ElectroMagnetic Wafer Sort (EMWS) was developed from Electrical Wafer Sort (EWS), performed at the end of wafer processing and before package assembly and final test. In EMWS, each die contains a tiny antenna. Automated test equipment (ATE) supplies power and communicates with the die via electromagnetic waves.
The ATE uses probes only to power-up the wafer in high-power products. Low-power products are tested with no contact at all.
EMWS is the result of UHF TAG Antenna Magnetically Coupled to Integrated Circuit (UTAMCIC), an R&D initiative led by Alberto Pagani, Giovanni Girlando and Alessandro Finocchiaro from STMicroelectronics and Professor Giuseppe Palmisano from the University of Catania.
The die, such as RFID ICs, can be tested with higher yields, shorter testing times, and lower product cost, under close-to-real-operation conditions, ST asserts. Die size can be reduced with fewer test pads required.
The biggest benefit will go to customers using ST’s low-power RF circuits, said Alberto Pagani, Test R&D and Competitive Intelligence, ST. "Because the RF circuits, anticollision protocol, and embedded antenna are tested under the same conditions they will operate under in the customer