characteristics was carried out in various ways. One such technique
involved testing and marking each device with ink in a color code
and then physically sorting the dies according to the color coding.
Other techniques also have been employed but none have been
entirely satisfactory from the standpoint of speed of operation,
cost and overall efficiency. Accordingly, it is an object of the
present invention to provide a new and improved method and
associated apparatus for quickly, accurately and efficiently
sorting individual semiconductive devices from a monolithic
wafer.
SUMMARY OF THE INVENTION
This invention features a method of sorting semiconductive devices
from a monolithic wafer, comprising the steps of testing each
device in the wafer, electro-optically encoding the test data and
preparing a photographic record thereof, mounting the wafer on a
pressure sensitive web then breaking the wafer so as to separate
individual devices into dies while maintaining their orientation,
then mounting the wafer with its supporting film on a frame
together with the coded record. The frame is electro-optically read
and the output signals employed to deliver each device to a
pre-selected station where devices of common characteristics are
stored, packaged or the like.
This invention also features associated apparatus for sorting
devices including an electro-optical system for producing a
photographic record pattern in coded form corresponding to the
characteristics of each die, a mounting and alignment station by
which the wafer and film are mounted in side by side registration
and an electro-optical reading instrument by which the coded
pattern on the film is read out to produce appropriate driving
signals for the sorting the apparatus. The sorting apparatus
includes a novel separation apparatus for removing devices from the
wafer film comprising cooperating and reciprocating vacuum collet
and needle by which individual devices are separated from the film
and an indexing table for depositing the devices at selected
stations.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a somewhat schematic diagram of a die-sorting system made
according to the invention,
FIG. 2 is a cross-sectional view in side elevation, somewhat
schematic, of an electro-optical system for producing a
photographic record of test data and made in accordance with the
invention,
FIG. 2a is a view in perspective of the optically encoding matrix
of FIG. 2,
FIG. 2b is a plan view of a typical film record of the test data of
a wafer,
FIG. 3 is a view in front elevation of an alignment apparatus made
according to the invention,
FIG. 4 is a view in side elevation, partly in section, of a film
reading apparatus made in accordance with the invention,
FIG. 5 is a view in end elevation of the sorting apparatus showing
the film reading apparatus of FIG. 4 plus details of the mechanism
removing individual dies from the pressure sensitive web,
FIG. 6 is a cross-sectional view showing details of the pickoff
mechanism of FIG. 5 on an enlarged scale,
FIG. 7 is a view in side elevation of the indexing mechanism which
may be employed at each delivery station and made in accordance
with the invention,
FIG. 8 is a detail perspective view showing a portion of a
packaging tape made in accordance with the invention, and,
FIGS. 9 through 14 illustrate code patterns employed in conjunction
wit this invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
GENERAL
Referring now to the drawings and particularly to FIG. 1, a general
description of the system will be given by way of introduction.
