US3453714A

US3453714A - Vacuum operated chip placement head

Info

Publication number: US3453714A
Application number: US615262A
Authority: US
Inventors: Kendall Clark; Thomas J Rajac; George R Santillo Jr; Walter J Schuelke
Original assignee: International Business Machines Corp
Current assignee: International Business Machines Corp
Priority date: 1967-02-10
Filing date: 1967-02-10
Publication date: 1969-07-08
Anticipated expiration: 1986-07-08

Description

July 8, 1969 K. CLARK ET AL VACUUM OPERATED CHIP PLACEMENT HEAD Sh'eet of '7 Original Filed May 27, 1 965 CHIP PLACEMENT STATION 34h CHIP T'BAR ORIENFOR 21 3 I L G M II. 1W 3 Fh 1 A m m m l m m v a n u 1 B w" W M h lliffi m w h W h 1 I o k m W W 4 W H w h 4 h 4 Q h 1 w. m l i; H m i1 1 s N FIG.

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Original Filed May 27, 1965 July 8, 1969 K, CLARK ETAL V VACUUM OPERATED CHIP PLACEMENT HEAD Sheet ,3 of 7 Original Filed May 27, 1965 K. CLARK ET AL VACUUM OPERATED CHIP PLACEMENT HEAD July 8, 1969 Sheet f of 7 Original Filed May 27, 1965 FIGJO A FIGJOA HOh y 1969 K. CLARK ET AL VACUUM OPERATED CHU PLACEMENT HEAD Sheet '5 of? OriginalFiled May 27 1965 VACUUM July 8, 1969 K. CLARK ET AL VACUUM OPERATED CHIP PLACEMENT HEAD Original Filed May 27, 1965 Sheet 4 017 Se N2 :26 52 52% Z inn. .5 E: E5 :2 E5

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United States Patent Int. Cl. B65g 65/00 US. Cl. 29-203 18 Claims ABSTRACT OF THE DISCLOSURE An article-handling apparatus having a head with pickup means for an article, such as a semiconductor chip, from a supply thereof, transporting it in an elevated position to a placement station at which it is lowered for deposit on a concurrently arriving new support, as for example on a conductive land pattern of a substrate. The pick-up means is provided with sensing means which detects for the presence of an article on the pick-up means to prevent the pickup from being lowered when an article is absent or dislodged from the pick-up means. Also included is a provision for preventing discharge of the support or substrate from the placement station when the pick-up means arrives without an article for deposit. The support or substrate remains at the station for the next cycle of the pick-up means. On deposit of an article (or chip) on the support (or substrate) the latter is permitted to be discharged and replaced by a new unit.

This application is a continuation of prior copending application, Ser. No. 459,340, filed May 27, 1965, now abandoned, entitled, Vacuum Operated Chip Placement Head, Kendall Clark et al.

This invention relates to semiconductor chip positioning machines and, more particularly, to a vacuum operated chip placement head usable therewith.

With the advent of hybrid transistor circuit technology, there arose more stringent requirements for precision, Speed and uniformity than had theretofore been achieved in the art of automated circuit manufacture. This hybrid technique involves first the screen printing of resistors and conductive lands on an alumina substrate. A layer of solder flux is then applied to the substrate and then transistors or diodes in the form of thin, square or rectangular semiconductor chips are positioned on to the lands, with the flux providing the necessary adhesive qualities to keep the chips in place. Because the chips are almost microscopic in size, each measuring .028 inch square, and are joined to the lands by contact elements in the form of copper balls which are only .005 inch in diameter, they cannot be handled by conventional automated assembly techniques. The problem was further complicated by the need for extreme accuracy and precision in positioning the chips on the relatively small and closely spaced conductive lands which are only .005 to .015 inch wide and .005 inch apart, as well as by the extreme delicacy of the structure involved. Furthermore, the vast number of circuit substrates required in the manufacture of each digital computer, which is at present the primary use for this hybrid circuit technology, demands that the chip positioning and placement operation be performed at relatively high speeds and with a high yield in order to maintain the high volume required in production.

In co-pending US. patent application 459,179, filed on even date herewith, May 27, 1965, entitled Chip Positioning Machine, by Clark et al. (IBM Docket 14,415), a machine capable of automatically preparing a sub- 3,453,714 Patented July 8, 1969 strate to receive semiconductor chips, placing the chips in place on the substrate, and testing for their proper placement is disclosed. In co-pending US. patent application 459,379, filed on even date herewith, May 27, 1965, now abandoned, entitled Semiconductor Chip Placement Head, by Clark et al., (IBM Docket 14,416) a semiconductor chip placement head usable with the aforesaid chip placement machine is described which sequentially picks up a chip from a vibratory feed bowl, senses the chips orientation, reorients the chip to a desired configuration, and places it upon the prefluxed substrate. The placement head basically comprises a plurality of vacuum needles which are selectively actuated to pick up and place the semiconductor chips. Two problems may occur in the operation of this head which serve to deteriorate both its own operation and its operation in combination with the overall chip positioning machine. First, if for some reason a chip is not picked up at the vibratory feed bowl, and the vacuum needle arrives at the chip placement station and is lowered into placement position, it may immerse itself in the substrates prefluxed surface. This obviously causes the vacuum needle to become clogged and useless during succeeding operations. The flux adhering to the vacuum needle also acts to adhere to anything which the needles contact thereby completely gumming up the machine. The second problem relates to the fact that the prefluxed substrates are continually being indexed past the placement station. Thus, if any vacuum needle comes down at the placement station without a semiconductor chip, and the substrate is allowed to continue on its travels, it is obviously a reject which. subtracts from the overall production capability of the machine.

Accordingly, it is an object of this invention to provide a highly reliable vacuum operated chip placement head.

It is a further object of this invention to provide a vacuum operated chip placement head with means to prevent vacuum needles from being emersed in the flux coating on prefluxed substrates.

It is still another object of this invention to provide a chip positioning head with means for indicating when no chip is carried at the end of a vacuum needle.

