A comparative study of the thermomechanical reliability of fully-filled and conformal through-glass via

This study investigates the thermomechanical response of the copper TGV during thermal cycling. Two different geometries of copper TGV, the fully-filled TGV and conformal TGV, are compared concerning their in-plane and out-of-plane deformation. The TGV samples were heated from room temperature (RT) 23 degrees C to 400 degrees C and then cooled to RT. The protrusion height of the copper TGV was recorded as a function of temperature, and unrecoverable copper protrusions were observed because of the creep of the copper at high temperatures. Two-dimensional digital image correlation (2D DIC) measurements were employed to obtain the in-plane deformation of the glass substrate near the copper TGV. It was found the copper protrusion height and the in-plane deformation of the glass substrate were significantly reduced in the conformal TGVs compared to the fully-filled TGVs.