Methods of and apparatus for mounting articles to a carrier member

An apparatus aligns small articles, such as semiconductor chips, to a reference axis and loads them on predetermined sites of a carrier, such as a tape. The loading requires precisely positioning adhesive dots and the articles at the sites of the tape. Precision within desired limits is achieved by aligning both an applicator for applying the adhesive and the articles in sequence to a common centerline. The tape is maintained in contact with two diametrically opposed locations of an index wheel located on the common centerline. The index wheel is then reciprocated along the centerline to alternately apply adhesive to one of the sites on the tape and then load the aligned article to another one of the sites. An additional article is aligned to the centerline each time loading is completed of a previously aligned article to its respective site. The aligning facility is operated by a cam which controls the vertical position of a plunger and acts as a valving means for selective vacuum and air purge applications.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to methods of and apparatus for mounting articles to 
a carrier member. More particularly, another aspect of the invention 
relates to handling small articles, such as beam-lead integrated circuit 
chips, prior to bonding the chips to the substrates. Adhesive dots are 
applied around the periphery of apertures in a tape. The size and shape of 
each of the apertures are chosen to form pockets for the chips. The chips 
then are loaded from an expanded array into the pockets of the tape, 
suspended by at least some of the beams attached by the adhesive dots to 
the periphery of these pockets. Thereafter, the tape is run onto a spool 
to store the loaded chips for future bonding of the chips onto substrates. 
The bonding is accomplished during a transfer of the chips directly from 
the tape to the substrate. Bonds are preferably formed by a 
thermocompression process, wherein the tape serves as a compliant member 
between the chips and a thermode applying the thermocompressive energy. 
2. Description of the Prior Art 
U.S. Pat. Nos. 3,785,903 and 3,871,936 to J. A. Boyer, D. P. Ludwig and F. 
Zwickel issued Jan. 15, 1974, disclose prior art apparatus and methods, 
respectively, which relate to the subject matter of the present invention. 
The Boyer et al. patents also make reference to other prior art patents 
which relate to beam-lead semiconductor devices, compliant bonding and 
other related subject matter. 
The Boyer et al. patents particularly disclose apparatus and methods for 
loading beam-lead chips into preselected locations of a compliant tape. 
The compliant tape can then be supplied to a bonder, the beam-lead chips 
being already loaded in the tape and aligned for sequential bonding to 
respective substrates. 
A load station of the apparatus disclosed by Boyer et al. includes 
facilities for first indexing one of the preselected locations into rough 
alignment with the load station. Thereafter, other facilities precisely 
align such locations. The disclosed apparatus further includes facilities 
for applying a plurality of dots of adhesive to the tape. The adhesive 
dots are applied prior to loading the chips to the tape. The dots form a 
pattern about the periphery of each of the locations on the tape. The 
pattern is intended to be coincident with selected leads of the chips to 
be loaded. Successive locations of the tape are first indexed into at 
least rough alignment with the applying facilities. Indexing the tape 
shifts other locations away from the applying facilities and toward the 
load station. After the tape is indexed, roughly aligned locations are 
precisely aligned to both the applying facilities and to the loading 
station so that the applying facilities can be simultaneously activated 
with the facilities for loading one of the chips. 
It is desirable to integrate and simplify the alignment of preselected 
locations or sites on a length of tape with respect to a chip load 
station. 
SUMMARY OF THE INVENTION 
Therefore, an object of the invention is to provide new and improved 
methods of and apparatus for mounting articles to a carrier tape. 
Another object of the invention is to provide efficient handling to 
repetitively align successive chips to a preselected position in 
preparation for loading them onto the tape. 
Still another object of the invention is to achieve a high degree of 
repetitive accuracy in loading the chips onto the tape, the accuracy being 
commensurate with extremely small beam lead sizes of integrated circuit 
chips presently known in the art. 
These objects are accomplished by engaging a portion of the tape with a 
locating means; moving a site in the engaged portion against an adhesive 
applicator; maintaining the engagement of the tape while indexing the site 
into alignment with a chip and then moving the site toward and against the 
chip without releasing the portion from engagement with the locating 
means. 
