A very important property of substrate materials for microelectronic packaging with high propagation speed is an appropriate dielectric constant. The VLSI demand will require even higher transmission speed on the substrate, and the use of an even lower dielectric constant material system. From the viewpoint of substrate propagation delays, the key factor for reducing signal propagation delays is hollow structure design between ground plane and signal plane, as well as the low dielectric constant material around signal lines. Another important factor for transmission properties is the ground plane design. Test samples of a new kind of packaging were made for estimation, and basic properties were measured. From this estimation, characteristics for a new kind of packaging substrate are summarized. As a result, this new structure substrate, with low dielectric constant, can be applied to high-speed VLSI packages in the future.
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