Method and apparatus for removing die from a wafer and conveying die to a pickup location

• US 6,173,750 B1
• Filed: 02/17/1999
• Issued: 01/16/2001
• Est. Priority Date: 02/18/1998
• Status: Expired due to Term

• Current Assignee: UI Holding Company (UI Acquisition Holding Company)
• Original Assignee: Hover-Davis, Inc.
• Inventors: Davis, Peter, Tarrant, Dean
• Primary Examiner(s): Osele, Mark A.
• Application Number:
  US09/251,541
• Time in Patent Office: 699 Days
• Field of Search: 156/344, 156/584, 438/33, 438/68, 438/113, 438/114, 438/464, 438/465, 438/976, 438/FOR.38, 294/261, 294/263, 294/265, 294/266, 297/62
• US Class Current: 156/765
• CPC Class Codes: H01L 21/67144 Apparatus for mounting on conductive members, e.g. leadframes or conductors on insulating substrates
• CPC Class Codes: Y10S 156/942 with reorientation means
• CPC Class Codes: Y10T 156/1132 Using vacuum directly against work during delaminating
• CPC Class Codes: Y10T 156/1978 Delaminating bending means
• CPC Class Codes: Y10T 156/1983 Poking delaminating means
• CPC Class Codes: Y10T 29/49819 with conveying of work or disassembled work part
• CPC Class Codes: Y10T 29/49824 to elastically deform work part or connector

Abstract

A direct die feeder picks known good die from a wafer and places them on a conveyor belt, which conveys the die to a pickup location. Frame (111) supports a wafer (105) which is a wafer that is sawed while adhered onto a flexible film, which is then stretched and mounted in a ring (110). A fork member (125), on which a pick head (150) is mounted slides along a horizontal axis and frame (111) slides along a vertical axis to allow the pick head (150) to access any die from the wafer. A camera (160) is directed downward at a 45° mirror (162) adjacent to the pick head to capture images of the wafer and determine the precise locations of die and qualify them. The pick head (150) can pick die from the wafer and place them directly on the conveyor belt (170) in the conventional orientation, or pass the die to a flip head (140) which then shifts to the left and lowers the die down past the pick head, placing the die on the conveyor belt in the flipped orientation. The conveyor belt operates until a die is detected at a pickup location (173) at one end of the conveyor except during placing operations of the pick head or flip head or during burst mode operations, during which the conveyor belt is loaded with closely spaced die, then fed in rapid succession to a multi-head host pick and place machine.

Claims

1. A die feeder for feeding in series a collection of components attached to a flexible film having a substantially planar surface, the die feeder comprising:

a support operable to support said flexible film in the substantially planar configuration;

a component conveyor belt adjacent to the flexible film and extending substantially horizontally from a location adjacent to said support to a pickup location; and

a pick head operable to remove a selected component from said collection of components on said flexible film and place said selected component directly on said component conveyor belt at the location adjacent to said support for transport of the selected component by said component conveyor belt to the pickup position.

2. The die feeder set forth in claim 1 wherein said collection of components is arranged in a two dimensional pattern on said flexible film and where said feeder further comprises a means for moving at least one of said pick head and said flexible film so that said pick head has access to every component in said collection of components.

3. The die feeder set forth in claim 2 wherein

a region of space adjacent to said collection of components is divided by the plane of the substantially planar flexible film into a first side and a second side such that the first side includes said collection of components and extends away from the surface where said collection of components is attached to the flexible film and the second side is one the opposite side of the flexible film and extends away from said first side, where said pick head is located on said first side of said collection of components, said die feeder further comprising:

a strip head, located on the second side away from said collection of components, said strip head maintaining a position corresponding to said pick head such that an imaginary line extending from said strip head to said pick head is substantially perpendicular to the planar surface of the flexible film, said strip head having a pin structure comprising at least one pin operable to extend from said strip head toward said selected component to release said selected component from said flexible film and pass said selected component to said pick head; and

where said pick head includes a suction port operable to hold said selected component against said suction port by applying a vacuum to said suction port.

