Dr. Ron, I make ceramic modules, so I am assuming that I am excepted from RoHS (See Annex 4.) My ceramic models use lead containing solder and ink. What do you think?
I wish I could be so sanguine for your application. Let's look at RoHS Annex 4:
4. - Lead in high melting temperature type solders (i.e. tin-lead solder alloys containing more than 85% lead),
- lead in solders for servers, storage and storage array systems (exemption granted until 2010),
- lead in solders for network infrastructure equipment for switching, signalling, transmission as well as network management for telecommunication,
- lead in electronic ceramic parts (e.g. piezoelectronic devices).
The reference to piezo devices in ceramic parts is curious. A little reseach shows that lead zirconate titanate (PZT) has the highest piezoelectric constant of common materials (see table below). I'm not an expert in this field, but my sense is that the EU was being sensitive to the need for high performance piezo materials with this exemption. I think exempting your application is not in the spirit of what the EU is trying to accomplish with RoHS. So as a minimum, someone on your team needs to do a lot more research, before believing that your application is exempted. I would also be concerned that your competitors might recognize the EU's intent and "turn you in" when they ship their RoHS compliant products if yours are not.
Material Piezoelectric Constant
Barium titanate 100-149
Lead niobate 80-85
Lead zirconate titanate 250-365