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Date: | Mon, 17 Jun 1996 08:15:12 -0700 |
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On Thu, 13 Jun 1996 08:13:18 -0700 joef wrote:
> From: joef <[log in to unmask]>
> Date: Thu, 13 Jun 1996 08:13:18 -0700
> Subject: FAB: LPISM over Reflow Sn/Pb
> To: [log in to unmask]
>
> Problem: We phased out our last CFC-degreaser to help patch the
> alleged ozone hole.
> Problem: We phased in Probimer 65M which ostensibly has slightly lower
> adhesion than Probimer 52.
> Problem: curtain-coated S/M peeling from reflowed tin/lead
>
> Our standard surface prep for SMOBC is pumice (no brushes) but pumice
> dulls the reflow finish and has been rejected by the customer for
> aesthetics in the past. Customer is high-rel avionics and will likely
> be a bit stubborn with design change recommendations.
> Does anyone have a successful pre-clean method for S/M over reflow?
>
> a conveyorized solder brite?
> a non-CFC degreaser?
> a solvent?
>
> Thanks in advance.
> Joe Felts
> PC World, Toronto
>
Joe: Could you supply a little more information?
What is it you are tying to clean/remove?
Is it oxides,is it fusing fluid residues on the Sn/Pb or are you
trying to create a higher surface energy(rougher)to bond to?
When/where is it peeling,at your bare board level or assembly?
Is it peeling on large ground planes,all Sn/Pb cicuits or on
everything?
What type of adhesion test are you doing,tape?
Quite a bit of our LPI work is done on fused Sn/Pb and we have
not had any adhesion problems.
Depending on what you're trying to accomplish there are some
things that can be done for surface modification and LPI bake/cure cycles to
improve adhesion.Call me if you would like (206)356-6076.
Regards
Michael Barmuta
Staff Engineer
Fluke Corp.
Everett Wa.
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