Dear Sir,

Is it possible that your tin-lead plating solution may be aggressively
attacking the photoresist at the base of the copper, causing the resist to
lift? It is possible that the resist may not be compatible with the
parameters you are using in your plating process.  

Suggest that you try increasing the metal content of the tin-lead
electrodeposition solution and lower the acid content.
You did not mention if you are using a methanesulfonic acid or fluoborate
type electrolyte for your plating process. Since you are seeing tin-lead
plating on the base, it may be caused by the tin-lead plating process.

Good luck,

Mike Carano   
        -----Original Message-----
        From:   CIPSA [SMTP:[log in to unmask]]
        Sent:   Monday, J, uly 12, 1999 4:22 AM
        To:     [log in to unmask]
        Subject:        [TN] RV: Dry film adherence problems

         

         
        Dear Sirs,
         
        The reason why we send this e-mail is because we are having 
        problems of adherence of our dry film Dupont 4615.
        The problem always appears beside the track/pads, and in the final
pcb
        you always can see a bigger track, because the adherence of the film
has
        not good and some Sn/Pb has get on the base copper (the film has not

        protect correctly the base copper, beside the track).
         
        We have done the following corrective actions and there has not been
        any success at all:
        1. We have increased the lamination temperature from 105 to 115ºC.
        The presion is about 4 bars. The lamination rolls speed is about
1,6-2 m/min.
        2. We have checked the pH of the revelator solution and goes from pH
        11 at the beginnig to 10,4 at the end of the solution live.
        3. We are quite sure that is not a electrolitic line problem,
because in the
        same bath position, we have panels with and without problems.
        4. We have checked all the insolation parameters and everything is
OK.
         
        What we are doing now, is changing from Dupont film 4615, to 215.
        Maybe, it will solve the problem, but we don't know the cause of our
problem.
         
        Does anybody knows the cause of our problem ???
         
        Thank you in advance for your colaboration.
         
        Albert Varon
        Quality Manager.
         
         
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