Stuart ;

  I have just one answer.
  OSP coatings can't support oven reflow temperatures and the answer is the
OSP is removed by the processing, I had problems in the past with a double
pass board ( glue bottom side, solder top side ) and had insufficient fillet
or not wetting at solder wave machine, due to OSP removal at the previous
process ( solder reflow ) ,the solution were switch the boards to HASL
finish.

I hope this help ( at least first question !!! )
Jorge Dourado de Santana
Maintenance / Process Engr
Microtec - Brazil



> -----Original Message-----
> From: Stuart Korringa [SMTP:[log in to unmask]]
> Sent: 22 de Fevereiro de 2000 10:45
> To:   [log in to unmask]
> Subject:      [TN] Entek question
>
> TechNet,
>
>     We have some SMT CCAs which we receive with Entek OSP coating. The
> vias on
> the PWB are not solder masked nor during assembly processing are they
> screened
> and pasted. After convection oven reflow, is there still some Entek on the
> vias
> or is the OSP removed by the processing?
>
> The CCAs are later conformally coated which puts down 1-5 mils of type AR
> protection on the vias. However the vias underneath large QFPs do not get
> conformally coated by the Nordson sprayer. Is there a reliability concern
> here?
>
> Also, after 120 hours of humidity/temp cycling, the tin-lead pasted areas
> exhibit some white residue while the non-solder masked and non-conformally
> coated Entek areas appear fine.
>
> In anyone's experience, is there a long term issue for Class 3 goods?
>
> Stu Korringa
> Smiths Industries
> Grand Rapids, Mi
> [log in to unmask]
>
>

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