Low temperature co-fired ceramics; physical and electrical properties as a function of firing temperature

The electronic and physical properties of two LTCC dielectrics (Ferro L8 and A6M) were investigated as a function of peak firing temperature. One dielectric (L8) consists of a ceramic-filled glass composite while the other (A6M) consists of a crystallizing glass. Physical properties such as shrinkage vs. firing temperature are presented in each case. In the case of the crystallizing glass, x-ray diffraction studies are presented where two crystalline phases were observed along with residual glass. The microwave electrical properties of both materials were measured at a nominal frequency of 10 GHz. The two materials show very different relative permittivity and loss tangent dependence on firing temperature due to the different physical manner in which the final, fired state is achieved - crystallization in terms of A6M and vitreous densification in terms of L8. The dependence of conductivity on firing temperature for a typical gold conductor system (CN30-080M) compatible with both dielectrics is also presented.