In accordance with the above stated objects, there is provided a multi-headed apparatus in which each head is adapted to transport a device from a. pick-up point to a placement point and deposit it at said placement point upon a coincidentally arriving prefluxed substrate, a new substrate presenting itself to the placement point coincidental with the arrival of each head. A vacuum pick-up means is associated with each head of the apparatus and is adapted to manifest a signal indicating whether or not it is carrying a device. An actuation means is associated with each head of the apparatus and. is responsive to a signal from the vacuum pick-up means that it is not carrying a semiconductor device, to raise the vacuum pick-up sufiiciently to prevent it from contacting the prefluxed substrate and thereby becoming clogged.

A switch actuating lever is also connected to the actuation means and is adapted to interact with a reset switch which, when closed, delays the departure of a substrate from the placement point. Control means couples the vacuum pick-up means with the actuation means on each head and is responsive to a signal from the vacuum pickup means that it is not carrying a semiconductor device to position the switch actuating lever to a switching interacting position. Thus, a substrate is delayed in its travel until a device bearing vacuum pick-up arrives at the placement point.

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings.

In the drawings:

FIG. 1 is a side elevation of the chip placement head.

FIG. 2 is a plan view of the chip placement head in combination with each of the specific stations associated therewith.

FIG. 3 is a partial sectional view of the chip blow-off mechanism.

FIG. 4 is an isometric view of a representative arm of the chip placement head showing details of the vacuum pin arrangement.

FIG. 5 is a section view of a representative arm of the chip placement head taken along line 5-5 in FIG. 2.

FIG. 6 is a view taken along line 6-6 in FIGS. 4 and 5 to show the superimposed positions of the vacuum distributor and vacuum manifold.

FIG. 6A is a section view showing a representative vacuum nozzle and portion of the vacuum manifold taken along line 6A6A.

FIG. 7 is a plan view of the vacuum distributor with the vacuum manifold removed.

FIG. 8 is a view of the bottom portion of the vacuum manifold which normally mates with the upper portion of the vacuum distributor.

FIG. 9 is a side elevation of the cam and drive mechanism which causes relative movement between the vacuum distributor and vacuum manifold.

FIG. 9A is a plan view of the mechanism of FIG. 9.

FIG. 10 is a complete section of a vacuum probe.

FIG. 10A is a view of a vacuum probe taken along line 10A10A.

FIG. 11 is a timing chart helpful in understanding the operation of the chip placement head.

FIGS. 11A11D are line drawings showing the relative positions of the vacuum manifold and the vacuum distributor at discrete times during the operation of the chip placement head.

Chip placement head Referring now to FIGS. 1 and 2, chip placement head 17 includes eight stations, four of which are idle and four of which perform specific functions in regard to feeding, orienting and placing the transistor chips in their proper position upon a substrate. The major moving part of chip placement head 17 is spider 30h which is provided with eight radial arms, each of which supports a vacuum needle 18. Each vacuum needle 18 is adapted to pick up a transistor chip, transport it between stations, and place it in its proper position upon a prefluxed substrate. The spider is actuated by an index mechanism to be described hereinbelow. Prior to each arm of the spider reaching a station, the entire mechanism is in an elevated position to allow the needle to clear obstructions between stations. Upon arriving at the stations, the spider is lowered by the indexing mechanism and lower the vacuum needles into the respective stations. At the termination of the stations operations, the indexing mechanism raises the spider and rotates the spider arm to succeeding stations.

Before proceeding to a more detailed description of chip placement head 17, the following summary of operations performed at each of the stations will aid in understanding the operation of the system. The ultimate purpose of chip placement head 17 is to provide a transistor chip at placement station 34h (FIG. 2) with its copper ball contacts oriented in such a manner as to exactly mate with the dimple pattern on the substrate land configuration, and deposit the chip in place upon the substrate at the correct time. To accomplish this function, vibratory feed bowl 19 performs the function of providing chips to a chip pick-up station 32b in a queued-up ball-contact down configuration. While the ultimate desire is to place each semiconductor chip on a substrate, this cannot be done unless the chips ball-contacts are arranged to precisely mate with the substrate dimpled land pattern. Vibratory feedbowl 19 is incapable of assuring this required preset orien- 4 tation. Accordingly, a vacuum needle 18 picks up a chip at pick-up station 32b and carries it to chip orientation sensor 20. Upon receiving a semiconductor chip, chip orientation sensor 20 performs two functions. First, a pair of guide jaws within the sensor 20- precisely locate the chip with respect to the tip of vacuum needle 18. In addition, when vacuum needle 18 inserts a chip in the ballcontacts down orientation into chip orientation sensor 20, an oddly placed ball-contact acts to deflect a lever arm thereby providing an indication of the chips orientation. A signal is produced indicating the sensed orientation and is transmitted to chip T-bar orientor 21. The T-bar orientor responds to the signal by pre-rotating to a position where its T-bar head will mate with the ball contact pattern. The aforemenioned guide jaws are opened and the chip is readied for the next index step. When vacuum needle 18 and its associated chip are next indexed to T-bar orientor station 21, the vacuum needle places the chip upon a rotatable T-bar which as aforestated has been prerotated to fit within the interior of the chips contact pattern. The T-bar orientor 21 then rotates the chip on the end of vacuum needle 18 to the correct orientation for placement. In addition to correcting the angular orientation of the chip, the mating of the T-bar with the contact pattern of the chip provides a final precise orientation of the chip and assures that its contacts will exactly mate with the substrate dimple pattern. Vacuum needle 18 and its associated chip is then indexed through an idle station to chip placement station 34h where it is placed upon a prefl-uxed substrate borne by a conveyor tape (not shown).

