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Due Diligence Verification - Ensuring RoHS Compliance
December 31, 1969 |Estimated reading time: 4 minutes
ROHS compliance will require manufacturers to incorporate measures to ensure all electronic components meet the EU’s directive. Manufacturers must take measures to have suppliers verify product compliance, including certification of all parts and creating segregated storage areas. This article looks at the program one EMS provider instituted to document compliance.
By Scott Mazur and David Mercuro
Given the complicated supply chain, there are several chances for mistakes and oversight when dealing with lead-free compliance. The RoHS Directive will require manufacturers to incorporate measures to ensure all electronic components, cable assemblies, and hardware meet the guidelines. A percentage of components may not be certifiable by the manufacturer. One component error on a PCB assembly with hundreds or thousands of parts can result in a rejection of product with the potential for significant legal penalties or loss of sales. Manufacturers must take measures to have suppliers verify product compliance, including certification of all parts and creating segregated storage areas. This high risk of non-compliance has driven one company* to institute a program that reduces the exposure to risk dramatically, while improving documentation to help substantiate compliance.
XRF Technology
X-ray fluorescence analysis is based on the phenomenon of the emission of X-rays by the constituent atoms of a sample when excited by an external source of radiation. The energy difference between the two energy shells involved in the process is released in the form of X-ray radiation. We call this radiation a characteristic X-ray because its energy is specific and unique to the emitting element (atom).
A practical embodiment of an instrument capable of performing those tasks is called an X-ray fluorescence (XRF) spectrometer. It consists of three essential components: a source of exciting radiation (a radioisotope or X-ray tube), a means of reproducible sample presentation, and a detector with a multi-channel analyzer (MCA) and analytical software. During measurement, the instrument acquires an X-ray spectrum of the sample that contains information about its elemental composition. It is the information extracted from the spectrum that is then converted into qualitative and quantitative data of the elemental concentrations in the material tested (Figure 1).
Figure 1. Analyzer display indicating the concentration of five elements: cadmium (Cd), lead (Pb), bromine (Br), mercury (Hg), and chromium (Cr), which are controlled by RoHS. In this test, lead and bromine are at non-compliance levels; and cadmium is determined questionable in 30 seconds.
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Verification Program
Through screening using a portable, handheld analyzer, we understand the first phase of testing, during which an assessment is made as to whether additional, more expensive, and labor-intensive testing is required. With the deadline for RoHS-compliance approaching, and the entire industry transitioning, many material declarations and certificates of conformance programs are being developed to certify RoHS compliance. One program was developed to verify the supply chain. This program includes the use of a portable XRF unit** to support the materials declaration process. The program consists of material verification at several locations in the production process. The initial step of this process is incoming inspection. This detection point is the first line of defense to verify that a specific material is RoHS-compliant (Figure 2).
Figure 2. Component analysis is done using a handheld XRF analyzer during the incoming inspection verification process.
Two additional detection points are included in the production process. The verification of process-input parameters is critical to the compliance program. Evaluation of the assembly process and mapping of critical input and equipment parameters will support the compliance program. A failure mode effects and analysis (FMEA) can be completed. It is important to develop a comprehensive list, as process material and equipment could escape the RoHS-compliance analysis, and may introduce one of the banned substances into the assembly process. The XRF unit can be deployed to verify that input and equipment parameters are RoHS-compliant. Some examples of critical process inputs could include solder during a PCB assembly process or adhesive during a mechanical assembly process.
The final detection point during the production process is the finished product. The goal is to complement incoming inspection and the critical input-parameter process by verifying compliance at the final assembly process step. Documentation of record retention of XRF results must be maintained to provide proof of the results and a history of compliance. Streamlining the record retention will simplify the process, especially if a request or non-conformance is detected during entry into the EU.
Conclusion
Instituting a compliance program strategy enables detection of non-conformance during the manufacturing process where problems can be corrected, rather than during the RoHS-compliance process, which can result in disastrous consequences. Without the XRF-compliance process, electronic manufacturers must depend on supply chain verification and due diligence. The deployment of such a program will provide customers with a verification process, while reducing the risk involved with manufacturing product that will reside in EU member states.
* Benchmark Electronics.** XLt 797 portable XRF unit, Thermo Electron Corp.
Scott Mazur, RoHS specialist, principal quality engineer, Benchmark Electronics, may be contacted at (603) 879-7000, ext. 8004; e-mail: scott.mazur@bench.com. David Mercuro, XRF product specialist, Thermo Electron Corp., Niton Analyzers unit, may be contacted at (781) 670-7460, ext. 333; e-mail: dave.mercuro@thermo.com.