A monolithic wafer 10, comprised of a grid array of small
semiconductive devices formed thereon, is mounted as by a vacuum
chuck on the upper face of an XY indexing table 12 adapted to move
the wafer incrementally along mutually perpendicular X and Y axes
so that by probes and associated test equipment, which are known in
the art, each device may be tested to determine its particular
operating characteristics and quality, and for this purpose a test
set, generally indicated by block 14, is employed. Such test sets
are commercially available and form no part of this invention per
se. Test data from the set 14 are electro-optically encoded by an
electrooptical recording instrument 16 to be described more fully
in conjunction with FIG. 2. In general, this instrument includes a
member 18 extending from the XY table 12 so that it moves together
with the wafer as it is indexed. The member carries an optical head
20 which is adapted to project onto a photographic film 22 a
pattern that is coded in accordance with the test data obtained
from the test set with respect to each individual circuit which has
been probed. Since the film 22 is fixed in position the head 20
will index in the same manner as the wafer 10 producing multiple
photographic images in a grid-like pattern each image containing a
photograph code corresponding to the characteristics of a
particular circuit device in the wafer 10. When all of the devices
in the wafer 10 have been probed and a photographic record has been
made of the film 22, the wafer 10 is removed from the XY table and
mounted on the adhesive face of a pressure sensitive adhesive web
24. The wafer is then scribed so as to form score lines in a grid
pattern between each device on the wafer. The wafer is then broken
into individual dies as by passing the wafer and film over an edge
as disclosed in copending application Ser. No. 665,635 entitled
"Method and Apparatus For Sorting Semi-Conductive Devices" filed
Sept. 5, 1967 and assigned to the same assignee. The dies are
broken from one another while remaining attached to the web in
their original position and orientation. The film 22, in the
meantime, is developed and both the photographic film 22 and web
26, with the wafer 10 are mounted in side by side alignment to a
frame 26 formed with suitable apertures 28 and 30. The photographic
film and dice are assembled to the frame by an alignment and
mounting instrument generally indicated in block form in FIG. 1 and
shown in greater detail in FIG. 3. Once the components are
assembled in precise relation so that the position of a particular
die corresponds exactly with its corresponding photographic code on
the film 22, the frame is transferred to a die-sorting instrument
generally indicated in block form 34 in FIG. 1 and shown in more
detail in FIGS. 4, 5, 6, and 7. The die-sorter includes second XY
table 36 to which the frame 26 is mounted. The sorter includes an
electro-optical reading instrument, best shown in FIG. 4, including
a stationary optical head 36 which reads each coded pattern on the
film 22 as the frame 26 is indexed by the XY table. The XY table is
located adjacent a transfer turret 38 having a plurality of radial
pick-off heads 40 which remove individual dies from the
pressure-sensitive web 24 and, in accordance with instructions fed
from the electro-optical reader, delivers each die to one of a
plurality of radial delivery stations 42, which may have an
automatic packaging unit, each station collecting dies having the
same characteristics. Alternatively the sorted dies may be
delivered directly to a die-bonding machine thereby avoiding the
packaging requirements.
ELECTRO-OPTICAL RECORDER
REferring now to FIG. 2 of the drawings, the electro-optical
recording instrument 16 will now be described in detail. The
recording instrument includes the extension member 18 which is
comprised of a pair of parallel tubes 43 and 44 rigidly secured to
the XY table 12 so as to move in unison with the wafer 10 as it is
probed. The tubes 43 and 44 are fixed rigidly at one end to the
optical head 20. At their opposite ends the tubes are connected to
independent light sources adapted to project separate images along
parallel paths to a beam-splitter 46 mounted in the optical head
and adapted to direct the images in a reduced size downwardly
through a lens 48 onto the photographic film 22. The film 22
preferably is mounted to a fixed vacuum chuck 50 adapted to hold
the film flat against the planar supporting upper surface of the
chuck.
The tube 43, as viewed in FIG. 2, at its right-hand end is provided
with a bulb 52 which is adapted to project a reference image 54
onto the chuck surface 50 for focusing purposes only.
The tube 44 is provided with an electro-optical encoding unit 56
focused along the tube towards the beam splitter. This unit is
comprised of a bundle of light pipes 58 tapered towards the beam
splitter and typically ten in number in a grouping such as shown in
FIG. 2a. Each of the light pipes is provided at its right-hand end
with an individual light source such as a bulb 60 or the like. Each
of the bulbs 60 is connected by a lead 62 to a power source 64
which in turn is controlled by the output from the test set 14.
Test set 14, as previously described, is operatively connected to
the probe so that information derived as to the operating
characteristics of each semiconductive device in the wafer 10 will
be fed from the test set encoded to the power source so as to
illuminate the bulbs 56 in selective patterns or coding
arrangements corresponding to the particular characteristics of the
devices tested on the wafer. It will be understood that by
illuminating certain one or more of the bulbs 56, various code
combinations may be produced which will be projected onto the film
22.