In addition to the above-described stations, chip placement head 17 is provided with blow-off mechanism 27h and a recycle switch VD1. Blow-off mechanism 27h is positioned intermediate chip orientation sensor 20 and chip T-bar orientor 21. Blow-off mechanism 27h is shOWn in section in FIG. 3 and comprises an airblast head 31h and an operatively disposed channel 33h which leads to a receptacle. Blow-off station 27h is so positioned that during the indexing of a vacuum needle from chip orientation sensor 20 to chip T-bar orientor 21, the needle tip and its associated semiconductor chip pass directly between airblast head 31h and channel 33h. If for any reason chip orientation sensor 20 provides an output which is indicative of a malformed chip, a chip held on end, a chip with insufilcient ball-contacts, etc., it energizes a logic circuit which causes a blast of air to be applied to head 31h. This airblast is sufiicient to dislodge a chip from the tip of a vacuum needle and cause it to enter channel 33h to the receptacle.

Recycle switch VD1 (FIG. 1) is basically a microswitch with a downwardly extending switch actuating lever 35h. Its operation in combination with other portions of chip placement head 17 will be described in greater detail hereinafter.

The main drive for chip placement head 17 comes from shaft 26 which feeds directly into head indexing mechanism h. This mechanism is described in greater detail hereinafter, but for the time being it will sufiice to say that the mechanism provides an indexing drive motion via shaft 40h to spider h. It also provides a required vertical displacement of shaft h and spider 30h during the time when vacuum needles 18 are being indexed between stations (to prevent damage to the needle tips). As shown in FIG. 5, shaft 40h has a threaded portion which threads into interior threads in bushing 42h. Clamp 44h prevents rotary movement between shaft 4011 and bushing 42h once the desired orientation between them has been established. Clamp 44h is tightened by virtue of a bolt which extends through hole 45h. Bushing 42h is shrunk to fit into spider collar 46h to prevent any relative movement therebetween. A centering plate and shaft 48h are rigidly affixed to spider collar 46h via a plurality of set screws. Vacuum distributor 50h fits down over the centering shaft 48h and provides the means for distributing both vacuum and positive air pressure to the respective arms of spider 30h. Directly over and mating with distributor 50/1 is vacuum manifold 52h which provides the function of supplying and switching vacuum and positive air pressure between various ones of the outputs of distributor 50h. Distributor 50/1 is rigidly affixed to and rotates with spider collar 46h by virtue of pins 54/1 which extend through centering plate 48/1, bushing 42h and into collar 46h. A manifold top plate 56h fits directly over manifold 52h and is afiixed thereto by set screws. Retaining plates 58h fit down over shaft 48h and rigidly force manifold 52h to bear against distributor 50/1 and provide an airtight seal therebetween. A bushing 60h is rigidly attached to the side of manifold top plate 5611 by set screw 62h. The relative position of vacuum manifold 52h with respect to vacuum distributor 50h can be varied by causing a force to be applied to bushing 60/1 thereby causing a rotation of manifold top plate 56h and manifold 52/1 about centering plate shaft 48h. The specific operation of this apparatus will be described in detail hereinafter.

Since each arm of spider 30h is structurally identical, only one need be explained. An isometric view of one arm is shown in FIG. 4 and the same arm in section is shown in FIG. 5. Spider arm 30h has an enlarged and slotted end portion 60h with a vertical hole drilled therethrough which is adapted to accommodate a vacuum needle holding fixture 62h. Fixture 62h comprises a round portion of bar stock 64/1 which has been slotted to accommodate vacuum needle 18. A cap 66h is attached to bar stock portion 64/1. The center line of bar stock portion 64h falls to the right of the end of enlarged portion 60h of spider arm 30h. If it is thus desired to adjust the exact location of vacuum needle 32/1, cap 66h may be grasped and rotated with a resultant lateral movement of vacuum needle 18 occurring due to the offset between the center line of bar member 64/1 and the enlarged end 60h. When set screw 68h is tightened, it draws the slotted portions of enlarged member 60h together, thereby gripping vacuum probe holding fixture 62h and preventing any further lateral movement thereof. Vacuum needle 18 is slidably mounted in necked cylinder 70h which is in turn held to vacuum probe holding fixture 62h by spring clip 72h.

The structure of a vacuum needle 18 is shown in FIG. 10. Outer housing 90h is a hollow tube with one closedoif end. At the upper extremity of housing 90h, a downward limiting stop 92h and slotted nut 94h are attached. Interior to housing 90h is a fixed bushing 96h which has slidably mounted therein hollow probe pin 98h. Attached to one end of probe pin 98h is an extended diameter collar 100h. A compression spring 102h bears down upon extended collar 100k and acts to maintain probe pin 98h in a downwardly extended position. Extending through housing 90h are a pair of tubes 104h and 106'h. It should be noted that bushing 96h is attached to the inner surface of housing 90h only below the entry point of tubes 104h and 106k. Above their attachment point, there is a clearance space between housing 90h and the outer circumference of bushing 96h. Thus, if a vacuum is applied to tube 104k, not only will air be drawn up through probe pin 98h and down through the clearance area between bushing 96h and probe body 90h, but also, air will be drawn into tube 106h, around bushing 96h and into tube 104h. Thus, if a vacuum is applied to tube 104/1 and there is a semiconductor chip held at the end of probe pin 98h, all of the air drawn through vacuum needle 18 must come via tube 106h. If on the other hand, there is no chip held by probe pin 98h, a significant portion of the air drawn into tube 4h will be drawn through probe pin 98h thereby considerably reducing the vacuum applied via tube 106h. As will become hereafter apparent, this fact is utilized to control the recycle actuating mechanism.

An adjustable stop 110/1 surrounds housing 90h and provides a lower limiting stop for the travel of vacuum needle 18. FIG. 10A better shows the details of stop 110h. By causing nut =112h to be loosened, stop 11% may be moved either up or down on housing 90h. As can be seen by examining FIG. 55 of the aforesaid copending application Serial No. 459,379, vibratory feed bowl 19 has a stop normally associated therewith. When vacuum probe 32h. is lowered into feed bowl 19, stop h is adjusted to impact with the stop to prevent the tip of probe pin 98/1 from touching the surface of a semiconductor chip and thereby being damaged.

