The interfacial reliability of through-glass vias for 2.5D integrated circuits

Purpose Glass is a promising interposer substrate for 2.5 D integration; yet detailed analysis of the interfacial reliability of through-glass vias (TGVs) has been lacking. The purpose of this paper is to investigate the design and material factors responsible for the interfacial delamination in TGVs and identify methods to improve reliability. Design/methodology/approach The interfacial reliability of TGVs is studied both analytically and numerically. An analytical solution is presented to show the dependence of the energy release rate (ERR) for interfacial delamination on the via design and the thermal mismatch strain. Then, finite element analysis (FEA) is used to investigate the influence of detailed design and material factors, including the pitch distance, via aspect ratio, via geometry and the glass and via materials, on the susceptibility to interfacial delamination. Findings ERR for interfacial delamination is directly proportional to the via diameter and the thermal mismatch strain. Thinner wafers with smaller aspect ratios show larger ERRs. Changing the via geometry from a fully filled via to an annular via leads to lower ERR. FEA results also show that certain material combinations have lower thermal mismatch strains, thus less prone to delamination. Practical implications The results and approach presented in this paper can guide the design and development of more reliable 2.5 D glass interposers. Originality/value This paper represents the first attempt to comprehensively evaluate the impact of design and material selection on the interfacial reliability of TGVs.

Effect of Temperature/Humidity Treatment on Interfacial Reliability on Screen-Printed Ag / Polyimide for Advanced Embedded Packaging Technologies

The effect of temperature/humidity treatment conditions on the interfacial adhesion energy between a screen printed Ag film and a polyimide substrate was evaluated by using a 90° peel test. The measured peel strength values decrease from 254.7 N/m to 59.3 N/m after the temperature/humidity treatment at 85°CC/85% relative humidity for 500 h. X-ray photoelectron spectroscopy analysis of the peeled surfaces indicates that peeling occurs cohesively inside of the polyimide, which is closely related to both the decrease in the interfacial adhesion energy and the polyimide degradation due to weak boundary layer formation.