In another aspect of the invention the chip is precisely located and 
oriented with respect to a predetermined centerline. A centering mechanism 
is activated by a combination cam to (1) selectively raise and lower a 
pedestal, and (2) control a selective application of a vacuum between the 
pedestal and the chip. The cam has a contoured surface for moving a 
plunger terminating in the pedestal in a predetermined manner and further 
includes at least one fluid duct section positioned in a planar surface of 
the cam to selectively couple a fluid port in the pedestal to a fluid 
circuit in response to a relative movement between the plunger and the 
cam, whereby a vacuum or fluid flow is selectively applied at the fluid 
port of the pedestal.

DETAILED DESCRIPTION 
The Apparatus in General 
Illustrated in FIG. 1 is an apparatus designated generally by the numeral 
11, for precisely orienting and loading articles, such as beam-lead 
semiconductor chips 12 (FIG. 2) onto designated locations or sites 13 of a 
tape 14. The tape 14, a portion of which is shown in FIG. 2, is used in 
the semiconductor industry for compliantly bonding the beam lead chips 12 
to a substrate (not shown). Referring back to FIG. 1, the apparatus 11 
includes such major assemblies as an adhesive applicator unit 15, a tape 
transport and alignment unit 20, a chip supply unit 25, and a chip 
locating unit 30. 
In the apparatus 11, an adhesive applicator 32 of the adhesive applicator 
unit 15 and a pedestal 34 (refer also to FIG. 5) of the chip locating unit 
30 are aligned to a common centerline 33. Furthermore, the position of the 
adhesive applicator unit 15 and that of the chip locating unit 30 remain 
stationary with respect to a common frame structure or base 35 during the 
normal operation of the apparatus 11. The tape transport and alignment 
unit 20, on the other hand, reciprocates with respect to the base 35 
between the applicator unit 15 and the chip locating unit 30. The 
reciprocating movement of the wheel 39 moves two sites 13 on diametrically 
opposite locations of the wheel 39 along a reference axis which is 
coincident with the centerline 33. 
During each cycle of operation, the reciprocation of the tape transport and 
alignment unit 20 moves one of the sites 13 on the tape 14 into contact 
with the applicator 32. As the site 13 contacts the applicator 32, 
adhesive is deposited on the site. During the continuation of the same 
cycle, the alignment unit 20 reciprocates away from the applicator 32 and 
toward the chip locating unit 30. Moving another site 13 on the tape 14, 
one to which adhesive has already been applied, into contact with one of 
the chips 12 located on the pedestal 34, the chip is transferred to the 
site 13 of the tape 14. Since the chip is being transferred from the 
pedestal 34 to the site 13, the location of the pedestal 34 in the 
apparatus 11 is also referred to as a load station. 
Each such site 13 of the tape 14 remains engaged on an index wheel 39 of 
the tape transport and alignment unit 20 while it is indexed between the 
adhesive applicator unit 15 and the chip locating unit 30. Once having 
become engaged by the index wheel 39, the tape 14 does not become 
disengaged from the index wheel 39 until after the tape has advanced past 
the chip locating unit 20, and the chips 12 have been loaded onto the 
respective sites 13. 
The engagement and disengagement of the tape 14 from the wheel 39 is 
brought about, one site 13 at a time, by indexing the wheel 39. For each 
increment of the tape 14 which becomes disengaged from the wheel 39 with 
one of the chips 12 loaded onto one of the sites 13, a new increment of 
the tape engages the wheel 39 and a new one of the sites 13 becomes 
aligned with the applicator 32. 
The continued engagement of the tape 14 by the index wheel 39, and the 
capability to adjust both, the adhesive applicator 32 and the pedestal 34, 
to the common centerline 33 permit the adhesive and the chips 12 to be 
applied to respective sites 13 with a high degree of repetitive accuracy 
with respect to the sites and consequently, with respect to each other. 
THE ADHESIVE APPLICATOR UNIT 15 
The adhesive applicator unit 15 is best explained in reference to FIGS. 1, 
2 and 3. The applicator 32 includes a reservoir 42 which holds a supply of 
liquid adhesive resin. A lower end 43 of the applicator 32 terminates in a 
plurality of centrally located applicator tips 44. 
Referring to FIG. 2, there is shown a portion of the tape 14 including a 
typical site 13 to which a chip 12 has been loaded. The site 13 includes a 
peripheral embossment 46 and a central aperture 47. When the adhesive 
applicator 32 contacts the tape 14, a plurality of dots 48, each issuing 
from one of the tips 44, are deposited on the surface of the peripheral 
embossment 46 of the site 13. The positions of the dots 48 on the 
peripheral embossment 46 are chosen to correspond to intended positions of 
selected leads 49 of the chip 12 when such chip is deposited on the site 
13. 
