US3653268A

US3653268A - Tool moving mechanism

Info

Publication number: US3653268A
Application number: US18153A
Authority: US
Inventors: John C Diepeveen
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-03-10
Filing date: 1970-03-10
Publication date: 1972-04-04
Anticipated expiration: 1989-04-04

Abstract

Apparatus for moving a tool along a predetermined path and in accordance with a preselected sequence wherein the apparatus includes a slide unit shiftably mounted for movement along a generally vertical path, the slide unit having a pair of relatively shiftable members which are normally releasably interconnected. One of the members of the slide unit is adapted to be coupled to a tool and is released from coupled relationship to the other member when the slide unit is at several positions along the path. The invention is suitable for use with a thermal compression bonding tool for bonding wires to a die and to the terminals of a supporting frame for the die.

Description

United States Patent Diepeveen [451 Apr. 4, 1972 [54] TOOL MOVING MECHANISM [21] Appl. No.: 18,153

[56] References Cited UNITED STATES PATENTS 3,199,358 8/1965 Bradlee ..74/55 3,306,116 2/1967 Ross et al v ..74/55 3,341,682 9/1967 Fegley ..228/4 3,342,395 9/1967 Diepeveen ..74/54 Primary Examiner-William F. ODea Assistant Examiner-Wesley S. Ratliff, Jr.

Attorney-Townsend and Townsend 57 ABSTRACT Apparatus for moving a tool along a predetermined path and in accordance with a preselected sequence wherein the apparatus includes a slide unit shiftably mounted for movement along a generally vertical path, the slide unit having a pair of relatively shiftable members which are normally releasably interconnected. One of the members of the slide unit is adapted to be coupled to a tool and is released from coupled relationship to the other member when the slide unit is at several positions along the path. The invention is suitable for use with a thermal compression bonding tool for bonding wires to a die and to the terminals of a supporting frame for the die.

20 Claims, 10 Drawing Figures PATENTEDAPR 4 I972 SHEET 1 [IF 7 INVENTOR.

JOHN c. mEPEvl-fri ATTORNEYS I INVENTOR.

JOHN C. DIEPEVEEN WW M,

ATTORNEYS PATENTEDAPR 41912 SHEET [1F 7 INVENTOR. JOHN C. DIEPEVEEN PATENTEUAPR 4 I972 3,653 ,268

SHEET 5 UF 7 FIG 8 [EH54 222 new I44 r 80 @IZG I 4 Q, Im 50 2 67 54 I46 I90 l a 0""; '84 *50 I76 9 I82 I86 I14 I80 I & M 66 0 50 2 SEARCH 'G- 9 CAM I I TORCHSWCAM' M 2"BOND CAM TAIL PULLER 1 V CAM HOMING CAM W MUIORSWCAML V A v 2 BOND TIMER SW. CAM' INVENTOR. LOOPING CAM I JOHN c. DIEPEVEEN BY REMOTE J W W INDEX IMPllSt v ATTORNFYS PATENTEDAFR 4 I972 SHEET 7 BF 7 INVENTOR. JOHNJC. DIEPEVE EN vATTORNEYS any suitable manner to the upper portion of base 22 in spaced relationship to surface 20 as shown in FIG. 1. A microscope assembly 28 is secured to housing 24 by means of a pivot structure 30 whereby the operator of apparatus 10 can view a die carried by mount 18 on a greatly enlarged scale.

In a general way, apparatus 10 operates to bond a number of connecting wires to various locations on a die defining an integrated circuit, a hybrid circuit or other component, the opposite end of each wire being bonded to a post or terminal on the frame which supports the die. Thus, the finished product can then be packaged to form an electronic component for use in electronic circuitry.

Initially, a wire 32 carried on apparatus 10 in some suitable manner, such as on a spool or the like, is caused to extend through tool 16 and to project outwardly from its lower end. A hydrogen torch 34 having a tip 36 is provided adjacent to the bottom of tool 16 so that the frame at the torch tip can be used to heat and melt the lower end of the wire to cut the wire and to form a bead thereon to assure movement of the wire downwardly toward a die upon downward movement of horn 14. Tool 16 is heated by an electrical resistance heater 38 by means of electrical power supplied in any suitable manner by leads 40 so that tool 16 does not provide a heat sink for the die, the latter being heated in some suitable manner by a heater (not shown) within mount 18.

Assuming the first bond of the wire to be made on a die held by mount 18, mechanism 12 operates to cause horn l4 and its mounting means to move downwardly from an uppermost or home position to a first search position with the tool spaced above and in proximity to the die, then to a bond position with the tool forcing the bead at the end of wire 32 into bonding relationship to the die, then upwardly to an intermediate search position which is below the home position whereby the tool moves relative to the wire since the wire is attached at its one end to the die, then from the intermediate search position downwardly to a second search position spaced above and in proximity to a terminal or post on the die supporting frame, then into a second bond position wherein the wire is moved into bonding relationship with the terminal on the frame, then finally upwardly to the home position at which torch 34, carried by a pivotal structure 42, is caused to sweep across the wire to cut the same as well as to heat and melt it to form a bead on the outer end of the wire for the next bond operation.

