Deleting Hexavalent Chromium From Electronics
Hexavalent chromium (Cr VI) is prohibited by several green initiatives. At first glance, most people can’t think of any place it is used in electronics. In reality, it is as pervasive as lead (Pb).
The culprit is generally zinc chromate. This ubiquitous plating finish inhibits corrosion on many different parts commonly used in electronics products. It is readily identified by a yellowish color it imparts to plated metal parts. The plating process that applies the chromate produces Cr VI in sufficient quantity to greatly exceed the concentration limits set by all of the current green regulations.
Most small audio speakers and small electric motors are made with zinc chromate plated steel sheet metal. In addition, many fasteners and other stamped, sheet steel parts have chromate finishes. It is also used on large sheet metal parts, such as enclosures. All of these parts contain hexavalent chrome in the finish. Consequently, all of them will cause a product to fail a green compliance test.
To be compliant, you will have to find components that do not use chromate finishes. Research in this area has been underway for decades and there are many choices. Some are organic finishes and others are inorganic. So far, it has been mostly Asian companies taking the steps to commercialize the chromate-free finishes.
Finding hex-chromium-free parts is not nearly so easy as finding lead-free parts, but it is getting easier. Most suppliers still advertise zinc chromate finishes as a beneficial marketing feature. Chromate-free is generally advertised only by the steel makers. Consequently, you need to do some digging to locate hex-chromium-free components.
The best way to proceed is to talk with your suppliers. If they are on top of the compliance issues, they could already have chromate-free parts to offer. If not, you can try asking them to look into it. They have several sources to choose from. JFE Steel, Kobe Steel, Nippon Steel, and NKK Steel all offer chromate-free sheet steel products.
Chromate-free is already a marketing advantage among the steel makers. Kobe Steel claims to be the first Japanese steel company to go completely chromate-free. Kobe released this claim January 12, 2005. Others are touting the environmental friendliness of their particular corrosion protection coatings. This competitiveness should make your job a bit easier. If nothing else works, you could email some of these steel companies, sending the contact information for one of your suppliers who is resisting the switch to chromate-free steel. At least one of the salesmen is likely to get through.
Below are the links to the chromate-free steel products, and a couple of technical papers on the coating research and standards.
NKK Steel (PDF)
Nippon Steel (PDF)
Kobe Steel
JFE Steel (PDF) - detailed product guide
The Singapore Standard for lead and chromate-free primers
Technical paper (PDF) discussing the benefits of chromite finishes versus chromate.