Not all chips manufactured in the industry are of the same size. A small 
variation in the size of the chip can be tolerated by the aperture 47 in 
the tape 14. In general, it is advantageous to select the size of the 
aperture 47 in the tape in relation to the size of the chip 12 which is to 
be loaded onto the site. Also, depending on the size of the chip 12 and 
the number of beams extending from each of the four edges of the chip 12, 
one or more adhesive dots 48 may be applied along each edge of the 
peripheral embossment 46 at the site 13. Loading of the chip 12 to the 
site 13 suspends the chip in the aperture 47 while a portion of the beams 
49 extend onto the peripheral embossment 46. 
Required skewing of the applicator tips 44 to cause the adhesive dots 48 to 
be coincident with the offset beam leads 49 is achieved in a manner 
similar to that described in U.S. Pat. No. 3,785,903 to Boyer et al. 
However, in the Boyer et al. patent only a single dot 48 of adhesive is 
disclosed as being deposited along each edge of the aperture 47. FIG. 3 
depicts an end view of the lower end 43 of the applicator with an 
arrangement of eight such applicator tips 44 located in a square pattern. 
Each pair of tips 44 is skewed by an angle "a" with respect to the 
orthogonal direction of the pattern. Machined grooves 50 extend in the 
orthogonal and in the skewed direction to form the tips 44. The preferred 
hole size of the aperture in each applicator tip 44 is approximately 
0.0024 inch. The flat end portion of each tip 44 is approximately 0.004 
inch square. 
A machined flat 51 on a flange 52 determines the angular orientation of the 
applicator 32 to locate each tip 44 coincident with a desired position of 
one of the adhesive dots 48 on the peripheral embossment 46. The lower end 
43 of the applicator 32 is preferably cylindrical. The end 43 fits 
slidably through a corresponding aperture in a mounting bracket 53, 
thereby permitting a vertical movement of the applicator 32 along the 
centerline 33. During such movement, the flat 51 slides along a vertical 
ledge 54 of the mounting bracket 53 to maintain the orientation of the 
applicator 32 with respect to the bracket 53. 
Full contact of the applicator tips 44 with the respective site on the tape 
14 is assured by the extent of the vertical movement of the index wheel 
39. The vertical excursion of the wheel 39 is chosen to lift the 
applicator 32 slightly. The flange 52 consequently separates from a 
bearing surface 55 of the mounting bracket 53, and the applicator 32 rests 
on the site 13 of the tape. 
In contrast with the prior art apparatus described in the Boyer et al. 
patent, the position of the applicator 32 is precisely adjustable in a 
horizontal plane with respect to the stationary base 35 of the apparatus 
11. A horizontal plate 57 supports a precision adjustment mechanism 58 
including two adjustable slides 59 and 61 operating at right angles to 
each other. The positions of the slides 59 and 61 are adjusted by 
respective adjustment screws 62 and 63 to align the center of the 
applicator 32 with the common centerline 33. Setting of lock screws 64 and 
65 prevents inadvertent further movement of the slides 59 and 61 to retain 
the applicator 32 in a desired, aligned position. 
A desirable adhesive for holding the beam-lead chips 12 on the tape has 
been disclosed in the Boyer et al. patent. For instance, a silicone resin, 
available from Dow Corning Corporation, Midland, Mich., exhibits desirable 
characteristics. The material is available under the designation WE-648 or 
XR-62-047 Resin. It is sufficiently flowable to be used in the applicator. 
It is also sufficiently tacky after deposition on the tape 14 to hold the 
chips 12 in the tape. 
THE CHIP LOCATING UNIT 30 
Referring to FIGS. 4 and 5, the chip locating unit 30 centers chips 12, one 
at a time, with respect to the centerline 33, and orients the chips so 
that their leads 49 become aligned with the tape 14 (see FIG. 1). The 
centering mechanism consists of a block 67 having a centering cavity 68 in 
the form of an inverted truncated pyramid in its top surface. The pedestal 
34 is slidably mounted along the vertical axis of the cavity. The pedestal 
extends below the cavity and is biased downward by a spring 69 to rest 
against a plunger 71. A lower end 72 of the plunger has a cam follower 
surface which is preferably a rotatably mounted roller 73. The roller 73 
rides against a contour 74 of a cam 75 which may be a rotary disc cam. For 
the present embodiment however, a linearly sliding cam is preferred. 