While the foregoing has been described with respect to making the first bond on the die and the second bond on a terminal or post, it is clear that the first bond could be made on a terminal or post and the second bond be made on the die. Also, mount 18 is shifted to permit tool 16 to be in the proper positions directly above the locations at which the bonds are to be made. To shift the mount, a pivot assembly 44 (FIG. 10) is provided in base 22 below surface 20, such assembly being hereinafter described in greater detail. The operator of apparatus l grasps knob 46 at one side of the apparatus, the knob being secured to a rod 48 which permits manual manipulation of assembly 44, the latter being connected to mount 18 by two spaced pins 49 which project upwardly through two openings 51 (FIG. in base 22. Pins 49 are complementally received within bores in the bottom of mount 18 so that the latter can be shifted about simultaneously in two degrees of freedom, namely, from right to left and forward and backward. Thus, the various locations of the die and the various posts of the die-supporting frame can be properly positioned relative to tool 16, the movement of the latter being confined to the vertical plane of movement of horn l4.

Modular mechanism 12 is shown in greater detail in FIGS. 2-8 and includes a slide unit 50 providing the mounting means for horn 14 and formed of a front plate 52 and a rear plate 54 adjacent to and directly behind plate 52. Horn 14 is secured to and extends forwardly from plate 52 as shown in FIGS. 5 and 7, horn 14 having an enlarged rear end 56 which is received within an opening in plate 52 adjacent to its lower end. Plate 52 has a pair of slits 58 which extend laterally from the opening so as to render the lower portions 60 of plate 52 yieldable whereby a pair of screws 62 can be used to urge portions 60 against enlarged portion 56 of the horn to releasably hold the latter firmly fixed to plate 52. Thus, the horn will move with this plate.

Plates

52 and 54 move downwardly together from the home position to the first search position, then plate 52 moves downwardly relative to plate 54 to the first bond position as plate 54 remains stationary. Then, plate 52 returns to the first search position, following which,

plates

52 and 54 move upwardly together to the intermediate search positions then downwardly together to the second search position, following which, plate 52 moves relative to plate 54 downwardly to the second bond position as plate 54 remains stationary, then plate 52 returns to the second search position, whereupon

plates

52 and 54 move upwardly together back to the home position.

Slide unit 50 is mounted for vertical reciprocation by a pair of spaced side plates 64 (FIGS. 2 and 5) which are secured in any suitable manner to a generally horizontal base plate 66 and are interconnected by a brace 67. Bearing means is provided to mount slide unit 50 for movement relative to plate 64, each of

plates

52 and 54 having a pair of bearings 68 on respective opposed sides thereof. Each bearing 68 can be of any suitable construction but, for purposes of illustration, it includes a plurality of balls 70 carried by a perforate strip 72 (FIG. 2) disposed between the corresponding plate of slide unit 50 and the adjacent side plate 64. Each strip 72 has a number of holes therethrough in which the corresponding balls can freely rotate. For instance, in FIG. 2, plate 52 is provided with a longitudinal groove 74 while the corresponding side plate 64 has a groove 76 in alignment with groove 74. A pair of spaced rods 78 are disposed in and extend along each of the

grooves

74 and 76, respectively. The four rods in the two aligned, facing grooves define tracks for balls 70 to allow for rolling movement of the balls and thereby permit slide unit 50 to move up and down relative to side plates 64. This type of bearing assured substantially frictionless movement of the slide unit, yet substantially eliminates any lateral movement of the slide unit relative to side plates 64. As a result, horn 14 is restricted to movement only in a substantially vertical plane and movements in other directions are positively prevented.

Plate 54 has a top plate 80 secured to it by machine screws 82 so that top plate 80 overlies and is spaced above plate 52 in the manner shown in FIGS. 5 and 7. Plate 80 has a first hole 84 (FIG. 2) therethrough whereby access to an adjustment screw 86 can be had, screw 86 being threaded into plate 52 from the upper margin thereof and having a lower end provided with a spherical tip 88 (FIG. 5). Plate 52 has an opening 106 therethrough intermediate the top and bottom margins thereof. Tip 88 of the screw 86 projects into opening 106 and is normally in engagement with a disk-like roller 90 carried on a shaft 92 (FIG. 7) secured to a pair of arms 94 (FIGS. 5 and 7) rigid to a plunger 96 (FIG. 7) which is shiftably mounted in a sleeve 98 secured to and extending rearwardly from plate 54. A pin 100 on plunger 96 is disposed within a slit 102 in sleeve 98 to prevent rotation of plunger 96 and thereby roller 90 so as to keep the axis of shaft 92 perpendicular to the length of screw 86. In this way, roller 90 can move freely with respect to screw tip 88 when plunger 96 is moved in a direction toward the left when viewing FIG. 7. A coil spring 104 engaging the rear surface of plate 54 and coupled with pin 100 biases plunger 96 to the right when viewing FIG. 7 and into engagement with the flat front face 105 of a projection 107 carried by an arm 109 mounted for pivotal movement relative to and about a shaft 111 spanning the distance between and rotatably mounted on side plates 64.

Roller 90 and arms 94 also extend into opening 106 as shown in FIGS. 5 and 7. The normal position of roller 90 is the position shown in FIG. 7 wherein shaft 92 is in substantial vertical alignment with screw 86. When so positioned, roller 92 prevents any downward movement of plate 52 relative to plate 54 so that

plates

52 and 54 can move together as a unit. When plunger 96 is moved to the left when viewing FIG. 7, plate 52 can be bonded to a die and to a number of terminals or posts on a frame for supporting such a die. The die can comprise,

for instance, an integrated circuit chip or a hybrid component using semiconductor'materialsto form an electronic circuit.

. Sincecomponents of this type are extremely small and must be handled with great care, it is important to bond the various wires to the various locations on the die and terminals in a manner such as to assure that good, firm bonds are made without structural damage to the die and terminals.

Bonding devices of conventional construction have structural drawbacks which make them unsatisfactory for one reason or another. For instance, they are generally quite complex in construction and oftentimes difficult to operate without causing structural damage to a die unless very skilled operators are available to operate them. Also, in such a device, the tool often bounces on the workpiece because of the way in which the tool is caused to approach the workpiece.

