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Design of New Solder Attach Technologies
Materials Tech |
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Authored By:Jim Hines, Kirk Peloza, Adam Stanczak Molex, Lisle, IL, USA David Geiger Flextronics International, San Jose, CA, USA TranscriptSurface mount technology has been in existence for decades and is continually becoming more important because as printed circuit board assemblies become more advanced and dense with componentry, the real estate savings afforded with SMT become more valuable and necessary. While the reliability data behind certain common surface mount technologies is in abundant supply and an operator's comfort level in processing such components is high today, introducing a new SMT concept requires many levels of support before design engineers, process engineers, product technicians and processing operators gain a high level of acceptance of the new design. When choosing components for a PCB layout and selecting a preferable solder attach method, board designers must consider processing capabilities such as reflow oven limitations, operator handling or placement, solder joint formation, effectiveness of inspection methods like x-ray or in-circuit-test as well as reliability concerns such as product life, circuit board retention and harsh environment resistance. Solder Charge SMT technology is a new PCB solder attach method introduced for the high density interconnect market to improve on shortfalls in some of the surface mount designs that exist today. This paper outlines the process of introducing a new SMT technology with a focus on three primary areas. 1. The grass roots design and research involved in the development of a new solder attach technology. 2. The proof of concept studies and partnership with experienced contract manufacturers and processing experts to validate the technology works. And 3. The reliability testing involved to analyze and predict the performance through harsh environments or industry standard specifications. SummarySurface mount technology (SMT) has been in existence for decades and is continually becoming more important because as printed circuit board (PCB) assemblies become more advanced and dense with componentry the real estate savings afforded with SMT become more valuable and necessary. It allows for improved electrical performance when compared to through-hole vias and offers a conventional reflow process versus the traditional wave solder techniques. While the reliability data behind certain common surface mount technologies is in abundant supply and an operator's comfort level in processing such components is high today, introducing a new SMT concept requires many levels of support before design engineers, process engineers, product technicians and processing operators gain a high level of acceptance of the new design. When choosing components for a PCB layout and selecting a preferable solder attach method, board designers must consider processing capabilities such as reflow oven limitations, operator handling or placement, solder joint formation, effectiveness of inspection methods like x-ray or in-circuit-test (ICT) as well as reliability concerns such as product life, circuit board retention and harsh environment resistance. Solder Charge SMT technology is a new PCB solder attach method introduced for the high density interconnect market to improve on shortfalls in some of the surface mount designs that exist today. The new technology required many steps of development before being introduced to the electronics industry. This paper outlines the process of introducing a new SMT technology with a focus on three primary areas: the grass roots design and research involved in the development of a new solder attach technology, the proof of concept studies and partnership with experienced contract manufacturers and processing experts to validate the technology works and the reliability testing involved to analyze and predict the performance through harsh environments or industry standard specifications. ConclusionsMany different aspects must be considered when designing and validating a new solder attach process. SMT SC performed well in regards to tests performed to validate processing capabilities, reliability through thermal cycling and mechanical factors such as PCB retention and positional mismatches through side load forces. Both Mezzanine A and Mezzanine B had no failures during the first 6,000 temperature cycles of the IPC-9701 test. Also, retention forces for SMT SC were over 2.5x the pull force of similar surface mount technologies and retention strength from side loads showed a significant safety buffer when considering 6 sigma tolerance stack for both multiple parts per board and a mated set of components with SMT SC. Initially Published in the SMTA Proceedings |
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