Solder joints, thermal fatigue analysis

[homutow]

Hi,
Recently I got a task to perform thermal fatigue analysis of solder joints. Till now I had nothing to do with such objects.
Does anybody perform such a task?? I can prepare the FEA model but there are many questions:
- what would be the material model?
- Is there any approach to calculate the fatigue of solder joints?
- Is there any source of material properties??
If you have any idea or experience with this topic I would appreciate.
Regards

 

[mechengdude]

A good place to start might be:
Cooling Techniques for Electronic Equipment by Dave S. Steinburg.
Chapter 7 is "Thermal stress in Lead wires, solder joints, and plated throughholes"

 

[unclesyd]

Here are several reports available from NASA concerning your OP. They may not have the answer you need but there are some great references such as the one below, the doctoral thesis of D.R. Fear, at U.C., Berkeley

http://ntrs.nasa.gov/search.jsp?No=0&Ntt=solder+fatigue&Ntk=all&Ntx=mode matchall&N=0

Frear, D.R. 1987 “Microstructural Observations of the Sn-Pb
Solder/Cu System and Thermal Fatigue of the Solder Joint”,
PhD Thesis U Calif, Berkeley, Ca.

 

[Tmoose]

Here are some shots of automotive relays with cracked joints.
They run kind of warm, and each start up begins a new heat cycle. I figure Ball park 10,000 cycles to failure.

http://home.comcast.net/~tatng/Auto/MainRelay-5-cracked-joint.JPG

http://www.volvoclub.org.uk/faq/ImagesProcedures/ClimateControlSolderJointRepair.gif

http://edge-op.org/images/volvo-relay.jpg

 

[dvd]

I wrote an undergraduate paper on solar cell solder joint low-cycle fatigue way back in '85. The fatigue calculations were based on the modified Coffin-Manson model. I did a quick google search on the spelling and got hits so I think the spelling is correct.