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RoHS Wins Converts Despite Exemptions
December 31, 1969 |Estimated reading time: 5 minutes
In SummaryMedical devices currently are exempt from RoHS. Yet, many medical device manufacturers are requesting RoHS conversion from their EMS providers due to concerns about long-term component availability and reliability. Narragansett Technologies examines the process involved in taking medical instruments lead-free.
BY William P. Ulmschneider, Narragansett Technologies
Medical device manufacturers face two critical challenges. First, the regulatory environment limits their ability to change components without some level of product re-qualification. As a result, any component change requires significant review. Second, many of their products have longer life cycles which are out-of-sync with normal component life cycles, driving requirements for end-of-life buys or obsolescence-driven redesign. RoHS increases this complexity because in many cases component manufacturers are discontinuing leaded versions of products with little or no advance warning. In other cases, lead times on leaded components are stretching out to nearly 12 months.
RoHS conversion is becoming a necessary skill for most EMS companies. However, in this case, complexity is increased beyond the standard EMS model because medical device OEMs aren’t simply buying contract manufacturing capacity. Instead, they are leveraging off the economies of scale of an electronics assembler that should boast design and manufacturing experience in the medical sector. High-mix/low-volume manufacturing is the norm for applications ranging from medical and biometrics to imaging and related fields. Complex assembly and test requirements are major factors.
At Narragansett Technologies, we’ve chosen to focus on core competencies and outsource board-level manufacturing. Customers gain access to product development and test expertise and infrastructure with the flexibility of choosing a board-level manufacturing facility suited to a project’s cost and capabilities requirements. Narragansett Technologies provides the engineering support associated with this PCB assembly (PCBA) manufacturing.
The RoHS Role in the Equation
With minor exceptions, all of our company’s imaging subassemblies, assemblies, and modules were converted to RoHS-compliant products. The exceptions are products built in volumes too low to justify a conversion. In these cases, leaded materials are stocked and segregated to support anticipated demand.
In all other cases, as products are converted, affected customers are given prototypes to test and qualify. Since there is no functional change in a RoHS-compliant imaging product, in most cases the end product in which a subassembly or system is used need not undergo extensive re-qualification. Internally, test data between leaded and RoHS-compliant products should be compared to ensure that no unanticipated performance or functionality changes arise.
Longer lead times and/or fears of unanticipated supply interruptions should a component manufacturer discontinue a leaded part are driving exempt EMS customers to request RoHS conversion on their products. In some cases, parts headed toward obsolescence may have 52-week lead times. Efforts can be made to secure shorter lead times through brokers, but this typically drives an additional cost of testing the purchased components to ensure quality and authenticity. Faced with this pay-now-or-pay-later likelihood, the vast majority of high-reliability EMS projects either have been converted or are scheduled for conversion. The fraction remaining may remain leaded as long as parts are available.
In converting customer products, the engineering team must perform an initial analysis of both the product and its bill of materials (BOM). The product is analyzed to determine if any crossed components will have critical dimension or materials compatibility issues. Preserving footprint, form, fit, and function are primary goals.
The engineering team handles the transition of critical components, which typically include all ICs, some connectors, programmable parts, FPGAs, certain variable inductors, and sensors. Distribution partners can transition less-critical parts. Typically, this formula results in a 50/50 division of labor in the conversion process.
Figure 1. An example of a dense PCBA for a medical camera assembly.
Actual process characteristics and consumables formulation will be determined on a product-by-product basis. Considerations in process and alloy selection include performance characteristics, customer-specified visual characteristics, and concerns about any perceived reliability issues. For example, customers concerned about tin whiskers might specify only immersion gold or immersion nickel.
Once the revised BOM and recommended approved vendor list (AVL) are greenlit by the customer, lead-free prototypes are built and tested in-house. Customers then can take delivery of these prototypes for further testing and qualification. Typically, customers perform a functional test (FT), higher-level assembly test, and visual inspection. If advanced reliability testing is not required, the re-qualification process should take three to four weeks.
Conversion can result in excess inventory. Cost impact is done as part of any engineering change order (ECO) process. In some cases, customers opt to absorb the cost of any excess inventory that can’t be liquidated, while in others they schedule ECO implementation after existing leaded inventories are consumed.
The approved product is fully documented with CFC RoHS certificates of compliance (CoCs) from all component suppliers.
Teaming with Suppliers
As mentioned above, distributors provide support in the conversion process. In selecting the core of board-level suppliers providing RoHS-compliant processes, Narragansett Technologies considers issues such as traceability support, robustness of internal procedures, and process capabilities.
Traceability includes the ability to trace components back to RoHS compliance. The majority of suppliers have product lifecycle management (PLM) systems that link electronic files containing test datasheets, certificates of conformance, and RoHS compliance statements to each part number. When a BOM is pulled up, all relevant data are available in this linked file.
During a RoHS site audit, focus is on determining how leaded and non-leaded materials and processes are segregated. Component inventories, consumables inventories, and manufacturing processes must be visually demarcated into leaded and RoHS-compliant.
Overall, board-level manufacturing supplier selection for Narragansett Technologies is based on a process of comparing customer requirements with supplier’s capabilities. Key areas for evaluation include projected volumes, quality, complexity, cost, and core competencies.
Conclusion
RoHS regulations are pushing widespread changes in component availability. Even companies in industries with RoHS exemptions are feeling the impact of component manufacturers’ efforts to adapt to this changing requirement. EMS providers can impart a valuable service in proactively supporting their customers’ needs to develop conversion and inventory liquidation strategies.
William P. Ulmschneider, chief operating officer (COO), Narragansett Technologies, may be contacted at (401) 767-4475; Bill.Ulmschneider@nimaging.com. Narragansett Technologies began in the digital imaging market with Philips Components, designing and manufacturing medical camera components and digital modules. The company, as Narragansett Imaging and Narragansett EMS, leverages its engineering skill to medical OEMs outsourcing assembly, focused on a core of complex diagnostic imaging subsystems.