Low firing temperature silicon oxide for microwave substrate

A novel material for making microwave substrates has been developed. The material is silicon oxide, which has a low dielectric constant (εr=5.0-5.2 at 10-20 GHz) and a low loss tangent (tanδ=8.3×10^-4-9.1-10^-4 at 10-20 GHz). The new process makes sintering of this silicon oxide possible at low temperature (below 1000°C). Consequently, substrates consisting of this silicon oxide are capable of forming copper conductors by cofiring. The key technologies of this process are using amorphous silicon oxide powder that has a particle diameter of the nanometer order, and firing in an atmosphere containing water. Additionally, a multilayer substrate was developed by applying a green sheet lamination technique