LARRY,

PLEASE BE AWARE THAT EPOXY BASED LPSM CANNOT BE STRIPPED AFTER BAKING, THE
SOLVENT NECESSARY WOULD ATTACK THE BUTTER LAYER. ONLY NON-EPOXY CAN BE
STRIPPED EFFECTIVELY, 130-150 F, PH>13 AND WITH AN RBP-CHEMELEX PROPRIETARY
SOLDERMASK REMOVER, ONLY 3 HOURS IS NECESSARY. 

BEST REGARDS,
LENNY KURUP
[log in to unmask]

On Sun, 15 Jun 1997 [log in to unmask] wrote: 
> I'm not sure if it has tremendously improved over the past two years;
> however, most PWB shops will try to strip LPI masks (even after final cure)
> in preference to scrapping out the boards.
> 
> The basic requirements for stripping cured LPI solder masks after final cure
> are:
>    1. High pH (>13.0)
>    2. High temperature (150-180 deg F)
>    3. Patience (it could take up to 48 hours)
> 
> A number of companies have proprietary solder mask strippers on the market
> which work well. Examples would include: Alpha Metals, Oliver Sales, Dexter
> Electronic Materials, etc.
> 
> Hope this helps
> 
> Larry Fisher
> Dexter Electronic Materials
> [log in to unmask] 
> 
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