Surprise Contamination, Part 1
An Electronics Weekly article from 2005-June-17 revealed surprising examples of contamination in RoHS compliant components. In this case, Pb was found in a connector, beneath Au and nickel sulphomate layers. The investigators surmised that the lead was an unintentional contaminant in or on the brass base material.
The article went on to note that contamination can result from mixing compliant and non-compliant runs through the same production machinery. For instance, lead-bearing materials in one machining run can easily contaminate lead-free materials in a subsequent run. Similarly, plastics containing Cd for a molding run will pollute a subsequent RoHS-compliant molding run. The best way to prevent this contamination is to remove the contaminating substances from the factory completely.
Recently, I also noted a comment by an engineer on a discussion board. He was annoyed that so many sales people were representing certain copper alloys as having a precise chemical composition. His contention is that most of these alloys contain high percentages of recycled content. The very nature of the recycling industry leads to frequent contamination. To claim a specific alloy content is pure fantasy unless the metal is guaranteed virgin material.
To me, all of this discussion is very familiar, though from a context that might surprise you. I have heard all of these kinds of comments, surprises, insights, and vexations before, from the organic food industry.
Yes, it turns out that RoHS and WEEE have very strong similarities to the USDA's National Organic Program and the global organic movement. The certified organic label only means something because the entire industry, from farmers to processors, complies with a unified set of rules. Everyone knows that if any single point in the supply chain fails to comply, then the entire chain is violated and the resulting product may not be labeled as organic.
With RoHS, the exact same pattern applies. Every supplier, from the fabricators to the finished goods producers, must be RoHS compliant. If anyone steps out of line and lets in a banned contaminant, then the entire chain is at risk.
So how can the integrity of the supply chain be guaranteed? The answer next week in Part 2.
Surprise Contamination, Part 2
Electronics Weekly article 2005-June-17
