Bloomington, Ind. — A joint study conducted by E-Certa Inc. and
Sanmina-SCI shows it's
possible to re-use lead- (Pb) containing parts by converting them to Pb-free
for use in consumer-grade electronics. E-Certa has also released an
information series based on the joint study that answers many questions
posed by OEMs and engineers after the European Union's Restriction of
Hazardous Substances (RoHS) directive imposed a new standard for product
design by restricting the use of several materials including lead.
The RoHS directive has imposed regulations that force manufacturers
that are outside of exempt sectors to design products that are Pb-free and
RoHS compliant. While this poses some reliability concerns, many OEMs have
found ways to design consumer products that are sufficiently reliable for
the consumer market and are lead-free, said E-Certa.
However, the problem for many companies is that they have millions
of dollars worth of leftover inventory comprised of Pb-containing
components, which have no use in the post-RoHS market, said E-Certa. By
converting these parts to Pb-free it will help OEMs comply with the
recycle/re-use initiatives brought about by the WEEE directive as well as
keep these leaded components from going to the landfill, said Michael L.
Baker, quality manager for E-Certa.
The joint study was developed to verify the conversion process for
leaded components to Pb-free and RoHS-compliant parts. The report
"Evaluation of Stripped and Replated Component Termination Finishes"
covers both forward conversion (SnPb to Pb-free) and backward conversion (Pb-free
to SnPb) of SOIC-packaged devices using E-Certa's stripping and retinning
processes. A sample size of 90 parts for each part type was converted for
this study.
"The study was performed to validate that the process used does not
damage the component in any way or compromise the functionality to an
unacceptable level due to the heat and stress the parts go through in the
retinning process," said Baker. "It also covers the validity of the strip
and tin process going from lead to lead free and lead free to lead."
The conversion was performed by E-Certa, followed by XRF testing to
ensure RoHS compliance. Sanmina-SCI performed the electrical and die
visual inspections using optical microscopy, DC pin-to-pin electrical
testing and acid de-encapsulation. Included were lead pull testing of the
devices "as assembled condition" and "after thermal aging" to determine
the mechanical reliability of the converted component termination
finishes. The results show that the converted components have almost the
same pull strength as the original components, according to the study.
The converted parts were also assembled on a printed-circuit-board
(PCB) using both tin-lead and lead-free processes. Three PCB surface
finishes — Immersion Silver (ImAg), Organic Solderable Preserve (OSP) and
Electroless Nickel/Immersion Gold (ENIG) — were evaluated. Key findings
indicate that the microstructures of the converted components were normal
in appearance and had well-defined IMC along the board and component
interface. A video presentation contains a summary of the Sanmina-SCI
report at the E-Certa web site.
Click on the "watch video" link on the homepage.
E-Certa has also released a media information series, which outlines
the process of converting leaded components to Pb-free. The series called
"Component Pb Conversion" covers techniques, concerns and costs associated
with component Pb conversion. The series also reviews conversions that go
in reverse to convert Pb-free components to Pb for use in
military/aerospace, medical or RoHS exempt applications.
In addition to component lead conversion (Pb-free to Pb, and Pb to Pb-free),
E-Certa also provides XRF testing for compliance, material declaration,
delidding for component verification, and WEEE recycling services.