Process validation trumps inspection in the new Directive.

Directive 2011/65/EU (Restriction of Hazardous Substances – RoHS2) became European law on July 21, 2011. In summary, the law does not introduce new banned substances, but does require manufacturers to follow specific obligations in Module A of decision 768/2008/EC, with a focus on technical documentation and product checks. The module emphasizes requirements that “the manufacturer shall take all measures necessary so that the manufacturing process and its monitoring ensure compliance of the manufactured products.”

With the latest directive, RoHS is becoming more focused on validation of process, rather than inspection of results. Here, we detail the methodology of developing a compliance system to address the electronics manufacturer’s obligations.

Technical documentation. The technical documentation package, as defined in Module A, must contain at least a general description of the product, design and manufacturing drawings of components and subassemblies, and describe the operation of the product. Also noted in the module is a list of the harmonized standards that have been published in the official journal of the European Union, results of calculations, examinations carried out, and test reports.

Test reports can be interpreted many different ways and include various formats and information. The reports should include how the product was determined to be compliant during design and introduction to manufacturing; what controls are deployed to continuously mitigate the risk of noncompliance; and ongoing verification of product compliance.

Test reports can be created to qualify the initial compliance of the product and to describe how the product will be continuously verified as compliant. Technical documentation is required to be retained and readily accessible if an EU member authority inquires about product compliance.

Compliance software packages and systems exist to gather the above technical documentation. These systems can be purchased from various third-parties that provide this service. Alternately, some organizations have created the process and systems internally. The goal of either system is to gather and store the documentation required by the legislation and have the information readily available. 

The next two sections detail how product can be verified as compliant on an ongoing basis.

Production control. Production or manufacturing control within this article is defined as the controls in place to mitigate the risk of product becoming noncompliant to RoHS.

The foundation of production control is the upfront component and material analysis completed to ensure that the electronics components are RoHS compliant with all supplier tests and declarations on file. These declarations and supplier test reports are part of the technical documentation package as described above.
If the facility is building non-RoHS-compliant product or still using leaded solder, controls are required to eliminate the risk of cross-contamination. Part number strategies and visual management are the two main tools for risk mitigation. Signs, color codes, and special part number nomenclature all can be used to educate the workforce on the RoHS-compliant material. As noted by European Union compliance enforcement last year, several instances of noncompliant product found during surveillance audits were the result of cross-contamination (leaded and lead-free solder) within the production process. If the risk exists, an analysis is required to determine cross-contamination opportunities. Examples of specific actions may be to color code tooling and equipment in the hand solder and wave solder operations.

Visual management can also be used on manufacturing materials such as solder. Most lead-free solders are marked with a separate part number, but also have a green color on the containers or packaging. Special attention is required for the risk of cross-contamination of reused solder paste. If dual (lead and lead-free) solder pastes are used, and the opportunity for cross-contamination is high, secondary green containers for lead-free are a good way to separate reused solder paste. Another example of visual management: Some solder bar manufacturers use triangular shaped bars to designate RoHS-compliant solder.

Product checks. One way to check and verify the product is through auditing the manufacturing process. This audit can be a quality systems type process audit that verifies the production controls and technical documentation detailed above. The audit will verify compliance to the system in place. A second type of check is testing the product and process to verify compliance.

Different types of testing exist to verify RoHS compliance, varying in cost, destruction of product and time of testing method. All have advantages, although one testing type has the added benefit of being portable, which enhances the ability of an electronics manufacturer to verify equipment, products and materials in real-time during the production process. This testing type is XRF technology. XRF technology (x-ray fluorescence analysis) is nondestructive and portable (Figure 1). A second benefit of XRF is the testing time, typically 30 to 60 sec.



XRF testing can be the facility’s internal production control and technique to satisfy the process monitoring requirement of the directive. During electronics manufacturing, many variables and cross-contamination opportunities exist. XRF technology can verify that the various processes, equipment, tools and materials are compliant.

XRF testing during manufacturing. Many areas of the electronics manufacturing process can be verified with XRF. The testing intervals and areas to verify depend on product technology and risk of cross-contamination with leaded solder. The following manufacturing areas are potential XRF test points:

• Surface mount technology.
• Wave solder.
• Hand soldering.
• Final assembly.

The key is to verify the different process technologies (SMT, wave solder, etc.) and confirm compliance to the RoHS directive and banned substances.
The above testing method mirrors the compliance verification that several European Union enforcement authorities conduct during surveillance product audits. The results of the XRF product checks become an important part of the technical documentation package.

The RoHS2 Directive emphasizes product checks and technical documentation. We have described the compliance system methodology for which the technical documentation file can be provided to show due diligence. XRF verification has many benefits and mirrors the testing used by EU enforcement authorities and shows objective evidence of product checks.

References:

1. Sammy G. Shina, Green Electronics Design and Manufacturing – Implementing Lead-Free and RoHS Compliant Global Products, McGraw-Hill, 2008.

Scott Mazur is a manufacturing staff engineer and environmental management representative for Benchmark Electronics (bench.com) and contributing author of Green Electronics Design and Manufacturing; scott.mazur@bench.com.