Seishiro Yamakawa

Development of glass fiber with high dielectric constant

Abstract Glass fibers with high dielectric constant have been developed to miniaturize printed circuit boards used at high frequencies. The dielectric constant of the glass is 11.6 at 1 GHz while that of E glass is 6.7. In the glass composition system, SiO 2 CaOSrOBaOTiO 2 ZrO 2 NbO 2.5 , it was found that the NbO 2.5 plays an important role in decreasing the liquidus temperature of the glass, resulting in successful fiber-drawing. Using the above glass composition system, glass fibers consisting of 200 filaments with an average diameter of 8 μm have been continuously drawn from a conventional platinum alloy bushing. This glass fiber was then woven into cloth. Laminates with a dielectric constant of 10.5 at 1 GHz have been made with glass cloth impregnated with the thermosetting polyphenylene oxide resin and titanium oxide powder, resulting in high uniformity in the dielectric constant.