The IPC 610 uses the two terms Non-wetting and Dewetting side by side. This
doesn't mean they are both the same, but the observed result may be the
same. The failure of the solder to wet to the pad (or a termination) is
non-wetting, quite why the word solderability doesn't appear at this point I
don't understand.

De-wetting is a process (usually related to the presence of precious
metals), where solder has taken to a surface, but on subsequent reflow
cycles refuses to wet again to the surface. As further reflow cycles take
place the degree of de-wetting increases.
So don't confuse the cause with the observed result.



At 07:43 01/04/98 PST, you wrote:
>Hi guys,
>
>Please help me out on this. I need your help regarding the exact
>definition of de-wetting defect on smt land or pad (PCB manufacturing)
>Based on the IPC definition, the way I understand it, is that,
>de-wetting is a defect that is caused by the failure of solder
>coating/plating process to coat the copper surface evenly. The solder
>coating is unevenly distributed on the copper surface. Thus, there is
>thin and thick coatings on the surface. Am I right? What's the
>accept/reject criteria for this defect? What is the minimum and maximum
>thickness of solder coating?
>Thank you very much for your time. I'll be waiting for your responses.
>
>regards,
>Martin
>
>P.S. I'll appreciate it very much if you can send me a photo via
>attachment file.
>
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