The present invention provides apparatus which, in operation, circumvents the problems encountered with the operation of conventional thermal compression bonders. To this end, the invention utilizes a mechanism which operates to move a thermal compression bonding tool in a manner such that the tool slowly approaches a die or any of the various terminals from a search position after having been moved at a relatively fast rate from an initial position to the search position. Thus, the-tool can be gently moved into bonding engagement with a wire tobe bonded to the die or to a terminal, following which the bonding operation can occur, all of which can be accomplished without causing structural damage to the die. Moreover, the mechanism of the invention readily permits adjustments to be easily 'made'in the locations of the search positions relative to the die and the terminals to minimize the need for very skilled machine operators.

All of the foregoing advantages of the mechanism are realized by the provision of a slide unit to which a thermal compression bonding tool can be coupled, the slide unit being formed of two separate parts to represent a relatively large mass with one of the parts being movable through a relatively short distance when theslide unit is in a search position immediately before a bond operation. Thus, the one member can move the tool through the relatively short distance so as to cause the tool to gently approach the die or a terminal without causing the tool to bounce. In effect, therefore, the relatively large mass of the slide unit is moved through long distances and a relatively small mass is moved through a relatively short distance. The result is avoidance of structural damage to the die and terminals and movement of the tool in a manner to assure a positive bond each time the tool moves into bonding relationship to a wire aligned either with the die or a terminal.

Means is provided for sequentially moving the slide unit from a home or initial position to a first search position at which the height of the tool with respect to the die or terminal can be readily adjusted with a simple manual adjustment. The

v member of the slide unit which carries the tool is then released from coupled relationship with the other member of the slide unit and 'pe'rmitted to move through a limited distance to a bond position and to remain in the bond position for a predetermined bond interval, whereby a wire can be bonded either to the die or a terminal. At the end of this interval, the toolis then elevated to thefirst search position, following which the slide unit moves to'an intermediate search position whereanother simple manual adjustment of the height of the slide unit can be made. This adjustment provides for a desired length of wire to span the distance between the die and a respective terminal.

From the intermediate position, the slide unit is'caused to move to a second search position from which position the member carrying the tool can move further downwardly through a limited distance to move the tool into a second bond position where it'remains for a predetermined'period of time. At the end of the period of the seeond'bond, the slide-unit'is returned to the home position. All of the aforesaid movements of the slide unit and tool are under the control of an operator viewing the working areaof the die and terminals through a microscope assembly and the operator can readily manipulate the die and the terminals by the use of an improved die shifting assembly which utilizes, among other things, a parallelogram unit for shifting the mount for the die.

The primary object of this invention is to provide a mechanism for moving a tool sequentially into various locations along a predetermined path of travel so that the tool, when coupled to the mechanism, can be used as a thermal compression device for bonding a number'of connectingwires to a die and a number of terminals or posts'on the frame which supports the die.

Another object of this invention is to provide apparatus of the type described wherein adjustments can be quickly and easily made in the heights of a tool-carrying unit with respect to a die and the associated terminals when the unit is at certain of the positions along its path of travel to thereby facilitate the positioning of the tool with respect to the die and terminals as well as to provide for variations in the lengths of wires which interconnect the same.

A further object of this invention is to provide apparatus of the aforesaid character wherein is includedan improved shifting assembly adapted to be coupled to a mount for a die and its supporting frame so that the mount can be moved quickly and easily into and out of any one of a number of operative locations relative to a bonding tool to thereby allow the tool to be limited in its movement to a specific straightline path of travel and to eliminate the need for rotational movements of the tool.

Other objects of this invention will become apparent as the following specification progresses, reference being had to the accompanying drawingsfor an illustration of the embodiments of the invention.

In the drawings:

FIG. 1 is a side elevational view of the housing for the mechanism of this invention with the mechanism being shown within the housing in dashed lines and illustrating a bonding tool adjacent to a die holder for bonding wires to the die;

FIG. 2 is an enlarged, top plan view of the mechanism of the invention; 7

FIG. 3 is a side elevational view looking in the direction of lines 3-3 of FIG. 2;

FIG. 4 is a side elevational view of the mechanism looking in the direction of lines 4-4 of FIG. 2;

FIG. 5 is a front elevational view of a portion of the mechanism looking in the direction of lines 5-5 of FIG. 2;

FIG. 6 is a cross-sectional view looking in the direction of lines 6-6 of FIG. 2;

FIG. 7 is a cross-sectional view of the mechanism looking in the direction of lines 7-7 of FIG. 2;

FIG. 8 is a cross-sectional view looking in the direction of lines 8-8 of FIG. 2;

FIG. 9 is a view of a timing sequence showing the relationship between the various cams used to operate the various moving parts of the mechanism; and

FIG. 10 is a bottom plan view of the housing for the mechanism'showing the linkage mechanism for moving the die holder with respect to the bonding tool of the mechanism.

The apparatus of this invention is broadly denoted by the numeral 10 and includes a modular mechanism 12 having a reciprocal tool holder or horn 14 which moves in a substantially vertical plane to, in turn, move a die bonding tool 16 coupled thereto toward and away from a die holder or mount 18 carried on a surface 20 on the base 22 of apparatus 10. Mechanism 12 is disposed within an upper housing 24 which is supported by a lower housing 26, the latter being secured in is allowed to move downwardly relative to plate 54 through a distance determined by the distance by which roller 90 moves forwardly of tip 88. The force causing this downward movement of plate 52 is determined by the weights of horn l4 and plate 52 less the upward force exerted on plate 52 by a coil spring 108 (FIG. 5) secured at its upper end to top plate 80 and at its lower end to a rigid, horizontal extension 110 projecting forwardly through a second opening 112 in plate 52 (FIG. 5) extending parallel to and being of substantially the same size as opening 106. Extension 110 has a hole through it to receive the tip 112 of a screw 114 threaded into plate 52 from above.

