Overview
Requalification of Components and Assemblies
Recovery and Recycling of Waste Electrical and Electronic Equipment (WEEE)
FLASH! Read about DCA's RoHS/WEEE Compliance Services and our seminars (conducted with our partner EPTAC) on the Management Impacts of RoHS and WEEE.
The European Union (EU) Directives on waste electrical and electronic equipment (WEEE) 2002/96/EC (as amended by 2003/108/EC) and on the restriction of the use of certain hazardous substances in electrical and electronic equipment (RoHS) 2002/95/EC, among other things, restrict the use of certain hazardous substances in electrical and electronic equipment shipped in to the EU as of July 1, 2006 and require financing take-back/recycling as of August 13, 2005.
The substances identified by the RoHS Directive as hazardous are:
Cadmium (Cd)
Mercury (Hg)
Hexavalent Chromium (Cr6+)
Polybrominated biphenyls (PBB)
Polybrominated diphenyl ethers (PBDE)
Lead (Pb)
The restrictions do not call for the total elimination of these substances but set an upper limit based upon weight. The limit for all materials except Cadmium is 0.1% by weight, or 1000ppm, for “homogeneous” materials. Cadmium is limited to 0.01% by weight, or 100ppm. This was finally passed in to law in August, 2005 with Commission Decision 2005/618/EC. The guidance given by the TAC and agreed by the EU Commission, and supported by general industry consensus, is that “Homogeneous material means a material that cannot be mechanically disjointed into different materials”. Thus, the entire component is not a “homogeneous material”. Rather, the solder, for example, on a leadframe is.
California has enacted the Electronic Waste Recycling Act of 2003, California's very own version of the EU directives. If you sell “a covered electronic device” (i.e., contains a CRT, flat panel, or plasma display screen with a screen size that is greater than four inches in size measured diagonally) in California you are now affected. Some elements of the bill, directly affecting consumers and retailers, finally went into effect January 1, 2005. Material restrictions on “covered electronic devices” consistent with the EU directives are currently scheduled to take effect January 1, 2007.
Are Your Products Impacted? Use DCA's Decision Tree
DCA has consolidated information from the UK Department of Trade and Industry website into a single convenient document to help guide you in determining whether the RoHS and WEEE directives impact your product. Contact us if you have any questions.
Some Key Component-Related Concerns for EOEMs
Identification and Tracking of Compliant Components
Component manufacturers have not agreed to a consistent method of identifying devices manufactured using Pb-free finishes. Texas Instruments has chosen to add a lead free logo and Moisture Sensitivity Level (MSL) rating based upon the higher reflow temperatures required, to their bulk packaging label and eventually decided to change ordering part numbers. Cypress Semiconductor will add a lead-free finish ID Mark to the device part marking. These two examples were chosen to demonstrate the lack of consistency and are by no means an endorsement for any specific method of identification.
Manufacturers have also indicated that not all package types will be converted to RoHS-compliant equivalents: lack of customer demand and incompatibility with the higher reflow temperatures are most often cited as reasons for this. EOEMs must contact your component manufactures for details regarding identification of compliant components and their availability.
Requalification of Components and Assemblies
The use of lead-free finishes and lead-free solders will require the use of higher reflow temperatures to achieve reliable solder joints. The leading Pb-free solder used in board assembly processes today has a melting temperature approximately 34°C higher than traditional Pb-based solders. Some common component-related problems that could arise from the higher temperatures are:
interfacial delamination
popcorn-induced cracking, or
warping
Component Manufactures are currently using the 260°C reflow profile considered by NEMI (National Electronics Manufacturing Initiative) as the benchmark. Some are presenting data to support lowering that to 250°C or even 240°C. It should be noted that there may be some down grading of MSL ratings (as much as two levels) to accommodate the higher reflow temperatures. It should also be noted that components manufactured with pure tin plating should not be stored for longer than one (1) week at temperatures below 13°C due to a phase transformation known as “Tin Pest”. Below these temperatures, the tin plating converts to a powdery form that can cause solderability or electrical continuity problems.
Further, component requalification by suppliers will be required in many cases. Changes in mold compounds and other aspects of plastic packaging for integrated circuits with large die will often be needed. Many passive devices, such as aluminum electrolytic capacitors, will require characterization and other changes to assure their ability to withstand the higher soldering temperatures without yield, reliability, or parametric degradation. AVX, for instance, found that “Foil Aluminum capacitors exploded during the [260°C] reflow process”. The lowly label, as well, may need to be revisited to ensure its ability to withstand the new environment without degrading.
Be prepared, as well, for an increase in End-Of-Life notifications for components that suppliers determine do not merit the investment in meeting these more stringent environmental requirements.
Finally, the effect of the higher reflow temperature on the reliability of the entire assembly will have to be assessed.
Lead-free solders for manufacturing have not been standardized yet. This has implications for the repair and rework process that have yet to be fully evaluated. Research is currently underway to evaluate the impact of using one solder composition in manufacturing and using a different solder composition for rework and repair. Traces of the original solder will remain after component removal. The combination of two different solder compositions may create a third alloy with very different properties that may have an impact upon solder joint reliability and the temperatures needed to properly reflow the solder. Thus the solder type used to manufacture the board may need to be identified on the board.
Recovery and Recycling of Waste Electrical and Electronic Equipment (WEEE)
The scope of the legislation covers essentially all electrical and electronic equipment used by consumers and electrical and electronic equipment intended for professional use which are likely to end up in the municipal waste stream. The provisions of the Directive apply to products and producers irrespective of the selling technique, including distance and electronic selling.
The act has two categories: one for "private households" and another for "professional users":
Private Households: Users of electrical and electronic equipment from private
households should have the possibility of returning WEEE free of charge. Producers shall therefore finance the treatment, recovery
and disposal of WEEE.
Professional Users: Member [EU] States shall take the necessary measures
to ensure that the financing of the costs for the collection, treatment, recovery and environmentally sound disposal of waste electrical
and electronic equipment from users other than private households is covered by agreements between the producer and the user of the
respective equipment at the time of purchase.
Article 11, paragraph 1 says that producers must "identify ... the different EEE components and materials, as well as the location of dangerous substances and preparations in EEE." While vague, the implication is a requirement for disclosing, upon request by recyclers, material content far beyond the six identified substances for the purpose of assisting recyclers in improving efficiency and reducing costs associated with recycling. While Annex II provides some additional material disclosure requirements, it is not the complete list. Contact DCA for more information about this.
Lead is in common use today as a finish for solder pads on printed circuit boards (PCBs) implemented as Hot Air Solder Levelling (HASL). Without a finish, the base material, copper, will oxidize when exposed to air, contributing to an increase of marginal or bad solder joints. HASL must be replaced, and each of the candidate replacement technologies has issues. This excellent article describes some of those issues, which include new challenges for In-Circuit Test (ICT).
Tin Whiskers and Long Term Reliability
With more and more component suppliers providing components with a pure tin finish in order to meet the EU directives, the risk of "tin whiskers" as a long-term reliability problem will increase. The NASA Goddard Space Flight Center has a great web site dedicated to this issue. Follow the link provided below to learn more.
DCA can help you learn about and manage the impact of the EU directives, and plan your transition to compliance. From identifying and managing your suppliers' RoHS compliance roadmaps, to updating key design and procurement supplier and component-related business processes, to identifying and configuring a systems solution that tracks material composition, to identifying and resolving potential and actual technical back-end risks, we can do it all. And with our partners, including EPTAC, we can do even more! Please contact us for more information.
