Here is the abstract you requested from the IMAPS_2013 technical program page. This is the original abstract submitted by the author. Any changes to the technical content of the final manuscript published by IMAPS or the presentation that is given during the event is done by the author, not IMAPS.
|A Novel Epoxy Flux On Solder Paste For Assembling Thermally Warped POP|
|Keywords: Epoxy, Solder Paste, Flux|
|For portable devices, the vulnerability toward drop failure of area array packages such as BGA, CSP, or PoP has called for reinforcement of those packages when being assembled onto PCB. While underfilling is regarded as one of the solutions, the increased cost of additional curing step plus the reduced temperature cycling reliability prompts the favoritism toward epoxy flux approach which eliminated the curing step. Epoxy flux serves as a flux when soldering array packages onto PCB at reflow, and gets cured after reflow thus provided the needed reinforcement without the need of additional curing step. Epoxy flux works well without the need of solder paste at assembly. However, when the area array packages warped upon heating, solder paste is indispensible in order to prevent open. Use of solder paste evoked challenge toward applying epoxy flux at the same time, mainly due to the oozing out of solder paste at reflow when immersed in the liquid epoxy flux. In this study, a newly developed epoxy flux compatible with solder paste was evaluated for assembly and reliability. Results on assembly process with epoxy flux on top of solder paste, drop test, temperature cycling, and SIR are presented and discussed.|
|Ning-Cheng Lee, VP Technology