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Are we meeting RoHS norm with hexavalent chromating?

As per Certification of Compliance with RoHS/WEEE requirements. % Chromium VI(Cr VI) should be less than 0.1% by weight.
Now question is - Our part is getting Zinc plated and Blue passivation Where passivation process is being carried out in Passivation bath which is containing H2O+HNO3+Hexavalent chrome (Cr VI) - QTY. 1800 LTRS..

Hexavalent chrome % in the bath is 0.033% level of concentration, after plating & passivation the concentration of Hexavalent chrome stands as 0.0058% since the component wt is 44.2615 gms.
With the above analysis we are declaring that we are meeting the RoHS norms.

We would like to know where our reporting / calculating method is right or wrong?

Vijaya Kumar S
- India
August 17, 2008

Hi, Vijaya. You are not calculating correctly. RoHS considers the plating plus the chromating to be one homogeneous material. While you and I may realize that this is very silly, that's the way it is. So the calculations must be based on the weight of the plating plus the chromate, not the weight of the whole part, and not the weight of the chromate layer. Good luck.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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August 18, 2008

August 22, 2008

Hi.
I am of the opinion, hexavalent base passivation after zinc plating are not RoHS compliant. There are trivalent passivation chemicals available. And yes, you do not calculate the amount of hex chrome in your bath and base that to the weight of your part and say that you are compliant.
I suggest you send your part to a third party , accredited laboratory and check the amount of hex chrome on your part using ICP-MS equipment. A certificate of analysis from them would be more authentic and reliable when presented to your customer.

SK Cheah
- Penang/Malaysia

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