Abstract
In recent years,mobile apparatus,such as mobile phones and PDAs,have become increasingly smaller and with more functions.For mounting LSIs in mobile apparatus,a method that enables high pin count and narrow pin pitch LSI bonding is needed.So,we have developed ultrasonic flip-chip bonding process for pin count and narrow pin pitch LSI bonding on PWBs(printed wiring boards). Based on the experiment date,we investigated the relationship between the 2-step bonding process and the conventional bonding process. Test chips bonded using this process have good bondability.It is confirmed that this process is applicable for high pin count and narrow pin pitch LSI JISSO.