Returning now to FIG. 4, hose /1 connects tube 104h to a vacuum outlet nozzle 230/1 from vacuum distributor 50h. A filtering agent 124h is shown in a cutaway portion of hole 120k and prevents debris from being drawn up into the vacuum mechanism. An additional hose 126h connects tube 106/1 to the recycle lever actuation mechanism via vacuum port 128h. A constrictor 127/1 is inserted into hose 127h for a purpose to be hereafter discussed.

The purpose of the recycle lever actuation mechanism is twofold. It is basically a pneumatic logic element which reacts to the absence of a semiconductor chip at the tip of a vacuum needle by (1) raising the vacuum needle and (2) raising the switch actuating lever so that it may engage the recycle switch. The recycle lever actuation mechanism is supported by a vertically disposed housing 13% which is rigidly afiixed to spider arm 30h. Pivotally mounted on the upper extended portion of vertical housing 130/1 is recycle actuation lever 132h. As can be more clearly seen in FIG. 5, a screw is threaded through recycle actuation lever 132h and is held in place by nut 136h. A hollow hex-head screw 138 h is threaded into the extended portion of vertical housing 130/1 and forms the guide for a slidably mounted push pin 140/1. Push pin 140/1 rests at its lower extremity upon impeller 142h. The lower portion of impeller 142h is threaded and extends through washer 144k, and diaphragm 146h to a diaphragm hold plate 148/1. A guide pin 150h is attached to and points downwardly from diaphragm hold plate 148/1. A bushing 152/1 is threaded onto the threaded portion of impeller 142/1 and holds Washer 144h, diaphragm 146k and diaphragm hold plate 148h in a sandwich-like configuration. The outer circumference of diaphragm 146/1 is clamped between members 15% and 156/1. Member 156/1 has an orifice 157/1 which houses compression spring 160/1. A communicating orifice 162k connects to vacuum port 128h and hose 126h.

A leaf spring /1 is restrained at one end by a nut and shaft arrangement 172/1. Compression spring 174h allows leaf spring 170h to pivot in the plane of the paper while maintaining it in its indicated position. A clearance hole 176h in leaf spring 170h mates with impeller 142h and locking pin 178/1 holds leaf spring 170/1 against bushing 152h. At its far extremity (see FIG. 4), leaf spring 170/1 is arranged to lock with slotted nut 94h via its separated arms h and 192h. Arm 194/1 bears upon the upper portion of slotted nut 94h.

In brief, the actuation of recycle lever 132h causes it to be tilted upwardly so that its end engages the downwardly extending arm 35h of recycle switch VD1 ('FIG. 1). This indicates to the machine that no semiconductor chip is held by the tip of the associated vacuum needle and that when the placement operation occurs with this respective vacuum needle, that the conveyor tape must be held in place until the next vacuum needle is indexed into the chip placement station 34h. If this does not occur, the substrate which arrives at the chip placement station at the same time with the particular needle without a chip arrives, the substrate will obviously have no chip placed thereon and will be defective. At the same time lever 132h is raised, leaf spring 170h also raises vacuum needle -18 and prevents it from being immersed in the prefluxe-d surface of the substrate at chip placement station 34h. This action thereby prevents the needle from being clogged and carrying the flux to other portions of the chip placement head. It is vitally important in the operation of this machinery that no flux enter any portions thereof.

In the detailed description of the operation of recycle lever actuation mechanism which follows, FIGS. 4 and 5 will be primarily referred to. When spider arm h arrives at chip pickup station 3211 it is lowered into place over the station through the action of the spiders movement. Stop 110/1 engages stop b in vibratory bowl 19 and causes leaf spring 170/1 to be flexed upwardly thereby preventing any vacuum needle bounce. At this time, no vacuum is applied via tube 120/1 to vacuum needle 18. In the recycle lever actuating mechanism, compression spring 160/1 pushes diaphragm 146/1 upwardly until washer 144/1 engages the bottom of member 154/1. Impeller 142/1 is thus also moved upwardly and push pin 140/1 bearing against threaded screw 134/1 causes recycle lever 132/1 to be tilted upwardly (as shown in phantom in FIG. 4).

When vacuum needle 18 is placed over chip pickup station 36h, a vacuum is applied via hose 120h to the needle. The air which is thus caused to be drawn up through probe pin 98/1 (FIG. 10) picks up a semiconductor chip and causes the tip of probe pin 98/1 to be sealed. The vacuum applied via hose 120/1 must thereby be satisfied by' the air flow through hose 12 6/1. The increased vacuum in hose 126k is reflected into orifice 157k in the recycle lever actuation mechanism via port 12811 and orifice 162/1. The increased vacuum opposes the action of compression spring 160/1 and thereby brings diaphragm 146/1 down to the unstressed position shown in FIG. 5. Note that diaphragm 146/1 completely seals the vacuum system from the atmosphere and so long as a significant vacuum is applied via hose 126/1 diaphragm 146/1 will remain in its indicated position. When diaphragm 146/1 is drawn downwardly by the applied vacuum, the impeller 142/1 and push pin 140/1 are also drawn down with the result being that recycle actuation lever 132/1 is lowered to the horizontal position.

Immediately after a chip is picked up by vacuum needle '18 the amount of vacuum applied to tube 120/1 is somewhat lowered by vacuum manifold 52/1 (in a manner to be described hereinafter), but so long as a chip remains on the tip of probe pin 98/1, the vacuum reflected through hose 126/1 is sufiicient to overcome spring 160/1 and maintain diaphragm 146/1 in its unstressed position.

