Cyclic deformation of sup 60 Sn-- sup 40 Pb solder joints during thermomechanical fatigue

Conference · Sun Jan 01 04:00:00 EST 1989

OSTI ID:5216361

Frear, D. R.; Jones, W. B.

Thermomechanical fatigue and isothermal fatigue tests were performed on {sup 60}Sn--{sup 40}Pb solder joints under a variety of strain ranges and rates. In isothermal fatigue deformation throughout the entire cycle occurs with the same mechanism. The mechanism at low temperatures is a dislocation process and at high temperatures it is a diffusional flow. In thermomechanical fatigue the deformation mechanism changes in each cycle from dislocation processes to diffusional flow which results in higher peak stresses at the high and low temperature portion of the cycle. This indicates thermomechanical fatigue behavior can not be accurately predicted using isothermal fatigue. It was also found that decrease in strain rate slowed the heterogeneous coarsening process in thermomechanical fatigue. This is due to the fact that the dislocation substructure recovers more quickly than it work hardens which tends to minimize recrystallization and growth in the solder microstructure. 13 refs., 14 figs., 2 tabs.

• Research Organization: Sandia National Labs., Albuquerque, NM (USA)
• Sponsoring Organization: DOE/DP
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 5216361
• Report Number(s): SAND-89-0720C; CONF-900271--1; ON: DE90004197
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102 -- Metals & Alloys-- Structure & Phase Studies
360103* -- Metals & Alloys-- Mechanical Properties
ALLOYS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DEFORMATION
DISLOCATIONS
FATIGUE
JOINTS
LEAD ALLOYS
LINE DEFECTS
MECHANICAL PROPERTIES
MICROSTRUCTURE
SOLDERED JOINTS
STRAIN RATE
THERMAL CYCLING
TIN ALLOYS
TIN BASE ALLOYS