The RoHS Directive 2011/65/EU (Restriction of Hazardous Substances) of the European Parliament and of the Council restricts the use of certain hazardous substances in electrical and electronic equipment. This directive regulates the use and placing on the market of hazardous substances in electrical appliances and electronic components. The full directive can be viewed on the official EUR-Lex website. In Germany, the Electrical and Electronic Equipment Substances Ordinance was created to implement the directive.
According to the RoHS Directive, lead is generally prohibited in electronic applications. However, there are a number of exemptions for the use of lead, which are precisely defined in RoHS Directive 2011/65/EU Annex III and whose expiry date is regularly reviewed. Lead as an alloying element in steel, aluminum and copper is regulated in exemption 6 a) to c), lead in refractory solders in exemption 7 a) and lead in electrical and electronic components made of glass or ceramics in exemption 7 c).
In January 2025, the EU Commission proposed new amendments and adjustments to the validity dates and areas of application of the exemptions. If there are no objections from industry, the drafts will come into force.
Exemption 7 c) of the RoHS Directive currently permits the use of lead in components if the lead is contained in a glass or ceramic or in a glass or ceramic matrix compound.
Exemption 6 a) of the RoHS Directive currently allows the use of up to 0.35% lead as an alloying element in steel.
The most recent amendment to the exemption now stipulates that a new decision will be made in mid-2025 on how to deal with the exemptions. Nevertheless, it is advisable to look for alternatives to lead-containing components as soon as possible, also in order to avoid costly requalifications of devices or expensive redesigns for applications with product lifetimes beyond the expiration date.
According to the JEDEC J-STD-609A standard, electronic components are considered RoHS-compliant if they do not exceed the maximum concentration of 0.1% by weight of a homogeneous material. They are not necessarily absolutely lead-free.
The varistors in the WE-VS SMT product family for use in surge protection applications with short response times, low leakage current and a nickel barrier layer for a lead-free soldering process were previously unable to dispense with lead in the ceramic.
A new material mix and an adapted manufacturing process now make it possible to dispense with lead in the ceramic. The previous WE-VS varistors are being completely replaced with lead-free components. A lead content of less than 1000 ppm (0.1 %) is considered "lead-free". A change in the formulation with permitted substances and a modification of the manufacturing process has resulted in the electrical, mechanical and thermal behavior corresponding to the previous products. Reliability tests in accordance with AEC-Q200, including a service life test of 1000 hours at 125 °C and maximum DC voltage, have confirmed the robustness of the new lead-free varistors.
With the lead-free WE-VS family, the aim was to achieve a one-to-one replacement, so that most customers can integrate the new components into their application without having to adapt the circuitry. However, selected electrical parameters may differ slightly, so testing in the target application is advisable.
SMT spacers are basically only designed as mechanical retaining components that are not intended to conduct electricity. A new material mix and a modified manufacturing process now make it possible to reduce the lead content in the steel alloy from the previous 0.35% in accordance with exception 6 a) to fully RoHS-compliant below 0.1%.
Although the steel alloy is changed, the surface coating of the lead-free SMT spacers remains unchanged and therefore ensures the same soldering behavior with the same mechanical properties.
