Ohhh, what the heck, I've got 30 minutes to kill.

Mary,
I hope that I can be of some help in this area.  I was the primary author of
many of the documents you are referencing.  If this response does not answer
your questions, please give me a call at 317-457-8095.  

Doug Pauls
CSL

<< Is there an IPC document number for this referenced document or test   
 report?  Where can I get a copy?

The documents for the cleaning and cleanliness test program are:

IPC-TR-580 - Phase 1 Benchmarking - covered CFC cleaning of RA flux/paste.

All Phase 2 test reports are available from the individual vendors.  I have a
current list of materials and contacts for the Phase 2 list if anyone is
interested.  Phase 2 examined alternative cleaning chemistries.

IPC-TP-1043 - Phase 3, Water Soluble Flux, Part 1 - B-24
IPC-TP-1044 - Phase 3, Water Soluble Flux, Part 2 - B-36
IPC-TR-582 - Phase 3, Controlled Atmosphere Soldering

I have misplaced my reports for the Phase 3, Low Solids flux effort, but the
IPC staff can give you the tech report numbers.
 
>> I'd like to learn more about the background of level two testing.  I   
 don't know if I am alone, but I find the description of level 2 tests in   
 Appendix D hard to follow, especially with respect to pre-test   
 preparation steps for PTH and manual soldering technology -  steps which   
 prepare the IPC-B-36 SMT test vehicle for PTH or manual soldering tests.   

You are not alone in this respect.  I suspect that if we wrote a
specification that was clear and made sense, western civilization would come
to an end as we know it.  To help address some of the questions that are
frequently asked, I generated a paper titled "The Laymans Guide to
MIL-STD-2000 and MT-0002" and turned it over to the IPC for their use.
 MT-0002 process qualification is identical to J-STD-001A, Appendix A
qualification.  I recommend that you read over that paper.  It might answer
some questions.  Dave Bergman ([log in to unmask]) or Doug Sandvick
([log in to unmask]) should be able to give you the reference.

>> Somehow these pre-test preparation steps all fit in with the pre-test   
 preparation procedures outlined in IPC-TR-580 but the text is confusing.
 
Keep in mind that several years of experimentation occured between TR-580 and
the J-STD-001A Appendix D testing.  We learned a few things in that time.

>> I assume that controls, irrespective of soldering technology, are just   
 pre-cleaned bare boards. Is this correct?  

Yes.  Bare copper, B-36 boards, no processing, precleaned to under 1 ug/in2.

>> Appendix D states that control boards shall not be processed beyond
pre-test preparation.  The pre-test preparations for PTH and manual soldering
include mounting of components.   Appendix D also states components shall not
be mounted on control assemblies.

The question of how to handle component mounting, especially if you don't
have reflow capabilities, periodically crops up for those who want to qualify
a wave solder process only.  Again, the Layman's Guide paper addresses the
problem.
 
>> A picture is worth a thousand words - and in this case Appendix D would   
 be much simpler to follow if it included  flow diagrams showing the   
 preparation and processing steps for each soldering technology and for   
 the control boards.
 
Yes it would.  I'll see what I can come up with.

>> I notice that J-STD-001A Appendix D requires SIR testing on uncoated   
 assemblies while MIL-STD-2000A Appendix D requires SIR testing on   
 conformally coated assemblies.  Why the difference?  Which approach makes   
 the most sense if your goal is to verify a process which includes   
 conformal coating?

Hmmmmm, depends on who you talk to.  Some of the technical background of
2000A, Appendix A, was from the TR-580, Phase 1 efforts.  The J-STD-001A work
had the benefit of more of the Phase 2 and Phase 3 experimentation to draw
upon.  From the military standpoint, Class 3 hardware is seldom put into the
field in an uncoated condition.  The conformal coating operation has the
potential to interact with existing residues to make a fault mechanism.  So,
the 2000A approach has you test your candidate process with each of the
coatings you intend to use on product.  Different coatings, different
potential faults.  The 2000A approach uses a cyclical environment (25C-65C,
90% RH) to better force moisture through the coatings.

The J-STD-001A approach used a smaller sample size and tested in the uncoated
condition to better accelerate fault mechanisms such as electrical leakage,
metal migration, and corrosion.  The J-1A approach uses a static 85C/85% RH
environment to accelerate these conditions.

Which approach is better?  Depends on what you are trying to prove and who
you talk to.  Since most of the cost of such testing is incurred with your
sample processing, it makes as much sense to process samples in both the
uncoated and coated condition, and test each.  This is a difficult question
to answer by e-mail.
 
I hope this has been helpful.  I will warn you that if you think J-STD-001A,
Appendix D is confusing, you should review the (now current) J-STD-001B,
Appendix D.  I haven't figured it out and I helped write it!

Doug Pauls
CSL

***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To unsubscribe from this list at any time, send a message to:           *
* [log in to unmask] with <subject: unsubscribe> and no text.        *
***************************************************************************