Bob: Yes the Entek CU-106A is completely compatible with the WS paste and
aqueous clean. In fact the WS paste should perform better from a
activation/solderability standpoint than the no-clean.

The coating degrades primarily from higher temp heat cycles(reflow)and flux,
however hot DI water and drying sections in the aqueous washer will also
affect it but to a lesser degree.

A couple of questions back to you.
Why are you washing these three times is it due to extended hold periods at
reflow 1 reflow 2 and hand solder? Would it be possible to reduce to two
washes or possibly a single post hand solder final wash? Less exposure to
hot DI water and drying will help solderability.
Is your main concern the solderability of the board by the time you get to
hand solder?
Are you using WS core solder for hand soldering? If so this will help
greatly in the activation of the copper.

All in all if the Entek is properly applied you should not have any great
problems. We have used the 106A since it first came out using similar
process flows as you.



Regards

Michael Barmuta

Staff Engineer

Fluke Corp.

Everett WA

425-446-6076

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Barr, Bob
Sent: Friday, March 05, 2004 9:29 AM
To: [log in to unmask]
Subject: [TN] OSP and Water Wash


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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