Bob: Most of the current main stream photoimageable soldermasks are good for
about 1500-3000 VDC/mil.

A couple of words of caution:
1. The test for dielectric breakdown strength that generates these voltage
numbers is for a very short duration not 168 hrs and 85/85.
2.A lot of soldermask deposits are not one mil thick, 0.5-0.8 is quite
common, especially over circuitry.
3. Polymerization or the lack of it can greatly affect dielectric
performance. The soldermask must be sufficiently cured both thermal and UV.

With that said you should be able to achieve the performance you're after if
the board is properly cleaned and processed.


Regards

Michael Barmuta

Staff Engineer

Fluke Corp.

Everett WA

425-446-6076

-----Original Message-----
From: Robert Coburn [mailto:[log in to unmask]]
Sent: Monday, November 15, 2004 11:50 AM
To: [log in to unmask]
Subject: [TN] Solder Mask expectations / pushing the envelope?


Hi T'Netters;

One of my customers stated they were experiencing what sounded like a
shorting problem due to ionic contamination.
Can't tell if the problem originates beneath the mask or not.
The customer was testing assemblies at 85o C, 85% RH, 400 volts for 168
hours.

The question is: is the Customer expecting too much from a Solder Mask?

TIA,
Rob

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