Flexible pick-up arm for pick-and-place apparatuses

Abstract

A pick-up arm for a pick-and-place apparatus for electronic devices comprises a body having a proximal end at which the pick-up arm is mountable to a pick-up arm support and a distal end at which a collet for gripping an electronic device is mounted. A first rigid body is located in the vicinity of the proximal end of the pick-up arm and a second rigid body is located in the vicinity of the distal end of the pick-up arm. A first flexible member and a second flexible member connect the first rigid body to the second rigid body. Furthermore, the first flexible member is spaced apart from the second flexible member and the first and second flexible members have opposing surfaces arranged substantially parallel to each other. An actuator is for applying a biasing force to the second rigid body to cause the first and second flexible members to flex relative to the first rigid body to thereby bias the collet of the pick-up arm to move.

Description

TECHNICAL FIELD

[0001] The present invention relates to a pick-up arm for a pick-and-place apparatus, such as an electronic device bonder for picking up electronic devices for bonding. BACKGROUND

[0002] Electronic device bonders for the semiconductor packaging industry have one or more pick-up arms for bonding electronic devices, such as semiconductor dies or chips. It is often required to design pick-up arms for rotational vertical movement / linear vertical movement during pick-and-place operations, which include picking up electronic devices from an electronic device supply at one location and bonding the electronic devices onto a substrate at another location.

[0003] In particular, with respect to the mechanism for moving the pick-up arm along a vertical axis, it is common to use a bearing arrangement to guide such movement. The bearing arrangement can for example include cross roller guides, linear motion guides or cage bearings. Such bearing arrangements can be used with a spring pivot on a cantilever to introduce a degree of flexibility along the vertical axis. Other advanced pick-up arm designs can also use a bearing arrangement for movement along the vertical axis, as well as a linear motor designed such that the pick-up arm can also move slightly in the vertical direction.

[0004] However, these bearing arrangements described above inevitably increase the load carried by the bonder's head module, and increase the moment of inertia of the head module, which is a significant disadvantage if the head module is used in a high speed die bonding system. Moreover, these bearing arrangements will have an axial play, which can cause side play or end point chatter during pick-and-place operations, resulting in poor positional accuracy. Furthermore, these bearing arrangements require regular maintenance, which is disadvantageous as improper maintenance can shorten the service life of the bonder head. From a production and design perspective, the implementation of these bearing arrangements further increases the complexity of the bonder arm structure, and increases the total number of parts used in the bonder arm module that must be maintained or replaced, leading to increased operating costs.

[0005] It would be beneficial to be able to reduce at least some of the aforementioned disadvantages faced by conventional pick-and-place apparatuses that use bearing arrangements in the pick-up arm, thereby avoiding the use of such bearing arrangements. SUMMARY

[0006] It is therefore an object of the present invention to seek to provide an improved pick-up arm for a pick-and-place apparatus that utilises a flexure in place of at least one conventional bearing arrangement to improve the performance of the pick-up arm.

[0007] Thus, the present invention provides a pick-up arm for a pick-and-place apparatus for electronic devices, comprising: a main body having a proximal end, at which the pick-up arm is mountable to a pick-up arm support, and a distal end, at which a collet for gripping an electronic device is mounted; a first rigid body located in the vicinity of the proximal end of the pick-up arm and a second rigid body located in the vicinity of the distal end of the pick-up arm; a first flexible member and a second flexible member connecting the first rigid body to the second rigid body, the first flexible member being spaced apart from the second flexible member and the first and second flexible members having opposing surfaces arranged substantially parallel to each other; and an actuator operable for applying a biasing force to the second rigid body to cause the first and second flexible members to bend relative to the first rigid body, thereby biasing the collet of the pick-up arm to move.

[0008] These and other features, aspects, and advantages will become better understood with reference to the following description, appended claims, and accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0009] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:

[0010] Figure 1 is an isometric view of a bonding apparatus comprising a plurality of pick-up arms according to a preferred embodiment of the invention;

[0011] Figure 2 is a side view of the bonding apparatus shown; Figure 1

[0012] Figure 3 is an isometric view of a pick-up arm according to a preferred embodiment of the invention;

[0013] Figure 4 is a cross-sectional side view of the pick-up arm shown; Figure 3

[0014] Figure 5 is a schematic view showing the collet of the pick-up arm contacting an electronic device when picking up the electronic device; and

[0015] Figure 6A is a schematic view of the pick-up arm in a standby position, Figure 6B is a schematic view of the pick-up arm after a vertical force has been applied to the pick-up arm to cause the collet to contact an electronic device.