4. The die set forth in claim 3 further comprising a flip head, wherein and said pick head is operable to remove said selected component from the flexible film and place said selected component directly onto said component conveyor belt in a conventional orientation and is also operable to pass the selected component removed from the flexible film to said flip head, where said flip head is operable to take the selected component from said pick head and subsequently place the selected component on said component conveyor belt in a flipped orientation.

5. The die feeder set forth in claim 4, further comprising a piston operating as a pressure-responsive valve disposed within said flip head, said piston lifting to permit air flow through said flip head when a suction is applied to said flip head, and dropping down to a resting position, blocking air flow when positive relative air pressure is applied to said flip head, said piston having a push-off pin axially extending down from said piston through a tip of said flip head only when said piston is in said resting position for mechanically pushing said selected component off said tip without releasing excess air.

6. The die feeder set forth in claim 5 wherein component handling parts including said suction port of said pick head, said pin structure, said strip head, and said flip head are all separately and independently easily removed and interchanged with different sized component handling parts for handling different sized components.

7. The die feeder set forth in claim 4 further comprising a fork-shaped support structure having a first arm for supporting said pick head on said first side of said collection of components and a second arm for supporting said strip head on said second side of said collection of components, said fork-shaped support structure maintaining alignment between said pick head and said strip head.

8. The die feeder set forth in claim 7 further comprising A shifting apparatus mounted to said first arm for shifting said flip head in a direction that is substantially horizontal and substantially parallel with first and second planes, said flip head further comprising means for lowering said pick head to place said selected die on said conveyor belt when said shifting apparatus has shifted said flip head.

9. The die feeder set forth in claim 7 wherein said fork shaped support is mounted for translation only along a horizontal axis that is parallel with said first and second planes and is substantially horizontal and said component support is mounted for translation only along a vertical axis that is parallel with said first and second planes and perpendicular to said horizontal axis, said die feeder further comprising:

a first automatic positioning motivator for positioning said fork support along said horizontal axis;

a second automatic positioning motivator for positioning said flexible film along said vertical axis; and

a conveyor belt motivator for operating said conveyor belt in forward and reverse directions; and

a machine vision system having a camera mounted to said first arm of said fork shaped support for precisely locating and inspecting said selected component.

10. The die feeder set forth in claim 9 further comprising a control unit controlling said first automatic positioning motivator, said second automatic positioning motivator, said conveyor belt, said strip head, and said pick head to automatically determine a precise location of said selected die, translate said fork support and said flexible film to align said pick head and said strip head with said selected die, stabilize a region of said flexible film surrounding said selected component against said strip head, actuate said pick head by applying suction to said selected component on said selected component'"'"'s first side, releasing said selected component from said flexible film by actuating said pin structure, and actuating said pick head to place said selected component on said conveyor belt.

11. A die feeder as set forth in claim 9 wherein said machine vision camera further comprises a half-silvered mirror adjacent to said pick head and angled at approximately 45°

with respect to said first and second planes, said camera being positioned to direct its line of sight in a direction substantially parallel and aimed at said half-silvered mirror, said half silvered mirror reflecting light from a position adjacent to said pick head on said second plane yet said half silvered mirror also allowing light to pass from a light source located on a side of said half-silvered mirror opposite said position and said camera.

12. The die feeder set forth in claim 3 wherein said suction port is mounted on an extensible pick plate which in turn is mounted on said pick head, said pick head is rotatably mounted and can pivot on a horizontal axis that is substantially parallel with said first and second planes and extends substantially horizontally;

said pick head thus operable to remove a selected component from said collection of components on said flexible film and place said selected component on said conveyor belt by pivoting on said horizontal axis to face said first plane, extending said pick plate toward said selected component to bring said suction port in contact with said selected component, applying suction to said suction port to hold said component against said suction port, retracting said pick plate to remove said component from said flexible film, pivot down to face said conveyor belt, extending said pick plate to bring said selected component in contact with said conveyor belt, releasing said component by discontinuing applying suction to said suction port, and retracting said pick plate.