Should it occur that no semiconductor chip is picked up at chip pickup station 136k or, that during the indexing operation of the chip placement head, the chip is dislodged from the tip of probe pin 98/1 (e.g. by chip blowoff mechanism 27/1), the following action occurs. The aforementioned reduced vacuum which was applied immediately after vacuum probe 32/1 left chip pickup station 36/1 is of sufiicient quantity to maintain diaphragm 146/1 in its unstressed position only so long as the tip of probe pin 98/1 is sealed. If for any reason a semiconductor chip is dislodged therefrom, the resulting reduction in vacuum through hose 126/1 allows compression spring 160/1 to expand and raise diaphragm 146/1 to a point where washer 144/1 bears against the bottom of member 154/1. This action, through the aforedescribed mechanism, causes leaf spring 170h to raise thereby raising vacuum needle 18 and also raises recycle lever 132/1 to its tilted position. Thus, when this particular vacuum needle leaves the chip T-bar orientor 21, the tilted portion of recycle lever 132/1 engages arm 35/1 of recycle switch VD1 (FIG. 1). The actuation of recycle switch VD1 inhibits the indexing of the conveyor tape for one cycle and allows a substrate on the tape to await the arrival of the following vacuum needle. The action of leaf spring 170/1 in raising vacuum probe 32/1 prevents the tip of probe pin 98/1 from being dipped into the flux on the surface of the positioned substrate, thereby preventing it from being clogged.

With reference now to FIGS. 6 to 8, vacuum manifold 52/1 and distributor /1 will be described. In FIG. 6, vacuum manifold 52/1 is shown in place over vacuum distributor 50h. The center shaft of centering plate 48/1 extends up through and aligns vacuum distributor 50/1 and vacuum manifold 52/1 with each other. To better visualize the structure of vacuum distributor 50h, refer to FIG. 7 where it alone is shown. A plurality of threaded fittings 200/1 are provided therein and adapted to accept vacuum nozzles (to be hereinafter described). Each threaded fitting is provided with two holes 202/1 and 204/1 both of which communicate with the upper surface of vacuum distributor 50/1. Turning now to FIG. 8, a vacuum manifold 52/1 has been flipped over to show its underside which normally mates with the upper side of vacuum distributor 50/1. Vacuum manifold 52h is provided with two inlet fittings, fitting 206k being utilized to provide vacuum and fitting 208h being utilized to provide pressurized air. Vacuum fitting 206/1 is provided with a hole 210k which communicates with a semicircular indented channel 212/1. At one extremity, indented channel 212k is provided with a perpendicular leg 213/1. Air inlet 208/1 is also provided with a hole 214/1 which communicates with the surface of vacuum manifold 52h. An atmospheric inlet 216/1 is also formed into the surface of vacuum manifold 52/1.

Referring now back to FIG. 6, the relative positions of the air and vacuum inlets 206/1 and 208/1 respectively are shown as is also hte location of channels 2121/1 with respect to holes 204k. Note that hole 202h only has vacuum applied to it when it is coincidently positioned with perpendicular vacuum channel 213h. Note also that hole 214/1 in an inlet 208h is coincident with hole 202/1 in vacuum fitting 215/1 when both the air inlet and fitting are aligned.

Referring to FIG. 6A, a sectional view of a representative vacuum nozzle 230/1 in place in a vacuum fitting in vacuum distributor 50h is shown. When nozzle 230/1 is inserted into the vacuum fitting and tightened down, it compresses 0 rings 232/1 and 23401 to provide airtight seals. Hole 236/1 provides communication between the interior hollow section of nozzle 230/1 and hole 202/1 in vacuum distributor 50/1. An additional smaller diameter hole 238/1 is drilled in aligning pin 240/1 and opens the interior of nozzle 230/1 to hole 204/1 in vacuum distributor 50/1. With vacuum manifold 52/1 in place as shown, perpendicular channel 213/1 communicates with both holes 202k and 204/1. Thus, if a vacuum is applied via vacuum inlet 208/1, air may be drawn through both holes 236/1 and 238k and 202/1 and 204/1 respectively, to create a substantial vacuum at the outlet of vacuum nozzle 230/1. If now, vacuum manifold 521/1 is rotated with respect to vacuum distributor 50/1 allowing only hole 204/1 to communicate with vacuum channel 212/1, a metered vacuum is applied via hole 238/1 to vacuum nozzle 230/1. This is the same reduced vacuum referred to hereinbefore which is applied to vacuum needle immediately after it leavs pickup station 32b.

Referring now to FIGS. 9 and 9A, the means for providing controlled relative movement between vacuum manifold 521 1 and vacuum distributor 50/1 will be described. Cam 300/1 is mounted on shaft 26 and makes a single revolution for each index of chip placement head 17. Cam 300/1 is provided with a high dwell which extends between 275 degrees65 degrees and a low dwell which extends from degrees-230 degrees. From 230 degrees to 275 degrees is a relative steep rise to the high dwell, whereas from 65 degrees-155 degrees is a relatively grad ual slope to the low dwell. Follower 302/1 is coupled to arm 304/1 which is in turn rigidly afiixed to shaft 306/1. Also rigidly affixed to shaft 306/1 is vertical arm 308/1 which terminates in ball joint 3101 1 (not shown in FIG. 9A). A threaded screw 332/1 is mounted on 308/1 and engages fixed stop 334/1 to provide a forward limit to the movement of arms 308k. Emanating from ball joint 310/1 in a generally horizontal direction is manifold actuating arm 312/1. The other extremity of arm 312/1 terminates in a bearing 3141/1 which is rotatably mounted via pin 316/1 to dis 318/1. Extending downwardly from, and rigidly aflixed to disc 318h, is camming bar 320/1 which engages the bearing surface of nut 62/1. Also attached to disc 31811 is a preloading spring 322k. Disc 9 318h is mounted to rotate about shaft 32412 which is anchored in a portion of frame 326h. Also forming a portion of frame 326h (FIG. 9A) are pressurized air inlets 328h and vacuum inlet 330k.

As cam 300k rotates, follower 302h rises up on the high dwell and causes arms 304h to rotate in a counter clockwise direction. This rotation imparts a like rotation to arm 308h which draws manifold actuating arms 312h to the left. This in turn causes a clockwise rotation of disc 318h which is transmitted to manifold top plate 56h via camming bar 320h and nut 62h. This action causes a relative clockwise rotation to occur between manifold 52h and distributor 50th and results in a movement of the relative positions of the vacuum channel and communicating holes respectively contained therein.

