I expect you will get a lot of responses like that.

Soldermask is not a reliable insulator. And to point out the other variable:
does the arcing come from the body of the part? Is its insulation changing
or unreliable (too)?

Ahne 




-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Hogg, Blair K.
Sent: Thursday, 05 July, 2007 08:37
To: [log in to unmask]
Subject: [TN] Soldermask Thickness

We switched PC board suppliers for one of our products a while back and have
started having hipot issues with components that are connected to main
110VAC input voltage arcing through the soldermask to tracks underneath at
1200V hipot voltage. 

I'm pretty sure I'll get a few responses that say that we shouldn't be using
the soldermask as an insulator, however, since the change in supplier seems
to coincide with the onset of problems, I've been asked to evaluate the
soldermask thickness as a potential contributor to the problems. 

I would some recommendations on how to measure the thickness of the
soldermask. 

Thanks,

Blair

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