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Inkjet printing technology for increasing the I/O density of 3D TSV interposers

Behnam Khorramdel ; Jessica Liljeholm ; Mika-Matti Laurila ; Toni Lammi ; Gustaf Mårtensson (Institutionen för mikroteknologi och nanovetenskap, Elektronikmaterial och system ) ; Thorbjoern Ebefors ; Frank Niklaus ; Matti Maentysalo
MICROSYSTEMS & NANOENGINEERING (2055-7434). Vol. 3 (2017), p. Article no. UNSP 17002 .
[Artikel, refereegranskad vetenskaplig]

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 degrees C to + 125 degrees C). 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.



Denna post skapades 2017-08-24.
CPL Pubid: 251377

 

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Institutioner (Chalmers)

Institutionen för mikroteknologi och nanovetenskap, Elektronikmaterial och system

Ämnesområden

Nanoteknik

Chalmers infrastruktur