My thanks to John Barnes for his posting today of the excerpt from the 1928 book. The earliest reference I was aware of for whiskers of any kind was the Bell Labs paper from the 1940's. This excerpt is amazingly detailed, including even the observation that coatings can't be counted on to prevent whiskers. There is even a reference to earlier study (unfortunately without citation).

My only quibble is with the 10 volts statement. It isn't volts but current that melts whiskers. A whisker could survive exposure to any voltage as long as the series resistance was high enough.

As for buying up a supply of tin-lead solder to ensure future availability, it is worth remembering that the RoHS directive does not apply to solder sold as a product, only solder in a covered electronic product. I have checked with a number of solder manufacturers, and they all say that they will make tin-lead solder available as long as there is a market for it. Perhaps a representative of the solder manufacturer's association would be willing to say so in this forum.

The idea that tin-lead solder might disappear (á la ozone-depleting substances) from the market has contributed to a bandwagon mentality among some manufacturers of products not covered by the RoHS directive that they will some day be forced to switch to lead-free anyway.


Gordon Davy
Baltimore, MD
[log in to unmask]
410-993-7399 


-------------------------------------------------------------------------------Leadfee Mail List provided as a service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Leadfree
To temporarily stop/(start) delivery of Leadree for vacation breaks send: SET Leadfree NOMAIL/(MAIL)
Search previous postings at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-------------------------------------------------------------------------------