I think you're correct; Steve was thinking of a different tool.

Two reflows then wave . . . HUMMM
I can see two reflows then selective . . . AHHH

But Dave, Ioan seemed to be having trouble after reflow. If the problem is
formation of unprotected IM, would in-coming SERA predict the process
problem?
SERA attempts to measure oxide species and thickness not the actual tin
thickness.

More importantly, and based on your experience, would you expect IT to
perform well in a multiple reflow process sequence?
Wasn't this one of the big complaints about OSP?

> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]]On Behalf Of Dave Hillman
> Sent: Thursday, June 20, 2002 5:03 PM
> To: [log in to unmask]
> Subject: Re: [TN] Immersion Tin
>
>
> Hi Steve! Sorry but I have to disagree with you. SERA is a tool which can
> be used to extensively characterize a variety of surface finishes on
> printed wiring boards and any other surface that can be tested within the
> SERA equipment configuration limitations. I believe you may be confusing
> SERA with ECI's CVS instrumentation. The CVS equipment measures certain
> plating bath chemistry parameters. The SERA equipment is similar to Auger
> spectroscopy in analyzing surface finishes. Rockwell Collins has been
> successfully using SERA since 1991 in a wide variety of applications (keep
> in mind I'm a bit biased on this subject - Rockwell Collins was heavily
> involved in the development of the SERA equipment).
>
> Dave Hillman
> Rockwell Collins
> [log in to unmask]
>
>
>
>
> Steve Kelly <[log in to unmask]>@ipc.org> on 06/19/2002 01:13:02 PM
>
> Please respond to "TechNet E-Mail Forum." <[log in to unmask]>;
> Please respond
>        to Steve Kelly <[log in to unmask]>
>
> Sent by:    TechNet <[log in to unmask]>
>
>
> To:    [log in to unmask]
> cc:
>
> Subject:    Re: [TN] Immersion Tin
>
>
> SERA will not help you - it is only a tool to measure tin /copper
> concentrations . We have been running immersion tin for 5 years with no
> issues but only one thermal excursion is allowed. The tin forms a
> copper/tin intermetallic after thermal. We even silkscreen before tin to
> eliminate this bake cycle. Regards Steve
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Tempea, Ioan
> Sent: Wednesday, June 19, 2002 12:07 PM
> To: [log in to unmask]
> Subject: Re: [TN] Immersion Tin
>
> Hi Tony,
>
> we experienced poor wave soldering after 2 reflows with immersion tin.
> So,
> please give me a few hints on SERA. Is it a test that the board house
> will
> do, or it has to be at our incoming? Does it imply additional charges?
> Where
> can I read more?
>
> Thanks,
> Ioan
>

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