Capacitors

Capacitors for RFID applications

QuickSil was one of the earliest companies to develop thin-film capacitors for the RFID market and is a proven leader in both RFID and smart card tuning loop capacitors. QuickSil understands the challenges of creating a low cost RFID solution that can stand up to the electrical, thermal, and mechanical stresses faced by RFID tags in the real world.

While other thin-film manufacturers typically use PECVD silicon nitride as their capacitor dielectrics, QuickSIl uses LPCVD silicon nitride. LPCVD (low pressure chemical vapor deposition) outperforms PECVD nitride in electrical and material uniformity, yielding capacitors that better tolerate the out-of-range voltages encountered in RFID antenna loops, while maintaining electrical integrity and precision.

Based on customer input, QuickSil has optimized these capacitors for RFID and smart card manufacturing flows such as chip-on-board (COB) assembly. The ultra-low thickness profile of only 0.18 mm supports thin packaging requirements while a tough exterior silicon nitride coating protects the capacitor during pick-and-place handling. The capacitors are designed for a wirebond manufacturing flow which offers a simple method of attaching the capacitors to both the loop antenna and RFID controller.

PolyCap Technology

For sub-400 kHz RFID applications, the PolyCap series of thin film capacitors are very popular. They offer an ultra-low 0.18mm profile in capacitance ranges of 220 pF to 820 pF. Please refer to the PolyCap datasheet for more information.

SmartCap Technology

For frequencies up to 100 MHz, including 13.56 MHz smart card applications, the SmartCap series of thin-film capacitors are recommended. These capacitors have a very low series resistance (ESR) and high Q for use in megahertz frequency tuning loops. Capacitances range from 22 pF to 82 pF. An optional backside metal flow allows the use of a single topside wirebond for manufacturing flexibility. These capacitors are also used for downbond decoupling applications. See the SmartCap datasheet for details.

DualCaps

The final product offering is the DualCap capacitor pair for use with MicroChip RFID controllers such as the MCRF355 and the MCRF450 devices. These RFID controllers require a pair of 68 pF external capacitors to tune and detune the RFID antenna. The QuickSil DualCap design provides two precision 68 pF capacitors on a single chip. See the DualCap datasheet for details including die size and pad placement.

Custom Capacitors

If these capacitors don't quite meet your need, QuickSil is always happy to talk about designing and fabbing the capacitors you require for your application. Contact us at sales@QuickSil.com.