Sol Gel Processing of Low Permittivity, Fiber-Reinforced SiO2-Polyimide Substrates
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.
S. C. Zhang et al., "Sol Gel Processing of Low Permittivity, Fiber-Reinforced SiO2-Polyimide Substrates," Journal of Sol-Gel Science and Technology, vol. 10, no. 1, pp. 91-100, Springer Netherlands, Jun 1997.
The definitive version is available at http://dx.doi.org/10.1023/A:10183924
Materials Science and Engineering
Keywords and Phrases
Composite; Permittivity; Silica; Sol-gel; Substrate; Composition; effects; Gelation; Infiltration; Polyimides; Porosity; Rheology; Sandwich structures; Pseudoplastic sols; Fiber reinforced plastics
International Standard Serial Number (ISSN)
Article - Journal
© 1997 Springer Netherlands, All rights reserved.