Bonding Capillaries Bonding Evolution 2018 by SPT - Small Precision Tools

More catalogs by SPT - Small Precision Tools | Bonding Capillaries Bonding Evolution 2018 | 41 pages | 2018-02-19

Ads

Page 13 of Bonding Capillaries Bonding Evolution 2018

gold copper wire bonding cycle the wire bonding cycle using copper wire is almost the same as the gold wire as it forms the ball bond loop and stitch sequence the introduction of forming gas during the free-air-ball formation for copper wire is the only difference in the process forming gas consist of 95 nitrogen to prevent copper wire from oxidation and 5 hydrogen for flammability enhancement to create concentric fab during efo electronic flame off firing highly oxidized copper free-air-balls are basically harder and more difficult to bond on sensitive silicon technology in addition the forming gas helps to inhibit the oxidation of copper wire once exposed to ambient temperature of wire bonders’ heater block 1 free air ball fab to achieve consistency of the free air ball size it requires consistent tail length after second bond formation and consistent electronic flame-off efo firing fabØ gold wire after the second bond application the capillary lifts up with its tail protruding outside the capillary tip this action would then enable the electronic flame off efo to be activated to form the gold fab and then the bondhead goes to the reset position for the next bonding cycle thus the fab is already formed before the next bonding cycle begins copper wire to form a concentric copper free-air-ball a “copper kit” is a must have to ensure continuous controlled flow of forming gas towards the tip of the capillary and torch electrode efo wand to prevent copper from oxidation after the stitch bond application the capillary lifts up with its tail protruding outside the capillary tip then the bondhead goes to the reset position with the absence of the fab the copper bonding cycle starts with a formation of the fab 2 free-air ball is centered inside the capillary chamfer area a wire tensioner is used to ensure that the free air ball is up and at the center of capillary face prior to being lowered onto the die bond area if this condition is not met there is a chance of producing an irregular ball bond deformation commonly known as “golf club ball bond” back to content 13