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Date: | Tue, 4 Mar 1997 16:27:08 -0800 |
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Mary:I think the 2mg/sq.in.NaCl equivalent maybe a little over
optimistic (hard to achieve in the real world without adding $ to your board
cost).What are the extraction measurements on the boards after assembly?
There is not much use in srewing down the specs on the bare board if they are
dirtied up in assembly.Ifyou really do need these low numbers make sure
you're clear on the test method;extraction solution chemistry,test equipment,
time,temp etc.
As to the issue of "glycols" be careful there more misinformation
running around out there than good technical data.I have some papers I can
share with you that help de-mystify it(Brous/Zado/Tautscher) along
with internal testing information.
Based on electrical testing of most current generation liquid PISM
that are epoxide/acrylic based the ones that meet 840B class 3 or 840C class
anything will "probably" meet your requirements.
Mary give me a call or stop bye we're just up the street from you.
Regards
Michael Barmuta
Staff Engineer
Fluke Corp.
Everett Wa.
206-356-6076
On Mon, 3 Mar 1997 12:04:16 -0800 Davis, Mary wrote:
> From: Davis, Mary <[log in to unmask]>
> Date: Mon, 3 Mar 1997 12:04:16 -0800
> Subject: No Clean Bare Board Controls
> To: TechNet <[log in to unmask]>
>
> I would appreciate some guidance on a subject that could be of interest
> to others in the same dilemma.
>
> We are specifying controls for unpopulated PWB's to be used in low
> residue/no clean process. We plan to restrict bare board bulk ionic
> levels to no more than 2 micrograms/sq.in. NaCl equivalent. Also, it
> has been suggested that we require that 'polyethylene glycol substances,
> as well as certain dry film and even some liquid photoimageable masks be
> avoided'. The bulk ionic requirement is easy to communicate but I am
> struggling with the verbiage and test methods that describe restrictions
> on polyethylene glycol substances and other potentially harmful
> materials.
>
> Any help in this matter will be greatly appreciated.
>
> Mary Davis
> Sr. Material & Process Engineer
> Hughes Aircraft
> Naval & Maritime Systems
> 206-356-3311
> [log in to unmask]
>
>
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