The projected image of the code pattern preferably has a perimeter
that is equal to or smaller than the area size of the device that
has been tested. As the probe indexes the wafer from die to die the
electro-optical encoder records the appropriate coded pattern on
the film, the pattern corresponding to the test results of the
respective die. Since the film record is made at the same time as
the test, the arrangement of the coded test results on the film is
similar to the grid arrangement of the devices on the wafer. The
film, therefore, provides the test result of every device on the
wafer in a corresponding arrangement. Typically, the ratio of the
film to the wafer is one to one. The film 22 is, of course, mounted
within a light type enclosure which, for sake of clarity, has not
been illustrated.
When the testing of the wafer has been completed and a photographic
record made of each and every device in the wafer, the film 22 is
developed. The film 22 may be conventional photographic film or may
be in the form of quick developing film such as sold by Polaroid
Corporation. In FIG. 2b there is illustrated a plan view of a
typical photographic record of the coded data corresponding to a
wafer produced by the FIG. 2 instrument. FIG. 2b also shows a
portion of the film greatly enlarged to show details of the code
pattern. It will be understood that for each tested device the
recording pattern for that device will be comprised of a group of
ten blocks 66 and in each group of blocks some will be clear while
others will be opaque providing a code which subsequently will
serve in a sorting instrument mechanism.
MOUNTING AND ALIGNMENT STATION
The exposed and developed film 22 is next mounted to the frame 26
in side by side relation with the now divided dies which are held
in their original orientation by means of the pressure sensitive
web 24 to which they have been transferred. The instrument employed
for the mounting and alignment station is best shown in FIG. 3 and
is comprised of a fixed frame 68 having a horizontal cross support
to which are mounted spaced magnifying viewers 70 and 72, each
adapted to register one with the dies and the other with the
film.
Mounted below the viewers 70 and 72 is a vacuum chuck 74 carried by
a manually operative positioning table 78 which is also angularly
adjustable whereby the photographic record and the circuit dies may
be aligned precisely with one another and, when properly aligned,
transferred to the mounting frame 26. In practice, the dies on the
web are oriented into position and transferred to the mounting
frame then the film record is oriented in a similar manner in
relation to the dies and thereupon transferred to the mounting
frame. The relative positions of the wafer dies and the test record
on the mounting frame are such that at a fixed distance of X and Y
from any die, a reader can pick up the test results for that
particular die.
DIE SORTING STATION
The mounted photographic record and dice array carried by the frame
26 are then transferred to the die sorting apparatus 34, best shown
in FIGS. 4, 5 and 6. The die sorter basically comprises the XY
indexing table 36 on which the mounting frame 26, supporting the
correctly oriented dice and film record, is mounted; the optical
reading head 36 for reading the coded data on the film 22; and the
sorting turret 38 equipped with a plurality of vacuum collets 80.
The XY table indexes in the same fashion as the XY table 12 for the
recording instrument, indexing from one device and one code image
to the next. It will be understood that the mounting frame 26 moves
so that the photographic record and the dies index in unison. The
mounting frame is positioned so that the film record is located in
optical alignment with the optical reading head 36 while the dies
are located in position opposite a pick-off collet 80.
The optical head 36 is comprised of a pair of mutually
perpendicularly tubes 52 and 54 extending from a beam splitter 86
located above a lens 88 focused on the coded film 22. The upper end
of the tube 84 is provided with an eye piece 90 having a cross hair
reticle an is used for visual alignment purposes. At the left-hand
end of the tube 82, as viewed in FIG. 4, are two banks of photo
diodes 92 and 94 which serve to convert a projected image of the
photographic code to usable electrical signals. This coded image is
projected by means of a light source, such as a bulb 96, located
below the film 22 along the optical axis of the lens 88. As the
film 22 is indexed onto the optical axis of the lens 88 the coded
pattern, which corresponds to a particular die in the corresponding
relative position amongst the group of dies, will be projected
against the photo diodes which will generate an electrical signal
corresponding to the quality and characteristics of the particular
die. These electrical signals are fed to a shift register memory
98. Programmed data will stop the XY table 36 and a vacuum collet
80 will pick up a desired die 100 while its address is entered into
the memory. The collet 80 is indexed with the sorting turret 38 and
carries the die until the collet arrives at a predetermines deposit
stations which may comprise a container or a packaging mechanism.
