Keith

Be careful when stating that Lead free solder performs better in thermal cycling. There are investigations that show this fact. However, they don't take in account that lead free solder creeps 10-100 x slower that lead containing solder ( depending on the temperature) when the accelerated tests are designed. The problem is, that degradation is strain driven. practically this means, that in a test with 5 min. dwell time, a lead containing solder joint sees much more strain per cycle than a lead free solder. Logically this results a priori in a longer lifetime.
In LEADFREE we did thermal cycling tests with slow ramp and long dwell times and we saw that after a given number of cycles the cracks in the SnAg(Cu) solder joints was approx. 1.2x the crack length in tin lead solder.
There is still concern about vibrations. What I heard so far is, that lead free solder performs not too good. But I can't quantify that.

Have a great day


Guenter

EMPA
Swiss Federal Institute for Materials Testing and Research
Centre for Reliability
Guenter Grossmann,  Senior Engineer

8600 Duebendorf
Switzerland

Phone: xx41 1 823 4279
Fax :     xx41 1823 4054
mail:     [log in to unmask]

-------------------------------------------------------------------------------Leadfee Mail List provided as a free 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/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
-------------------------------------------------------------------------------