Inkjet-printed interconnects for unpackaged dies in printed electronics

This work details manufacturing processes developed to integrate an unpackaged silicon die onto a paper substrate, as part of constructing a hybrid inkjet-printed paper-based circuit. This integration between rigid components and flexible substrates is beneficial in low-cost applications and capitalises on the advantages of both the well-established integrated circuit technology and the emerging paper-based electronics platforms. A superglue incline at the chip edge formed a ramp for printing the silver interconnects between the paper-based circuit and the chip pads. Two printing protocols are compared, the first a single layer using 5 μm drop spacing, and the second using a 35 μm drop spacing for three layers. An unpackaged RFID tag die is successfully integrated and is presented as proof of concept.