Methods to Get Volatile Compounds Out of Reflow Process
With the introduction of lead-free soldering operating temperatures increased, and the chemistry of solder paste has been modified.
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Authored By:
Gerjan Diepstraten
Vitronics Soltec B.V.
Oosterhout, Netherlands
Summary
Although reflow ovens may not have been dramatically changed during the last decade the reflow process changes step by step. With the introduction of lead-free soldering not only operation temperatures increased, but also the chemistry of the solder paste was modified to meet the higher thermal requirements. Miniaturization is a second factor that impacts the reflow process.
The density on the assembly is increasing where solder paste deposit volumes decreases due to smaller pad and component dimensions. Pick and place machines can handle more components and to meet this high through put some SMD lines are equipped with dual lane conveyors, doubling solder paste consumption. With the introduction of pin in paste to solder through hole components contamination of the oven increased due to dripping of the paste.
Conclusions
The first phase of implementation is to install the prototype flux collection unit to a test oven. Temperatures and gas flows will be measured to have the ideal exhaust conditions for the process gas. Different flux chemistries will be run through the oven in order to quantify the efficiency of the different catalyst and granulate materials before the unit will be installed on a production line to investigate the impact on maintenance.
Different granulates will be benchmarked to identify performance of a pyrolysis process. Two catalysts will be evaluated to see if a catalyst oxidation process is a more efficient way to clean ovens.
Initially Published in the IPC Proceedings
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