Low permittivity ceramic substrates with a sandwich structure consisting of a porous, fiber-reinforced SiO2 core and two thin polymer plates were fabricated by sol-gel processing, and polymer infiltration. The rheological behavior of an aqueous colloidal SiO2 sol, containing short SiO2 fibers was studied as a function of particle loading, fiber loading and gelation time. Short SiO2 fibers were introduced to limit drying shrinkage and thus minimize substrate cracking during drying. After the psuedoplastic sol was tape cast and sintered at 1150°C for 2 h, a polyimide solution was infiltrated into the porous SiO2 core. Permittivities ranging from 1.81 to 3.08 could be obtained by using 32-42% SiO2, 5-50% polyimide and 63 to 8% porosity. The substrate strength was increased from 1.93 MPa to 3.83 MPa after polyimide infiltration.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Condensed Matter Physics
- Materials Chemistry