Dave,

To take up one point in your very interesting and useful contribution- the
possible benefits of controlling the morphology of the intermetallics that are
one of the features that distinguish the lead-free solders from tin-lead
solder, cooling rate may be one option but that is difficult to control in real
soldered joints in complex assemblies.

However, the Ames laboratory and others have found some interesting effects
of ternary or quaternary additions of elements that incorporate preferentially
in the intermetallic crystal structure and modify its nucleation and growth
behaviour.   That is possibly are more effective and reliable way of managing
the intermetallic morphology than trying to control cooling rates.

Keith Sweatman
Nihon Superior Co., Ltd

-------------------------------------------------------------------------------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 delivery of Leadree for vacation breaks send: SET Leadfree NOMAIL
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 847-509-9700 ext.5315
-------------------------------------------------------------------------------