Reliability effect of prolonged exposure time after plasma cleaning process on integrated circuit package

Abstract

This research studied about an appropriate exposure time of plasma cleaning process on integrated circuit (IC) packaging. The plasma cleaning process is an option of IC packaging process to reduce the contamination on die surface and also control oxidation on lead frame to enhance bondability performance during wire bonding process. In wire bonding process, the bondability will be disturbed from the contamination and oxidation effect to bondability to increase lot reject rate. Limitation of plasma cleaning process is the exposure time after plasma cleaning need to be controlled to prevent contamination and recombination of oxidation on die surface and lead frame. The experiment studied for packages of 8L-PDIP with large die attach pad (DAP) size respectively. The packages were tested Gold (Au) wire.  IC packaging process were varied exposure time after plasma cleaning process with 5 minutes from 0 to 96 hours with a step of 12 hours to find the appropriate exposure time for wire bonding process. All packages were tested for contact angle measurement and bondability. The results confirmed that plasma cleaning process with 5 minutes to reduce the contamination on die surface and lead frame to enhance bondability performance for packages and wires. Moreover, the evaluation showed about not clearly possibility of prolonged exposure time at 36 hour for extending exposure time after plasma cleaning.