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Thu, 22 Aug 2002 09:05:29 -0500
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Well, thank you Guy for the kind words.  First round of beer at IPC is on
me.

I guess one thing to add to this is that the spec "is" based on agreements
between manufacturer and customer on what constitutes quality or acceptable
controls.  In my experience, this breaks down into a couple of different
scenarios:

a.  your customer is clueless about these factors or considerations.  The
frantic downsizing of the industry over the last decade has left many
companies without the old graybeards (a status which I approach far faster
than I care to) to wisely counsel customers or internal people.  If you do
have the corporate knowledge of these issues, it creates a golden
opportunity for you to educate your customer and cement relations.  If your
customer has no concept of how to demonstrate materials compatibility or
test for the long term effects of flux residues, how much more comfortable
will he be with your product after you explain all these things to him?
Customer for life?  Well, who knows these days, but the odds are better.

b.  neither side knows what they are talking about.  A case of the blind
leading the blind.  That's when you call in the cavalry and bring in a
Werner Englemeier or a Les Hymes.  Worth it at twice the price.

c.  The customer doesn't care. As long as your product works like it is
supposed to (or better), with the advertized MTBF (or longer), he doesn't
give a rodent rectum about your process.  That gives the OEM lots of
freedom in manufacturing and ability to make changes, but it also puts the
additional burden on the OEM to satisfy himself (or herself not to be
sexist) that changes do not negatively impact form, fit or function.  Now
THAT is one slippery eel to grasp.

Doug





"Guy Ramsey" <[log in to unmask]> on 08/22/2002 08:46:00 AM

To:    "'TechNet E-Mail Forum.'" <[log in to unmask]>,
       <[log in to unmask]>
cc:

Subject:    RE: [TN] J-Std-001C Qualification


Really enjoyed this reply, full of insight and based on real world
experience. I have one observation. It's related to the "It depends on
your customer" tone of the reply. I know the quality of work produced at
Rockwell Collins and know that Doug would not want to be misunderstood.

It is not likely that our customers will be able to tell us what they
really want. They simply want their product to work in its service
environment.

Doug and Dave have forgotten more about electronic manufacturing than
most of their customers will ever know. Rockwell Collins demonstrates
their commitment to customer expectations by staffing their organization
with people like Doug and Dave.

Don't dismiss Doug's observations on this matter as mere opinion.

Guy Ramsey
ACI / EMPF
Ph: (610) 362-1200 x107
Fax: (610) 362-1290



> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of
> [log in to unmask]
> Sent: Thursday, August 22, 2002 8:44 AM
> To: [log in to unmask]
> Subject: Re: [TN] J-Std-001C Qualification
>
>
> Bill innocently asks a question on J1C.  Doug, coming off a
> night of minimal sleep comes out of left field with a response:
>
> I have a general question for those folks out there who do
> J-Std-001C, class 3 work. We use fluxes that are stronger
> than the "allowed" L0 or L1 activity levels. Because of this
> I had to "qualify" our process per Appendix B of the
> J-Std-001C. This according to J-Std-001C, paragraph 4.2b. The
> cost of doing this test, including materials, labor and
> whatever is approximately $7000.
>
> **First off, you can use whatever flux you want, but if it is
> more active than the L1 or L0 level, you have to do
> additional testing to demonstrate you have removed the flux.
> L0 or L1 fluxes are not "allowed fluxes", it just means that
> there was a concensus at the time of drafting that the L0 and
> L1 fluxes were benign enough and were designed to be left on
> the board, such that you did not have to do the testing to
> show materials compatibility.  The whole intent of the
> paragraph on materials compatibility is that you either use a
> benign flux or you do testing to show you have removed the
> active flux residues to benign levels.
>
>
> Now I have a couple of questions...
>
> 1) If one of the solder pastes that you qualified is no
> longer available, do you have to do a re-qualification if the
> manufacturer of the paste suggests a new material? (This
> implies a material change)
>
> **In my opinion, yes.  You have changed materials.  But my
> opinions mean squat.  What do your customers feel?  The
> biggest background philosophy of J1C is that quality is
> whatever you and your customer agree to.  If the new paste
> you are using has nearly identical properties to the old
> paste, are they comfortable with the swap without a
> requalification?  Simple question, tough answer though.
> Would they accept a smaller, more focussed engineering study
> on the chemical residues present with the new flux, in lieu
> of a full requalification?
>
> 2) If you swap out a spray fluxer for a foam fluxer or apply
> flux with a different method at the wavesolder machine, do
> you have to do a re-qualification? (This implies a process change)
>
> **Again, in my opinion, yes.  But, my opinion and 50 cents
> will get you a cup of coffee (well outside of Starbucks).
> Same reasons as above.  I would be more concerned about this
> change than with the paste change.  90% of solder paste is
> metal, only about 2% actual flux, and after reflow it does
> not leave a great deal of residue, compared to wave solder. A
> foam fluxer (and why are you taking a step back into the evil
> dark ages?) will put on 3-4 times the amount of flux. If you
> do not adequately modify your reflow process to dry and
> activate that much extra flux, there is a high probability
> that you would have unreacted flux, which is a reliability
> hazard.  If I were your customer, danger klaxons would be
> going off (Danger Will Robinson Danger) regarding this change.
>
> I suspect the answer to both questions is yes.
>
> **No, the answer to both questions is "It depends".  On your
> customer primarily.
>
> With the number of possible
> changes within a soldering process, it seems inevitable that
> process qualification and re-qualification could happen on a
> regular basis due to circumstances beyond your control.
>
> **Not really.  Again, it comes down to the relationship with
> your customer. The whole point of paragraph 4.2 or the
> paragraphs on materials compatibility was that the
> manufacturer had better understand the compatibility of the
> chemicals in their assembly process and their long term
> effects on reliability.  The re-qualification thing is really
> a hold over from the good old days of mil-specs.  It is sort
> of the same arguments that come up with lot sampling vs. SPC.
>  The bottom line is that when changes occur in your process,
> how do you assess the impact of those changes.  The Appendix
> B testing won't guarantee that you are making good product.
> It is only ***one*** default way of demonstrating that you
> have done some investigations into the long term effects of
> the change.  Other methods are perfectly valid and a
> "requalification" may not be needed each time, but a re-evaluation is.
>
> So are the class 3 guys out there either doing regular
> qualification testing or are you all using L0 or L1 (no
> clean/Rosin) fluxes.
>
> **We have been transitioning to L0 or L1 fluxes and pastes
> and much of our stuff is class 3.  Hell, even our class 2
> stuff is class 3.  Me and Hillman make some damn good stuff here......
>
> Is there anyone out there who participated in the writing of
> this section who can shed some light on the thought process
> behind this section of the spec.
>
> **I have been involved with that spec.  A little less on the
> C revision, but Jim Maguire and I pretty much wrote the
> Appendix B protocol.  There  is an IPC technical paper,
> IPC-TR-467, that Jim and I wrote to explain the reasoning
> behind the protocol.  You might want to read that.  If you
> have other questions, send them my way.  Just be aware that
> as the day progresses, the Diet Mt. Dew count increases and
> the answers get progressively wackier.
>
> Doug Pauls
> Rockwell Collins
>
>

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