The adjustment in the tension of spring 108 is effected by rotation of screw 114, the latter being loosely received within an opening (not shown) in top plate 80. Screw 114 has a head 116 and is adjustable vertically so that the tension of spring 108 can be increased or decreased to, in turn, cause variations in the effective load or weight exerted on the wire during a bonding operation. In this way, the downward force on the wire can be selected as desired and can be as low as 20 grams or less. This relatively small force is exerted on the wire when plate 52 moves relative to plate 54 through a relatively short distance, i.e., from the first search position to the first bond position or from the second search position to the second bond position. Thus, there will be substantially no tendency for tool 16 to bounce on the die or the frame terminal so as to cause structural damage to the same.

When plate 52 is in the first search position, reciprocal movement of plunger 96 causes plate 52 to move into the first bond position and return. When this plate is in the second search position, reciprocal movement of plunger 96 causes the plate to move into the second bond position and return. Return of the plunger to its.starting position is caused by spring 94, resulting in upward movement of plate 52 relative to plate 54 until roller 90 has returned to the position shown in FIG. 7.

The means for moving slide unit 50 and horn 14 into and out of the various search and bond positions and the home position includes a number of cams and levers operated in timed relationship so that horn 14 and tool 16 mounted thereon will move in a predetermined sequence under the control of an operator of apparatus 10. The carns include a homing cam 118, a looping cam 120, a bond cam 122 and a second search cam 124. All of these cams are rigidly secured to a shaft 126 spanning the distance between and rotatably mounted on a pair of

rear sidewalls

128 and 130 secured in any suitable manner to base plate 66 as shown in FIGS. 2-4. Bearing blocks 132 rotatably mount shaft 126 on respective sidewalls so that shaft 126 is essentially parallel with shaft 111.

A pulley 134 is secured to one end of shaft 126 and is coupled by an endless, flexible belt 136 to a second pulley 138 on the shaft 140 of a timing motor 142 secured in any suitable manner to the rear extremity of rear sidewall 130 as shown in FIGS. 2 and 3. The cams and their associated levers, hereinafter described, operate to move horn 14 and slide unit 50 from the home position through the various search and bond positions and then back to home position for each complete revolution of shaft 126. This feature is more clearly set forth in diagrammatic form in FIG. 9 wherein timing lines are shown to illustrate the actions of the four above-mentioned cams when they rotate from 0 to 360, namely, for each revolution of shaft 126.

Homing cam 118 has a single lobe 144 as shown in FIG. 8 and an outer peripheral cam surface which engages a roller 146 rotatably mounted on one end of a lever 148 rigidly secured intermediate its ends to shaft 111. The opposite end of lever 148 is forwardly of shaft 111 and underlies and is engaged by the tip 150 of a screw 152 threadably mounted in plate 54 (FIG. 8) and extending above the same. Screw 152 has a head 154 to permit manual manipulation of the screw relative to plate 154. The weight of slide unit 50 is supported on the front end of lever 148 and, by rotating screw 152, the height of tool 16 on horn 14 can be adjusted relative to a die when slide unit 50 is in the first search position.

When lobe 144 of homing cam 118 engages roller 146, slide unit 50 will be at its highest or home position. As shaft 126 moves in the direction of arrow 156 (FIG. 8), lobe 144 moves away from roller 146 and allows lever 148 to rock in a counterclockwise sense when viewing FIG. 8 about shaft 111, whereby slide unit 50 can descend through a distance determined by the configuration of cam 118. Thus, slide unit 50 moves from the home position to the first search position.

A coil spring 164 (FIG. 5) is connected at one end to a lateral projection 166 secured to the proximal side plate 64. The opposite end of this spring is secured to another lateral projection 168 connected to top plate 80. Spring 164 biases slide unit 50 downwardly and thereby biases roller 146 of lever 148 into engagement with the peripheral cam surface of homing cam 1 18.

When slide unit 50 is in the first search position, bond cam 122 will be rotated by continued rotation of shaft 126 so as to urge arm 109 in a clockwise sense when viewing FIG. 7 relative to and about shaft 111. A roller 158 carried by the rear end of arm 109 normally engages the peripheral cam surface of bond cam 122. Thus, as arm 109 rotates in a clockwise sense, it forces plunger 96 forwardly or to the left when viewing FIG. 7 to thereby move roller partially out from beneath tip 88 of screw 86. This movement allows plate 52 to descend through a relatively short distance relative to plate 54 so that tool 16 on born 14 is moved into bonding relationship to the head of the wire carried by the tool and the wire bead is forced against a particular location on a die therebeneath. Bond cam 122 has a first lobe representing the first bond position and a second lobe 162 representing the second bond position. As shown in FIG. 7, the bond cam is in the second search position just prior to moving into the second bond position, assuming rotation of shaft 126 in the direction of arrow 156.

