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2016
Conference Paper
Titel
Non-conductive film (NCF) underfill: Materials, performance, and evolution to next generation devices
Abstract
NCF performance can vary significantly with device geometry. An NCF material that demonstrated good fluxing and uniform solder joint formation on an area array test vehicle performed poorly when pitch was reduced and die size was increased. The increased resistance to flow created by larger I/O count at smaller pitch appeared to prevent bump to pad contact during the TCB cycle. Reducing NCF viscosity and cure rate decrease the resistance to flow and extend the time before curing reactions interfere with bond formation; solder wetting can therefore take place more easily and with sufficient flow to displace the silica particles needed in NCF formulations.