Dear Technetters,

Sorry if the first e-mail I sent was incomplete.
I had asked if the mask in question is polyalcohol developable or carbonate
developable? My experience is that the polyalcohol types are more resistant
to attack from the gold solutions.
Also, the epoxy masks versus the acrylate ones are a factor, and actually
they may be tied together with respect to how they are developed.
Nickel solution pH will be a factor as well.
An additional post expose IR or thermal bump may help to make the mask more
resistant. The degree of crosslinking of the photopolymer will further aid
in making the mask more resistant.
It would also be prudent to investigate the actual exposure energy.
Insufficient exposure energies would have a serious impact on mask
resistance.

Also, is it possible to lower the operating temp of the ELNIC solution
and/or reduce the time for plating?

Good luck,

Mike Carano

        -----Original Message-----
        From:   Robert Jordan [SMTP:[log in to unmask]]
        Sent:   Tuesday, March 09, 1999 11:28 AM
        To:     [log in to unmask]
        Subject:        [TN] Immersion Ni/Au & Solder Mask

        Hello Techneters,

        I would like to solicit you comments, experiences, suggestions and
        hopefully success stories concerning the processing of Immersion
        Nickel/Gold with respect to LPI Solder Mask adhesion.
        Presently, we solder mask first then send out to subcontractors for
        Immersion Nickel/Gold. We use Tayio PSR4000AD as well as PSR4000BN.
From
        time to time we see peelers, leakers whatever you would like to call
it.
        The same solder mask performs fine in HASL and Entek enviroments.
I'am
        stumped. Are any of you runing a 6 sigma process reguarding this?

        Areas in question include;
        * Surface prep prior to LPI
        * LPI mask itself ...ie manufacturer?
        * Exposure and Development
        * Final Cure
        * Immersion Nickel/Gold
           Type/Manufactures
           Operation parameters ... ie temperature, concentrations, pH, time
           Thickness of Nickel deposit
        * Should we Immersion Nickel/Gold before mask?
        * Mystery or Magic?

        Thank You,
        Robert Jordan
        408-738-0693  x1116

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