Since the European RoHS (Reduction of Harzardous Substances) regulation came into force, lead, cadmium, mercury and chromium IV compounds may no longer be used in the manufacture of electronic printed circuit boards. This regulation has been converted into European law and will be binding for the manufacture of electronic assemblies from 1 July 2006.

For the PCBauch: gedruckte Schaltung, engl.: PCB – Printed circuit boar… More manufacturer, this means switching or substituting the classic hot air solder levelling (HASL) process with lead-free alternatives. From a technical point of view, the requirements of SMT assembly and COB technology for planar surfaces have not yet been met by the HASL process due to the crowned tin/lead surface.

These requirements resulted in the need to introduce alternative PCBauch: gedruckte Schaltung, engl.: PCB – Printed circuit boar… More end surfaces. As described above, these must fulfil the latest environmental guidelines, be suitable for modern assembly techniques, but must also be thermally resistant so that they are compatible with lead-free solders and the corresponding soldering processes.

In principle, the following lead-free end surfaces can be considered for printed circuit boards:

• HASL Hot Air Solder Leveling (leadfree variant to be defined!)
• OSP Organic copper passivation
• Immersion Nickel / Immersion Gold
• Immersion Nickel / Palladium / Immersion Gold
• Immersion Tin
• Immersion Silver
• Galvanical Tin