Clarification in RoHS - The meaning of % of Lead by Weight

[ROOTS]

When I went through the ROHS Directive, I found that there are some exemptions given as stated below;

1. The maximum concentrations are 0.1% (except for Cadmium which is limited to 0.01%) by weight of homogeneous material. This means that the limits do not apply to the weight of the finished product, or even to a component, but to any single substance that could (theoretically) be separated mechanically — for example, the sheath on a cable or the tinning on a component lead.

2. Steel up to 0.35 % lead by weight*
3. Copper alloys containing up to 4.0% lead by weight
4. Aluminum containing up to* 0.4 % lead by weight
5. Lead in lead-bronze bearing shells and bushes

I could not able to understand the meaning of % of lead by weight? Whether they meant about weight of the lead from the total component or anything else? If so, how to calculate the weight of lead (Constituent) in grams in a component. Is there any formula?

Can any one help me Pl.

Regards
M.Prabhakar

[chergh]

0.35% max lead in steel would work as follows: 1g of Steel could have a maximum 0.0035g of lead.

Calculation:

weight of material(steel) x percentage allowed / 100 = weight of allowed lead

The steel would be analysed by yourselves or a third party using ICPMS (Inductivley coupled plasma mass spectrometrey). The usual way of reporting this is in PPM (part per million). This is a simple ratio so to convert %(% is the same as parts per hundred) to PPM by multiplying by 10,000 so this would equate to 3,500 ppm. Or you could ask the persons doing the analysis to report it as % of weight

[sfkevin]

That is a good visual description of by weight. As for the verification, you have to be aware of the other amendments to the RoHS requirements allowing other materials to be in excess of 1,000PPM of some elements. We count one certification s from suppliers but also test with an X-Ray Fluorescence Spectrometer (XRF) unit to confirm the parts are within RoHS requirements. I have also come in handy for verification that we are getting the correct alloy for metal fabrications.

[gleclair]

Originally Posted by sfkevin

We count one certification s from suppliers but also test with an X-Ray Fluorescence Spectrometer (XRF) unit to confirm the parts are within RoHS requirements. :

When you use the x-ray for testing can you also test for chromium VI or any other repoartables with it. If you can E-mail me with what company you used to do this. This would come in handy for me.

Glen

[cthyau]

There is no formula. The lead content has to be determined by lab test. So when it says 0.35% of lead by weight in steel, it means if I were to take a piece of steel (e.g. 1kg) to the lab and perform a composition analysis, I can only find 0.35% of 1kg (i.e. 3.5g) of lead. Otherwise, that piece of steel is considered not RoHS compliance. Sometime it is possible that a lab test is not necessary. For the steel case, most steel foundry will have a "mill certificate" or "analysis report" attached to each batch of steel. You can just ask the supplier for that.

[sfkevin]

Originally Posted by gleclair

When you use the x-ray for testing can you also test for chromium VI or any other repoartables with it. If you can E-mail me with what company you used to do this. This would come in handy for me.

Glen

Glen,

You can search the web and come up with several handheld or table top X-Ray Fluorescence Spectrometer (XRF) units. We had chosen a portable one for easy of transfer from one location to the other. As for the chromium VI, NO not the one we had. It would state if there was a high amount of chromium and we would then rely on the customer certification if it stated it passed ROHS.
“cthyau” is correct that the only true analysis in by sending it to a lab with the specialized equipment for analyses by digestion or in the case of an only metal parts ark test, this will measure the percentage of elements given off and give you a detailed reading of each element and the percentage at the given spot.
Hope that helps.