Cavities such as the cavity 68 for centering beam-lead chips are known in 
the art. Reference is made to an application, Ser. No. 414,481 filed in 
the Patent and Trademark Office on Nov. 9, 1973 in the name of Hentz et 
al. and published under the Second Trial Voluntary Protest Program on Jan. 
20, 1976, now U.S. Pat. No. 3,982,979 which is assigned to the assignee 
hereof. The referred-to Hentz et al. patent describes advantages of moving 
the equivalent of the pedestal 34 up and down in an oscillating motion 
superimposed on the general downward motion of the pedestal 34 which 
occurs during the centering operation, to intermittently engage the device 
or chip 12 as it is lowered into the cavity 68. The publication also 
refers to the advantage of applying a slight vacuum to the pedestal. In 
the past, a selective application of vacuum to a centering device had been 
controlled by activating and deactivating solenoid-controlled valves. 
Referring to FIGS. 5 and 6, the sliding cam 75 includes a high vacuum 
passage 77 and a low vacuum passage 78 in a vertical side face 79 of the 
cam 75. As the cam 75 moves to raise and lower the pedestal 34, the 
passages 77 and 78 selectively bridge a gap from a tube 82 and from a tube 
83, respectively, to an intake port 86 of a fluid passage to the pedestal 
34. The intake port 86 includes a vertical passage 87 in a sideplate 88 as 
shown in the sectioned view of the sideplate 88 in FIG. 6. 
A relatively high vacuum source of preferably 10 inches of mercury is 
connected to the tube 82 while a low vacuum source of preferably 5 inches 
of mercury is connected to the tube 83. Therefore, as the cam 75 is 
linearly displaced past the tubes and the plunger 71, the pedestal 34 
reciprocates vertically up and down in a predetermined pattern of motion 
while the low vacuum and the high vacuum sources connected to the tubes 82 
and 83, respectively, are selectively switched to draw air through a fluid 
port or opening 90 in a platform 91 of the pedestal 34. Consequently, the 
cam 75, as a single moving element, directly controls the movement of the 
pedestal 34 and the application of either a high or a low vacuum to the 
pedestal 34. The cooperation of both the vertical movement of the pedestal 
34 and the force on the chip by the vacuum results in the alignment of the 
chip 12 located on the pedestal to the centerline 33. 
The cam 75 also controls an air purge of the centering cavity 68 which is 
activated at the end of each centering operation, namely, when the 
centered chip 12 has been transferred to the tape 14. Referring to FIG. 6, 
the air purge is controlled by an air valve 92 which is integrated into 
the cam 75. An air supply tube 93 is spring loaded toward and terminates 
against the cam. An air connection 94 is also spring loaded against and 
terminates at the same flat surface of the cam 75. The air connection is 
coupled directly to the vacuum passage leading to the pedestal 34. When 
the cavity 68 is to be purged at the end of the centering operation, the 
cam 75 has moved to a position where both the low vacuum and the high 
vacuum sources are deactivated. In that position of the cam, a passage 95 
in the body of the cam couples the air supply tube 93 to the air 
connection 94. The resulting air purge through the pedestal 34 and the 
cavity 68 is intended to clear any debris or other particles from the 
cavity 68. Remaining particulate matter could jam the cavity to prevent 
the subsequent chip 12 from becoming properly centered during the next 
operational cycle of the apparatus 11. 
To initially establish precise positioning of the chips 12 with respect to 
the centerline 33 of the apparatus 11, orthogonally arranged adjustment 
screws 96 and 97, shown in FIG. 4, move respective slides 98 and 99 to 
center the cavity 68 on the centerline 33. Two lock screws 100 and 101 are 
preferably tightened after the slides 98 and 99 have been adjusted to 
prevent undesirable shifting of the adjusted position of the slides during 
the operation of the apparatus 11. The slide 98 supports a frame structure 
102 for the block 67. 
