Hello Technet,

A supplier made us some board-assemblies with a ionic contamination at least twice as high as the IPC and MIL-specifications allow. This is probably due to residues from RMA solder paste. The boards are washed after wave soldering with water/detergent, but there is no intermediate cleaning after the reflow soldering. It takes a couple of days before the reflow soldered boards are wave soldered, so the paste-flux is not very cleanable anymore.I've heard so often that bad cleaning of RMA is much worse than good cleaning or no cleaning. I'm not sure, but this is what I think is the cause of the problem..

The question : will this ionic contamination, concentrated around the topside-smd's, really result in early failures ? The boards are built in hermetically sealed boxes, but will be used in a wide variety of temperatures. There are no fine-pitch devices on the boards. Any advice or comments are welcome.

Andy

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