Tapes and thick films for high frequency packaging

Low-K dielectrics in both thick-film and tape formats have been developed for meeting advanced packaging requirements. Compositions were formulated which fired to dense films at 850 degrees C and provided a thermal coefficient of expansion (TCE) match to 96% Al/sub 2/O/sub 3/. Dielectric constants ranged from 4.0 to 5.0, depending on the termination and firing conditions. These dense low-dielectric-constant materials were characterized with respect to temperature dependence of K, dissipation factor, insulation resistance, and breakdown voltage. Moisture resistance, as determined by pressure-cooker testing, was also measured. Frequency effects in the range of 1 kHz to 1 MHz were determined with some measurements taken at frequencies as high as 9.3 GHz. Partial densification, binder decomposition, and controlled gas generation techniques were investigated as a means to introduce porosity and thereby lower K values. The most successful technique, controlled gas generation, produced pore porosity and K values as low as 2.5.<
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