Effect of Gd2O3 substitution for La2O3 on structure, physicochemical and electrical properties in aluminoborosilicate glasses for advanced microelectronics packaging

Currently, to develop new glass materials with lower dielectric constant (epsilon r) and dielectric loss (tans), low coefficient of thermal expansion (CTE), excellent thermal stability and chemical stability for advanced microelectronics packaging has been significant pursuits of many researchers. In this work, novel 58SiO2-20B2O3- 8Al2O3-10CaO-1Na2O-(3-x) La2O3-x Gd2O3 (x=0, 0.5, 1, 1.5, 2, 2.5 and 3 mol%) were successfully fabricated by the conventional melt annealing method. The results revealed that single addition of Gd2O3 or La2O3 (x=0, 3 mol %) strengthened glass network structure, which in turn improved performances of the glass. It was interestingly found that similar to the mixed-base effect, double-doped Gd2O3 and La2O3 played a greater role in improving glass structure and properties. The glass with x =1.5 mol% Gd2O3 exhibited the lowest dielectric permittivity, dielectric loss and low coefficient of thermal expansion (epsilon r = 4.72, tans = 0.0004 (@1 MHz), CTE = 3.78 ppm/ degrees C) and good chemical stability, which is optimal for the comprehensive performance compared with other aluminoborosilicate (Al-B-Si) glasses reported so far. These findings highlight that this glass is expected to be used in the microelectronics packaging field.