Ken,
I've been down this same road before and it may not be as simple as it
sounds.  Be prepared that this idea may not be a "drop in" replacement.
 Dependent on your assembly types (top side SMT w/ through-hole or top
and bottom SMT w/ through hole both pose multiple heating cycles that
have to be considered prior to using an OSP considering the solderability
challenge), you will undoubtedly have to investigate alternate fluxes and
process parameters.

If memory serves me correctly, the solderability of the OSP surfaces has
different characteristics if the heating cycles (reflow soldering, glue
cure or wave soldeirng) are performed in air or nitrogen.  The
solderability of termination areas on the solder side of the PCB may
degrade after exposure to reflow.

The PCB fabricator that I was using at the time did not have in-line
processing capability and could not offer a significant cost savings
(initially it would be the same cost but could go down as volume demand
increased).  I would contact your assembly house(s) and request a
quotation.  If memory serves me correctly, the cost reduction of the
board should have been around 10%.

Since you mentioned Enthone, contact them and request the technical
reports that they have on this material.  The reports do provide good
guidance on the transition from HASL to OSP and offer suggestions (most
of these have to do with their other products -- liquid fluxes and solder
pastes).  Good luck and tred slowly!

Steve Sauer
Sr. Mfg. Engineer
Xetron Corporation
[log in to unmask]

 ----------
From:  Ken Patel[SMTP:[log in to unmask]]
Sent:  Thursday, August 06, 1998 1:16 PM
To:  [log in to unmask]
Subject:  [TN] HASL v/s OSP

Fab/Assembly Expert:
I have two questions related to price reduction if I change my pcb
surface
finish from HASL to OSP coating (Enthone CU106A).

(1) How much price reduction (in terms of %) can I expect from fab house?
(2) And also how about cost reduction from assembly house?

You can provide me the range if number of layers matters.

re,
Ken Patel
______________________________________________________
Ken Patel                       Phone:  (408) 490-6804
1708 McCarthy Blvd.             Fax:    (408) 490-6859
Milpitas, CA 95035              Beeper: (888) 769-1808

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