13. The die feeder set forth in claim 3 wherein said flexible film is mounted in a support ring which is significantly thicker than said flexible film and said strip head is rotatable on an axis generally parallel with first and second planes for the purpose of rotating away from said flexible film allowing said support ring to pass during insertion and removal of said support ring and rotating towards.

14. The die feeder set forth in claim 3 wherein said strip head is operable to eject said selected component from said flexible film by first stabilizing a region of said flexible film surrounding said selected component then ejecting said selected component.

15. The die feeder set forth in claim 3 further comprising a fork-shaped support structure having a first arm for supporting said pick head on said first side of said collection of components and a second arm for supporting said strip head on said second side of said collection of components, said fork-shaped support structure maintaining alignment between said pick head and said strip head.

16. The die feeder set forth in claim 15 further comprising A shifting apparatus mounted to said first arm for shifting said flip head in a direction that is substantially horizontal and substantially parallel with first and second planes, said flip head further comprising means for lowering said pick head to place said selected die on said conveyor belt when said shifting apparatus has shifted said flip head.

17. The die feeder set forth in claim 15 wherein said fork shaped support is mounted for translation only along a horizontal axis that is parallel with said first and second planes and is substantially horizontal and said component support is mounted for translation only along a vertical axis that is parallel with said first and second planes and perpendicular to said horizontal axis, said die feeder further comprising:

a first automatic positioning motivator for positioning said fork support along said horizontal axis;

a second automatic positioning motivator for positioning said flexible film along said vertical axis; and

a conveyor belt motivator for operating said conveyor belt in forward and reverse directions; and

a machine vision system having a camera mounted to said first arm of said fork shaped support for precisely locating and inspecting said selected component.

18. The die feeder set forth in claim 17 further comprising a control unit controlling said first automatic positioning motivator, said second automatic positioning motivator, said conveyor belt, said strip head, and said pick head to automatically determine a precise location of said selected die, translate said fork support and said flexible film to align said pick head and said strip head with said selected die, stabilize a region of said flexible film surrounding said selected component against said strip head, actuate said pick head by applying suction to said selected component on said selected component'"'"'s first side, releasing said selected component from said flexible film by actuating said pin structure, and actuating said pick head to place said selected component on said conveyor belt.

19. A die feeder as set forth in claim 17 wherein said machine vision camera further comprises a half-silvered mirror adjacent to said pick head and angled at approximately 45°

with respect to said first and second planes, said camera being positioned to direct its line of sight in a direction substantially parallel and aimed at said half-silvered mirror, said half silvered mirror reflecting light from a position adjacent to said pick head on said second plane yet said half silvered mirror also allowing light to pass from a light source located on a side of said half-silvered mirror opposite said position and said camera.

20. A die feeder as set forth in claim 15 wherein said fork shaped support is limited in movement to translating only along a first axis that is generally parallel to said planes and generally horizontally disposed.

21. A die feeder substantially as set forth in claim 20 wherein at least one of said first and second arms further comprises an additional support including an extension of said at least on arm to a horizontally extending rail upon which said extension can bear its weight to stabilize and support said at least one arm.

22. A die feeder as set forth in claim 20 further comprising a machine vision system having a camera mounted to said first arm of said fork shaped support for precisely locating and inspecting said selected component.

23. A die feeder according to claim 1 further comprising a frame to support said flexible film, said frame defining the limit in size of said flexible film and said conveyor belt further comprises a deck disposed between two pulleys said conveyor belt slides against said decking and is held in tension by said two pulleys, said conveyor belt extends substantially along side and parallel to said first plane and includes a drop region spanning the width of said frame and extending in one direction beyond said drop region to a pickup location which lies outside of said drop region.

24. A die feeder as set forth in claim 23 wherein said conveyor belt further includes a ramp portion lying between said drop region and said pickup location, said ramp region having an greater slope than said drop region.