Referring to FIG. 5, the block 67 and the pedestal 34 are laterally movable 
with respect to the plunger 71 without affecting the precise vertical 
orientation of the pedestal 34 in the cavity 68. When an adjustment of the 
block 67 with respect to the centerline 33 is made, a bottom flat surface 
103 of the pedestal 34 simply slides laterally with respect to a mating 
flat surface 104 on the top of the plunger 71. It should be realized 
however, that such adjustments to align the cavity 68 to the centerline 33 
are precision adjustments only with very small lateral excursions. Vacuum 
passages between the pedestal 34 and the plunger 71 are consequently not 
adversely affected by such small lateral displacements of the pedestal 34 
with respect to the plunger 71. 
When one of the chips 12 is received on the pedestal 34 and aligned by the 
cavity 68 during the operational cycle of the locating unit 30, the 
alignment includes centering the chip 12 to the centerline 33, as well as 
orienting the chip by rotating it through an angle in the order of five 
degrees or less to align it to the direction of the tape. At the end of 
the centering operation, the chip is held by the high vacuum to the 
pedestal 34 and lifted to a load or transfer position above a top surface 
105 of the block 67. Upon reaching the transfer position the vacuum in the 
pedestal 34 is turned off by the cam 75 to permit a transfer of the chip 
12 to the site 13 on the tape. After the chip 12 is transferred to the 
tape, the pedestal 34 returns to the bottom of the cavity 68 and the air 
purge clears the cavity of any remaining foreign matter before the next 
chip 12 is received on the pedestal 34 from the chip supply unit 25. 
THE CHIP SUPPLY UNIT 25 
Referring to FIG. 1, the chip supply unit 25 is substantially a commercial 
chip sorting apparatus. Such an apparatus is available, for instance, by 
Teledyne Tac, Inc. under the tradename of "Minisorter." Basically, it 
comprises an indexable chip supply table 106 and a transfer arm 107 which 
is capable of both vertical and angular motion about a pivotal axis to 
advance a pickup tip 108 between a pickup position above the table 106 and 
a deposit position above the pedestal 34. The pickup tip 108 is connected 
to a vacuum source which is selectively operated to pick up the chip 12 at 
the table 106, to hold the chip 12 during its transfer to the pedestal 34, 
and to release it as it is deposited at the pedestal 34. The pickup tip 
108 is a tube having a flat end. The tubular opening in the end is coupled 
to the customary vacuum source (not shown) which produces the necessary 
suction to securely hold the chip during its transfer to the locating 
unit. 
THE TAPE TRANSPORT AND ALIGNMENT UNIT 20 
The function of the tape transport and alignment unit 20 is to handle the 
tape 14 for the chip loading operation. The unit 20 incrementally advances 
the tape 14 to align the sites 13 first with the adhesive applicator 32 
and then with the pedestal 34 of the chip locating unit 30. In addition to 
aligning the sites 13, the unit 20 reciprocates to move the aligned sites 
13 first into contact with the adhesive applicator 32, and then into 
contact with the chip 12 on the pedestal 34. The motion of the unit 20 is 
consequently used to apply the adhesive and to load the chips 12 to the 
sites 13. 
The unit 20 is supported by a frame which is designated generally by the 
numeral 121. The frame includes a vertical base plate 122 which supports 
the index wheel 39 and its drive, a special indexing drive 123 frequently 
referred to as a Geneva drive. The drive 123 comprises a revolving drive 
pin 126, which on each revolution engages one of a number of equally 
spaced drive slots 127 in the index wheel 39. The location of the center 
of revolution of the drive pin 126 in the baseplate 122 is chosen with 
respect to the index wheel 39 for the pin 126 to first engage and then 
disengage the respective slot 127 in a radial direction away from the 
center of the index wheel 39. The resulting motion of each indexing step 
of the wheel 39 is substantially sinusoidal. When the pin 126 first 
engages one of the respective slots 127, there is no initial angular 
velocity of the wheel 39. The drive 123 further includes a cam (not shown) 
which lifts a detent pin 131 from one of a number of detent slots 132. The 
slots 132 are equally spaced about the periphery of the index wheel 39 in 
an alternate arrangement with the slots 127. The detent pin 131 is lifted 
from the respective detent slot 132 when the drive pin 126 first engages 
one of the slots 127. Just before the pin 126 revolves out of engagement 
with the slot 127 at the conclusion of the index step, the detent pin 
re-engages the next detent slot 132. The alternate engagement of the 
detent pin 131 and the drive pin 126 with the index wheel 39 provides a 
continuous positive control over the position of the index wheel 39. The 
detent slots 132 are precision ground, such that the engagement of the pin 
131 with one of the slots 132 precisely locates the angular rest position 
of the index wheel 39. 
