To match the thermal expansion coefficient of copper foil,the thermal expansion properties of SiO2-TiO2 ceramic filled PTFE microwave substrate composites were investigated.SiO2 together with TiO2 were added to PTFE matrix by the wet process.The influences of the SiO2-TiO2 /PTFE composite density,ceramic particle size and volume fraction of ceramic filler on the thermal expansion coefficient(CTE)of the SiO2-TiO2 /PTFE composites were investigated.The results show that as the volume fraction of SiO2 increase...