Flexible LCP and paper-based substrates with embedded actives, passives, and RFIDs

Miniaturization with increased functionality at reduced cost historically has been the key driver for the evolution of electronics products. However, the size reduction was traditionally confined to lateral dimensions, until recently in the 21(st) century, the real estate in the Z-direction has been severely compromised, therefore, THIN has become the buzz word encompassing thin die, thin dielectric, thin passives, thin core and ultimately leading to thin packages. This paper overviews the trends from thick to thin electronic products, materials, processes, and manufacturing of the thick and thin packages with embedded passive components such as resistors, capacitors, inductors, and lately the Actives. Flexible organics with embedded IC and thin film passive materials and substrates that can perform at frequencies in the range 2-110 GHz has been established with liquid crystal polymers. A roadmap for the realization of highly integrated RFID tags with wireless sensors and thin film batteries on ULTIMATE low-cost synthetic material such as photocopy papers has been addressed. To this regard, special attention is given to miniaturization of antennas and on specific techniques for ultra-high-efficiency (95%) RFID's. Examples of paper-based conductive Ink-Jet printed circuits as well as copper circuitary by etching have been investigated as a means for further cost reduction including ultra-thin printed batteries and power-scavenging devices, as well as to miniaturized sensors (temperature, chemical, pressure) that would enable long-range ubiquitous sensing. Dielectric constants and dielectric loss measurements on paper-substrates are reported for the first time at frequency > 1GHz.