Lee,
Your suggestion is good. However, if the Pb layer is too thin, it
may make SEM/EDX analysis difficult. If this happens, an alternative
analysis is to perform XPS/Auger Electron Spectroscopy with sputtering.
This would be able determine the thickness distribution of Pb.
Best Regards,
Clavius Chin, Ph.D.
Failure Analysis & Lab Manager
Tel: +66-38-493561 EXT. 1249
+66-1-9839128 (H/P)
Lee parker <[log in to unmask]>
Sent by: Leadfree <[log in to unmask]>
01/28/2006 03:50 AM
Please respond to
"(Leadfree Electronics Assembly Forum)" <[log in to unmask]>; Please respond
to
Lee parker <[log in to unmask]>
To
[log in to unmask]
cc
Subject
Re: [LF]
Don
By viewing the cross section with a SEM plus EDAX you can determine what
is on the surface or at any other point in the structure, even if you do
not want to know!
Best regards
Lee
J. Lee Parker, Ph.D.
JLP Consultants LLC
804 779 3389
----- Original Message -----
From: Abbott, Don<mailto:[log in to unmask]>
To: [log in to unmask]<mailto:[log in to unmask]>
Sent: Friday, January 27, 2006 3:25 PM
Subject: Re: [LF]
Lee,
This bring up an interesting point - if the Pb is only on the surface,
as it is plated, then would it be considered "homogeneous" (as it can be
mechanically removed by scraping) - in which case is would be 100% Pb
and thus a clear violation?
XRF may be preferable to sectioning, in light of the above.
Regards,
Don Abbott
TI
508-236-1569
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Lee parker
Sent: Friday, January 27, 2006 3:17 PM
To: [log in to unmask]<mailto:[log in to unmask]>
Subject: Re: [LF]
Carol
I agree with George. XRF is only suitable for measuring the thickness of
an identified metal. It does not tell you where in the composite the
metal is located. An approach you may want to pursue is to make cross
sections of the problem area (probably a pad) and then use a SEM with
EDAX capability. Place the cross section into the SEM and then focus the
EDAX beam at several points on the cross section starting at the surface
and working down. You will then have an elemental analysis at several
points and you can then determine what metals are on the surface, the
transition region and the base material. If you do not have this
capability on site, there are many labs across the country that do.
Good luck
Lee
J. Lee Parker, Ph.D.
JLP Consultants LLC
804 779 3389
----- Original Message -----
From: Wenger, George M.<mailto:[log in to unmask]<
mailto:[log in to unmask]>>
To: [log in to unmask]<mailto:[log in to unmask]<mailto:[log in to unmask]<
mailto:[log in to unmask]>>
Sent: Friday, January 27, 2006 1:36 PM
Subject: Re: [LF]
Carol,
What are the units for the 0.14-0.19? Are they percent of XRF signal
or
are they XRF thickness measurements? How does the XRF analysis tell
you
the Pb is on top? Do you have an XRF spectrum you can send or post on
Steve's web page?
Regards,
George
George M. Wenger
Reliability / FMA Engineer
Base Station and Subsystems Group
Andrew Corporation, 40 Technology Drive, Warren, NJ 07059 (908)
546-4531
[log in to unmask]<mailto:[log in to unmask]<mailto:[log in to unmask]<
mailto:[log in to unmask]>>
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Carol Spiers
Sent: Friday, January 27, 2006 1:20 PM
To: [log in to unmask]<mailto:[log in to unmask]<mailto:[log in to unmask]<
mailto:[log in to unmask]>>
Subject: [LF]
I have just had an analysis completed on a first batch run of leadfree
boards. Results indicate we have uniform contamination of 0.14-0.19
layer of lead across the board. The testing and measurements were
obtained using xray flouresence and indicate the lead is on the top
layer of the melded solder. We confirmed that all parts were
documented
as being Lead Free (but not tested by us for compliance). Boards were
double sided silver immersion smt and thru hole combinations. Solder
paste used was SAC, wave solder bar used was SAC. The wave solder
machine is brand new (never used in a leaded process). SMT oven is
used
for both leaded and unleaded processes.
Because the contamination appears to be uniformly spread across the
board I tend to think this isn't a problem related to a couple of
components not actually being lead free and contiminating the huge pot
of solder in the wave. One suggestion was that there might have been
a
thin layer of lead over top of the silver immersion on the bare
boards.
Is there anyone out there that would care to offer some suggestions as
to where we should focus our investigation or if any alternative
testing
should be used.
So far we are going to:
1) do comparison testing of two batches of bare boards of the same
product coming from different suppliers and undergoing identical
processing.
2) have a sample of the wave solder evaluated for contaminates and to
establish the bench for future sample evaluations.
Once again, your input and help will be much appreciated.
Carol
C. M. Spiers
Director of Operations
Interalia Inc.
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