In any event a plurality of these deposit stations are located in
evenly spaced angular relation about the turret and when the collet
with the die arrives at the correct station the die is deposited. A
container or packaging unit is located at each receiving station
and the dies are collected according to their categories.
The mechanism for separating the selected die form the pressure
sensitive web 24 is comprised of a reciprocating needle 102 located
below the web 24 for registration with a collet 80 which indexes
into and out of position above the wafer array as the turret 38
indexes. The needle 102 may be reciprocating by any one of a
variety of techniques such as a rotary cam, a pneumatic or
hydraulic cylinder or by means of a solenoid. The needle is formed
with a slightly rounded tip which, upon reciprocation, comes up
under each die 100 forcing it upward away form the web and into a
conical annular recess 104, slightly larger than the die 100,
formed in the lower end of the collet 80. The collet 80 is formed
with a central passage 106 connected to a vacuum source whereby
when an individual die 100 is transferred from the web to the
collet it will be held there until subsequently deposited at a
selected deposit station.
The collet 80 is located on the outer end of a pair of parallel
leaf springs 108 and 110 extending out from the turret and located
below a radial arm 112. The arm 112 is provided with an upright
plunger 114 which is adapted to engage an eccentric rotor 116
driven by a rotary solenoid 118. When the collet 80 is in position
over the selected die, a signal is sent to the solenoid causing the
eccentric rotor 116 to rotate, this in turn causing the plunger 114
to be depressed, forcing the collet 80 down against the selected
die which is pushed up simultaneously by the needle. Continued
rotation of the rotor 116 permits the collet to retract with the
die and the turret is then indexed bringing the next collet 80 to
bear above the next die which has been moved into position by the
XY table. When the collet with its die reaches a pre-selected
deposit station the die is released.
A small XY stage 111 is drivingly connected to the optical head 36
and operated by separate stepping motors 113 and 115 for making
minor corrections to the alignment between the lens and the code
pattern as will presently appear.
OPTICAL RECORDING
The optical recording techniques employed in the system are
somewhat similar to multi-channel magnetic tape recording. However,
the technique herein employs photographic film to record light or
dark spots as logic signals which can be stored indefinitely and
read out at will. A block of data is recorded in a field typically
.015 inches square. This field, shown enlarged in FIG. 9, is
divided into two major areas which may be defined as a parking area
120 and a data area 122. The parking area, as shown, is an area 5 x
15 mils in which the reading scanner will rest between indexes.
Since reading is accomplished by three spots of an equivalent
diameter of 1 mil, the tolerance in indexing for reading is plus or
minus 2 mils in any direction. The data area 122 is divided into
three major rows 124, 126 and 128 in the direction of travel. When
the film passes under the reading head 36, three sensors in either
bank of photo diodes 92 and 94 detect the variation between light
and dark areas and issue the corresponding signals in the
appropriate channels. Channel allocation and reading head
configurations are illustrated in FIG. 10. The technique used in
the data readout is similar to the NRZI technique (Non Return to
Zero I) used in magnetic recording.
In this method the detection system is used to detect light changes
rather than light level. In other words, the system detects
transitions from light to dark or dark to light and signals a
transition as a logical 1 and no transition as a logical 0.
Therefore, the channels on the film record are the lines at which
the transitions will occur. It is worthwhile noting that a
transistion is a logical 1 regardless of its polarity, i.e. a
change from light to dark or dark to light will both be a logical
1. In FIG. 11 both A and B contain a logical 1 on channel 2.
However, A contains a logical 0 on channel 1 and a logical 1 on
channel 3 while B contains a logical 1 on channel 1 and a logical 0
on channel 3. Note that row 126 in FIG. 10 contains only one
channel (channel 4) the other two channels being used for machine
control purposes, the two blocks always being dark as shown.
Recording is performed while the film is stationary while reading
is done when the film is moving producing an AC signal. In order to
maintain channel location regardless of the direction of travel,
the reading circuitry will invert the signal sequence appropriately
so that all the data appears in the same visual form.