[0016] In the drawings, like parts are denoted by the same reference numerals. DETAILED DESCRIPTION

[0017] Figure 1 ​​is an isometric view of a pick-and-place apparatus or bonder including a plurality of pick arms 12 according to a preferred embodiment of the present application. The bonder can be a die bonder including a bonder head module 10 on which a plurality of pick arms 12 are rotatably arranged to bond electronic devices 56 (see Figure 5 ) such as semiconductor chips onto a substrate 14. The substrate 14 is placed and fixed on a substrate positioning table 16 which is mounted on two guide rails 18 which are stacked relative to each other and orthogonally arranged on a base 20. The guide rails 18 guide the substrate positioning table 16 to move in a horizontal plane to various positions to precisely position a plurality of bonding locations on the substrate 14 under the pick arms 12. Once positioned to the bonding locations of the substrate 14 under the pick arms 12, the pick arms 12 can bond the electronic devices 56 which are clamped onto the bonding locations.

[0018] The bonder head module 10 further includes a pick arm rotation motor 22 centrally located on the bonder head module 10 for rotating the plurality of pick arms 12 relative to the substrate positioning table 16. Thus, each pick arm 12 clamping an electronic device 56 can be rotated to a position above the substrate positioning table 16 to bond the electronic device 56 onto the substrate 14. Above the placement position on the substrate positioning table 16, there is also a vertical actuator 24 at the stop position of each pick arm 12. The vertical actuator 24 is used to press the top of the pick arm 12 located above the substrate positioning table 16 and apply a biasing force thereto to deflect the pick arm 12 to move it towards the substrate 14 during bonding of the electronic device 56.

[0019] Figure 2 is a side view of the bonder shown in Figure 1 . In this view, it can be seen that a rotor mount 26 connects a pick arm support which can be in the form of a rotary turntable 28 to the pick arm rotation motor 22, the rotary turntable 28 supporting a plurality of pick arms 12 mounted along the periphery of the rotary turntable 28. The pick arm rotation motor 22 drives the rotor mount 26 and the turntable 28 to rotate so that the pick arms 12 can be sequentially rotated to positions above the substrate positioning table 16.

[0020] The bonder head module 10 described in the preferred embodiment of the present application is used in a turntable bonder for bonding electronic devices such as semiconductor devices onto a substrate which can be in the form of a PCB circuit board having pre-printed solder or flux. However, it should be appreciated that the pick arms 12 according to the preferred embodiment can also be used in other types of pick-and-place apparatus such as bonder including a single pick arm.

[0021] An electronics supply 30 is located on one side of the bond head module 10, while a substrate positioning stage 16 is located on the opposite side of the bond head module 10. The electronics supply 30 can include a wafer ring that holds a matrix of singulated electronics devices, such as semiconductor dies singulated from a semiconductor wafer. Thus, an ejector 32 located below the electronics supply 30 can push each electronics device 56 upward to eject the electronics device 56 and facilitate its pickup by a pickup arm 12 above the electronics device 56. At the pickup position, a pickup actuator 24a is fixedly located above the electronics supply 30 to apply a biasing force to the pickup arm 12 that has moved to the pickup position relative to the pickup actuator 24a.

[0022] After the pickup arm 12 has picked up and clamped the electronics device 56, the pickup arm rotation motor 22 rotates the turntable 28 by a predetermined angle to position an adjacent pickup arm 12 above the electronics supply 30 to pick up another electronics device 56. Meanwhile, the electronics device 56 that has been picked up by the pickup arm 12 is gradually moved by the rotation of the pickup arm rotation motor 22 until the pickup arm 12 reaches a placement position on the substrate 14 that has been secured to the substrate positioning stage 16. A placement actuator 24b is fixedly located above the placement position to bias the electronics device 56 to apply a biasing force to the pickup arm 12 that has moved to the placement position relative to the placement actuator 24b. At the placement position, the electronics device 56 is lowered onto the substrate 14, where the electronics device 56 is bonded. Next, the next pickup arm 12 carrying the electronics device 56 is transported to the placement position on the substrate 14 to bond the next electronics device 56 to the substrate 14, and so on, until all of the bonding sites on the substrate 14 are occupied by bonded electronics devices 56.

