This is one of my favorite re-occuring problems.
We have had some success with the following:

Reducing developer pressure - 20 lb top, 16 lb bottom, watch what
this does to your break point.

Increasing exposure times to acheive a 10 step.

Paying attention to lamination exit temparature and lamination
pressure - resist thins around the hole edges.

Reducing drill burrs and ensuring adequate debur operation.

Reducing hold times between exposure, develop and plating.

Evaluating other vendors resists. We have used Dupont and Morton
resists. They seem about equal in this respect.

After saying all that, the problem  has not been eliminated, only
reduced to tolerable levels. Tents above .150 dia. are a bear. Good luck. - Scott


>                   We seem to have an issue with tents breaking on large
>      holes ( .180 to .250 dia. ) as well as slots, typically .118 x .250.
>      No matter whose film we have tried, the tents break. It is not always
>      every panel, nor every lot. We have an idea that it may be being
>      caused by the developer. Has anyone out there wrestled with this
>      problem, and if so how was it resolved. To switch to secondary drill
>      would just impact that departments output Any help will be deeply
>      appreciated.
>
>                   Ernie Smith
>                   Electropac Co. Inc.
>
>      e-mail to   [log in to unmask]
>

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