Since reading is preformed in both directions of travel, the
reading head contains six photo sensors arranged in the two banks
92 and 94 so that the leading bank is always reading the data in a
particular direction of travel. Switching between the two banks of
sensors is performed automatically by the machine's logic. The
timing signal is generated by the first transition occurring in row
126. Since this block is always black and the parking area is
always white this signal will appear in either direction of travel.
This signal starts a master clock controlled by the oscillator
driving the XY table thereby generating gating signals that are
always in time with the table speed. Turnaround signals are
generated at each line and recorded as a block 145 in the parking
area as shown in FIG. 5. Two blocks will appear in each line
allowing an extra index so that data will not be lost at
turnaround. During turnaround recording, data will not be
recorded.
POSITIONING COMPENSATION
In order to allow for variations in positioning, larger than the
plus or minus 2 mils called for previously, a compensating network
will return the reading spots to the center of the parking area. To
accomplish this, the reading lens is mounted on the small XY stage
111 referred to above capable of 1 mil steps upon command. A timing
signal is generated at the beginning of each index command and
compared to the time taken to reach the first transition line. Any
deviation will generate a pulse in the appropriate direction
driving the lens stage. This movement will result in returning the
reading spot to the center of the parking area. Compensation in the
direction of travel is achieved at each index while compensation in
the other axis is derived in a similar manner from the turnaround
block at the end of each line as shown in FIG. 14. Before the
beginning of a complete frame, a manual reset signal will return
the lens stage to a start position.
DIE INDEXER
Referring now more particularly to FIG. 7, there is shown in detail
a die indexing apparatus such as may be arrayed at each deposit
station 42, as broadly shown in FIG. 1. The die indexing mechanism
of FIG. 7 may be used both to package individual dies as well as to
remove dies from the packages for subsequent operations such as
bonding, for example. In the illustrated embodiment of FIG. 1, one
indexer is located at each deposit station so that each indexer
will serve to package dies all having the same quality and
characteristics.
Used in the indexer is a strip 140, shown best in FIG. 8, comprised
of a relatively narrow strip formed with indexing holes 142 along
one edge, in a manner similar to movie film, and storage holes 144
near the other edge of the strip. On the bottom side, a thin,
pressure sensitive adhesive tape 146 is laminated to the strip 140.
The adhesive tape thus provides an adhesive floor at the bottom of
the storage holes 144. The laminated strip is wound on a feed reel
148 which is mounted to the indexer as by a shaft 150 provided on a
frame 152. The strip 140 is threaded over an indexing track
provided on the indexer to a take-up reel 154.
The indexer includes a sprocket drive 156 and contoured guide
plates 158 and 160 which feed the strip 140 onto the upper reach of
the indexer before delivering the strip to the reel 154. A motor or
solenoid 162 is employed to actuate the indexer. The strip is
carried to the upper reach of the indexer where a storage cavity
144 will come into register with a collet 80 and, assuming that the
die carried by the collet 80 is addressed for this particular
indexer, the die will be deposited in the strip cavity. A signal
will then be generated to the solenoid 162 to advance the strip so
that another strip cavity will be brought into position for the
next die. As the strip cavities are filled, the strip will be wound
up on the reel 154, which is drivingly connected to the feed reel
148, the two reels rotating in unison. When the strip is completely
indexed and contains a device in each cavity all of the dies of the
strip will be of the same category.
The indexer, as previously indicated, may be used to remove the
dies from the packaging strip as well as to package them. When
employed to remove the dies from the strip a reciprocating needle
164 is employed to function in a manner similar to the needle 102
of FIGS. 5 and 6. This needle is mounted upright to a block 166
supported on parallel springs 168 and 170 and reciprocated by means
of pivotally mounted arm 172 urged downwardly by means of a spring
174 and pivoted upwardly by means of a cam 176. It will be
understood that each time the cam 176 is rotated, the arm 172 will
pivot upwardly forcing the needle 164 up through the adhesive floor
of the strip cavity, forcing the die contained therein upwardly
into a vacuum collet such as shown at 80 in FIG. 6 which then may
be used to transfer the die to a bonding station.
* * * * *