We think of flip chip as a solution for better performance, high I/O or absolute size reduction. But a new and exciting technology is now emerging where the flip chip is the unique answer to extreme cost reduction in a very low I/O product, the RFID tag. RFIDs are Radio Frequency Identification systems tiny two-way radios with immense commercial potential. The simplest design consists of an antenna mated to an IC using only two connection points. Power and query signals are sent as electromagnetic radiation. The energized chip returns information as a digital radio signal. RFID offers elegant solutions to old problems like finding things and counting them. 2-way RF in a miniature very low cost form factor is relatively new. The 2-way RF query-response system, with on-chip data processing capability, is a new product category. The simplest RFID tag is a smart bar code product that does not require line-of-sight access. The “look through” feature brings unequaled efficiency and flexibility to warehouse management, inventory control and related areas where items must be located, identified and tallied. Much more sophisticated products are planned, however. Broad success for RFID products requires extremely low cost and ultra-high volume manufacturing. Minimal circuit cost is achieved, not with traditional copper conductors on FR4, but with Polymer Thick Film (PTF) conductive ink on thin plastic film substrate. The adhesively bonded flip chip is the ideal means of interconnecting to the PTF circuit.
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