Make a simple wetting balance test, see what angle you get, then you have quantified the 'bad' wetting. Sometimes the poor wetting is corrected with exaggerated miracle medecines (different acid-based soups). In your case, Dave, I would have a look on the nickel over the copper, if you have such a design. When we had problems, in most cases it was a nickel problem and not a contamination problem. Just to give you ONE of many explanations... Steve will cover the remaining...and, Dave, look in your soldering 'bible' i.e. Klein Wassinks 'Soldering in Electronics'. Find the word dewetting in the index..you will certainly get a lot of ideas.
Ingemar

-----Original Message-----
From: Dave Kell [mailto:[log in to unmask]]
Sent: den 30 maj 2000 17:17
To: [log in to unmask]
Subject: [TN] Solder Non-wetting


As a flex-circuit manufacturer, we are seeing random areas of solder non-wetting through our HAL process.  The problem seems to occurr mostly on surface mount pads and large exposed copper areas.  We have tried several pre-cleaning operations to remove all suspected sources of contamination.

Any other clues would be appreciated.

Thanks

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