Inkjet printing technology for increasing the I/O density of 3D TSV interposers
Khorramdel, Behnam; Liljeholm, Jessica; Laurila, Mika-Matti; Lammi, Toni; Mårtensson, Gustaf; Ebefors, Thorbjörn; Niklaus, Frank; Mäntysalo, Matti (2017-04-10)
Khorramdel, Behnam
Liljeholm, Jessica
Laurila, Mika-Matti
Lammi, Toni
Mårtensson, Gustaf
Ebefors, Thorbjörn
Niklaus, Frank
Mäntysalo, Matti
10.04.2017
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201711222234
https://urn.fi/URN:NBN:fi:tty-201711222234
Kuvaus
Peer reviewed
Tiivistelmä
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 °C to +125 °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.
Kokoelmat
- TUNICRIS-julkaisut [16983]