[0023] Figure 3 is an isometric view of a pickup arm 12 according to a preferred embodiment of the present application. The body of the pickup arm 12 has a proximal end at which the pickup arm 12 is mounted or mountable to the turntable 28. A first or proximal rigid mount 40 is located near the proximal end of the pickup arm 12. The pickup arm also has a distal end at which a collet 44 for clamping an electronics device 56 is mounted. A second or distal rigid mount 42 is located near the distal end of the pickup arm 12, and the distal rigid mount 42 is connected to and supported by the proximal rigid mount 40 by a pair of resilient support members in the form of a pair of top leaf springs 34 located at the top of the proximal and distal rigid mounts 40, 42 and a pair of bottom leaf springs 36 located at the bottom of the proximal and distal rigid mounts 40, 42.

[0024] The top leaf spring 34 and the bottom leaf spring 36 are separated such that the distance between the top leaf spring 34 and the bottom leaf spring 36 at the proximal rigid mount 40 is substantially equal to the distance between the top leaf spring 34 and the bottom leaf spring 36 at the distal rigid mount 42.

[0025] In this pick arm configuration, the pair of elastic support members (in the form of top leaf spring 34 and bottom leaf spring 36) each have opposing surfaces arranged substantially parallel to each other. The top leaf spring 34 and the bottom leaf spring 36, together with the first rigid mount 40 and the second rigid mount 42, are configured as a flexible four-bar mechanism. Such a flexible four-bar mechanism includes two rigid bodies each configured to space apart the flexible leaf springs by an equal distance, and the two rigid bodies are fixed near the opposite ends of the pair of flexible leaf springs. When one of the rigid bodies (the proximal rigid mount 40) is fixedly mounted on the rotor mount 26 by the turret 28, the other rigid body (the distal rigid mount 42) is configured to be biased by the application of a pushing force from the vertical actuator 24 onto the other rigid body to control the vertical movement of the collet 44 of the pick arm 12. The collet 44 is mounted to the distal ends of the flexible leaf springs 34, 36 such that the collet 44 can be actuated by the biasing force applied by the vertical actuator 24 onto the rigid body next to the collet 44.

[0026] Figure 4 is Figure 3 A cross-sectional side view of the pick arm 12 is shown. Spacers 50, 51 are used to space apart the top and bottom of the proximal rigid mount 40 and the distal rigid mount 42 such that the top leaf spring 34 and the bottom leaf spring 36 are spaced apart from each other by a fixed separation distance. The proximal rigid mount 40 and the distal rigid mount 42 are each configured to have a top locking plate 46, 47 and a bottom locking plate 48, 49.

[0027] The top locking plate 46 and the bottom locking plate 48 are fixed to the respective spacers 50 at the proximal rigid mount 40, and the top locking plate 47 and the bottom locking plate 49 are fixed to the respective spacers 51 at the distal rigid mount 42 to sandwich the top leaf spring 34 and the bottom leaf spring 36 in between. Such fixing can be achieved by any suitable means of attachment, such as by riveting the individual components together using rivets 52, or by applying glue (such as epoxy glue or the like) onto the top leaf spring 34 and the bottom leaf spring 36. The spacers 50, 51 have equal thicknesses so as to keep the flexing axis of one leaf spring 34 or 36 coincident with the flexing axis of the other leaf spring. This results in an assembly with the required axial and torsional strength characteristics.

[0028] In the pick arm configuration as Figure 4In the illustrated standby orientation, when the vertical actuator 24 is in its retracted position and no biasing force is applied to the distal rigid mount 42, the surface of the top leaf spring 34 is generally disposed on a horizontal plane 54 and the surface of the bottom leaf spring 36 is disposed on another horizontal plane parallel to the horizontal plane 54 on which the surface of the top leaf spring 34 is disposed.

[0029] Figure 5 A schematic view of the pick arm 12 is shown after a vertical force is applied to the pick arm 12 to apply a biasing force to push the distal rigid mount 42 to move the collet 44 to contact the electronic device 56. To apply the vertical force, the vertical actuator 24 is actuated vertically downward a predetermined distance to push the distal rigid mount 42 downward. The vertical actuator 24 is configured to move the predetermined distance so that the top leaf spring 34 and the bottom leaf spring 36 flex and the tip of the collet 44 is lowered below the collet tip standby height 60 a sufficient amount so that the collet contacts the electronic device 56 to be picked. Optionally, the ejector 32 can simultaneously push the electronic device 56 upward toward the collet 44, in which case the collet 44 can be moved downward a lesser amount.

