Bob - The Entek Cu-106a is completely compatible with a water wash process
and with the Alpha WS-609 solder paste.

I have soldered boards with some version of the Entek coating since 1989 in
conjunction with water soluble pastes and fluxes. I have specifically used
it with the Alpha WS-609 paste and various wave fluxes for several years.
The OSPs (organic solderability preservatives of which the Entek brand is
one)  were originally designed as an alternate to HASL finishes for people
soldering fine pitch components. Entek leaves a flat surface and HASL did
not. Copper with OSP is also typically the cheapest finish available on the
market.

The biggest issues for Entek relate to shelf life and the number of thermal
soldering cycles. Incoming boards needs to remain in sealed packages until
use. The first thermal cycle (typically reflow)  breaks down the Entek so
you need to minimize time between thermal cycles to retain good
solderability. Worst case is a board that sees 2 reflows and wave. After
the first reflow, the Entek is basically gone and the exposed copper is
free to oxidize. Wave solder joints usually suffer so Entek users typically
have a strong OA flux available.

Thanks,
Cheryl Tulkoff
Phone:(512) 683-8586
Fax: (512) 683-8847
National Instruments
11500 N. Mopac Expressway
Building A
Austin, TX 78759-3504





                      "Barr, Bob"
                      <[log in to unmask]        To:       [log in to unmask]
                      COM>                     cc:
                      Sent by: TechNet         Subject:  [TN] OSP and Water Wash
                      <[log in to unmask]>


                      03/05/2004 11:28
                      AM
                      Please respond to
                      "TechNet E-Mail
                      Forum."; Please
                      respond to "Barr,
                      Bob"





I would like to draw on the experience of others who have may have used an
OSP coating with an aqueous wash process.

The material is Entek Plus CU-106A and was specified for boards intended
for
a no-clean process. The board will sees two passes thru a surface mount
line
plus some hand soldering of thru-hole parts.

My questions:

1. Is this coating compatible with a water soluble flux (Alpha WS609 paste)
process with cleaning in 130 degree F DI water (in-line cleaner, no
chemistry). Keep in mind it will go thru the cleaner at least three times
(two surface mount and one thru-hole pass.)
2. Is OSP in general compatible with aqueous cleaning or is it primarily
designed for a no-clean process?

Thanks in advance for all help.


=========================
Bob Barr
Manufacturing Engineering
Formation, Inc.
=========================

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