The index wheel 39 itself is a composite of machine elements which are best 
described in reference to FIGS. 1 and 7. An index rim 133 has the drive 
slots 127 and the detent slots 132 evenly spaced about its periphery. The 
index rim 133 is mounted to a sprocket wheel 135 which mounts onto a shaft 
assembly 136. The shaft assembly 136 is rotatably supported in the base 
plate 122 to accurately locate the index wheel 39 as a whole with respect 
to the base plate 122. The index rim 133 mounts concentrically onto the 
sprocket wheel 135; however, the angular position of the index rim 133 may 
be shifted with respect to the angualar position of the sprocket wheel 
135. The sprocket wheel 135 has circumferentially spaced sprocket teeth 
138 which correspond to spaced guide apertures or guide holes 139 of the 
tape 14 as shown in FIG. 2. The sites 13 are symmetrically spaced between 
the guide holes 139. When the angular position of the index rim 133 is 
shifted, the tape 14 in engagement with the sprocket wheel 135 is advanced 
or retarded with respect to the detent position of the index rim 133. Once 
a desired angular position between the index rim 133 and the sprocket 
wheel 135 is established, the position of the index rim 133 is locked with 
respect to the sprocket wheel 135 by fastening screws 140 shown in FIG. 1. 
A length of the compliant tape 14 is unreeled from a supply reel 141 and 
routed across a number of guide rollers 142 onto the index wheel 39. 
Additional guide rollers 143 insure full engagement of the tape 14 with 
the index wheel 39 past a position in alignment with the centerline 33 
adjacent the pedestal 34. The guide rollers 142 and 143 form an assembly 
144, the rollers being mounted to a common backing plate 146. The backing 
plate 146, in turn, is attached to the base plate 122. Guided past the 
rollers 143, the tape 14 is reeled onto a take-up reel 148. 
The supply reel 141 and the take-up reel 148 are rotatably mounted in the 
base plate 122. Also, both the supply reel 141 and the take-up reel 148 
are subjected to a torque. The torque as applied to the supply reel 141 
opposes unreeling of the tape from the supply reel 141 to keep tension on 
the tape as it is being advanced by the index wheel 39. On the take-up 
reel 148 the torque initiates the necessary motion to wind the tape onto 
the take-up reel as the tape becomes disengaged from the index wheel 39. 
To maintain accuracy in the positioning of the index wheel 39, a drive 150 
including a motor 151 and respective torque clutches 152, 153 on each of 
the reels is shut off when the forward motion of the index wheel 39 ceases 
but prior to the disengagement of the pin 126 with the slot 127. At that 
time, the two sites 13 on the tape 14 have become positioned adjacent the 
applicator 32 and the pedestal 34, respectively. Even though the torque 
drive 150 is shut off it is still desirable to maintain under tension a 
portion 154 of the tape between the index wheel 39 and the take-up reel 
148. Consequently, a one-way clutch 155 is engaged with the take-up reel 
148 to prevent the take-up reel 148 from releasing the tension of the tape 
once the torque drive 150 is deactivated. During each operational cycle, 
the entire tape transport and alignment unit 20 reciprocates vertically. 
The unit 20 first advances toward the adhesive applicator 32 and then 
toward the pedestal 34. To facilitate the reciprocating movement the frame 
structure 121 is mounted directly to the movable slide portion 160 of a 
precision slide 161. The fixed portion 162 of the slide 161 is mounted to 
the base 35 of the apparatus 11. 
