How can you identify which products are in compliance with RoHS and which are not, while they are WIP and not the finished product?

Different colored labels (other than white) are being introduced in process to differentiate between the new, RoHS/WEEE compliant “green” products or assemblies, and those that are still produced by lead-based soldering. Many companies are identifying the new compliant products with these colored labels, while still using standard white labels to identify standard, but non-compliant products. Most often, we have seen the use of green or yellow colored labels to identify RoHS compliant products, although many other colors are also available. Colored labels that are based on a pigmented coating containing colorants are the most robust. The colors of these labels tend toward pastel because the colorants are typically added to the proven “white label” coating formulations. However, the color differences are very clear in contrast to the conventional, white labels.

Attempts have been made to overprint an ink layer (or “floodcoat” as it is called in the trade) on top of the white pigmented layer of label material in an effort to have labels with bright, Pantone colors. The tradeoff here is these labels are more likely to have the color easily washed away or removed by the cleaning chemistries employed, as the ink is washed away when compared to the more robust but lighter colored labels discussed above. We have seen situations where an ink-coated green barcode label turns yellow because the blue colorant used in the ink is leached out by the solvents and temperatures of the manufacturing process.