Looping cam 120 operates through a lever 170 (FIG. 4) to move slide unit 50 from the first search position to the intermediate search position and then to the second search position. In the intermediate search position, variations can be made in the length of the loop of wire which spans the distance between the die and a corresponding frame terminal. Looping cam 120 has a single lobe 172 (FIG. 4) which is movable into engagement with a roller 174 (FIGS. 2 and 8) rotatably carried by a shaft on an arm 176 forming a part of lever 170. Arm 176 extends forwardly from roller 174 and is pivotally mounted intermediate its ends on a second arm 178 which extends upwardly from arm 176 as shown in FIG. 4. The forward end of arm 176 is connected to one end of a coil spring 179 whose opposite end is connected to pin 166 projecting laterally from the adjacent side plate 64 (FIGS. 4 and 5). Thus, spring 179 biases arm 176 in a clockwise sense when viewing FIG. 4 so that roller 174 is urged into engagement with the cam surface of looping cam 120.

The upper end of arm 178 is rigidly secured to shaft 11 1. A second roller 180 (FIGS. 2, 7 and 8) is carried on the same shaft as roller 174. Roller 180 engages a flat surface 182 on a crescent member 184 projecting laterally from a cylindrical bearing member 186 (FIGS. 2, 7 and 8) rotatably mounted in any suitable manner in the sidewall 128. Bearing member 186 has a laterally extending outer portion 188 to which a handle 190 is rigidly secured. The handle extends forwardly from portion 188 and operates to permit manual rotation of bearing member 186 and thereby crescent member 184 so hat the inclination of flat surface 182 can be changed. Normally, surface 182 is at least slightly inclined with respect to the vertical. Also, the common axis of

rollers

174 and 180 is substantially axially aligned with the axis of cylindrical bearing member 186.

As lobe 172 of looping cam 120 moves into engagement with roller 174, the roller is forced downwardly along surface 182 so that the common axis of

rollers

174 and 180 moves out of axial alignment with the axis of bearing member 186. When this occurs, such downward movement of roller 174 causes a forward movement of arm 176 of levers 170 to, in turn, cause counterclockwise rotation of shaft 111 when viewing FIG. 4.

In effect, this causes lever 148 to elevate slide unit 50 and this movement commences when the slide unit at the first search position after plate 52 has moved into and out of the first bond position. Thus, initial movement of lever 148 under the influence of lever 170 causes slide unit 50 to move from the first search position to the intermediate search position.

In the intermediate search position, adjustment can be made in the length of the wire to be looped between the die and a respective frame terminal by manually rotating handle 190 which causes rotation of bearing member 186 about its axis. This is done when lobe 172 engages roller 174, i.e., when the axis of

rollers

174 and 180 are out of axial alignment with the axis of bearing member 186. The effect of this handle movement is to change the inclination of flat surface 182 of crescent member 184 and, when the surface becomes more inclined, such as by rotating handle 190 upwardly, arm 176 is moved further forwardly to, in turn, cause additional counterclockwise rotation of shaft 111 and thereby upward movement of the forward end of lever 148. This elevates slide unit 50 further upwardly and thereby increases the length of wire to be looped between the die and a frame terminal. Downward movement of handle 190 has the effect of shortening this loop.

After lobe 172 moves out of engagement with roller 174, the common axis of

rollers

174 and 180 returns to substantial axial alignment with the axis of bearing member 186 so that movement of handle 190 will have no effect. However, in most cases, it is desirable to have a constant length of wire in the loop between a die and the various frame terminals; hence, one adjustment of handle 190 is all that is necessary. Also, when lobe 172 of looping cam 120 moves out of engagement with roller 174, lever 170 is allowed to pivot in a clockwise sense when viewing FIG. 4 so as to allow slide unit 50 to move from the intermediate search position to the second search position.

During the time that slide unit 50 moves into the second search position, second search cam 124 having the single lobe 214 as shown in FIG. 6 is rotated so'that lobe 214 moves into engagement with a roller 194 rotatably mounted on a shaft secured to the rear end of an arm 196 forming a part of a lever 192 which is substantially the same in construction as lever 170. Lever 192 also has a second arm 198 which is pivotally mounted at its lower end to arm 196 intermediate the ends of the latter. The upper end of arm 198 is rigid to shaft 111. A coil spring 200 is connected to the forward end of arm 196 and to a lateral projection 202 (FIG. 6) extending from the adjacent side plate 64 to bias arm 196 in a counterclockwise sense when viewing FIG. 6.

A second roller 204 mounted on the same shaft as roller 194 engages the flat surface 206 of a crescent member 208 rigid to a cylindrical bearing member 210 (FIG. 2) which is rotatably mounted in any suitable manner in rear sidewall 130. Bearing member 210 has an outer lateral projection 212 to which a handle 214 is secured, the handle extending forwardly as shown in FIG. 3, While slide unit 50 is in the second search position, the common axis of

rollers

194 and 204 is held out of substantial axial alignment with the axis of bearing member 210 by lobe 214 so that rotation of bearing member 210 upon manual rotation of handle 214 can cause a change in the inclination of flat surface 206. This, in turn, will cause forward or rearward movement of arm 196 and thereby clockwise or counterclockwise movement of shaft 111. In this way, the height of tool 16 from a frame terminal can be varied when slide unit 50 is in the second search position prior to movement of the tool. into the second bond position. Thus, the tool can be placed at a desired distance from the frame terminal before the wire is bonded to the same.

To effect the proper timing in the sequence of operation of mechanism 12, a number of timing cams and switches are provided, there being a switch for each timing cam, respectively.

'As shown in FIG. 2, such timing cams are rigidly secured to shaft 126 and include a timer switch cam 216 having a timer switch 218 associated therewith, a motor switch cam 220 having a motor switch 222 associated therewith, a torch switch cam 224 having a torch switch 226 associated therewith, and a tail puller cam 228 having a tail puller switch 230 associated therewith. The time intervals during which the

various switches

218, 222, 226 and 230 are actuated for each cycle of operation of mechanism 12 are shown in hatched areas of the respective timing lines of FIG. 9. Also, FIG. 9 shows the operational sequences of homing cam 118, looping cam 120, bond cam 122 and second search cam 124.

