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Subject:	Re: Just a few Questions
From:	[log in to unmask]
Reply To:	TechNet E-Mail Forum.
Date:	Mon, 30 Jul 2001 13:37:26 -0500
Content-Type:	text/plain
Parts/Attachments:	text/plain (97 lines)

Because a few of the "icons" of the industry(Doug Pauls,etc.) tell you to.
Unless you have a Freudian sense of humor,which can be attributed to
drinking too much Mountain Dew(Doug Pauls,etc.),I believe you meant to say
ionic wash.
There are many reasons to clean an assembly,besides just removing flux or
it's postreflow by-products.Knowing the end use enviroment,whether it is to
be conformally coated,as well as many other factors will determine whether
you need to clean after a no-clean process.If you would to talk to me
off-line give me a call.
Doug Pauls is also an excellent source of information.

**Oh, hell. Now I have to buy Dewey another beer at IPC. "Industry
Icon?". That means when you click on me, I crash and give you the blank
look of the Blue Screen of Death. Any time someone mentions my name three
times in an e-mail, I turn into a large Norwegian rat for 1 day. Thanks a
lot, Dewey.

The way I read the original question, I don't know if Cathy was referring
to the final rinsing, a general cleaning, or to the ROSE/SEC cleanliness
test.

I don't disagree with any of the former commenters, but the issue of
cleaning and cleanliness can be a complex one. If you have an assembly
process which incorporates cleaning, then you have the opportunity to
remove residues. If you have a no-clean assembly process, you must
determine, in advance, if the constituent parts (boards and components) are
clean enough to avoid electrochemical failures. How clean is clean enough?
A very difficult question to answer and can only be done on a case by case
basis in my opinion.

I would recommend that you get the following documents to assist in your
education on the matter:

IPC-TP-1115: SELECTION AND IMPLEMENTATION STRATEGY FOR A LOW-RESIDUE
NO-CLEAN PROCESS. This document discusses all the factors that an
assembler has to consider, cleanliness being a big one, when switching to
no-clean assembly methods.

IPC-HDBK-001: This document is a companion to J-STD-001. I was the editor
or writer for sections 4 (Fluxes) and 8 (Cleaning and Cleanliness). It
goes into the various cleanliness tests and cleaning in general. I
understand that a similar document is being initiated as a companion to
IPC-A-610.

EMPF Report RR0013: An In-Depth Look at Ionic Cleanliness Testers. This
may also be available as an IPC technical paper. If not, the paper is
available from www.empf.org. The paper discusses ROSE/SEC testers and why
they should be used ONLY for process control and not product acceptance.

I authored a column for Circuits Assembly Magazine
(www.circuitsassembly.com) called Process Rx for a number of years, with
topics including cleaning and cleanliness testing. You can check their
archives or the Library section of CSL (www.residues.com) for copies.

I wrote two articles for the October and November 2000 IPC Review on bare
board cleanliness specifications and assembly cleanliness specifications in
general.

Jack Brous, often considered the father of the Omegameter, wrote a paper
that outlined the origins of the ROSE test and how it can and can't be
used. IPC should have it as a technical paper. If not, I have it around
here somewhere.

If that is not enough to put you to sleep, I wrote another few documents
called the Layman's Guide to MIL-STD-2000A and the Layman's Guide to
J-STD-001B. They cover the aspects of cleaning and qualifying the process.

Well, that should be enough for a start. Let me know if I can help some
more.

Doug Pauls
Rockwell Collins
Industry Court Jester

(Now where did I put that Mountain Dew.....)

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