Study on plasma cleaning and strength of wire bonding

In IC and MEMS (micro electric mechanical systems) packaging processing, the successful application of plasma cleaning technology depends on cleaning process parameters such as pressure, RF power, cleaning time and cleaning gas etc. The effects of cleaning parameters on the strength of wire bonding are investigated in this paper. We select a type of hybrid PCB to do cleaning experiments using difference process parameters, and then do wire bonding and pull tests. The experimental results demonstrate: (1) the cleaning effect is very good when RF power is around 200∼600 W, and typical PF power value is 600 W; (2) in the condition between 400-600 W RF power, cleaning for about 10-15 minutes can get a good cleaning effect; (3) the cleaning effect is better when the samples were placed in the ground electrode rather than in the anode; (4) when the gas pressure is 100∼120 mT or 140∼180 mT, we can obtain a better cleaning effect; (5) smaller distances and symmetrical electrode structures have a better cleaning effect.