Wafer-level Chip Scale Package (WLCSP) is the packaging technology for IC chips still in the form of wafer, compare to the conventional method of dicing the wafer into individual chip and then packaging them. WLCSP is essentially a true chip scale package (CSP) technology, since package is the same size as the silicon chip. Wafer-level packaging allows the integration of wafer sort, packaging, final test, and burn-in test at wafer level in order to streamline the manufacturing process. WLCSP is a process designed to complete packaging and testing operations of semiconductor devices before wafer dicing. Normally, semiconductor devices will be placed in the carrier tape after dicing and sealed with the cover tape in order to protect the IC for subsequent processing. WLCSP provides the best solution to meet the requirements of small foot print, light weight, and miniaturization for the devices to be used in communication products like cellular phones, TWS and other portable electronics. WLCSP generally employ lead free solder balls to form joints with substrate in order to provide electric connections. The solder joints serve the purpose to reduce the stresses resulting from the thermal mismatch between substrate and device as well in order to enhance the service reliability.
ChipMOS provides the BOP (Ball on Pad, 4 masks) and BOT (Ball on Trace, 3 masks) solutions to customers.