摘要
Interposers with through-silicon vias(TSVs)play a key role in the three-dimensional integration and packaging of integrated circuits and microelectromechanical systems.In the current practice of fabricating interposers,solder balls are placed next to the vias;however,this approach requires a large foot print for the input/output(I/O)connections.Therefore,in this study,we investigate the possibility of placing the solder balls directly on top of the vias,thereby enabling a smaller pitch between the solder balls and an increased density of the I/O connections.To reach this goal,inkjet printing(that is,piezo and super inkjet)was used to successfully fill and planarize hollow metal TSVs with a dielectric polymer.The under bump metallization(UBM)pads were also successfully printed with inkjet technology on top of the polymer-filled vias,using either Ag or Au inks.The reliability of the TSV interposers was investigated by a temperature cycling stress test(−40℃ to+125℃).The stress test showed no impact on DC resistance of the TSVs;however,shrinkage and delamination of the polymer was observed,along with some micro-cracks in the UBM pads.For proof of concept,SnAgCu-based solder balls were jetted on the UBM pads.
基金
This work is supported by ENIAC-JU Project Prominent Grant No 324189 and Tekes Grant No.40336/12 and Vinnova Grants Nos.2012-04301,2012-04287,and 2012-04314
MM is supported by the Academy of Finland Grant Nos.288945 and 294119
The work of Silex and KTH was funded in part through an Industrial Ph.D.grant from the Swedish Foundation for Strategic Research(SSF),Grant No.ID14-0033.