25. The die feeder set forth in claim 24 further comprising belt reversing structures at interface between said drop region and said ramp portion to gently curve said belt upward from said drop region, said reversing structures comprising two gently curving overhangs extending a small fraction of the width of said belt over said belt such that edges of an outer surface of said belt slide against said overhangs, and said overhangs hold said belt down against said decking.

26. The die feeder set forth in claim 25 further comprising two continuous strips of low friction material applied to an outer surface and along both edges of said conveyor belt to reduce friction between said belt and said belt reversing structures.

27. A die feeder as set forth in claim 23 further comprising at least one continuous column of guide bumps extending from the bottom of said belt, each said column of guide bumps riding in a respective groove formed in said deck and said pulleys to maintain transverse alignment of said conveyor belt.

28. A die feeder as set forth in claim 27 wherein said at least one continuous column of guide bumps comprises two columns of guide bumps, each bump being generally doughnut shaped with an inner hole having a smaller circumference at its center than at the top and bottom.

29. A die feeder as set forth in claim 28 wherein Said two columns of guide bumps are formed equidistantly from a centerline of said conveyor belt, said decking having two corresponding grooves within which said columns slide, said decking including a rubber magnet covered with low friction material, said rubber magnet disposed longitudinally between said two grooves and operating to hold said conveyor belt against said low friction material.

30. The die feeder set forth in claim 27 wherein said guide bumps are formed from acetal resin.

31. The die feeder set forth in claim 27 further comprising at least one pinch point along said decking, said at least one pinch point comprising a gentle narrowing and widening of said at least one groove to precisely position said guide bumps in the transverse direction, thereby positioning said belt in said transverse direction.

32. The die feeder set forth in claim 31 wherein said at least one pinch point comprises three pinch points, of which one is located near either end of said drop region and one is located near said pickup location.

33. The die feeder set forth in claim 31 wherein at least one of said at least one pinch point further includes a hold-down clamp, said clamp comprising overhangs on either side of said conveyor belt to maintain said at least one column of guide bumps in said respective groove and said conveyor belt against said decking.

34. A die feeder as set forth in claim 23 wherein said conveyor belt is formed of stainless steel, said feeder further comprising a magnet formed in said decking to magnetically couple said conveyor belt to said decking.

35. A die feeder as set forth in claim 23 wherein said two pulleys each include a central groove and said decking includes extensions at either end which extend into a respective central grooves of each of said two pulleys thereby maintaining alignment between said decking and said pulleys.

36. A die feeder as set forth in claim 1, said conveyor belt further comprising an elastomer coating to increase friction between said selected component and said conveyor belt.

37. A die feeder as set forth in claim 36 wherein said elastomer coating comprises polyurethane and is textured to reduce adhesion between said die and said coating.

38. The die feeder set forth in claim 37 wherein said components comprise bumped flip chips and said texture comprises grooves formed in said elastomer coating, said grooves being spaced approximately by the same distance as solder bumps in said flip chips.

39. The die feeder set forth in claim 36 further comprising an ultra high weight polyethylene material applied to said conveyor belt on areas of said conveyor belt that slide against said decking.

40. The die feeder of claim 1 further comprising a belt cleaning device comprising at least one brush disposed adjacent to a returning portion of said conveyor belt, said belt cleaning device further including a magnet for holding said belt against said at least one brush and to aid in removing any metal and magnetic particles present on said belt.

41. A method for removing a component from a flexible film conveying said component to a pickup location using a die feeder, comprising the steps of

extracting said component from said flexible film using a pick head;

placing said component directly on a conveyor belt adjacent said flexible film; and

operating said conveyor belt to transport said die to a pickup location.

42. The method of claim 41, said step of extracting further comprising

locating said component'"'"'s precise location using machine vision;

positioning a pick head over said component; and

removing said component from said flexible film.

