LTCC Materials and Processes for Wireless Communication Technologies

Abstract

Low-Temperature Co-fired Ceramics (LTCC) have become a key technology for further miniaturization of RF circuits. Capacitors and inductors can be buried in the ceramics because LTCC can be co-fired with Cu or Ag electrode, which have low electric resistivity. LTCC, which have various dielectric constant and high Q-value, is applied to functional circuit boards and chip monolithic devices. Recently constrained sintering technology, co-firing technologies of various materials and high Q-value LTCC materials have been developed.

Constrained sintering technology improves size accuracy and flatness of substrates, and co-firing technologies contribute to further integration of microwave devices by co-firing various materials, for example high or low dielectric constant materials, printed resistors and so on. And high Q-value LTCC materials can reduce electric loss of devices. In the recent trend of using higher frequencies for wireless communication, e.g. 5G system, controlling electric loss is the biggest challenge. The higher the used frequency is, the higher the electrical loss of wireless devices is. In order to suppress stray capacitance between electric circuits, substrate material of lower dielectric constant was developed. Therefore, these technologies will integrate more passive circuit elements and contribute to further miniaturization of microwave devices and higher frequencies.