(Huazhong University of Science and Technology, Wuhan 430074, China)
Keywords:
-
CLC:
PACS:
-
DOI:
10.7502/j.issn.1674-3962.2012.07.03
DocumentCode:
Abstract:
Low permittivity (ε r) can minimize crosscoupling loss between substrate and conductor and shorten the time for the electronic signal transition, and high quality factor (Q·f) can increase selectivity and simplify heat dispersing structure, moreover near zero temperature coefficient of resonant frequency (τf) can ensure stability of the frequency against temperature change. Especially as working frequency gradually expands, thermal conductivity of substrate should be considered carefully due to an increase in dielectric loss and calorific value. Thermal conductivity of ceramics is about 20 times as that of organic materials, therefore, lowpermittivity microwave dielectric ceramics become promising materials for high performance substrate applications. In addition, high strength and excellent surface/interface characteristics are also required. So an overview on low permittivity microwave dielectric ceramics with εr <15 are present firstly, and then measures on reducing permittivity and increasing surface densification are introduced. Finally, some suggestions of investigating high performance lowpermittivity microwave dielectric ceramic substrates are also proposed.