Bill- thanks for your excellent question. I have been faced with the
same issue where lead in resistor elements has been presented as a RoHS
exemption by suppliers, using the following logic:
1. RoHS Annex, Item 5, which exempts: "Lead in glass of cathode ray tubes,
electronic components and fluorescent tubes"
2. Resistor Construction: The resistive element is "RuO2 + Glass"
3. Other OEM specs: Specification of "resistor elements" as RoHS lead-
exempted materials.
In my view, this MAY represent a RoHS-exempted application, however, at a
minimum, confirmation that the resistor element qualifies as an electronic
component glass material as intended by RoHS Annex, Item 5 is necessary.
In theory, this could be presented to the RoHS Technical Advisory
Committee (TAC) for a ruling, however, to my knowledge, there is currently
no effective means of getting a real-time definitive answer from
regulatory authorities on specific exemptions. A logical, documented
approach which passes the "laugh test" may be the best alternative for
now, with recognition that the issue may need to be revisited later. If
others have developed ideas around this, I'd be interested to hear them.
Thanks,
Joe Johnson
Environmental Regulatory Manager
Microsoft
(425)707-4364
[log in to unmask]
On Wed, 5 May 2004 13:23:53 -0600, Haas, Bill <[log in to unmask]> wrote:
>Colleagues,
>
>Recently our material science lab evaluated 0402 surface mount lead-free
>resistors from 10 major world resistor suppliers. The specimens were
>dissolved in aquaregia (3:1 hydrochloric:nitric acid) and the extract
>examined using inductively coupled plasma mass spectroscopy. 6 of the 10
>samples showed lead concentrations greater than 1000 ppm. The explanation
>from resistor suppliers is that the lead comes from the lead oxide
resistive
>element and not from the terminations, which is probably true. But they
>further state that this usage is in accordance with RoHS legislation.
Would
>any readers here be able to explain what RoHS Annex exemption applies to
the
>resistive elements of common resistors?
>
>Thanks and regards,
>
>Bill Haas
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