Thermoplastic packaging and embedding technology for ID-cards

State of the art ID-cards contain an RFID chip connected to a wired copper coil. For advanced smartcard applications the security-relevant data processing will be transferred from public terminals into the smartcards itself. In this paper we demonstrate the possibility to realize complex circuitries in polycarbonate based ID-cards by using a combination of printed circuit technology and conventional assembly-processes. With this approach a very high packing density for the circuitry consisting of the wiring architecture and components (active and passive) can be achieved. The realized ID-card demonstrator consists of a 125 μm thick polycarbonate inlay containing active and passive components, an antenna, a capacitive key pad and an OLED-display. The inlay is encapsulated by lamination of polycarbonate foils resulting in an 800 μm thick card body. The inlay is equivalent to a double sided printed circuit board. For its fabrication through holes are drilled in a copper-clad polycarbonate (125 μm polycarbonate foil, with 12 μm copper on both sides) and electroplated, followed by copper structuring and application of a silver finish. The chemical stability and handling of polycarbonate in PCB processing was excellent. Components are assembled using different types of conductive adhesives: ICA for passives, ACA for ICs, and ACF for OLED. Assembly of chips with fine contact structures was possible due to the precise Cu-structuring of the inlay: line/space is 50 μm and 40 μm, respectively. For the encapsulation cavities are milled into polycarbonate foils to accommodate component topographies. The prepared foils are then laminated onto the inlay to yield an 800 μm thick ID-card. The electronic system is hermetically sealed and still flexible like a standard ID-card.