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June 2000

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From:
Douglas Pauls <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Mon, 5 Jun 2000 08:40:25 EDT
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In a message dated 06/02/2000 8:27:31 AM US Eastern Standard Time,
[log in to unmask] writes:

> Hello all (specifically SIRGuru),

Good morning Cara.

>
>  Thanks for the advice.  I am actually looking to verify the performance and
>  gauge the impact of introducing a new flux to our wave solder system.
>
>  I was indeed seeking labs that run certified IPC lab testing.  I simply
want
>  to determine if the fluxes work on our boards with no problems.

The question I have is what do you mean by "no problems".  When you are
looking at new fluxes, there are (IMHO) three primary factors to consider:
solderability, residues (and their effects), and materials compatibility.
Many people do flux screening on solderability.  Hole fill and fillet
formation can be objectively measured by IPC criteria (e.g. A-610).  Residues
can be measured (e.g. ROSE or IC) but fewer people understand the data and
the objective criteria not as widely known.  Materials compatibility is a
huge gray area (kind of like Indiana this morning), where there are very few
standards and hundreds of different definitions and approaches.


>  This is not  really that simple, compare to hurling a dead chicken 56feet
(16.8m) from a
>  hill top into a full moon...!?!  :-)

For the non-informed, Cara has not taken leave of her senses.  She refers to
some of my more warped writing from a past IPC technical paper.

>  I have obtained Bellcore and IPC
>  qualification data from all of the fluxes that I am interested in.  I have
>  narrowed my pool of fluxes through specifying VOC free, halide free
>  ,no-clean or water wash and low residue.

One question I have is how nervous are your customers about visible residues?
 Going the no-clean route, especially if you are now doing high solids rosins
or OA fluxes, can be a paradigm shift in your operations as well as in your
customers perceptions.  I have several clients who are using low solids
fluxes and cleaning, but the answer is most often for purely cosmetic
reasons.  The only valid reason I have seen for cleaning a no-clean flux is
that it can reduce the amount of solder balls on the assembly.

>
>  The first phase of the testing is to determine if solder balls, bridging,
>  other defects are reduced using the new fluxes, compared to the current
>  flux.  Any fluxes that do not perform well will be eliminated.  The next
>  phase we plan on using IPC standard boards and/or our own boards.  These
>  boards will be tested in a lab (specifically to determine if there is any
>  corrosion) and in our test department.  I'm still not clear on if I can
have
>  my production boards tested in a lab or if I need to use the IPC boards.

The issue of testing on actual hardware vs. testing on standard IPC test
boards comes up a great deal (at least for me).  I have seen many fluxes do
well on IPC standard test boards, only to do poorly on the product.  I think
this is due primarily to the lack of solder mask on the IPC test boards, and
the fact that the IPC test boards usually do not mimic the hardware very
well.  Do you have customers who have to see IPC data to accept your process?
 Does your company claim to be ANSI J-STD-001 compliant?  Otherwise,
demonstrating success on actual product through accelerated life tests (e.g.
power temperature cycling) is stronger technically than demonstrating success
on IPC standard boards.

>  Again any fluxes that do not perform well in this phase will be eliminated.

What are you using as your evaluation criteria?

>  The final phase will be to run the remaining fluxes for a least a week and
>  test and monitor any problems that arise.  If anyone can offer any further
>  insight into this plan it is more than welcome.

What is it you are running for a week?  Production for a week or some form of
accelerated life test for a week?

>
>  Crossing the boarder causes no problem, converting the Canadian dollar
>  does...  :-)

Heck, do what our high school students seem to be adept at - print up your
own.  Of course, the Treasury agents take a real dim view of
this..............

>
>  Your input is very helpful.

Hope so.  Otherwise, it was worth every penny you spent on it................

Doug Pauls

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