EMS companies getting RoHS certifications.

Rochester, MN -- A pair of EMS companies have gained third-party validation of their lead-free SMT processing. Pemstar Inc. (pemstar.com) and Sparton Corp. (sparton.com) in September announced compliance with the RoHS directive.

The surprise, Sparton director of engineering services Gene Vigilante told CIRCUITS ASSEMBLY, was that under visual inspection solder joints were of higher quality than expected. However, as expected, wetting was not as good as with a comparable SnPb part.

In both cases, the companies submitted assemblies on which the auditing company conducted complete visual and microstructural analyses to verify microstructural integrity. All solder connections were examined to be compliance with IPC-A-610D.

The certification is company-based and covers the manufacturing process, although a third-party auditor contacted by CIRCUITS ASSEMBLY questioned this, calling the results "clearly product certification." The audits took six to seven weeks and were performed by Cookson Electronics.

Ron Bulwith, manager of Cookson's Analytics and Technical Services Laboratory, told CIRCUITS ASSEMBLY that Cookson has offered the service for close to two years. Since September, however, he has seen a "big spike" in requests for certification. "Business has taken hold pretty quickly," he said.

According to Bulwith, there's been great variance in how companies are approaching third-party validation of their conversions. Cookson offers three programs, ranging from visual and microscopic exam of product built using a standard test kit, to capability validation that includes a greater number of component assessments and BGA void inspection against IPC-A-610D. The simplest program costs $3,350 (including a lead-free test kit), while the most extensive runs just under $10,000 (for more details, see cooksonelectronics.com/analytics.aspx).

The length of the evaluation varies greatly as well. Some companies' audits have taken a couple of months, others just a few weeks. It depends, Bulwith says, on how tentative the manufacturer is toward its lead-free conversion. He adds that while the program is called Lead-Free Process Capability Certification, Cookson's role is to perform analysis of the final product.

A big issue is the standardization of the program. Cookson uses (and supplies) a standard kit, but says dummy boards and components can also be bought from companies such as Practical Components (practicalcomponents.com). Meanwhile, trade groups are getting in on the action. IPC (ipc.org) has just launched a task group to study process certification, while SMTA (smta.org) has been offering process certification for years.

Bulwith doesn't see the trade groups as competitors, however. "Lots of companies have hinted that they would send more samples in order to be confident that they pass."

Asked what Sparton learned, Vigilante said that manufacturers "must be convinced" to change their part numbers. Those companies that are not assigning a unique ID to Pb-free parts are at risk for mixing SnPb and Pb-free parts within the same BoM. More important, he said, a significant percentage of these "intrusions" could make it to the board-level design without the knowledge of the OEM. Jon C. Silvernail, worldwide project engineer, said Pemstar noted "differences in metal surfaces, reflow characteristics, and printing parameters."

In March, the EIA (eia.org) released a standard--EIA/ECCB-954--that tracks with ISO 9000 and covers a company's documentation of processes for handling RoHS-type materials. According to Sparton, however, documentation for RoHS requirements is embodied in and certified by ISO 9001, ISO 13485 and AS 9100, Vigilante said.

Edited by Mike Buetow