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Reply To: | TechNet Mail Forum. |
Date: | Fri, 7 Nov 1997 00:10:28 UT |
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Ashok,
Vesication is the result of Osmotic reactions.
Osmosis is the pumping action of air containing water vapor transmitted thru a
film over a substrate upon which is a solubalising (Ionic) residue (salt).
When this sees the water it becomes liquid and swells causing a "vesicle" or
blister. When the water vapour departs (high temp low humidity) then the
"salt" re-crystallises leaving the "vesicle" or blister behind.
Hope this helps
Graham Naisbitt
Concoat Ltd Email: [log in to unmask]
Alasan House, Albany Park Tel: +44 (0)1276 691100
Camberley, Surrey GU15 2PL UK Fax: +44 (0)1276 691227
-----Original Message-----
From: TechNet On Behalf Of Dhawan, Ashok
Sent: Thursday, November 06, 1997 7:39 PM
To: [log in to unmask]
Subject: [TN] FW: [TN] [AS] What parameters do other companies use when
evaluat ing the e ffectiveness of
Assembly houses builds
Can you clarify what is Vesication testing?
Sorry, i have not heard of this term.
ashok
> ----------
> From: Max Bernhardt[SMTP:[log in to unmask]]
> Sent: November 4, 1997 4:23 PM
> To: [log in to unmask]
> Subject: [TN] [AS] What parameters do other companies use when
> evaluating the e ffectiveness of Assembly
> houses builds
>
> Technet,
>
> We are in the process of qualifying a board assembly house to build
> some
> of our assemblies. Since we have never gone to an outside house
> before,
> we are kind of flying blind. Right now, we want to qualify a vendors
> process and have come up with a test plan. The plan includes SIR
> testing, Ionic board contamination testing, Vesication testing and a
> thermal cycle of 10 excursions over the storage temperature of the
> board
> to test the solderability of the assembly. Does anyone have any other
> tests or recommendations that they follow when qualifying outside
> assembly houses. We build to an IPC class II with some exceptions.
> Any
> help would be appreciated.
>
> Max Bernhardt
> Woodward Governor Co.
> 970-962-7376
>
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