Waste from Electrical and Electronical Equipment (WEEE)
This directive deals with the recovery, sorting und processing of electric and electronic products. Corresponding legislation had to be adopted by August 2004 and implemented one year later. In Europe, more than 90% of waste electric and electronic devices are disposed of safely. This amounts to approx. six million tons of scrap materials per year. In the future, these scrap materials are to be separated, sorted and preferably re-used to promote responsible treatment of available resources. To ensure these goals are met, member states will hold the manufacturers of the devices sold in the European Union to account.
Restriction of certain Hazardous Substances (RoHS)
The RoHS directive (Restriction of certain Hazardous Substances) of the European Union furthermore governs restrictions applying to the use of hazardous substances. Since 1st July 2006, the use of certain substances in electric and electronical devices has no longer been permitted. This applies to cadmium (Cd), mercury (Hg), hexavalent chrome (Cr[VI]), polybrominated biphenyls (PBB), polybrominated diphenyl ethers (PBDE) and lead (Pb).
Lead is only one of the substances banned by the RoHS directive. Despite the fact that the industry often uses the term “lead-free”, this does not mean that compliance with the RoHS directive is ensured by the replacement of lead alone. However lead is the most relevant substance for us in terms of this directive.
The RoHS directive applies to all member states of the European Union. Its provisions have to be implemented in the same way across all member states to avoid differing interpretations. The WEEE directive is not a single market directive. It describes minimum standards for the collection of waste, which can be exceeded by the member states if required.
Despite the fact that the implementation of the directive is based on EU legislation, it also has to be complied partially with at a worldwide level, because the sale of appliances is the key factor in this context. Japanese manufacturers have been reducing the lead content in their products for three or four years already, and in the United States, the state of California also adopted legislation that, in principle, corresponds to the implementation schedule of the European Union. It is unlikely that manufacturers of electric and electronic devices will offer “lead-free“ products in Europe and products containing lead in the rest of the world.
According to this EU directive, electric and electronic devices that are placed on the market after 1st July 2006 are not allowed to contain lead (Pb), mercury (Hg), cadmium (Cd), hexavalent chrome or brominated flame retardants (PBB, PBDE). There are exceptions for lead as an alloy component for content in steel (up to 0.3%), in aluminium (up to 0.4%) and in copper (up to 4 %).
The following values were suggested as maximum limits: a maximum of 0.1 percent per weight for Pb, Hg, Cr[VI] and a maximum of 0.01 percent per weight in homogenous materials. For this purpose, the term “homogenous materials” describes a unity that cannot be mechanically divided up into individual materials. A high number of different product areas are affected by this provision. For us, this concerns in particular the wide range of component coatings containing lead:
- Solder connections of components
- Contact surfaces of connectors
- Screen covers
- Stamped grids etc.
Preferably, matte pure tin layers are used as a substitute in the field of contact components of connectors, for press-in pins and for the solder connection area of components. In comparison to bright tin, matte tin offers several advantages:
- Less prone to whisker formation
- Stable contact resistance after ageing
- Better solderability after ageing
- Better optical identification (contour determination)
- Bigger processing window for depositing of galvanic layers
Through dialogue with our customers and producers of the electrolyte additives, we started to search for alternative, RoHS compliant surfaces at a very early stage. We looked at tin, silver, tin bismuth and tin-copper layers in addition to the pure tin layers that already existed.
The existing requirements included those stemming from the RoHS directive (“green chemistry“ without lead and nonylphenols), as well as the maintenance of technical parameters (solderability, prevention of whisker formation, low level of ageing effects).
For us, and our customers, a changeover to pure tin (bright or matte) has proven to be the optimum choice of surface for connecting and soldering processes.
For effective prevention of whisker formation, we always recommend prior application of a nickel sub-layer (in individual cases also application of a copper sub-layer, e.g. in the case of bronzes) of the base material and/or the reflow of the tin surface.
