Double sided surface mount assembly (SMA) can increase packing density but also poses significant problems to manufacturing engineers. During double pass reflow soldering (DPRS), component misalignment or falling off problems may result....[ Read more ]

Double sided surface mount assembly (SMA) can increase packing density but also poses significant problems to manufacturing engineers. During double pass reflow soldering (DPRS), component misalignment or falling off problems may result.

An industrial survey has been conducted through the internet. The results confirm the popularity of double sided SMA manufacturing. Also, common practices and problems associated with double sided SMAs are revealed.

A detailed classification of component layout during DPRS will be presented. Methodologies are proposed in this research to improve the robustness of this double pass process. Considering thermal analysis, certain combinations of surface mount component types and sequences of the reflow process should be avoided. Two thermal management techniques: (1) directional heating, and (2) screened differential heating, are proposed to improve the robustness of DPRS. The former technique eliminates the excessive heat energy that melts the solder joints of the components facing downwards. In the presence of thick BGAs, the latter technique is proven to be an effective heating technique that ensures the robustness of the manufacturing process.