Referring now to FIGS. 11 and 11A and B, the complete operation of chip placement head 17 will be described. Before proceeding, however, it should be noted that in FIGS. 11A and B, each of the eight arms (a-h) of spider 3012 is represented by a straight line and each of the patricular stations is located as shown. Each straight line also denotes the location of the vacuum distributor nozzle associated with a respective spider arm. Superimposed on the line drowing is a representation of vacuum channel 212h and pressurized air hole 214h as they are both contained in vacuum manifold 52h. For purposes of explanation, only spider arm H will be hereinafter discussed. In FIG. 11, to which reference is now made, the horizontal axis is plotted in degrees of rotation of index shaft 26. The bars running horizontally in the figure are indicative of the actions at each station as well as the actions of the various portions of chip placement head 17.

Assuming now that index shaft 26 is at 170 degrees, index mechanism 25h has just lowered the spider down to its low dwell and spider arm H is positioned directly over chip pickup station 32b. The stop on vacuum needle 18 is an engagement with the stop in vibratory feed bowl 19 and all is in readiness for a chip pickup operation to occur. Shaft 26 continues to rotate and at 230 degrees, cam 300h (FIG. 9) begins to cause follower 302h to rise towards the high dwell. This, in the course of events, causes a clockwise rotation to occur in disc 318k with a like rotation occurring in vacuum manifold 52h. Thus, manifold 52h begins a clockwise rotation of 22 /2 degrees with respect to vacuum distributor 52h, causing vacuum channel 212h to also rotate clockwise. At approximately 245 degrees, vacuum channel 212k loses communication with vacuum hole 204h associated with spider arm D. Substantially simultaneously, positive pressurized air hole 214h is positioned over hole 202/1 and causes a flow of pressurized air therethrough. Since at this time, spider arm D is directly over the prefluxed substrate at placement station 34h, the puff of pressurized air is transmitted to vacuum needle 18 via hose 120h (FIG. 4) and positively pushes the chip down onto the fluxed surface of the substrate thereby assuring a positive connection therebetween. At this point restrictor 127h in hose 126h comes into play and delays the amount of the puff of pressurized air to the recycle lever actuation mechanism. This allows the chip to be set before the pressurized air causes the actuation of the recycle lever mechanism via diaphragm 146h. At 275 degrees (FIG. 11B) perpendicular vacuum channel 21311 is in full communication with

holes

202h and 204h of vacuum nozzle 230k associated with spider arm H. This applies a full vacuum to the associated vacuum needle 18 and causes a chip to be drawn up to the end of probe pin 98h. The application of the full vacuum to the vacuum needle acts to draw diaphragm 146h to its nonstressed position whether there is a chip present at chip pickup station 32b or not.

When shaft 26 and cam 300h reach approximately 325 degrees, index mechanism 25h raises the spider and begins to rotate it and vacuum distributor 50h in a counterclockwise direction. Vacuum manifold 52h does not change position, however, since came follower 302/2 is still riding on the high dwell of cam 300k. As can be seen from FIG. 11C, spider arm H has only hole 204h communicating with vacuum channel 213h. This relative rotation results in metered vacuum being applied via hold 204h to the vacuum needle on spider arm H. It is at this time that the operation of the recycle lever actuation mechanism occurs if no chip was picked up at chip pickup station 32b. As will be recalled, the metered vacuum which passes through hole 204h is suflicient to maintain diaphragm 146h in its nonstressed position only if a chip seals the bottom of probe pin 98h. If no chip has been picked up, recycle actuation lever 132/1 is tilted to interact with recycle switch lever 35h. At 65 degrees each arm of spider 30h is halfway between stations (FIG. 11C). At this point, follower 302h enters the gradual fall on cam 300h to the low dwell. Thus, vacuum manifold 52h begins to rotate in a counter-clockwise direction back to its original position. The combined rotations of vacuum manifold 52h and spider 30h continue until at degrees (FIG. 11D) follower 302k reaches the low dwell of cam 300h, at which point the rotation of vacuum manifold 52h ceases. As can be seenfrom FIG. 11, spider 30h is at this point in the middle of its downward travel in preparation for the next cycle of operation.

In FIG. 11D, the positioning of the various spider arms A-H at the end of the cycle is indicated. The next cycle commences immediately after the operations at each of the respective stations.

What is claimed is:

1. In a multi-headed apparatus each head adapted to transport a device from a pick-up point to a placement point and deposit it at said placement point upon a coincidently arriving substrate, a new substrate normally presenting itself to said placement point coincidently with the arrival of each head, the combination comprising:

switch means positioned between said pick-up and said placement points for delaying the departure of a substrate from said placement point;

device pick-up means associated with each head of said apparatus said pick-up means adapted to manifest a signal indicating whether or not it is carrying a device; switch actuating means associated with each head of said apparatus, said actuating means adapted to be positioned to interact with said switch means; and

control means coupling the device pick-up means and the switch actuating means on each head, said control means responsive to a signal manifesting the fact that said device pick-up means is not carrying a device, to position said actuating means to its switch interacting position;

whereby said substrate is delayed in its travel until a device-bearing pick-up means arrives: at said placement point.

2. The invention defined in claim 1 further including means coupling said device pick-up meansto said switch actuating means for retracting said device pick-up means in response to the positioning of said switch actuating means to its switch interacting position to a position which prevents it from contacting a substrate at said placement point.

3. In a multi-headed apparatus each head adapted to transport a semiconductor device from a pick-up point to a placement point and deposit it at said placement point upon a coincidently arriving substrate, a new substrate, normally presenting itself to said placement point coincidently with the arrival of each head, the combination comprising:

recycle switch means positioned between said pick-up and said placement points for delaying the departure of a substrate at said placement point;

a source of vacuum;

vacuum pick-up means associated with each head of said apparatus, each said pick-up means connected to said vacuum source and provided with an output which manifests a vacuum signal indicating whether or not said pick-up means is carrying a semiconductor device;

recycle switch actuating means associated with each head of said apparatus, said actuating means adapted to be positioned to interact with said recycle switch means; and

control means coupling said pick-up means output with the recycle switch actuating means on each head, said control means responsive to a change in vacuum signal manifesting the fact that said pick-up means is not carrying a semiconductor device to position said actuating means to its recycle switch interacting position;

whereby said substrate is delayed in its travel until a semiconductor device-bearing pick-up means arrives at said placement point.

