Phil and Bev
Not necessarily strange.
Phil, you say you passed ROSE test "of course". What is your pass/fail criteria <1.54microgrammes NaCl? If yes, then no wonder it fails IC.
IC is intended to tell you EXACTLY what is on an assembly surface that might be causing an electro-chemical problem …that should have been established as a problem from SIR tests.
If it passed SIR tests, then is that "pesky result" really an issue?
As I have maintained:
Use your ROSE test to control your process - not based upon some spurious pass/fail limit.
Then run SIR
If there's a problem, run IC or FTIR or more to find out what the root cause is.
As regards your control coupon failing - Might I presume that there is a solder resist / mask present on the bare board? In most of our test work it is the bare board that harbours the most problems - get that right, and…bazinga!
Graham Naisbitt
On 9 Oct 2012, at 08:09, Bev Christian wrote:
> Phil,
> Very strange.
>
> Has the ROSE tester been calibrated?
> Physically what is different between one test sample and the other two?
> Were all three test samples ROSE tested together or separately?
> Were they shipped together or in separate bags or even in totally separate
> packages?
> How far away is your manufacturing facility from the lab? Next door? Next
> city? Next state?
> What are you getting for chloride readings for your blanks?
>
> Bev
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Phil Bavaro
> Sent: Monday, October 08, 2012 7:30 PM
> To: [log in to unmask]
> Subject: [TN] ION CHROMATOGRAPHY - EXCESS CHLORIDE CONTENT
>
> We have some results that have left me puzzled. We are processing the
> IPC B-52 test PWAs using water soluble paste/flux and we can pass the
> ROSE test (of course) and the SIR test, but fail the IC test for
> excessive choride anion content.
>
> Here is what baffles me.....our control sample is similar and worse than
> the test samples.
>
> There seems to be some documentation that the chloride ion might be
> related to mishandling and/or soldermask not being properly cured but I
> don't have any experience with this test result so I am not sure how to
> respond to that (hopefully Terry will chime in on this). We processed
> all the samples using the proper gloves and bags and doubt that we
> contaminated them.
>
> We are trying to meet the requirement of 0.9 micro-gm/cm-cm maximum and
> our failing control sample is 3.36, one test sample is 4.67, and the
> other two samples are running at .91 and .90. What value for chloride
> anion content does a normal WS process yield? Are these numbers way out
> of range for normal test results or is chloride always a pesky result?
>
> I am looking for the answer to the question "is this really a problem?"
>
> The control sample was washed but did not have any paste applied to it
> at all. The test samples were run through the full assembly reflow
> process then cleaned and Rose tested before shipment to the lab.
>
> All the rest of the results for the IC test are passing so I don't know
> quite how to proceed from here.
>
> My current plan is to run another set of tests with more than one
> control sample, and then to simulate various phases of clean (IOW barely
> cleaned, half cleaned, and then a couple of fully cleaned samples). As
> I am not really familiar with IC test results, I want to see the what
> the constituents of the "dirt" really look like from an IC test
> perspective as well as repeat the previous test results.
>
> One item I have noted is that we did not have our chosen board supplier
> build these boards but instead bought these off the shelf from one of
> the dummy component suppliers. But the thought was that as long as they
> were cleaned using our normal process, they should be acceptable.
> These particular test samples use FR4 and not the high Tg polyimide that
> most of our PWBs are built from.
>
> Any comments on this would be appreciated.
>
> ----------------------------------------------------------------------------
> --
> This message and any attachments are solely for the use of the addressee and
> may contain L-3 proprietary information that may also be defined as USG
> export controlled technical data. If you are not the intended recipient, any
> disclosure, use or distribution of its content is prohibited. Please notify
> the sender by reply e-mail and immediately delete this message and any
> attachments.
>
>
>
>
> ______________________________________________________________________
> This email has been scanned by the Symantec Email Security.cloud service.
> For more information please contact helpdesk at x2960 or [log in to unmask]
> ______________________________________________________________________
>
>
> ______________________________________________________________________
> This email has been scanned by the Symantec Email Security.cloud service.
> For more information please contact helpdesk at x2960 or [log in to unmask]
> ______________________________________________________________________
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________
|
