Subject: | |
From: | |
Reply To: | |
Date: | Fri, 30 Oct 2009 17:01:07 +0200 |
Content-Type: | text/plain |
Parts/Attachments: |
|
|
As you say, ionic contamination testing detects only ionic species. SIR
can detect some non-ionic species, as well, which are even slightly
hygroscopic, because they bond with water vapour molecules. Another test
that will detect both non-ionic hygroscopic and ionic species under a
solder mask or conformal coating is the pressure cooker test. I know one
company that used this on normally uncoated boards. They took a test
sample board from production and sprayed it with a very thin coating of
CC from an aerosol spray can and pressure-cooked it, then examining it
for vesicles. This had the advantage that they could see where the
contamination was, as well as the severity.
Brian
Blair Hogg wrote:
> A ROSE by any other name would smell as sweet, right SIR?
>
> Happy Friday, Technetters! As you may have guessed, I've spent a bit of time
> over the last few days looking over cleanliness testing specs, searching
> through the archives and what not to get more information on the different
> types of testing. Now it is time to visit the well of knowledge and see if the
> Technet gurus can help me along the road to cleanliness enlightenment.
>
> From what I understand, the ROSE test measure the change in resisitivity /
> conductivity of a test solvent solution (75% IPA / 25% DI Water) that is
> rinsed over a board / assembly. This will detect contaminants and provide a
> relative level of the contamination. However, it will only detect those
> contaminants that are ionic in nature or will affect the resistivity (is that
> redundant?). The results are near immediate.
>
> The SIR test measures the insulation resisitance change that occurs when an
> assembly is exposed to humidity and voltage, and thus has the capability of
> detcting the presence of contaminants that may not be ionic, but can cause
> corrision and / or dendrites to grow. The drawback is that the samples must
> be exposed to controlled humidity / temperature for a priod of time.
>
> Does that sound right? Am I missing anything?
>
> Are there any other options?
>
> Thanks,
>
> Blair
>
> ---------------------------------------------------
> Technet Mail List provided as a service by IPC using LISTSERV 15.0
> To unsubscribe, send a message to [log in to unmask] with following text in
> the BODY (NOT the subject field): SIGNOFF Technet
> To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
> To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
> Search the archives of previous posts at: http://listserv.ipc.org/archives
> Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
> -----------------------------------------------------
>
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------
|
|
|