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August 2002

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Subject:
From:
Dave Hillman <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 29 Aug 2002 08:04:32 -0500
Content-Type:
text/plain
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text/plain (174 lines)
Hi Doug! OSP surface finishes are great in many situations, however, there
are some assembly thermal profiles which an OSP just can not withstand. We
process several Class 3 assemblies which require long multiple bake cycles
due large heatsinks and other pwa design issues which results in the
breakdown of the OSP and a loss of solderability. OSP surface finishes are
just one of the finish "tools" in the toolbox and unlike the traditional
HASL finishes, the new alternative surface finishes are not a "one size
fits all" selection. Immersion tin is more robust to thermal degradation
due to it being a metallic finish. Additionally, I am no fan of thiourea
but a properly run immersion tin plating bath is not hazardous to the
operators nor the planet. OSP surface finishes should be utilized where
possible but they will not work in all situations.

Dave Hillman
Rockwell Collins
[log in to unmask]





Dougal Stewart <[log in to unmask]>@ipc.org> on 08/29/2002
03:58:40 AM

Please respond to Dougal Stewart <[log in to unmask]>

Sent by:    TechNet <[log in to unmask]>


To:    [log in to unmask]
cc:

Subject:    Re: [TN] Talk to me about Omikron White Tin board finish,
       please.


I still don't understand why you assembly people don't use OSP ! It is the
easiest process to use in bare board fab, it is reworkable at the fab
house,
if you have kept the parts on a shelf for too long and are suspicious that
they may not solder so well, you can send them back to the FAB for
reprocessing (assuming they have not gone bust meantime, or moved half way
around the planet) and you are not contributing to polluting the planet
with
Thiourea, or killing the board shop operators ! So what has white tin over
OSP?
Dougal Stewart

email:  [log in to unmask]
phone: +44 1896 822204
mob:    +44 7984 629667
----- Original Message -----
From: "Jason W. Gregory" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, August 28, 2002 11:03 PM
Subject: Re: [TN] Talk to me about Omikron White Tin board finish, please.


> Barbara,
>
> I love white tin! It is absolutely, positively my favorite finsih. The
flatness,
> which is it's main attribute, is perfect for fine pitch, 50mil and lower,
and
> the wetting characteristics are superb. The only downside is the thiurea
(sp?).
> Apparently it's pretty toxic and carcinogenic. I'm sure Brian Ellis will
chime
> in soon (I hope).
>
> Jason Gregory
> Production Supervisor
> LaBarge Inc.
> (918)459-2367
> [log in to unmask]
>
>
>
>
> Barbara Burcham <[log in to unmask]> on 08/28/2002 01:29:06 PM
>
> Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please
respond to
>       Barbara Burcham <[log in to unmask]>
>
> To:   [log in to unmask]
> cc:    (bcc: Jason Gregory/LABARGE)
>
> Subject:  [TN] Talk to me about Omikron White Tin board finish, please.
>
>
>
> Who is using this and is it working for you?
> What do y'all think about the "Omikron" process as opposed to other White
Tin
> applications?
> Is one better than the other?
>
> Barbara J. Burcham, C.I.D.
> Sr. PCB Designer
> Fairfield Industries
> Sugar Land, TX 77478
> 281-275-7687 Work
> 281-275-7550 Fax
> [log in to unmask]
>
>
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