Who says the chlorine comes from your tap water? Our PTOW dumps boat loads of chlorine into our water periodically. Sometimes it's so bad you can smell it. We doubt that it is the source of your problem. This chlorine will volitize very quickly, be cleaned by your carbon bed, and probably will not cause a reaction to form salts on your boards.
What are the halide levels of the fluxes you use in soldering?
Consider that a better direction for your efforts to be to understand the residues left on your boards and components [shipped to you] by your suppliers.
Ion chromatography [IPC-TM-650, Method 2.3.38] is a reasonable method for measuring chlorine. CSL says, "We recommend maximum chloride levels of 4.5 � 5.0 micrograms per square inch for final assemblies processed with water soluble fluxes and 2.0 � 3.0 micrograms per square inch for a bare board (tin-lead coated) intended for a water soluble flux process. These recommended maximums do not presently appear in any nationally accepted specifications or standards, but are based on our failure analysis efforts with numerous customers."
How does your customer measure chlorine? What level of chlorine do they find unacceptable?
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