4. The invention as defined in claim 3 wherein said control means comprises:

a diaphragm;

a shaft connecting said diaphragm to said recycle switch actuating means;

resilient means coupled to said diaphragm for biasing said diaphragm and shaft to cause said recycle switch actuating means to be in its recycle switch interacting position;

a vacuum connection between the output of said vacuum pick-up and said diaphragm, the vacuum applied therethrough when said vacuum pick-up means is carrying a semiconductor device being sufficient to overcome the action of said resilient means and to return said recycle switch actuating means to a position where it does not interact with said recycle switch means.

5. The invention as defined in claim 4 further includleaf spring means coupling said shaft to said vacuum pick-up means, said spring means responsive to the biasing of said shaft to raise said vacuum pick-up means to a position Where it is prevented from contacting a substrate at said placement point.

6. The invention as claimed in claim 4 wherein said vacuum pick-up means comprises:

a vacuum inlet connected to said source of vacuum;

a resilient tube, one end of which communicates with said vacuum inlet, and the other end of which is adapted to contact and be sealed by a semiconductor device;

a vacuum output, communicating with said vacuum inlet, the vacuum at said output being greatest when a semiconductor device contacts and seals said other end of said tube, the absence of a semiconductor device at said other end of said tube allowing air to be drawn u into said tube which thereby lowers the vacuum at said output.

7. In a multi-headed chip handling apparatus, each head adapted to transport a semiconductor chip from the pick-up point to a placement point and deposit it at said placement point upon a coincidently arriving prefluxed substrate, a new substrate normally presenting itself to said placement point coincidental with the arrival of each head, the combination comprising:

a recycle switch positioned between said pick-up and said placement points for delaying the departure of the substrate from said placement point;

a vacuum pick-up needle attached at an extremity of each head of said apparatus, said vacuum needle having a vacuum inlet, a vacuum outlet communicating with said inlet, and a resiliently mounted tube, one end of which communicates with said vacuum inlet and the other end of which is adapted to contact and be sealed by a held semiconductor chip, said vacuum outlet adapted to provide to substantially 12 lessened vacuum when no chip is held by said resilient tube;

a diaphragm connected to said vacuum outlet;

a recycle switch actuation lever operatively connected to said diaphragm;

a spring coupled to said diaphragm for moving said diaphragm to a stressed position, the action of said spring being normally overcome by the vacuum applied via said vacuum outlet except when no chip is held by said resiliently mounted tube, at which time said spring moves said diaphragm and actuation lever to its recycle switch engaging position.

8. In a multi-headed apparatus, each head adapted to transport a semiconductor device from a pick-up point to a placement point and deposit it at said placement point upon a coincidently arriving prefluxed substrate, a new substrate normally presenting itself to said placement point coincidently with the arrival of each head, the combination comprising:

vacuum pick-up means associated with each head of said apparatus said pick-up means adapted to manifest a signal indicating whether or not it is carrying a device;

actuation means associated with each head of said apparatus and responsive to a signal from said pick-up means that it is not carrying a semiconductor device to raise said vacuum pick-up sufi'iciently to prevent it from contacting said prefluxed substrate and becoming clogged.

9. In a multi-headed apparatus, each head adapted to transport a semiconductor device from a pick-up point to a placement point and deposit it at said placement point upon a coincidently arriving prefiuxed substrate, a new substrate normally presenting itself to said placement point coincidently with the arrival of each head, the combination comprising:

vacuum pick-up means associated with each head of said apparatus said pick-up means provided with a vacuum outlet and adapted to manifest a reduction in vacuum at said outlet indicating that it is not carrying a device;

spring biased actuation means associated with each vacuum pick-up means of said apparatus said actuation means connected to said vacuum outlet and normally held inactive by the vacuum from said outlet, said reduction in vacuum at said outlet allowing said spring bias to actuate said actuation means and raise said vacuum pick-up sufficiently to prevent it from contacting said prefluxed substrate and becoming clogged.

10. In a multi-headed apparatus, each head adapted to transport a semiconductor device from a pick-up point to a placement point and deposit it at said placement point upon a coincidently arriving prefluxed substrate, a new substrate normally presenting itself to said placement point coincidently with the arrival of each head, the combination comprising:

a source of vacuum;

a vacuum pick-up means including a vacuum inlet connected to said source of vacuum, a resiliently mounted tube, one end of which communicates with said vacuum inlet, and the other end of which is adapted to contact and be sealed by a semiconductor device;

a vacuum output, communicating with said vacuum inlet, the vacuum at said output being greatest when a semiconductor device contacts and seals said other end of said tube, the absence of a semiconductor device at said other end of said tube allowing air to be drawn up into said tube which thereby lowers the vacuum at said output;

a diaphragm;

a leaf spring having one end coupled to said vacuum pick-up and another end to a pivot point;

a shaft connecting said diaphragm to a point between said ends of said leaf spring;

a compression spring coupled to said diaphragm for biasing said diaphragm, shaft, leaf spring and vacuum pick-up means to their upper limit of travel, the tip of said vacuum pick-up being thereby prevented from contacting said prefluxed substrate at said placement point;

a vacuum connection between the output of said vacuum pick-up and said diaphragm, the vacuum applied therethrough when said vacuum pick-up means is carrying a semiconductor device being sufiicient to overcome the action of said compression spring to return said diaphragm, shaft, leaf spring and vacuum pick-up means to their lowermost point of travel.

11. The invention as defined in claim further including:

a source of pressurized air;

a restrictor air delay connected in said vacuum output;

switchable means connecting both said source of pressurized air and said source of vacuum to said vacuum pick-up means;

means for actuating said switchable means when said vacuum pick-up means is positioned at said placement point, said switchable means being actuated to apply said pressurized air to said vacuum pickup means to push said chip from said pick-up means onto said substrate, said restrictor air delay acting to delay the application of said pressurized air to said diaphragm until said chip has left said vacuum pickup means.

