We found some very good comments on the question of lead-free solders and finishes from Joe Fjelstad on the Listserv LEADFREE page. Fjelstad makes a great case against going lead-free.
The point of concern and the lead-free movement was predicated in concernof the poisoning of children, especially the very young, in early,formative years, where the effects are most pronounced. Nearly all casespoisoning of children have been due to the ingestion of lead acetate used inpaint. Acetic acid (aka vinegar) will dissolve lead to form lead acetate(aka lead sugar) It was used in paint and paint chips are sweet. Lead acetatewas even used to sweeten wine in centuries past. Also there is tetra ethyl leadwhich was (and still is in some places) used as an antiknock ingasoline (petrol, benzene) This can be inhaled from fumes of combustion andan accumulation of lead in the body. Neither of these have the remotestrelationship to electronics save that the element lead was used in the creationof the organic products.
Elemental lead does not require the employment of a precautionaryprinciple. It simply requires due caution. Man made compounds, especially those without known analogues do require precautions.
In sum lead-free solder will not make the environment better, butit could well make it worse. It will not use less energy, it will usemore. It will not be cheaper, it will be more expensive. It will not makeelectronics more reliable, evidence is that it will make them less so.However, the crowning point is that the provisions of WEEE which requirerecycling, makes the matter of lead from a risk point totally moot while thenegatives and risks associated with going lead-free, in terms ofelectronic solders, will remain.