Thermomechanical fatigue of solder joints: A new comprehensive test method

Conference · Sat Dec 31 23:00:00 EST 1988

DOI:https://doi.org/10.1109/ECC.1989.77763· OSTI ID:6294785

Frear, D. R.

This paper presents a new comprehensive method to test solder joint in thermomechanical fatigue. The method involves simultaneous imposition of temperature cycles and strain on discrete solder joints in a shear orientation. The stress, microstructure, and number of cycles to failure were monitored. Cycles to failure were determined by a continuous electrical detection method. 60Sn-40Pb and 40Sn-40In-20Pb solder joints were tested using this new method at 20% shear strain. The 60Sn-40Pb alloy has a shorter fatigue lifetime than did 40Sn-40In-20Pb. This is attributed to heterogeneous coarsening that concentrates strain into a small area of the 60Sn-40Pb microstructure. In contrast, the 40Sn-40In-20Pb microstructure becomes refined. The heterogeneous coarsening also results in cyclic softening in 60Sn-40Pb, which was not observed in 40Sn-40In-20Pb. Failures initiated within the coarsened band in 60Sn-40Pb at Sn-Sn grain boundaries or phase boundaries. In contrast, failures initiated at the surface of 40Sn-40In-20Pb joints and propagated through both phases of the microstructure. 41 refs., 16 figs.

• Research Organization: Sandia National Labs., Albuquerque, NM (USA)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 6294785
• Report Number(s): SAND-89-0401C; CONF-8905102-1; ON: DE89008045
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
42 ENGINEERING
420500 -- Engineering-- Materials Testing
ALLOYS
CRYSTAL STRUCTURE
FATIGUE
GRAIN BOUNDARIES
INDIUM ALLOYS
JOINTS
LEAD ALLOYS
MATERIALS TESTING
MECHANICAL PROPERTIES
MICROSTRUCTURE
SOLDERED JOINTS
STRAINS
STRESSES
TESTING
THERMAL FATIGUE
TIN ALLOYS