New ESD challenges in RFID manufacturing

The introduction of dual-band RFIDs (Radio Frequency Identification Devices) in chip cards created new ESD risks with unconventional discharge paths. On a plastic foil, a more or less grounded coil antenna for radio frequency (RF) is aluminium-printed on one half of the card. On the other half, an electrical floating, but thus, highly electrostatic charged folded dipole for ultrahigh frequency (UHF) is arranged. When the chip is placed by a flip-chip assembly process, a strong discharge takes place through the RF-UHF-path of the chip. Usual ESD protective structures are only of limited use in these cases. Discharge paths and specific risks are described in this paper as well as useful countermeasures in foil and assembly processes.