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.
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