Address,

     The following questions are related to Enthones Entek 106A and Kesters
     5631-C2 Protecto OSPs.

     With resepct to OSPs, a majority of my surface finish experience has
     been with Entek 106A.  After thorough First Article testing the Entek
     Cu56 and then 106A basically replaced HASL as the surface finish.  Our
     Wireless group introduced Kester's OSP into the assembly process
     without notifying Process QE.


     1. Of the assembly houses that use Entek 106A, are there any special
        assembly process' you have incorporated prior to solderpaste
        applicationm?  If so, why.

        The Technical data sheets from Enthone do not require any special
        process parameters.

     2. Of the assembly houses that use 5631-C2, (assuming a low residue NC
        paste - 3%) do you wash the fabs in a 3-5% acid prior to
        solderpaste deposition and reflow assemblies in an Inert
        environment?

        The Technical Data sheets from Kester are vague in this issue.

     3. Kester claims 3 thermal excursions with an OSP thickness range of
        215-315A, while Enthone claims 5-6 thermal excursions with a OSP
        thickness range of 1000-2000A when measured with a Spectrometer.

        Is the Kester that robust that is allows the adjacent side to be
        solderable following 1 thermal pass?

     4. Have others found incompatibility issues with using the above OSPs
        with NC, OA and RMA fluxes/solderpaste?

     5. FAB:  Are you applying the OSP in a controlled environment or have
        you determined it to be necessary?

     6. Its been commented that an OA is recommended with Kester's OSP,
        then with NC's.  Have others found this to be true?

     Please advise.  Call me @ 972-578-3928 if we need to talk offline.
     Thank you.

     John Gulley
     INET Inc.
     www.inetinc.com

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