Hi Brian:
                Wires can be soldered on to the traces and then the joints be coated. The wires are hooked to the proper voltage sources and the Surface Insulation Resistance test is done.  This test under these conditions is being done by a local lab that is sanctioned by IPC. Is dendrite growth or molecular migration  impeded within the inner layers and facilitated by air, temp and humidity on the outer layers? 
        Thanks for your input and clarifications
        Ramon

	

   -----Original Message-----
From: Brian Ellis [mailto:[log in to unmask]]
Sent: Wednesday, November 17, 2004 1:50 AM
To: Dehoyos, Ramon
Subject: Re: [TN] Solder Mask expectations / pushing the envelope?


First of all, your question should not be "...testing the voltage should 
not exceed 100V/mm" but "...testing the voltage GRADIENT should not 
exceed 100V/mm". This is not semantics but accuracy. I emphasize the 
point deliberately to try and instill this important notion into popular 
thinking.

Secondly, how can you measure SIR (SURFACE IR) on a coated board, when 
the conductors are no longer on the surface?

Thirdly, if you measure the IR of a coated board, the ionic migration 
within the polymers is not going to change just because it's coated, is 
it? What are you trying to measure, IR or breakdown voltage? They are 
not the same thing.

Brian

Dehoyos, Ramon wrote:
> 
>       Hi Brian:
>                   To obtain good results during SIR testing the voltage should not exceed 100V/mm. Is that a true statement? This is for uncoated boards. For coated boards it should be higher, Shouldn't it?
>       Regards,
>       Ramon

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