At the ConFab conference in Las Vegas this week Mike Ma, VP of Corporate R&D at Siliconware (SPIL), announced a new business model for interposer based SiP’s, namely the “turnkey OSAT model.”
Over the past few years, TSMC has been proposing a turnkey foundry model which has met with significant resistance from their IC customers. Under the foundry turnkey model, the foundry handles all operations including chip fabrication, interposer fabrication, assembly and test. Foundry rivals UMC and GlobalFoundries, have been supporting a OSAT/Foundry collaboration model where the foundries would fabricate the chips with TSV and the OSATs would do assembly of chips and interposers that could come from several different sources.
SPIL is the first OSAT to propose this OSAT centric model where the interposer is fabricated by the OSAT who then assembles and tests modules made with chips from multiple sources. The impediment to this route in the past has been the lack of OSAT capability to fabricate the fine pitch interposers which require dual damascene processing capability, which until now was only available in the foundries. This week SPIL announced the equipment for fine pitch interposer capability (>2 layers, 0.4-3um metal line width and 0.5um TSV ) has been purchased and is in place.
Ma indicates that while the foundries are not happy with this SPIL proposal, their customers, especially their fabless customers have been very supportive. He feels the inherent lower cost structure of OSATS will have a positive impact on the 2.5/3D market which has been somewhat stagnant since the FPGA and memory product announcements in 2010.
SPIL also announced a wafer level fan out (WLFO) program on 370 x 470mm organic based panels which they feel is a potential low cost solution for those with lower density interposer requirements.