Initially, 0.6 g sodium chloride so

Initially, 0.6 g sodium chloride solid powders were firstly moisten with 0.15 g deionized water and mixed thoroughly with pestle and mortar for about 1 min until uniformly wetted, and then mixed with 0.6 g of Al2O3 to form a uniform semi solid paste. The mixture was then transferred into 13 mm heatable die to carry out the CSP fabrication. To identify desired sintering conditions, first group of mixtures were hot pressed at constant temperature of 120°C, with different pressure ranging from 100 to 500 MPa but same holding time of 50 min. Second group of mixtures were hot pressured under constant uniaxial pressure of 400 MPa, with different temperature ranging from 80°C to 140°C but same holding time of 50 min. Third group of mixtures were hot pressed at constant temperature of 140°C and constant pressure of 400 MPa, but with different holding time of 10, 30, 50, 60 and 90 min. All the resulting pellets were dried in an oven with maintained temperature of 100°C for 2 h to ensure residual water if any was removed.