Switches

218, 222, 226 and 230 are secured in any suitable manner to

rear sidewalls

128 and 130. Electrical circuitry (not shown) connects these switches to the appropriate circuit elements for actuating the same when the switches are actuated.

FIGS. 4 and'6 show looping cam I20 and second search cam 124, respectively, when slide unit 50 is in the home position. FIGS. 7 and 8 show the positions of bond cam 122 and homing cam 118, respectively, when slide unit 50 is in the second search position.

In FIG. 1, torch 34 is carried by a horizontally disposed arm which is mounted for swinging movement about the vertical axis of a shaft 230 secured in any suitable manner to upper housing 24. A flexible hose 232 is coupled in any suitable manner to the source of hydrogen or other suitable gas mixture to support a flame at the tip 36 of torch 34. Hose 232 may be coupled to a control panel on the upper part of upperhousing 24, the control panel having a number of controls, such as a main on"-off switch, one or more indicator lights, and a switch for heater 38. Other controls can be utilized, if desired.

To swing am 228 about the axis of shaft 230, a linkage 234 is provided, the linkage extending rearwardly to an arm 236 mounted for rotation on a shaft 238 which, in turn, is rotated through a limited are by an eccentric 240 secured to the vertically disposed shaft 242 of a synchronous motor 244 mounted in lower housing 26. An impulse of index switch 246 is actuated in response to the rotation of shaft 238 and thereby arm 236. Each time shaft 238 moves the limited distance, arm 228 moves in a direction to cause torch tip 36 to sweep across wire 32 to cut the same and to form a bead on the lower end of the wire to make the wire ready for the next bond operation. Arm 228 is biased in any suitable manner so that it returns to an initial position after a wire has been cut and after a bead is formed on the end of the wire.

Pivot assembly 44, shown in FIG. 10, includes a parallelogram linkage including a pair of

rigid side members

248 and 250 and a pair of

rigid end members

252 and 254, the side members and the end members all being pivotally interconnected. Rod 48 is rigid to and extends longitudinally out wardly from end member 254 through a slot 258 in the side of base 22. Knob 46 on the outer end of rod 48 is hollow and houses a switch which is manually actuated by a push-button 256 carried by knob 46 in a position accessible to a finger of the hand grasping the knob. The switch is used for controlling timing motor 142 to cause cyclic operation of mechanism 12. Thus, each time the push-button 256 is depressed, slide unit 50 will move from one position to another, such as from the home position to the first search position, or from the first search position to the first bond position and return to the first search position. Suitable wiring (not shown) interconnects the switch in knob 46 with timing motor 142 and a source of electrical power.

A base plate 260 is secured in any suitable manner to base 22 and extends outwardly therefrom beneath slot 258. Base plate 260 provides a support over which knob 46 moves, the knob being in sliding engagement with the upper surface of base plate 260.

End members

252 and 254 are pivotally secured to

side members

248 and 250. Also, a pin 262 pivotally mounts the proximal ends of side member 250 and end member 252 on the underside of base 22 for rotation about a generally vertical axis. Side member 248 can be adjustably mounted on

end members

252 and 254 and, to this end, a number of holes are provided in the end members, there being a hole in one end member for each hole in the other end member. When side member 248 is connected in the manner shown in FIG. 10, a

ratio of 6 to l is obtained between the movement of knob 46 and the movement of pins 49 which extend through openings 51 and are coupled to mount 18. When side member 248 is connected by pins to the second or middle set of holes of

end members

252 and 254, a ratio of to I is obtained between the movement of knob 46 and pins 49. A ratio of 4 to 1 between such movements is obtained when side member 248 is connected by pins to the left-hand set of holes in

end members

252 and 254.

Side member 248 is pivotally connected by a pin 264 to an extension 266 rigid to a shiftable member 268 mounted for movement along a rigid bar 270 secured at its ends to a pair of bars 272 disposed in perpendicular relationship to bar 270, bars 272 being shiftably mounted on respective guides 274 rigid to the underside of base 22.

By manipulating knob 46, the operator of apparatus 10 can cause the parallelogram linkage to pivot simultaneously about

pins

262 and 264 so as to move pins 49 in any desired direction and thereby move mount 18 coupled with pins 49. When knob 46 moves to the left as shown in FIG. 10, side member 48 rotates in a counterclockwise sense and causes extension 266 and thereby shiftable member 268 to move to the left also. This causes pins 49 to move to the left-hand sides of openings 51 when viewing FIG. 10. When knob 46 is moved upwardly when viewing FIG. 10, this causes end member 252 to move side member 248 and thereby extension 266 upwardly to, in turn, move pins 49 upwardly in openings. 51. Knob 46 can move diagonally in any direction as well as up and down and left and right. Thus, mount 18 can be moved in any desired direction and such movement is limited only by the size of each opening 51.

DETAILED OPERATION With mechanism 12 mounted in upper housing 24 and with tool 16 coupled to horn 14, a die is placed in mount 18 and the latter is coupled with pins 49 so that the operator of apparatus 10 can manipulate or move mount 18 upon movement of knob 46. The operator will view the die by means of microscope assembly 28 so as to properly align the tool with respect to the die and the supporting frame therefor so that bonding of wire 32 to the die and the terminals of the supporting frame can be accomplished.

Initially, a flame will be provided at the tip 36 of torch 34 and a bead will initially be formed on the end of the wire by the torch so that the wire can be carried downwardly to the die upon downward movement of the tool.