43. The method of claim 42 wherein said machine vision includes a camera positioned to the left of said pick head, said method further comprising determining if said locating step or said removing step should be performed next, or whether both steps can be performed from the same position of said camera and said pick head, said step of determining being based on the criteria of which step requires positioning of said camera and said pick head closest to said camera and said pick head'"'"'s current location after having removed a component from said flexible film or having located a component to be removed.

44. The method of claim 43 wherein said step of locating further comprises employing machine vision to determine if a located die known to be good or bad, and said step of determining includes skipping known bad die.

45. The method set forth in claim 44 further comprising determining if last known good die in a row has been removed, and if so, then positioning said camera at the far right side of next row above current row.

46. The method of claim 44 wherein said step of determining whether a located die is good or bad includes detecting ink dots on known bad die.

47. The method of claim 44 wherein said step of determining whether a located die is good or bad includes determining if said located die is positioned at the same location as a known bad die is located.

48. The method of claim 44 further comprising employing said machine vision to check for the presence of solder bumps if said components are flip chips and to ensure that corners of said components are present.

49. The method of claim 42 wherein said step of positioning further comprises sliding said pick head along a first, substantially horizontally disposed axis, and raising and lowering said flexible film along a second, substantially vertically disposed axis, said first and second axes being substantially parallel to plane defined by said flexible film.

50. The method of claim 41 further including expanding said flexible film by stretching it in all directions, thereby separating said components from one another prior to extracting die from said flexible film.

51. the method set forth in claim 41 wherein said step of placing a die includes rotating said pick head 90°

down to face said conveyor belt and placing said die on said conveyor belt.

52. The method of claim 41 wherein said step of operating said conveyor belt includes stopping said conveyor belt when either a component is being placed on said conveyor belt or a die is present at said pickup location.

53. The method set forth in claim 52 wherein said conveyor belt includes a stop at the pickup location and said method of operating further comprises operating said conveyor belt to over-travel when said component reaches said stop to square said component against said stop and loosen said component from a surface of said conveyor belt.

54. The method of claim 53 further comprising determining if said feeder is in a burst mode, and if so, moving said conveyor belt only enough to separate successive components by a small distance as they are placed on said conveyor belt until a predetermined number of die are present and conveying said predetermined number of die to said pick point for feeding said predetermined number of die in rapid succession to a host machine.

55. The method of claim 41 further comprising employing a strip head on an opposite side of said flexible film from said components by stripping said die from said flexible film during said step of extracting, wherein said step of stripping includes stabilizing said flexible film using a suction anvil then pushing at least one pin through said flexible film, pushing said component away from said flexible film.

56. The method of claim 55 wherein said flexible film is mounted in a ring which is thicker than said flexible film, said method further comprising automatically assisting loading said ring through loading doors and into a mounting clamp by rotating said strip head away from said flexible film, translating said strip head to a position within said ring, then rotating said strip head to face said flexible film, then translating said strip head away from said loading doors, engaging an inside rim of said ring, and continuing to translate away from said doors while dragging said ring until said ring is positioned in said mounting clamp.

57. A method of removing components from a flexible film and presenting said components in one of a conventional and a flipped orientation comprising the steps of:

extracting a component from said flexible film using a pick head;

placing said component directly on a conveyor belt if said component is to be presented in a conventional orientation;

passing said component to a flip head then placing the component on the conveyor belt if the component is to be presented in a flipped orientation; and

operating said conveyor belt to transport said component to a pick-up location.

58. The method set forth in claim 57 wherein said step of extracting a component from said flexible film and said step of placing said component on the conveyor belt using a flip head are carried out concurrently when said component is to be presented in a flipped orientation.

59. The method set forth in claim 58 wherein said step of extracting a component from said flexible film and said step of operating said conveyor belt occur concurrently when the conveyor belt carries a component and there is no component present at said pick-up location.

60. The method set forth in claim 59 wherein said steps of extracting a component from said flexible film and said steps of passing said component to a flip head occur concurrently with the step of operating said conveyor belt when the conveyor belt carries a component and there is no component present at said pick-up location.