Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

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flux residue problem

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flux residue problem | 3 September, 2009

I have a customer that is having a flux residue problem after wave soldering. Flux is roaring through the board to the top side and leaving a residue. This is only happening on the flat stamped leads. The round leads are fine. They are using Superior #312 alcohol-based no-clean flux. Solderability does not seem to be an issue. However some leading edges or trailing edges (I don't know which direction it was ran) lack solder coverage at all. Can anyone help us trouble shoot this issue?

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flux residue problem | 4 September, 2009

Hi Walter, Do you refer to a sprayfluxer operation? The problem seems to be a parameter setting issue. 1. Ensure the wide angle spray reaches PCB with optimum jet pressure. You could pass a glass plate to understand flux coverage and view Jet pressure. 2. Synchronise Nozzle motion with PCB speed to avoid/minimise fluxing overlap on board. 3. If operated under track mode, verify the track sensor timing on machine. Some machines have a PLC that needs to be programmed to synchonize conveyor speed, Fluxing duration, and solder wave activation. 4. Check the performance of the exhaust system near fluxer. Any flux that penetrates through open via or large PTH should be sucked away from the board. This prevents/reduces flux residue deposition on top side of PCB.

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flux residue problem | 27 September, 2009

Hi, Walter,

Why don't you try no-clean flux? We ever met the same condition, later, we changed to no-clean flux solved the problem.

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