Ken Patel has said that Pb is intentionally added to plating baths such
that it is found at 600 ppm in Ni and 50 ppm in Au plated coatings. I
grant that you as a user of a board could with great effort find and
possibly measure Pb at these levels in the land finish as it is
received, but I do not think that even your most aggressive rival would
be able to find Pb (let alone prove that it was intentionally added) on
your product (i.e., covered by the RoHS directive) when put on the
market as a soldered assembly. This is particularly true for Au, which
unless there is a solderability problem dissolves in the solder
entirely. The Pb becomes distributed in a homogeneous material of much
greater volume and hence has a much lower concentration. Perhaps John
Sieber of NIST or other experts would care to comment on this.

And if the issue is the presence of Pb in trace quantities in the
termination finish of a component, how is the scrupulous user to
determine the intent of the supplier? How hard must he try? Even though
intent is in the language of ELV, there is a very good reason why it was
omitted from the RoHS directive, which was written later. (This topic
was, I recall, discussed at length in this forum a few years ago.)

If trace Pb in Ni and Au on a soldered assembly can not for all
practical purposes be detected, what are the implications? Isn't a
manufacturer who decides to avoid scrupulously the use of intentionally
added Pb in plating baths used on purchased boards (for which there
would presumably be performance consequences) going to be at a
disadvantage in competing against a manufacturer who decides that the
risk of being charged with a violation is acceptably small?

From my point of view, those who choose to self-impose this additional
test for products covered by RoHS (just to be safe) are actually
increasing risk. They may conceivably reduce the risk of being charged
with a  nonconformance by some aggressive inspector who decides to
impose his own opinion in place of the actual law. But they increase the
risk associated with the use of a substitute material as well as the
risk of reducing market share due to the resulting higher price. 

 

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
-------------------------------------------------------------------------------