Reciprocation of the unit 20 to effect a contact between one of the aligned 
sites 13 of the tape 14 and the tips 44 of the applicator 32, and to move 
the other aligned site 13 into contact with the chip 12 on the pedestal 34 
occurs when the index wheel 39 is securely detented. Reciprocation of the 
unit 20 moves both aligned sites 13 along the centerline 33. To effect the 
reciprocating motion, the unit 20 rests on a pivotably mounted cam lever 
163 (shown in FIG. 7) which raises and lowers the entire unit 20 including 
the movable portion of the slide 161. On its downward motion, the unit 20 
remains in contact with the surface of the cam lever 163 which controls 
the motion of the unit 20 until the unit 20 comes to rest against an 
adjustable stop 166 (shown in FIG. 1). A precise adjustment of the stop 
166 determines the lowest excursion of the unit 20 and, consequently, 
establishes the extent of engagement between the beam leads 49 of the chip 
12 and the adhesive dots 48 located on the peripheral embossment of the 
respective site 13. An insufficient downward excursion of the index wheel 
39 toward the chip 12 to be loaded may prevent a proper placement of the 
chip on the tape 14. On the other hand, an excessive excursion of the 
index wheel 39 toward the chip 12 might cause the beam leads 49 to be 
excessively deformed or damaged during the loading operation. A precise 
adjustment of the stop 166 is therefore important to the proper operation 
of the apparatus 11. Advantageously, a proper adjustment of the stop 166 
is, therefore, made prior to the continuous operation of the apparatus 11. 
To facilitate an adjustment of the stop 166, and also of the adjustment of 
the adhesive applicator 32 and the chip locating unit 30 with respect to 
the common centerline 33, two closed circuit television cameras are 
preferably mounted along axes 168 and 169 in the plane of rotation of the 
index wheel 39. The first camera, not shown, viewing the tape 14 along the 
axis 168, monitors the position of the adhesive dots in relation to the 
aperture 47 at each of the sites 13 in the tape. The second camera, not 
shown, viewing the tape 14 along the axis 169, monitors the position of 
the chip 12 within the aperture 47 of each of the sites. 
In addition to monitoring the position of the chip 12 within the aperture 
47, the second camera views the beam leads 49 to establish whether or not 
the downward excursion of the unit 20 is sufficient. The image of the 
second camera provides a view of the amount of engagement of the beam 
leads 49 with the adhesive dots 48. The vertical position of the stop 166 
may then be adjusted accordingly to obtain an optimum lowermost excursion 
of the unit 20. 
THE TIMING SEQUENCE 
Referring now to the timing diagram of FIG. 8, a cycle of operation is 
initiated by the chip supply unit 25. The chip transfer arm 107 moves 
initially from an "off" or rest position to the pickup position above the 
table 106. A chip is then transferred from the table 106 to the pedestal 
34. As the chip is deposited on the pedestal 34 for centering, the chip 
locating unit 30 and the tape transport and alignment unit 20 are 
triggered. 
Referring briefly to FIG. 7, the cam 75 of the locating unit 30 and the cam 
lever 163 are both driven by a power assembly 176 which includes a shaft 
177 mounted for rotation, a cam 178 to pivot the lever 163, and a slider 
crank mechanism 179 which imparts reciprocating motion through a 
connecting link 181 to the cam 75. The completion of a revolution of the 
assembly 176 completes an operational cycle of the apparatus 11. 
The index wheel 39 moves the site 13 into contact with the applicator 32 in 
the very beginning after the unit 20 starts its vertical reciprocation. As 
the unit 20 reciprocates, the chip 12 is also being aligned to the 
centerline 33. The alignment of the chip 12 extends in time beyond the 
application of the adhesive to the site 13. Also during the alignment of 
the chip 12, the table 106 is indexed to present the next chip 12 to the 
transfer arm 107 for pickup at the beginning of the next cycle. 
At the end of the alignment operation, the normally present low vacuum is 
switched to a high vacuum as the pedestal 34 is raised toward the transfer 
position above the surface of the block 67. In the meantime, the unit 20 
has reciprocated away from the applicator unit 15 and toward the pedestal 
34. During the loading of the chip 12 to the site 13 the high vacuum is 
turned off. 
After completion of the chip-loading contact with the pedestal 34, the unit 
reciprocates toward a neutral position near the applicator 32. During the 
movement toward the neutral position, a motor 183 is energized to operate 
the Geneva drive 123 and advance the index wheel 39 by one increment. 
Simultaneously with the indexing of the wheel 39, the cam 75 reaches a 
position where the air purge clears the cavity 68. Prior to the completion 
of the operational cycle, the cam 75 returns to a neutral position. Before 
reaching the neutral position the air purge is turned off and shortly 
thereafter the low vacuum is again applied to the pedestal 34 in 
preparation for the next cycle. 
Although the invention has been described herein with respect to a certain 
preferred embodiment as shown in the drawing, it is to be understood that 
the invention is not limited thereto. Modifications, additions and 
deletions are possible without departing from the spirit and scope of the 
invention.