The RoHS/REACH directive bans the use of lead in PCB layouts, ASIC designs and other electronic systems, which has had far-reaching consequences for the engineering industry worldwide. Following the global adoption of the RoHS regulations, there has been a monumental shift towards lead-free solders by component manufacturers and PCB designers. However, the decision has proven both controversial and costly, not least to the customers.
The problem with omitting lead from tin solders is that, in its absence, spontaneous crystalline ‘whiskers’ can form. Electrically conductive, they can take anything from a few days to several years to develop, and sometimes (no-one knows why) don’t grow at all. They can bridge contacts, short electrical circuits, bridge traces, and no printed circuit board or VLSI design is exempt. In a piece of military (or civil) avionic hardware, the results can be catastrophic.
There is currently no fail-proof way to test susceptibility of new PCB designs to whiskering, no way of predicting its occurrence, and no guaranteed prevention, except a minimum 3% lead addition. Many of the hardware systems using embedded firmware – for example, military applications – are exempt from environmental legislation. However, in a predominantly OTS (off the shelf) industry, component manufacturers aren’t prepared to start making specialist one-off products. It costs them money.
Can we live without lead solders? It seems we may have to. The race is on to find suitable alternatives, but in the meantime those still using traditional lead-containing components will find them harder and harder to obtain. Part obsolescence management and PCN alerts are just two of the solutions we at Enventure Technologies offer, to help you cope with problems caused by environmental compliance.
