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Dip Solder Paste for BGA Rework
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Authored By:David Hillman, Douglas Pauls, Andrew Steinmetz Rockwell Collins, Cedar Rapids, Iowa USA TranscriptThis paper is an examination of the process feasibility, solder joint reliability, and materials/process compatibility of a dippable solder paste material for an area array component rework/repair process. The Ball Grid Array components in this investigation were reworked according to typical production procedures and a new dipping procedure. The components were tested for thermal cycle solder joint reliability and flux process compatibility. The thermal cycle and flux process compatibility test results demonstrated that the dippable solder paste material and BGA rework process were acceptable for IPC Class 3 high performance products. SummaryThis paper is an examination of the process feasibility, solder joint reliability, and materials/process compatibility of a dippable solder paste material for an area array component rework/repair process. The Ball Grid Array (BGA) components in this investigation were reworked according to typical production procedures and a new dipping procedure using the AirVac Onyx 29 BGA rework machine. The components were tested for thermal cycle solder joint reliability and flux process compatibility. The thermal cycle and flux process compatibility test results demonstrated that the dippable solder paste material and BGA rework process were acceptable for IPC Class 3 High Performance products. Conclusions1. The use of dippable solder paste is a new concept for BGA rework but is a widely established methodology in the electronics industry for wafer bumping and package-on-package technologies3. The use of dippable solder paste in electronics assembly soldering processes such as repair/rework or area array assembly is a viable option, as demonstrated by this study. 2. The thermal cycle solder joint integrity and flux compatibility results were acceptable for IPC Class 3 High Performance products. 3. The residues from the BGA attachment process, both for the dippable-paste-only and for the dippable paste and tacky flux combination, where found to be desirably low, following saponified aqueous cleaning, as measured by ion chromatography. 4. When tested using standard SIR protocols and the IPC-B-52 test vehicle, the remaining residues did not show deleterious behavior when combined with an electrical potential in a hot and humid test environment. The lack of electrochemical failure mechanisms, such as dendritic growth or electrolytic corrosion, showed there were no harmful effects from the Heraeus dippable paste residues and no harmful interactions between the Heraeus dippable paste flux residues and the Alpha Metals UP-78M tacky flux. Initially Published in the IPC Proceedings |
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