12. In a feed mechanism having a head adapted to transport an article from a pick-up point to a placement point and deposit it on a support which is automatically fed from a supply thereof one-by-one to said placement point and having means for subsequent discharge of said support from said placement point with a new support fed to said placement point upon the said discharge of the first said support, the combination comprising:

retention means operatively associated to said placement point and adapted upon activation thereof for preventing the said discharge of the first said support;

means associated with said head to pick-up said article from a supply thereof for said transfer between said pick-up point and said placement point;

sensing means cooperatively associated with said pick-up means and adapted to provide a signal indicating Whether or not said pick-up means is carrying said article; and

actuating means responsive to said sensing means for activating said retention means in response to a signal indicating that said pick-up means is not carrying said article thereby preventing discharge of the first said support from said placement point.

13. In a feed mechanism having a head adapted to transport a semiconductor device from a pick-up point to a placement point and deposit it on a substrate which is automatically fed from a supply thereof one-by-one to said placement point, and having a means for a subsequent discharge of said substrate from said placement point with a new substrate fed to said placement point upon the said discharge of the first said substrate, the combination comprising:

retention means operatively connected to said placement point and adapted upon activation thereof for preventing the said discharge of the first said substrate;

means associated with said head to pick-up said device from a supply thereof for said transport between said pick-up point and said placement point;

sensing means cooperatively associated with said pick-up means and adapted to provide a signal indicating whether or not said pick-up means is carrying said device; and

actuating means responsive to said sensing means for activating said retention means in response to a signal indicating that said pick-up means is not carrying said device there-by preventing the discharge of the first said substrate from said placement point.

14. In a multi-headed apparatus each head adapted to transport a device from a pick-up point to a placement point and deposit it on a substrate which is automatically fed one-by-one from a supply thereof and having means for subsequent discharge of said substrate from said place ment point with a new substrate fed] to said placement point upon discharge of the first said substrate in timed relationship with the arrival of a succeeding head of said mechanism carrying a second said device, the combination comprising:

retention means operatively connected to said placement point and adapted upon activation thereof for preventing the said discharge of the first said substrate; means associated with each said head to pick up said device from a supply thereof for the said transport between said pick-up and said placement point;

sensing means cooperatively associated with each said pick-up means and adapted to provide a signal indicating whether or not said pick-up means is carrying a device during the said transport movement thereof;

an actuating means responsive to said sensing means for activating said retention means in response to a signal indicating that said pick-up means is not carrying a device during the said transport thereof thereby preventing the discharge of said substrate from said placement point until a device bearing pick-up means arrives at said placement point.

15. In a feed mechanism having a head adapted to transport an article from a pick-up point to a placement point and deposit it on a support, the: combination comprising:

means associated with said head to pick-up said article from a supply thereof for said transfer between said pick-up point and said placement point, with said pick-up means mounted reciprocable movement between a retracted inoperative position and an extended operative position wherein said operative position is adapted for the said deposit of said article on said support and wherein said pick-up means is normally disposed in the said retracted inoperative position;

sensing means cooperatively associated with said pickup means and adapted to provide a signal indicating whether or not said pick-up means is carrying an article; and

actuation means operatively associated with said pickup means and responsive to said sensing means on a signal therefrom, that said pick-up means is carry- 1 ing an article, to orientate said pick-up means in the said extended operative position,

16. In a feed mechanism having a head adapted to transport a semiconductor device from a pick-up point to a placement point and deposit it on a substrate, the combination comprising:

pick-up means associated with said head to pick up said device from a supply thereof for said transfer between said pick-up point and said placement point, with said pick-up means mounted for reciprocable movement between a retracted inoperative position and an extended operative position with said operative position adapted for the said deposit of said device on said substrate and wherein said pick-up means is normally disposed in the said retracted inoperative position;

sensing means cooperatively associated with said pick-up means and adapted to provide a signal indicating whether or not said pick-up means is carrying a device; and

actuating means operatively associated with said pick-up means and responsive to said sensing means upon a signal therefrom, that said pick-up means is carrying a device, to orient said pick-up means in the said extended operative position.

15 17. In a multi-headed feed apparatus with each head adapted for transport movement to transport a semiconductor device from a pick-up point to a placement point and deposit it on a substrate, the combination comprising: pick-up means associated with each head to pick-up said device from a supply thereof for said transport between said pick-up point and said placement point with said pick-up means mounted on its respective head for reciprocable movement between a retracted inoperative position and an extended operative position wherein said operative position is adapted for the said deposit of the said device on said substrate and wherein said pick-up means is normally disposed in the retracted inoperative position; sensing means cooperatively associated with each pickup means and adapted to provide a signal indicating whether or not said pick-up means is carrying said device during the transport movement thereof between said pick-up point and said placement point; and actuating means responsive to said sensing means upon a signal therefrom, indicating that said pick-up means is carrying a device to orient said pick-up means in the extended operative position. 18. In a multi-headed apparatus with each head adapted to transport a semiconductor device from a pick-up point to a placement point and deposit it at said placement point upon a coincidentally arriving pre-fluxed substrate, with a new substrate normally presenting itself to said placement point coincidentally with the arrival of a subsequent head, the combination comprising:

pick-up means associated with each head of said apparatus, with said pick-up means adapted to manitest a signal indicating whether or not it is carrying a device; and actuating means operatively associated with each pickup means of said apparatus and responsive to a signal from said pick-up means that it is not carrying a semiconductor device to orient said pick-up means in a raised position sufiicient to prevent it from contacting said prefluxed substrate and becoming clogged.

References Cited UNITED STATES PATENTS 2,494,474 1/ 1950 Fermanian et al. 219- 3,056,317 10/1962 Huber et al. 228-6 3,083,291 3/1963 Sotfa et al. 214-158 3,165,818 1/1965 Sofia et a1 29-203 X 3,337,941 8/ 196 7 Drop 29-203 3,344,900 10/ 1967 Drop 29-203 THOMAS H. EAGER, Primary Examiner.