Hello Roger Can you tell us what LPI you are using?
I would ask you to ckeck the final bake and make sure it is done right(time
and temp) Let me know what LPI you use   AFRI Canada

On Tue, 30 Sep 1997, [log in to unmask] wrote:

> Has anyone any experience of blisters (delamination) of solder resist on copper
> planes at hot air solder levelling.
>
>         We have been through a range of checks and tests to find the cause, including:-
>
> Surface conditioning before resist application.
> Water rinses on the brushing machine.
> Surface moisture.
> Predrying before exposure.
> In line  resist filter.
> Quality of electroplated copper.
> Final resist cure.
>
>         We are curtain coating liquid photoimageable solder resist. Hasl is carried out
> at 250 deg.C dwell time is 6 seconds. The boards are allowed to cool before post
> cleaning. There is minimal hold time between final cure and hasl. We have been using the
> same solder resist and hasl process for years. Now we have this problem.
>
>         Screen printing the same boards with photoimageable resist, containing more
> epoxy, we do not get blisters.
>         Any response would be appreciated.
>
> Roger Hammond.
>
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