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September 2000

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Subject:
From:
"Massey, Roger" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Mon, 25 Sep 2000 11:23:41 +0100
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Hi Ingemar,

        For all my Sins, I did Indeed move back to the grim North, and
currently work in the South Shields plant, would'nt know what Otterburn was
like in 1330, but its still a nice place today, if a bit chilly round the
"ankles" when the wind blows the wrong way.
        Anyhow, regarding mothers ideal receipt for cleaning up gunked pads.
To be perfectly honest, Ive got no idea what the chemical lads use in the
event of a solderability or other problem, I work in outer layer imaging, so
I dont hear whats giving a problem further down the line,  I dont know if
anybody else from an other PCB fabber who is familiar is listening, but I
just dont know, and I aint gunna shoot myself in the foot by claiming to
know owt about what works as a real process.

        Sorry, but if there is anybody out there who has an answer, Im sure
there are alot of folks who be interested!

                Roger



-----Original Message-----
From: Ingemar Hernefjord (EMW)
[mailto:[log in to unmask]]
Sent: Friday, September 22, 2000 3:10 PM
To: [log in to unmask]
Subject: Re: [TN] Silver Epoxy Bleed on imersion Ni Au PCBs


Hi Roger,
don't tell me you work in Newcastle, was there last week, could have brought
some job with me for you, OK, may be other occasion. What I wanted was
having Via's opinion about bleeding from solder mask when selective Ni/
immersion Gold is applied. Also about Lead Carbonate and Adipin Acid and
such stuff in vias bleeding up on solderpads during solder oven process.
Been looking at samples from you before. May speak offline with you later,
today other UK Co will solve the problem (I hope).

As for Humbria my wife and I lived in Otterburn Tower from AD1330, I love
the moors up there, also like Balvini and Ad Cnoc. 

Back to issue, good to hear plasma tricks or/and vacuum bake can make bad
boards useful again. But according to specialists on my company you (Via)
and others do other things when you get 'dirt' on pads, namely some kind of
activation by means of Purasolve or special mild acidous mixtures. We tried
such an activation bath in order to get better solderability on ENIG SMD
PWBs, but found no improvement. Our solder test is this: screenprint solder
spheres approx. 1/3 of pad dia and let pass oven at normal. Wetting diameter
and yield is measure on what good surface we have to do with. 

What do you thing in general, general Massey? Is 'reactivation' as described
a recommended way? Mother's all-curing recipe, do you have that?

Ingemar Hernefjord
Ericsson Microwave Systems


-----Original Message-----
From: Massey, Roger [mailto:[log in to unmask]]
Sent: den 21 september 2000 09:39
To: [log in to unmask]
Subject: Re: [TN] Silver Epoxy Bleed on imersion Ni Au PCBs


Dave,

        In a previous life as a supplier of a similar automotive sensor, we
found that the vacuum bake recommended by Steven when combined with using
the absolute minimum of epoxy did the trick, easy to say I know but it took
us weeks to get the thing sorted.  Also found that plasma cleaning after
bond helped a bit with fighting off resin bleed, dont know why it just did

                Good luck

Roger Massey
Via Systems - Tyneside


-----Original Message-----
From: Creswick [mailto:[log in to unmask]]
Sent: Thursday, September 21, 2000 3:29 AM
To: [log in to unmask]
Subject: [TN] Silver Epoxy Bleed on imersion Ni Au PCBs


Dave,

In the hybrid (or MCM) industry we have found a vacuum bake to be helpful in
this situation.

Try 50 mT @ 150°C for 2-4 hours.

Steven Creswick 
CTS RFIM

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