[0030] Figure 6A A schematic view of the pick arm 12 is shown after a vertical force is applied to the pick arm 12 to apply a biasing force to push the distal rigid mount 42 to move the collet 44 to contact the electronic device 56. To apply the vertical force, the vertical actuator 24 is actuated vertically downward a predetermined distance to push the distal rigid mount 42 downward. The vertical actuator 24 is configured to move the predetermined distance so that the top leaf spring 34 and the bottom leaf spring 36 flex and the tip of the collet 44 is lowered below the collet tip standby height 60 a sufficient amount so that the collet contacts the electronic device 56 to be picked. Optionally, the ejector 32 can simultaneously push the electronic device 56 upward toward the collet 44, in which case the collet 44 can be moved downward a lesser amount.

[0031] Figure 6B A schematic view of the pick arm 12 is shown after a vertical force is applied to the pick arm 12 to apply a biasing force to push the distal rigid mount 42 to move the collet 44 to contact the electronic device 56. To apply the vertical force, the vertical actuator 24 is actuated vertically downward a predetermined distance to push the distal rigid mount 42 downward. The vertical actuator 24 is configured to move the predetermined distance so that the top leaf spring 34 and the bottom leaf spring 36 flex and the tip of the collet 44 is lowered below the collet tip standby height 60 a sufficient amount so that the collet contacts the electronic device 56 to be picked. Optionally, the ejector 32 can simultaneously push the electronic device 56 upward toward the collet 44, in which case the collet 44 can be moved downward a lesser amount.

[0032] At this time, a vacuum suction force is generated at the nip of the chuck 44, so that the chuck 44 can hold the electronic device 56. Thereafter, the vertical actuator 24 can be retracted again, so that the biasing force 58 is no longer applied to bend the top leaf spring 34 and the bottom leaf spring 36, and thus the top leaf spring 34 and the bottom leaf spring 36 return to their standby positions arranged on the parallel horizontal plane 54. Once the top leaf spring 34 and the bottom leaf spring 36 are no longer biased and return to the horizontal plane, the pick-up arm rotation motor 22 can drive the turntable 28 to rotate the pick-up arm 12 holding the electronic device 56 toward the substrate positioning table 16 to an incremental rotation position for bonding the electronic device 56 onto the substrate 14.

[0033] Attention should be paid to align the axes of the two leaf springs 34, 36 during assembly to ensure that the flexible leaf springs can operate within the specified limits required for stable performance. Since the leaf springs 34, 36 are vulnerable to damage due to angular deflection beyond certain limits, it is preferable to allow vertical displacement of the distal rigid mount 42 to be less than 4 mm, and the extent of displacement can be controlled by software. The leaf springs 34, 36 can be made of any suitable elastic material, such as austenitic stainless steel plate (SUS301 or SUS304) or carbon fiber plate. If a carbon fiber plate is used, the moment of inertia of the pick-up arm 12 can be reduced by about 20% compared to a conventional pick-up arm incorporating a retainer bearing design. In summary, such a flexible bonding arm can provide lighter mass, smaller moment of inertia, and more stable end point settling, so that more accurate pick-and-place operations can be performed on electronic devices. Advantageously, since such a flexible design has higher stiffness, it is subject to less lateral and longitudinal vibration.

[0034] The pick-up arm 12 has many other advantages as described in the preferred embodiment of the present application. First, the manufacturing cost of the pick-up arm 12 is reduced due to the reduction in parts and the avoidance of the need for complex assembly operations. Also, due to the flexible construction of the pick-up arm 12, it is less vulnerable to damage compared to conventional pick-up arms. Since the assembly eliminates the unnecessary side play commonly found in conventional bearing rails, it has higher precision and stiffness with respect to the flexible axis. Furthermore, the pick-up arm 12 is relatively robust in both longitudinal and lateral directions compared to the prior art, with less torsional and longitudinal vibration.

