Effect of magnesium additive on structure and properties of Al2O3–B2O3–SiO2 glass system

Abstract

Printed wiring board is an important component of electronic devices. Low dielectric constant materials are expected to reduce the time delay of signal propaganda and dielectric loss. E-glass fibre as reinforcing material of printed wiring board does not meet the requirements. To reduce the operating temperature of glass, bivalent metal oxides must be introduced, often at the expense of dielectric properties. Aluminoborosilicate glass is a typical glass system with low dielectric constant. Al2O3–B2O3–SiO2 glasses that replaced Al2O3 by MgO were melted, and their microstructure, some physical properties and chemical durability were investigated. In addition, the role of Al2O3 in borosilicate glasses was investigated. The glass system was characterised with lower dielectric constant (4·8–5·7) and loss tangent (10−3) at 1 MHz. By replacing Al2O3 with MgO, the density and viscosity–temperature characteristic points of the studied glasses showed a decreasing tendency. The average dissolution rate of the studied glasses was <4·51×10−8 g cm−2 min−1. When the molar ratio of RO/Al2O3 is >2·5 (R = Ca2+, Mg2+), the trivalent, tetrahedral [BO4] and [AlO4] network units increased at the same time as indicated by infrared spectra. The paper has designed a group of glasses that has both satisfactory processing properties and dielectric properties. The present glass system could substitute E-glass and be a possible candidate for many applications.