Hi Joyce - modern board immersion finishes (silver, tin, palladium, gold)
are not self limiting in the manner you describe so XRF is an appropriate
methodology. I agree with your details but pwb surface finishes don't
fall into that category. We routinely test pwb surface finishes with XRF
with no issues. Of course, we use calibrated standards as you detailed.
Dave
From: Joyce Koo <[log in to unmask]>
To: "[log in to unmask]" <[log in to unmask]>,
"[log in to unmask]" <[log in to unmask]>
Date: 11/01/2012 05:08 PM
Subject: Re: [TN] ImAg thickness measurement / verification methods
Immersion is self limiting process, depend upon exposed based metal
without contamination on the surface. If the surface is rough, you got
more surface area, on XRF, the reading would be high compare to the
relatively smooth flat surface. It depends surface roughness compare to
the calibration std (usually smooth). My 2 cents. I am piggy (picky).
--------------------------
Sent using BlackBerry
From: [log in to unmask] [mailto:[log in to unmask]]
Sent: Thursday, November 01, 2012 05:30 PM
To: TechNet E-Mail Forum <[log in to unmask]>; Joyce Koo
Subject: Re: [TN] ImAg thickness measurement / verification methods
Hi Joyce - Kevin has flat circuit boards and it was recommended that he
must use calibrated standards. On what point is there a disagreement?
Dave
From: Joyce Koo <[log in to unmask]>
To: <[log in to unmask]>
Date: 11/01/2012 09:58 AM
Subject: Re: [TN] ImAg thickness measurement / verification methods
Sent by: TechNet <[log in to unmask]>
Sorry to disagree. It only works with proper calibration std and your
specimen plating is relatively flat. If your surface is very rough, you
got error in reading (unless you use another method to validate)
--------------------------
Sent using BlackBerry
----- Original Message -----
From: Kevin Glidden [mailto:[log in to unmask]]
Sent: Thursday, November 01, 2012 10:35 AM
To: [log in to unmask] <[log in to unmask]>
Subject: Re: [TN] ImAg thickness measurement / verification methods
Thanks, everyone, for your responses. It appears XRF is a valid tool for
measuring ImAg thickness.
I still have a need to have a few PCB samples analyzed. I have some PCBs
that show ImAg copper-like discoloration after only 1 reflow cycle on the
non-populated side. I would like to confirm what this discoloration is,
and investigate / confirm if it is due to ImAg plating thickness or
porosity issues.
Offline responses ok.
Thank you.
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