Bev - Agreed.
All good thoughts and discussion.
And yes solderability via functional test was fine and the more convincing factor to that particular auditor.
Now that I dwell upon this topic further, I seem to recall that in our case we actually baked out a PCA prior to wave solder in this oven and showed that we had no solderability.
Albeit in our case the exposure risk to silicone was very minor.
Rich Kraszewski
Senior Staff Process Engineer
Phone: (920) 969-6075
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-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bev Christian
Sent: Wednesday, January 8, 2020 10:33 AM
To: [log in to unmask]
Subject: Re: [TN] [COM] Evaluating/Monitoring Silicone Contamination
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Rich,
A couple of things:
1) If you are using SEM/EDX, it will only tell you that you have the element silicon present. It could be in the form of SiO2 (quartz), glass or a silicate mineral or ceramic. So I hope you really mean the AND in SEM/EDX and spread test. And a diamond anvil FTIR can be had for $20-25K USD, a whole heck of a lot less than a SEM/EDX.
2) Nortel actually quantified the amount of silicone that could be on the surface per unit area. Wish I had that info to share, but I don't. Whatever it was, it was pretty small. So if one did find silicones via FTRIR of any amount I would be a bit leery. The insidious thing about short chain silicones is that they creep. They can move across considerable distances, get into switches and of course when any switch is closed there is a small spark of very high temperature which destroys silicones and produces - silica, a most excellent insulator.
Regards,
Bev
-----Original Message-----
From: TechNet <[log in to unmask]> On Behalf Of Richard Kraszewski
Sent: Wednesday, January 8, 2020 10:47 AM
To: [log in to unmask]
Subject: Re: [TN] [COM] Evaluating/Monitoring Silicone Contamination
So Grivon I have been in your position with an auditor as well on this same topic.
While FTIR is a great tool to detect the presence of silicone compounds (if you actually have one - unlike me who very jealously wishes we did), you can also use a functional test such as a solder spread copper/brass coupon to show that even if silicon is present, it has a negligible if any impact on solderability. IPC TM 650 has a method.
The downside of using only chemical analytical instrumental is that now it is so sensitive that you can detect trace levels on & of almost anything. Issue is trying to define (correlate)a level at which you need to have concern. Hence adding a functional test such a solder spread can provide additional supporting evidence and value.
In our case, we used both SEM/EDX and solder spread tests to avoid a potential audit finding at one of our sites.
Every auditor is different.
Good luck!!
Rich Kraszewski
Senior Staff Process Engineer
Plexus
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-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of GRIVON Arnaud
Sent: Tuesday, January 7, 2020 8:00 AM
To: [log in to unmask]
Subject: [TN] [COM] Evaluating/Monitoring Silicone Contamination
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Happy New Year TechNet !
Here is a first query for 2020...
We all know about the need of carefully segregate acrylic/urethane from silicone conformal coatings, but how about evidencing and demonstrating (say for an angry auditor) the actual lack of silicone cross-contamination on toolings, ovens and workspaces ?
Are you aware of any reliable test system to perform silicone contamination evaluations? What are their principles and related test methods & acceptance criteria?
It looks like some suppliers offer Surface Silicone Contamination Test Kits :
- Henniker Plasma<https://ddei3-0-ctp.trendmicro.com:443/wis/clicktime/v1/query?url=https%3a%2f%2fplasmatreatment.co.uk%2fwp%2dcontent%2fuploads%2f2016%2f09%2fHenniker%2dPlasma%2dTechnology%2dOverview.pdf&umid=8FB268C1-9BA3-7205-A1D7-AFBE16EA21D0&auth=a79cf964896a44925c32628edeb2301b3739bcef-91b1c8db610e553c6f8b2d911a9913d76503f4f2> : https://ddei3-0-ctp.trendmicro.com:443/wis/clicktime/v1/query?url=https%3a%2f%2fplasmatreatment.co.uk%2fhenniker%2dplasma%2dtechnology%2fproducts%2fsurface%2dtest%2dequipment%2ftest%2dfor%2dsurface%2dsilicone%2dcontamination%2f&umid=5D81E98C-9B8D-3105-A422-6CBEC76778FA&auth=fa0282dc3c44b189bcc708f19c936975d8469bfe-99a2c633c2b699940a1b64811a5d44fb38a31589
- Anderson Materials Evaluation : http://www.andersonmaterials.com/test_methods/testing-facilities-for-silicone-contamination.html#<http://www.andersonmaterials.com/test_methods/testing-facilities-for-silicone-contamination.html>
Any practice of such test kits and return of experience to share?
Thanks in advance for your feedbacks.
Best regards,
Arnaud Grivon
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