[0035] It should be understood that the use of a pair of leaf springs on a single pick-up arm design or a multiple pick-up arm design is not a limitation of the present application, but is described by way of example only. The use of such pick-up arms 12 is not limited to application in a die bonder, but can also be used in any machine design where precise node connections are required to manipulate a device. Two pairs of leaf springs can be used instead of one pair, with two leaf springs deployed along each plane instead of one. Of course, other variations to the specific construction and arrangement of the pick-up arms 12 disclosed above can be made by those skilled in the art without departing from the present application as defined in the appended claims.

[0036] While the application has been described in some detail with reference to certain embodiments thereof, other embodiments are possible.

[0037] Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein.

Claims

1. A pickup arm for a pickup and placement device for electronic devices, comprising: The body has a proximal end and a distal end, wherein at the proximal end the pickup arm can be mounted to a pickup arm support, and at the distal end a chuck for holding electronic devices is mounted. A first rigid body located near the proximal end of the pickup arm and a second rigid body located near the distal end of the pickup arm; A first flexible member and a second flexible member are mounted on a first rigid body and a second rigid body, such that the first flexible member and the second flexible member are spaced apart, and the first flexible member and the second flexible member have opposing surfaces arranged substantially parallel to each other. as well as An actuator operable to apply a biasing force to the second rigid body to bend the first flexible member and the second flexible member relative to the first rigid body, thereby biasing the chuck of the pickup arm to move it to pick up or bond the electronic device. The chuck is mounted on the first and second flexible members at the distal end of the pickup arm, and the chuck is spaced apart from the second rigid body such that the second rigid body is positioned between the chuck and the first rigid body.

2. The pickup arm according to claim 1, wherein, The pickup arm support includes a rotary table configured to mount a plurality of pickup arms along the periphery of the rotary table.

3. The pickup arm according to claim 1, wherein, The actuator includes a placement actuator that is fixedly positioned above a placement location for bonding electronic devices, and the pickup arm is movable relative to the placement actuator to be located near the placement actuator, thereby being biased by the placement actuator at the placement location.

4. The pickup arm according to claim 3, wherein, The actuator further includes a pickup actuator fixedly located above the electronics supply at the pickup position, and the pickup arm is movable relative to the pickup actuator to be located near the pickup actuator, thereby being biased by the pickup actuator at the pickup position.

5. The pickup arm according to claim 1, wherein, The first flexible member is mounted on top of the first rigid body and the second rigid body, and the second flexible member is mounted on the bottom of the first rigid body and the second rigid body.

6. The pickup arm according to claim 5, wherein, The distance between the first flexible member and the second flexible member at the first rigid body is substantially equal to the distance between the first flexible member and the second flexible member at the second rigid body.

7. The pickup arm according to claim 6, wherein, The flexible axis of the first flexible member coincides with the flexible axis of the second flexible member.

8. The pickup arm according to claim 5, wherein, The first flexible member and the second flexible member, as well as the first rigid body and the second rigid body, are configured as a flexible four-bar linkage, wherein the second rigid body is configured to be biased by the actuator to control the vertical movement of the chuck.

9. The pickup arm according to claim 5, wherein, Each rigid body includes a spacer separating the first flexible member and the second flexible member, a first locking plate for locking the first flexible member to each rigid body, and a second locking plate for locking the second flexible member to each rigid body.

10. The pickup arm according to claim 9, wherein, The first flexible member and the second flexible member are fixed to the first locking plate and the second locking plate by riveting or by applying glue to the first flexible member and the second flexible member.

11. The pickup arm according to claim 1, wherein, When the actuator does not apply a bias force, in the standby position of the pickup arm, the surfaces of the first flexible element and the second flexible element are arranged on the corresponding horizontal plane.

12. The pickup arm according to claim 11, wherein, The actuator applies the biasing force to the second rigid body, causing the first flexible member and the second flexible member to bend, thereby causing the second rigid body to deflect away from the horizontal plane.

13. The pickup arm according to claim 1, wherein, The actuator is capable of moving a predetermined distance between a retracted position and an extended position. In the retracted position, the actuator does not apply a biasing force to the second rigid body, and in the extended position, the actuator applies a biasing force to push the second rigid body to move.

14. The pickup arm according to claim 13, wherein, When the second rigid body is pushed by the actuator, the distance it moves is limited to less than 4 mm.

15. The pickup arm according to claim 1, wherein, Both the first flexible member and the second flexible member include leaf springs.

16. The pickup arm according to claim 15, wherein, The first flexible member and the second flexible member are made of austenitic stainless steel plate or carbon fiber plate.

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