Application of die attachless process for plastic packages (Thermoplastic Polyimide-Transferred Wafer Technology)

The mechanical stability of plastic packages such as QFP, BGA, and CSP used in surface mount technology is our primary concern. The dominant issue is the interfacial delamination around the die attach materials. Furthermore, significant production cost increases occur due to a variety of chip sizes requiring numerous die pads for lead frame designs. To address these issues, a unique process has been developed, called “Polyimide-Transferred Wafer Process”. This technology allows the thermoplastic polyimide to be perfectly transferred from its coating dicing tapes to the wafer backside at an elevated temperature prior to the dicing process. The polyimide-deposited chip replaces the die attach dispense process and has given rise to the possibility of all sorts of cost efficient lead frame designs