Design of Flexible RFID Tag and Rectifier Circuit using Low Cost Screen Printing Process

Flexible electronics is the future trend of the worldwide electronic industry. The RFID tag is one of the main applications in flexible electronics currently. This paper presents a flexible HF RFID tag which is manufactured by a low cost screen printing technique. The inductive coupling antenna is constructed by printing conductive silver paste on PET substrate to achieve good flexibility. The inductance and quality factor value of the antenna were designed using an EM simulator tool. Several design issues such as metal thickness, line width, and spacing between conductive coils related to the performance of inductive coupled antenna have also been analyzed carefully. The optimized antenna structure is properly chosen based on EM simulation results and measurements of several prototypes. A Philips I-CODE label IC was mounted on the inlay after being thinned. (The details of the manufacturing process flow will be examined in this paper later.) Finally, a half-wave rectifier circuit is proposed in this paper to demonstrate the potential of designing flexible circuitry using a screen printing process. In this design, one special High-DK material (with DK=20) which was developed by ITRI MCL was adopted to manufacture the capacitors in rectifier circuit. The experimental results shows that the rectifier which is powered by general RFID reader can be used to light up one typical SMD type LED successfully. The whole circuit size is about 16 cm.