GB2156710A

GB2156710A - Micro-electronic component placement mechanism

Info

Publication number: GB2156710A
Application number: GB08508413A
Authority: GB
Inventors: Stanley Robert Vancelette
Original assignee: USM Corp
Current assignee: USM Corp
Priority date: 1984-04-06
Filing date: 1985-04-01
Publication date: 1985-10-16
Also published as: FR2562751B1; FR2562751A1; KR920005074B1; JPS60229396A; GB2156710B; BE902032A; DE3511132A1; KR850007364A; GB8508413D0; CA1246625A

Abstract

A placement mechanism (14) for vertically displacing a micro- electronic component to place the component (C) on a printed circuit board. The mechanism (14) has a spindle (36) that is displaceable on a vertical axis and rotatable on the vertical axis to align the component leads with the lands of the circuit on the board. The spindle (36) carries a placement rod (40) in communication with a vacuum source to enable the component (C) to be retrieved and placed on the board. The placement rod (40) has a resilient interconnection with the spindle (36) to allow for varying board heights and to buffer the impact of the placement of the component (C) on the board. <IMAGE>

Description

SPECIFICATION Placement mechanism This invention relates to a mechanism for picking up and placing on a substrate small articles such as micro-electronic components.

In the processing of micro-electronic com ponents (chips), the component is obtained from a supply source and transported to a placement head having a placement mecha nism which picks up the component and places it on a printed circuit board, see for example our U.K. Patent Application No.

8225424 (Serial No. 2105224), in which the placement head performs a motion on a verti cal axis from the position of receiving the component to positioning the component on the printed circuit board.

There are machines for automatically ob taining chip size components from a supply source and transporting the component to a placement head which positions the compo nent on a printed circuit board. Examples of these machines are illustrated in U.S. Patent Nos. 4,307,832; 4,327,482; 4,346,514 and 4,393,579. None of these machines have a placement mechanism with a vertical motion on a single axis during which the mechanism picks up the component and moves the component down to the board for positioning between the conductive lands of the circuit on the board. Further, the place ment mechanisms are not rotationally posi tionable on the same axis to align the compo nent with the circuit on the board.

It is an object of this invention to provide a placement mechanism that is vertically dis placed to receive a micro-electronic compo nent and place the component between the conductive lands on a printed circuit board.

It is also an object of this invention to provide a placement mechanism which can be moved on a single axis vertically from a position to receive a component and place the component on a board and also be rotated on the same vertical axis to align the leads of the component with the conductive lands of the circuit on the board.

There is hereinafter described, to illustrate the invention by way of example, a head including a placement mechanism comprising a housing adapted to be positioned above an article conveyor for receiving an article from the conveyor and placing the same on a substrate. A spindle is mounted in the hous ing for up and down movement on a vertical axis and is adapted to rotate on that axis to properly align the article with preselected portions of the substrate. A placement rod is -mounted in the spindle and has a tip for receiving and holding the article. There is a resilient interconnection between the spindle and the placement rod to buffer the impact of the placement of the article on the substrate and to accommodate variable thicknesses in the substrate. A resilient part of the tip also buffers the impact of the placement of the component on the substrate.The rod and tip have a central opening which when subjected to a vacuum will retain the article on the tip and when subjected to an air blast will release the article from the tip onto the substrate.

There now follows a detailed description, to be read with reference to the accompanying drawings, of a placement head embodying the invention. It will be realised that this head has been selected for description to illustrate the invention by way of example and that the invention may reside in any novel features of the head, singly or in combination with other features.

In the accompanying drawings: Figure 1 is a side elevational view of a placement head embodying the invention; Figure 2 is a sectional view of placement mechanism of the head; and Figure 3 is an exploded view of the placement mechanism.

The micro-electronic component assembly machine in which the placement mechanism of this invention is utilized is of the type disclosed in our aforementioned copending patent application. That component assembly machine utilizes an air conveyor to transport a component from a supply source to apparatus receiving the component beneath the placement head which positions the component on the board. The component receiving means is adjustable in position to accommodate various sizes of components to centre the component in the placement head to assure the component leads are placed on the conductive lands of the circuit on the board.

The component placement head 8 illustrated comprises an air conveyor 10 which transports a component C from a supply source (not shown) to a receiving means 12 positioned below a placement mechanism 14.

The receiving means 12 comprises an adjustable shelf 16 positioned by a piston 18 in a cylinder 20. The air in line 22 will move the piston 18 to position the shelf 16 inward underneath the placement mechanism 14 so that the component C in the shelf 16 can be picked up by the placement mechanism 14.

Thereafter, air in line 24 will move the piston 18 to the right to move the shelf 16 outward to permit the placement mechanism to move toward a board (not shown) to place the component on the board. A stop mechanism 26 controls the rearward movement of the piston 18 to control the position of the shelf 16 underneath the placement mechanism.