Assuming that the die is ready to be bonded, the operator manipulates knob 46 until the tool, as viewed through microscope assembly 28, is directly above the die. The operator then depresses push-button 256 to actuate the switch coupled thereto whereupon timing motor 142 is energized to rotate shaft 126 through a predetermined arc to cause homing cam 118 to be rotated in a direction of arrow 156 so that lobe 144 will move out of engagement with and away from roller 146. This movement allows member 148 to rock in a counterclockwise sense when viewing FIG. 8 to thereby allow slide unit 50 to move from the home position to the first search position. In the first search position, the height of the tool with respect to the die can be adjusted by rotating screw 152 which will either raise or lower slide unit 50 with respect to lever 148. When this adjustment is made, no further adjustment is generally necessary since the first search position is constant for a given type of die in mount 18.

The operator then depresses push-button 256 once again to cause timing motor 142 to be energized for a second time interval to thereby rotate shaft 126 through a second predetermined arc in the direction of arrow 156. This movement causes lobe 160 of bond cam 122 to move into engagement with roller 158 to, in turn, cause arm 109 and thereby projection 107 to be rocked about and relative to shaft 1 11. This action causes plunger 96 to move to the left when viewing FIG. 7, whereupon plate 52 descends relative to plate 54 so that tool 16 is moved into bonding relationship to wire 32, forcing the latter against a particular location of the die. The wire is held for a predetermined time interval in engagement with the die so as to effect the desired bond, such time interval being capable of being varied such as by a control carried on the control panel of upper housing 24. After this time interval has elapsed, shaft 126 will move through a third predetermined arc, whereupon spring 104 returns plunger 96 to its initial position, causing the return of roller to a location beneath screw 86 to thereby elevate plate 52 relative to plate 54. During this time, rotation of looping cam causes movement of lever in a direction to rotate shaft 111 in a counterclockwise sense when viewing FIG. 4 so that slide unit 50 is moved from the first search position to the intermediate search position. In this position, the operator can manipulate handle to vary the length of the wire extending between the die and the tool so as to vary the loop length of the wire between the die and the terminal on the frame supporting the die. This loop length is varied by changing the inclination of flat surface 182 of crescent member 184. Generally, a single adjustment is all that is necessary since a uniform loop length is generally desired.

The operator then depresses push-button 256 once again to cause energization of timing motor 142 to cause rotation of shaft 126 about a fourth predetermined arc whereupon rotation of looping cam 120 causes slide unit 50 to move from the intermediate search position to the second search position. In the last-mentioned position, the second search position can be varied relative to the frame terminal by manipulating handle 214 to vary the inclination of flat surface 206 of crescent member 208 since the common axis of

rollers

194 and 204 is out of substantial axial alignment with the axis of bearing member 210 when slide unit 50 is in the second search position. Following any needed adjustment of the second search position, the operator again depresses push-button 256 to cause further rotation of shaft 126 and thereby cause second lobe 162 of bond cam 122 to move into engagement with roller 158 to cause rocking movement of arm 109 in a clockwise sense when viewing FIG. 7 to thereby cause plunger 96 to move to the left and allow plate 52 to descend a relatively short distance relative to plate 54. When this occurs, the tool moves into bonding relationship with wire 32 and forces the latter against the frame terminal for a predetermined period of time. At the end of this time period, timing motor 142 is automatically energized to rotate shaft 126 to cause'it to complete its 360 arcuate travel and, when this occurs, homing cam 118 rotates so that its lobe 144 once again engages roller 146 to rotate lever 148 in a clockwise sense and thereby return slide unit 50 to the home position. The operator can then manipulate knob 46 to move mount 18 into a new position for bonding another location of the die to a second frame terminal. However, before this is done, torch 34 is automatically rotated so that its flame sweeps across the wire to cut the same and to form a bead on the wire for the next bond operation.

I claim:

1. Apparatus for reciprocating a tool comprising: a slide unit having a pair of relatively shiftable members, one of the members having means thereon for mounting a tool in a predetermined position; means releasably interconnecting the members and being actuatable to permit limited reciprocation of said one member relative to the other member; means coupled to said slide unit for mounting the same for reciprocal movement along a preselected path of travel; means coupled with said slide unit for reciprocating the same along said path; and means coupled with said interconnecting means for actuating the same when the slide unit is at a predetermined location along said path.

2. Apparatus as set forth in claim 1, wherein said interconnecting means is shiftably carried by said other member, said actuating means being operable to shift said interconnecting means relative to said other member.

3. Apparatus as set forth in claim 1, wherein said interconnecting means includes structure adjustably coupling said one member to the other member.

4. Apparatus as set forth in claim 1, wherein said reciprocating means includes an operable power device, and cam means coupled to the slide unit for moving the same as a function of the operation of said power device.

5. Apparatus as set forth in claim 1, wherein is provided means adjustably coupling said slide unit to said reciprocating means.

6. Apparatus as set forth in claim 5, wherein said reciprocating means includes a lever, said coupling means including a screw threadably carried on said slide unit, said lever engaging one end of the screw in supporting relationship to said slide unit.

7. Apparatus as set forth in claim 1, wherein is provided means coupled with said slide unit for adjusting the position of the same with respect to said mounting means when the slide unit is at a predetermined location along said path.

8. Apparatus as set forth in claim 1, wherein said reciprocating means includes a rotatable shaft having a cam thereon, and a lever coupled to said cam for moving the slide unit as a function of the rotation of said shaft.

