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Reply To: | TechNet Mail Forum. |
Date: | Fri, 5 Dec 1997 04:45:10 -0600 |
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Bill,
Not necessarily true. With regards to which method is best, Batch or
In-line, EITHER process is great. Consider this, Enthones patented
method is an Automated In-line Process that submerges the entire PCB
in Entek Plus Cu-106A. The prior and post steps are Spray bar (e.g.
Soak, Microetch, Acid Dip, etc.). The important consideration here is
Solution Temperature and utmost, the dwell time. Regardless of what
method is used, the dwell time will make or break the assembler (your
customer). A nominal OSP thickness should be .2-.5 microns. Perform
a coupon test and verify via a Spectrometer method. Again, either
process will work, provided the latter items are monitored.
With regards to Thermal Excursions, I do not recommended a bake
following an OSP application. A board bake to remove moisture prior
to typical Assembly process is not the same. Consider this, a typical
bake is 1-2 hours @ 110°C (230°F), again dependent on the oven
convection. The Thermal Excursions encountered in Assembly are quick
with respect to a bake. Reflow is typically 5 minutes max per side
and same for Wave Solder (pre-heat plus solder pot) and then consider
the 130°F wash should you use an OA (Water Soluble Paste).
Maybe someone else can answer this, what Temp/time ratio is equivalent
to removing "X" OSP thickness. There are alternative methods for
monitoring moisture absorption at the Fabricator.
John Gulley
Inet Inc
972-578-3928
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