The placement mechanism 14 is carried in a housing 28 supported on the machine support (not shown). The housing 28 has a stepped bore 30 having an upper portion 32 and a lower portion 34. A spindle 36 is carried in the bore 30 and has a lower open ing 38 carrying a placement rod 40. The placement rod 40 has an upper area 42 received within the opening 38 and a lower area 44 having threads 48 into which a nozzle or tip 46 is threaded. An opening 50 passes through the placement rod 40 and communicates with the interior of opening 38. A vacuum line 52 is attached at 54 to the lower portion 34 of the bore 30 and provides vacuum to the tip 46 through openings 56 in the spindle 36. A seal 58 surrounds the end 60 of placement rod 40. The rod 4Q is normally biased downward by a spring 62 positioned between the end 64 of opening 38 and a plug 66.A collar 68 is threaded around the end 70 of the spindle 36 and has set screws 72, 74 which ride against flattened sides 76, 78 of the placement rod 40 to prevent rotation of the placement rod 40 in the spindle 36 for reasons that will become apparent hereafter. The position of the collar 68 on the spindle 36 will adjust the spacing of the tip 46 from the shelf 16. The collar 68 is locked on spindle 36 by lock nut 69 to vertically position the tip 46 from the shelf 16. A bearing gland 80 and seal 82 are positioned around the spindle 36 to seal the lower portion 34 of the bore 30 and provide a lower bearing surface for the spindle 36. An additional seal 83 surrounds the spindle 36.

In the operation of the placement mechanism thus far described, vacuum in the placement rod will retain a component on the tip 46. As a component is placed on the board, the spring 62 acting against the end of the placement rod 40 through plug 66 and will allow for varying board heights and buffer the impact of the placement of the component on the board.

Attention is now directed to Figures 1 and 2 which illustrate the portion of the placement mechanism which lowers the placement rod 40 so that after a component is removed from the shelf 16, the component can be lowered to a position on the board. An insert 84 and seal 86 are located in the upper portion 32 to isolate the upper and lower portions of bore 30. An additional seal 87 surrounds the spindle 36. Positioned against a shoulder 88 of spindle 36 is a piston 90. The piston 90 is retained on the spindle 36 by a nut 92. A resilient bumper 94 surrounds the spindle 36 between the piston 90 and the insert 84 to soften the impact of the piston 90 against the insert 84.

The top 96 of the upper portion 32 of the bore 30 in the housing 28 is enclosed by a cap assembly 98 which permits the spindle 36 to be moved up and down in the housing during the placement of the component on the board. The cap assembly 98 also permits the spindle 36 to be rotated so that the leads of the component (C) carried on nozzle 46 can be aligned with the lands of the circuit on the board.

The cap assembly 98 comprises a cup 100 having a bottom portion 102 extending into the top 96 of the upper portion 32 of the bore 30. An annular groove 104 surrounds the bottom portion 102 and contains a seal 106, to seal the upper portion 32. The spindle 36 is mounted through a bearing 111 and a seal 110 in the opening 11 2 in the bottom portion 102 of the cap assembly 98. The seal 110 is retained in opening 11 2 by a snap ring 114. The bottom portion 102 also has a recess 116 to accommodate the nut 92 when the piston 90 is in the upper position. A bumper 108 surrounds the bottom portion 102 to soften the impact of the piston 90 against the cap assembly 98.

A collar 118 is mounted in bearings 120, 122 which are separated by a spacer 124. A cap 126 is positioned between the bearing 120 and a pulley 128 integral with the collar 118. A snap ring 132 in annular groove 134 retains the bearings 120. 122 and spacer 124 on collar 118. Cap 126 is attached through cup 100 to housing 28 with screws 150. A spring washer 136 is positioned between the bearing 120 and the cap 126 in recess 138 to preload bearings 1 20, 1 22 for the purpose of removing bearing clearance which will give collar 11 8 a more precise and stable rotating motion.

A square rod i40 is positioned in the opening 142 in collar 118 and rests on the shoulder 144 on the spindle 36. An extension 146 is threaded onto the end 148 of spindle 36 and secures the rod 140 to the spindle.

The square opening 142 in the collar 118 through which the rod 140 is positioned permits the pulley 128 to rotate the spindle 36 while the spindle is reciprocating. The pulley 128 is driven by a belt 152 carried on a drive pulley 154 of motor 156. The motor 156, in response to programmed control, rotates the spindle 36 and thus placement rod 40 to align the component held on the end of the placement rod with the desired location on the board.

The cap 126 and cap assembly 98 are assembled to the housing 28 by screws 150.

In the assembled condition (Fig. 2) the bearing 122 rests against a shoulder 158 in opening 160 of the cup 100.

In operation, after the vacuum tip 46 picks the component from the shelf 16 and the shelf 16 moves forward, air in line 164 will lower the piston 90 and thus spindle 36 to permit the placement rod to lower the component onto the printed circuit board. With the resilient interconnection between the spindle and placement rod varying thickness of the substrate are accommodated.

