Talking about distorsion....what do you mean by "distorsion sometimes seen
on fine pitch product" ??

I am very interested in that.... because we have problems with fine pitch
alignment with the stencil when we want to apply solder paste. The PCB image
being larger than the stencil (from 1 to 8 mils from one extremity to the
other).  And when I talk about that to our PCB supplier, it seems like we're
the only one who complain about this kind of issue.

Our board are HASL, 20 mils pitch (I know we should switch to OSP or
something like that...).

ALaberge
Quality Eng.
Matrox



At 04:20 PM 6/30/97 -0500, you wrote:
>
>
>I would recommend applying idents after HASL. Hot air leveling takes the
>board well above its glass transition temperature and them cools it pretty
>rapidly. Typically this can cause some distortion in the panel. If a thermal
>cure ink is used for idents and the panels are cured horizontally, the
>boards are slowly brought to a temperature just above the glass transition
>temperature and then cooled slowly. This helps minimize the distortion
>sometimes seen on fine pitch product.
>
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