Low-k dielectric materials derived from ZSM-5 zeolite

Low-k dielectric materials were prepared by sintering ZSM-5 zeolite powder compacts at temperatures ranged 1200-1300(degrees)C, and the microwave dielectric characteristics were investigated together with the structure evolution during sintering. It was failed to obtain ZSM-5 ceramics by high temperature sintering because the densification could never occur below the tolerable temperature and the ordered porous structure completely collapsed above the tolerable temperature. The structure changed from ZSM-5 zeolite to SiO2-Al2O3 glass at 1240(degrees)C, and finally to SiO2-based cristobalite ceramics above 1275(degrees)C. A low dielectric constant (2.63-2.78) combined with low dielectric loss (< 0.0005 at 18 GHz) and small temperature coefficient of resonant frequency (varied from -18.6 to -8.1 ppm/C-degrees) was achieved in the present materials, and the value of dielectric loss was the lowest one achieved so far in the dielectric materials with a dielectric constant lower than 3. With the structure evolution from ZSM-5 zeolite to SiO2-Al2O3 glass and finally to SiO2-based cristobalite ceramics, the dielectric constant increased from 2.27 to 2.78, while the Qf value indicated a complicated variation tendency, and the higher Qf values were achieved in the amorphous and crystalline states, while significant drop was determined in the partial amorphous state. It should be a great challenge to prepare dense zeolite ceramics without collapse of ordered porous structure, and then the ultra-low dielectric constant materials with high Q could be expected.