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Proposal 2 for Handling Small KOZ Package – Gulisan on JEDEC Plastic Tray

Proposal 2 for Handling Small KOZ Package – Gulisan on JEDEC Plastic Tray. Date : 27 th May, 2004. Background 1. The handling / précising mechanism for Springdale G, Genting 6, etc., was proposed and reviewed Working fine according to the preliminary evaluation done on system #3 on WW22

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Proposal 2 for Handling Small KOZ Package – Gulisan on JEDEC Plastic Tray

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  1. Proposal 2 for Handling Small KOZ Package – Gulisan on JEDEC Plastic Tray Date : 27th May, 2004

  2. Background 1 • The handling / précising mechanism for Springdale G, Genting 6, etc., was proposed and reviewed • Working fine according to the preliminary evaluation done on system #3 on WW22 • KOZ of a new package – Gulisan (37.5x37.5) is much reduced from the previous common packages, say Springdale G, Genting 6, Gransdale G, etc., of same form factor • Not enough space for the vacuum ring adopted in the method handling Springdale G

  3. Background 2 • Two other approaches were proposed • Enlarge the KOZ as shown • Not accepted because of package design issue • Relocate the vacuum ring to the inner area of the package, without contacting the die and other components of the packages • Not preferred because the kit will become package specific Inner Vacuum Ring Enlarge KOZ

  4. Define Problems / Propose Solution • Small KOZ • Not enough space to provide vacuum ring or suction caps to hold the package against sticking force of flux on pin tips when pin head leaves after fluxing process • Make use of the limited area of KOZ to provide suction and package supports • Stabilize the package before the following clamping actions • Provide side force on 4 sides of the packages • Package is clamped by grippers around 4 sides • Create frictional force to overcome sticking force and provide package alignment

  5. Working Sequence 1 • Tray indexed to standby position by the conveyer belts • Package support vacuum is on to standby Patent Pending

  6. Working Sequence 2 • Top clamp moves to a middle level • Guiding edges of top clamp are not yet touching the packages • Plastic tray on conveyor belts is flattened by air cylinder of top clamp Patent Pending

  7. Patent Pending Working Sequence 3 • Push block moves up with the tray which is still being held by the cylinder of top clamp • Packages held by vacuum of supports on push block • Packages raise a bit from the tray and are still well within the pockets of the tray

  8. Working Sequence 4 • Top clamp moves down further to • Keep holding the tray • Provide guidance to packages by the guiding edges of the top clamp • Packages are still held by vacuum of the supports of the push block to avoid “out of pocket” from tray • BGA clamps of push block close • Thus bias the packages to the guiding edges of the top clamp • Provide frictional force to hold the package against sticking force of pin tips when pin head raises after fluxing process • Flux and ball placement processes can proceed Patent Pending

  9. Working Sequence 5 • Fluxing process completes • When fluxing pin head is leaving, packages are held by vacuum and frictional forces at package 4 sides introduced by BGA clamps to overcome the sticking force of the flux on pin tips Patent Pending

  10. Working Sequence 6 • BP process completes • BGA clamps (grippers) open • Top clamp moves up to the middle level • Cylinders of top clamp keep on holding the tray • Packages are still held by vacuum Patent Pending

  11. Working Sequence 7 • Vacuum of the package supports releases • Push block moves down • Packages sit back onto the tray pockets • Top clamp moves up further to the upper position • Tray rests onto conveyor belts and waits for next indexing Patent Pending

  12. Fsticking Ffriction (distributed at four edges) Fsuction Gulisan unit Unit side view Design Calculations • Estimation on clamping force required • Sufficient holding force must be applied to the singulated BGA unit to prevent the unit from picking up by the fluxed pins. Based on experiment, the sticking force (Fsticking) on a Gulisan unit is estimated to be 8.29N with 3x safety factor taken into consideration. • As the KOZ of Gulisan unit is limited, the suction force that can be provided to secure the unit is very small. The suction force (Fsuction) that can be provided on a Gulisan unit is around 0.44N (8 suction holes w/ 1mm opening, assumed 70% vacuum level), which is certainly not large enough to secure the unit • In order to secure the unit, we have to clamp the four edges of the unit to generate sufficient frictional force to balance the sticking force. The frictional force (Ffriction) required is 7.85N(8.29N – 0.44N)

  13. Fclamp Fclamp Fclamp Fclamp Fclamp Fclamp Gulisan unit Fclamp Fclamp Unit top view Design Calculations • There will be 8 clamping surfaces at the four edges of the Gulisan unit. Each of the clamping surface should be able to build up 7.85N  8 = 0.98N frictional force to secure the package. • In order to generate the 0.98N frictional force, we estimate the clamping force (Fclamp) required for each clamping surface is about 9.8N or 1kg with 2x safety factor taken into consideration (friction coefficient is predicted to be 0.2 based on literature finding)

  14. Possible Risks 1 • Sticking force variation • Flux viscosity may change quite a lot (up to a few times) because of flux property change, environmental factors change, etc.. • Sticking force of the flux on pin tips can change accordingly • 3x safety factor is added

  15. Possible Risks 2 • Clamping stability • Small height of package – about 1mm • Small margin for clamping • Small suction force due to small contact area allowed • Little force holding the packages against any vertical force component introduced by clamping due to non-perfectly vertical edges of package • Risk of package slippage / jumping during clamping • Risk of package co-planarity issue that may affect ball placement process • Material variation • Package thickness variation of 0.06mm and package warpage of 0.2mm as per the spec • Risk of package slippage / jumping during clamping

  16. Possible Risks 3 • Friction factor • A pretty theoretical value – 0.2 based on literature • Change with package edges and gripper conditions • 2x safety factor added • Complexity • More complicated design, comparing the one used for Springdale G….. • Potentially less stable and reliable • Limited clearance between BGA grippers, tray small rectangular openings and package edges • Potentially lower MTBA, MTBF,…..

  17. Advantages • An universal design for same form factor packages of these two KOZs • Design standardization • Less tooling conversion • Etc….

  18. Other Concerns • Higher in cost • More complex, more parts and component • Longer leadtime • Longer debugging / fine tuning time • Limited use – cannot place balls on both rows of units in two passes in one BP unit.

  19. Development Schedule *Remark: If possible, test on system #5

  20. Contingency Plan • Provide an alternative design similar to that for Springdale G • Inner vacuum ring • Make use of the rest of the précising mechanism is same as Springdale G / Gransdale G

  21. Business Concerns • Higher price – The cost for this design of tooling set is higher than the initial design due to the greater number of components and the details involved. • Gulisan toolset pricing – USD 23,375.00 • If design is approved, then please proceed to update the PO for Gulisan • Indah toolset pricing* - USD 27,550.00 • If design is approved, then please proceed to update the PO for Indah *PO will be accepted pending results of Gulisan package tests

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