9. Apparatus for moving a tool along a predetermined path comprising: a slide unit having a pair of relatively shiftable members, one of the members having means for mounting a tool thereon; means coupled to said slide unit for mounting the same for reciprocation along a generally vertical path; means releasably interconnecting said members and being actuatable to permit limited downward movement and return of said one member relative to the other member; means coupled with said slide unit for moving the same successively from a first position to a second position below the first position, from the second position to a third position above the second position, from the third position to a fourth position below the first and third positions, and from the fourth position to the first position; and means coupled with said interconnecting means for actuating the same when the slide unit is at the second and fourth positions.

10. Apparatus as set forth in claim 9, wherein said moving means includes a rotatable shaft, power means coupled to said shaft for sequentially rotating the same through predetermined arcs, lever means coupled to said slide unit for moving the same relative to said mounting means when the lever means is shifted, and cam means carried by the shaft and coupled to said lever means for shifting the latter as a function of the sequential rotation of said shaft. 7

11. Apparatus as set forth in claim 10, wherein said slide unit is biased downwardly, said lever means including first lever structure disposed for supporting said slide unit, said cam means including first cam structure coupled to said first lever structure and operable to permit movement of the slide unit from said first position to said second position when said shaft is rotated through a first predetermined arc.

12. Apparatus as set forth in claim 11, wherein said lever means further includes second lever structure coupled to said first lever structure and disposed for moving the same and thereby said slide unit when said second lever structure is shifted, said cam means further including second cam structure coupled to said second lever structure for shifting the same ina direction and through a distance sufficient to permit the slide unit to move from said second position to said third position when said shaft rotates through a second predetermined arc and from said third position through a third predetermined arc.

13. Apparatus as set forth in claim 12, wherein is provided means coupled with said second lever structure for adjustably shifting the same with respect to said second cam structure when said slide unit is in said third position, whereby the slide unit can be adjustably moved relative to its mounting means.

14. Apparatus as set forth in claim 12, wherein said secondlever structure includes a pair of levers, said second cam structure including a cam for each of said levers, respectively, each lever having a pair of axially aligned rollers at one end t ereof,

one of the rollers being in engagement with the respective cam, and wherein is included a crescent member rotatably mounted adjacent to each cam, respectively, each crescent member having a bearing surface spaced from the axis of rotation thereof, the other roller of each lever being engageable with the bearing surface of a respective crescent member, the rollers of one of the levers being out of axial alignment with the axis of rotation of the respective crescent member when the slide. unit is in said third position and the rollers of the other lever being out of axial alignment with the axis of rotation of its respective crescent member when the slide unit is in said fourth position, and including a handle for each crescent member, respectively, for rotating the latter relative to the respective cam.

15. Apparatus as set forth in claim 12, wherein is provided means coupled with the second lever structure for adjusting the operative position of the same relative to said second cam structure when said slide unit is in said second position.

16. Apparatus as set forth in claim 11, wherein is provided means coupled with said second lever structure for adjusting the position thereof relative to said second cam structure when the slide unit is in said fourth position.

17. Apparatus as set forth in claim 16, wherein said adjusting means includes a rotatable member having a bearing surface spaced radially from the axis of rotation of the member, said second lever structure having a bearing element engaging the bearing surface, said bearing element being eccentric with respect to the axis of rotation of said rotatable member when the slide unit is in said fourth position, and means coupled with said rotatable member for rotating the same.

18. Apparatus for positioning a workpiece relative to a tool comprising: a support; a first member; means mounting said first member on said support for movement along a first path of travel, said first member adapted to be coupled to said workpiece for moving the same in response to the movement of the first member; a second member; means mounting said second member on said support for movement relative thereto along a second path of travel substantially perpendicular to said first path of travel; and parallelogram means coupled to said first member for moving the same along said first path and for moving said second member along said second path to thereby vary the position of the workpiece along two directions.

19. Apparatus as set forth in claim 18, wherein said parallelogram means includes a first pair of parallel side members pivotally mounted on said support, a second pair of parallel side members pivotally secured to the first side members and means for moving one of the side members relative to the support to thereby cause movement of the other side members in a manner to cause movement of said workpiece.

20. Apparatus as set forth in claim 18, wherein said first and second members are movable simultaneously under the influence of said parallelogram means.

Claims

10. Apparatus as set forth in claim 9, wherein said moving means includes a rotatable shaft, power means coupled to said shaft for sequentially rotating the same through predetermined arcs, lever means coupled to said slide unit for moving the same relative to said mounting means when the lever means is shifted, and cam means carried by the shaft and coupled to said lever means for shifting the latter as a function of the sequential rotation of said shaft.

12. Apparatus as set forth in claim 11, wherein said lever means further includes second lever structure coupled to said first lever structure and disposed for moving the same and thereby said slide unit when said second lever structure is shifted, said cam means further including second cam structure coupled to said second lever structure for shifting the same in a direction and through a distance sufficient to permit the slide unit to move from said second position to said third position when said shaft rotates through a second predetermined arc and from said third position through a third predetermined arc.

14. Apparatus as set forth in claim 12, wherein said second lever structure includes a pair of levers, said second cam structure including a cam for each of said levers, respectively, each lever having a pair of axially aligned rollers at one eNd thereof, one of the rollers being in engagement with the respective cam, and wherein is included a crescent member rotatably mounted adjacent to each cam, respectively, each crescent member having a bearing surface spaced from the axis of rotation thereof, the other roller of each lever being engageable with the bearing surface of a respective crescent member, the rollers of one of the levers being out of axial alignment with the axis of rotation of the respective crescent member when the slide unit is in said third position and the rollers of the other lever being out of axial alignment with the axis of rotation of its respective crescent member when the slide unit is in said fourth position, and including a handle for each crescent member, respectively, for rotating the latter relative to the respective cam.