Experimental demonstration of the effect of copper TPVs (Through package vias) on thermal performance of glass interposers

Glass has been proposed to be an ideal material for interposers to address the limits of both organic and silicon, except for its poor thermal conductivity compared to silicon. This paper proposes to use large number of copper through package vias (TPVs) that can be fabricated at low cost to improve this shortcoming. We report on experimental fabrication and evaluation of the effect of copper TPVs on thermal performance of glass interposer structures. Copper via arrays with different via densities (0.62 vias/mm² ~ 22 vias/mm²) were fabricated in glass interposer structures by using low cost laser drilling and electroplating. The thermal performance of such structures was quantified by measuring spatial temperature distribution, including the maximum value around the heat source. This study provides fundamental understanding of heat transfer within thermally-enhanced glass interposers, and offers guidelines for the design of copper via arrays to improve their thermal properties.