Good morning Ryan,
The question of what tests to run to investigate the ability of a conformal
coating to protect your product against your end use environment for the
anticipated life of your product is, in itself, probably at least a
Master's level thesis to adequately cover.
Having done this for a long time, here are some of my recommendations:
1. I have generally found that repeating the CC-830 qualification tests
to be a waste of time and money, unless you want to test against a
different SIR environment than the cyclic test in IPC method 2.6.3.1. Keep
in mind that CC-830 is not a specification to tell you that coating will
work on your product. It is a materials qualification protocol that
separates coatings designed for use on high performance electronics from
those you get at Lowes/Menards/Home Depot, not designed for electronics.
Recommendation 1: start with a coating that is qualified (with suitable
test reports) to either IPC-CC-830 or MIL-I-46058.
2. What testing you do on product will depend on what your end use
environment is. Aerospace has one set of primary environmental
challenges. Industrial controllers a different set. Automotive a
different set, and so forth. What are you asking your conformal coating to
protect against. That will determine what tests make sense to run.
3. Your test matrix should include thermal cycling, with extremes 10C
higher and lower than any product burn in you run. Thermal cycling causes
your assembly to go through expansion and contraction. Visual examination
can show a coating's propensity to crack or delaminate when that happens.
Thermal shock will also show cracking and delamination, but is a pretty
severe test. Don't run it if you don't have a thermal shock condition in
your end use environment. DO use thermal shock if you use Highly
Accelerated Stress Screening (HASS) testing as a product burn in
methodology.
4. You can find waterproofness tests in MIL-STD-810/883 which can be
illuminating. Those documents also have fluid susceptibility tests that
are useful.
Something to think about. You can contact me off line if you want to go
into more depth.
Doug Pauls
Principal Materials and Process Engineer
Rockwell Collins
On Wed, Nov 8, 2017 at 5:42 PM, Elson, Ryan(BHGE) <[log in to unmask]>
wrote:
> Thanks for the input. I know this test is part of IPC-CC-830, so I wonder
> if it's worth having tested again. I wasn't planning to have the retest the
> rest of the tests from 830, but I will look into it.
>
> Thanks!
> Ryan Elson
> Manufacturing Engineer
> Bently Nevada
> Baker Hughes, a GE company
> [log in to unmask]
>
> -----Original Message-----
> From: SALA GABRIELE [mailto:[log in to unmask]]
> Sent: Wednesday, November 08, 2017 3:32 PM
> To: 'TechNet E-Mail Forum' <[log in to unmask]>; Elson, Ryan(BHGE) <
> [log in to unmask]>
> Subject: EXT: R: [TN] Conformal Coating qualification
>
> Have you already considered also IPC-TM-650 2.6.3 MIR test
> http://www.ipc.org/TM/2.6.3F.pdf
>
> 1 Scope This test method is to determine the degradation of insulating
> materials by examination of the visual and electrical insulation resistance
> properties of printed board specimens after exposure to high humidity and
> heat conditions. This method allows testing with (Method A) or without
> (Method B) Conformal Coating. When not specified, Method A is the default
> method.
>
>
>
>
> -----Messaggio originale-----
> Da: TechNet [mailto:[log in to unmask]] Per conto di Elson, Ryan(BHGE)
> Inviato: mercoledì 8 novembre 2017 23:49
> A: [log in to unmask]
> Oggetto: [TN] Conformal Coating qualification
>
> Hello all,
>
> We are looking at qualifying a new conformal coating, and have a number of
> requirements for manufacturability and inherent properties, meets
> IPC-CC-830 requirements, certain CTI rating, etc., and we have put together
> a lengthy test plan that includes different types of boards, including
> those with sensitive circuitry, boards with low surface energies, and the
> like. But I wanted to see what other industry standards we need to check
> and make sure we're not missing anything.
>
> I think SIR testing with our existing solder paste & wave flux is the big
> one, and I was planning to use B-24 test coupons. We are also doing
> adhesion testing, checking against IPC-A-610 requirements, HASS testing,
> final testing, as well as various checks for manufacturability (such as
> viscosity and ability to coat with our selective spray equipment, good
> wetting at lower surface energies, ease of rework).
>
> What else are we missing? Any other IPC test methods or compatibility
> checks to be concerned with?
>
> Thanks!
> Ryan Elson
> Manufacturing Engineer
> Bently Nevada
> Baker Hughes, a GE company
> [log in to unmask]<mailto:[log in to unmask]>
>
>
> ---
> Questa e-mail è stata controllata per individuare virus con Avast
> antivirus.
> https://www.avast.com/antivirus
>
|
