Glass Reflow and Thermo-Mechanical Stress Simulation for Through Glass Via in Glass-Silicon Composite Interposer

This paper investigates glass reflow process and thermo-mechanical stress of Through Glass Via (TGV) in glass-silicon composite interposer by Finite Element Analysis (FEA). The TGV structure in this work is composed of highly conductive silicon as vertical feedthrough and borosilicate glass as insulation. The relationship between reflow depth and reflow time is investigated in glass reflow simulation. The simulation results show that the reflow depth reaches its maximum at about 90s, and it takes about 360s for the glass reflow fill the mold completely, where the mold is a ${1.6*0.8*0.3mm^{3}}$ cavity with a cylinder of 0.2mm in diameter and 0.3mm in height at its center. The effects of TGV structural parameters on Von Mises (VM) stress is analyzed in thermal-mechanical stress simulation. The maximum VM stress of glass-silicon composite TGV in the temperature load range of -40~ 85°C is around 8 MPa, where the aspect ratio varies from 1 7, the via diameter ranges from 50 ${125 \mu m}$ , and the pitch changes from ${50 to 400\mu m}$ . The maximum VM stress can be reduced by 14% with structural parameter optimization.