Since there is a clearance 165 around the spindle 36 in the lower bore 34, the vacuum will continue to hold the component on the tip 46. Also, at the time the component reaches the board, the vacuum in line 52 wili be relieved and an air blast in line 52 will release the component from the tip or nozzle 46 onto the board.

Thereafter, air in line 162 will raise the spindle 36 and the shelf 16 will move inward to receive another component so that the tip 46 can pick another component from shelf 16. Further, during this placement sequence, the rotational mounting of the spindle permits the component to be aligned to assure that the component leads are properly placed on the lands of the circuit on the board.

The extension 146 on spindle 36 coacts with switches 166 on the housing 28 to give an indication of the position of the spindle 36.

Attention is also directed to the fact that the tip 46 has a recess or groove 170 into which the chip type component nests. The groove 170 has an energy absorbing material 172 to help buffer the impact of the placement of the component on the board. Further, the component is held between the sides 174,176 of the groove 170 when the spindle 36 is rotated during the alignment of the component with the circuit on the board.

It can thus be seen with the use of a spindle rotatably mounted in the placement head housing and movable toward and away from the board, a component can be properly aligned with the circuit and easily and accurately placed on the board. Further, with the placement rod slidably mounted in the spindle, the component can be placed on uneven board surfaces with no damage to the component.

Claims

1. A placement mechanism for retrieving a micro-electronic component and placing the component on a substrate, comprising: a. a stationary housing adapted to be positioned above means for conveying the component and receiving the component for positioning on the substrate by the placement mechanism; b. a spindle mounted in said housing for movement toward and away from said substrate on a vertical axis; c. means on said spindle adapted to rotate said spindle on said vertical axis in either direction any predetermined degree of movement to align the leads of the component with the lands of the circuit on the substrate; d. a placement rod slidably mounted in said spindle and having means adapted to retrieve the component from said receiving means and place the component on the substrate; and e. an interconnection between said rod and said spindle including means to buffer the impact of the placement of the component on the substrate and allow for varying substrate heights.

2. A placement mechanism according to claim 1 wherein the interconnection between said rod and said spindle includes a spring biasing said rod toward the substrate.

3. A placement mechanism according to either one of claims 1 and 2 comprising a collar secured to said spindle by a lock nut surrounding said rod, said collar retaining said rod and said spindle in axial alignment while permitting a sliding interconnection between said rod and said spindle.

4. A placement mechanism according to claim 3 wherein said locknut positions said collar on said spindle to vertically adjust said rod.

5. A placement mechanism according to any one of the preceding claims wherein said spindle is mounted in a piston positioned in a bore in said housing with said piston being fluid actuated to move said spindle toward and away from the board on said vertical axis.

6. A placement mechanism according to claim 5, comprising a cap assembly mounted in an end of the bore in said housing with the upper end of said spindle being rotatably mounted in said cap assembly.

7. A placement mechanism according to claim 6 wherein said cap assembly includes a cup member sealed in said end of said bore and supporting said rotatable mounting.

8. A placement mechanism according to claim 7 wherein the rotatable mounting supports a driven pulley.

9. A placement mechanism according to any one of the preceding claims wherein said means on said rod for retrieving said component comprises a vacuum tip having means retaining the component in axial alignment with said rod during rotation of said spindle.

10. A placement mechanism according to claim 9 wherein said vacuum tip is subjected to an air blast to release the component onto the board.

11. A placement mechanism for positioning a small article on a substrate comprising: a. a housing adapted to be supported above the substrate and including a cylindrical opening; b. a spindle rotatably mounted in said opening on a vertical axis; c. a piston surrounding said spindle and carried in said opening and movable in response to a fluid medium to move said spindle toward and away from said substrate on said vertical axis; d. said spindle having a lower end portion slidably receiving a placement rod adapted to receive the article and place the article on the substrate; e. an interconnection between said spindle and said rod maintaining said spindle and said rod in axial alignment, and permitting the vertical adjustment of said rod relative to said spindle.

12. A placement mechanism according to claim 11 wherein said placement rod has a tip adapted to hold the article, a central opening in said rod and said tip when subjected to vacuum retaining the article on said tip and when subjected to air pressure releasing the article from said tip onto the substrate.

13. A placement mechanism according to either one of claims 11 and 12 comprising a resilient interconnection between said spindle and said rod to buffer the impact of the placement of the article on the substrate.

14. A placement mechanism according claim 12, wherein said rod tip includes means to confine the article during rotational movement of said spindle and buffer the impact of the placement of the article on the substrate.

15. A placement mechanism according to anv one of claims 11 to 14 comprising a cap assembly mounted in said opening and rotatably supporting said spindle.

16. A placement mechanism constructed arranged and adapted to operate substantially as hereinbefore described with reference to the accompanying drawings.