Copper dissolution—report and process guide
dissolution rate; each process requires close • Reflow soldering lead-free for customers. He will be running four
monitoring during production. The first workshops in South Africa during May, details
four processes normally have a significant A copy of the Good Practice Guide
are available from SMART Group South Africa
volume of solder that moves quickly across “Reduce Copper Dissolution in Lead-
at www.smartgroupsa.org Bob sets up and
exposed copper surfaces hence their posi- Free Assembly” and the full report can be
optimises production lines for users and also pro-
tion in the list. obtained by emailing Chris Hunt at chris-
vides conferences and workshops worldwide. For
hunt@npl.co.uk.
further information on workshops at ITRI in
• Rework solder fountains
Europe, training materials, lead-free and on-line
• Selective soldering processes Bob Willis is a process engineer working in the
process support visit www.ASKbobwillis.com
• Wave soldering
electronics industry, providing training, consul-
• PCB Solder levelling
tancy and product failure analysis. Bob also
• Manual soldering/de-soldering
offers on site workshops on conventional and
Figure 2. Example of copper dissolution could be the failure of track connections to Figure 3. Loss of through hole connections where the knee of the plated hole has
plated through holes or simply the loss of the copper pad. The printed board surface been dissolved during selective soldering with a lead-free alloy. The surface pad
finish in this case was silver. finish on this board was copper organic solderable preservative (OSP). It looks like
de-wetting, but all that is left on the surface of the board is the copper foil needles
where solder has wetted the tips.
2009 Global SMT & Packaging Reader Rework Survey
In the first quarter of this year, Global • Incorrectly
SMT & Packaging surveyed readers on programmed parts or
!"#$%&"''"()*%+,-"+.,/%/,0,&$#%
their rework activities and rework systems. parts that were not
:+-.4&<&-)*'+,$+-(-.#*
Here is a sampling of what we learned from programmed prior to
1&,&2()*.4&';#*
the nearly 500 respondents: installation
898*:+--('.+4#*
What users are looking for
6))*7+4,*'+,$+-(-.#*
Top three most important features in a
in future rework systems:
!"##"-2*'+,$+-(-.#*
rework system:
• More preheat
34+-2*$+%&4".5*
• BGA/QFP handling
capability
1&,&2()*'+,$+-(-.#*
• Profiling capability
• Faster heating/
/"0()*%(&)#*
• Tip selection
ramp up
!"#$%&'()*'+,$+-(-.#*
Some of the uses for rework systems, be- • Easier and better
yond our list of commonly rework defects, profiling
participate, email tgalbraith@globalsmt.net. A
that our readers listed: • Greater selection of nozzles or tips,
drawing will be held after the survey closes,
• Insufficient solder or universal tips
and one lucky respondent will receive a
• Testing new parts versions or • Capability for QFN/LGA/BGA/
brand new iPod Touch.
removal for failure analysis WL-CSP/01005/PoP
• Need to make additional compo- • Traceability
(Advertisers are eligible to contribue questions to
nent changes or swap out com- • Built-in inspection, x-ray
surveys and benefit from the full results. Contact
ponents at customer request not
your local rep for more information.)
Next up: our pick & place survey. To
necessarily due to defects
6 – Global SMT & Packaging – June 2009 www.globalsmt.net
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