Thermomechanical fatigue of solder joints: A new comprehensive test method
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 Lab. (SNL-NM), Albuquerque, NM (United States)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 6294785
- Report Number(s):
- SAND-89-0401C; CONF-8905102-1; ON: DE89008045
- Resource Relation:
- Conference: 39. electronic components conference, Houston, TX, USA, 22 May 1989; Other Information: Portions of this document are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
42 ENGINEERING
INDIUM ALLOYS
THERMAL FATIGUE
LEAD ALLOYS
TIN ALLOYS
GRAIN BOUNDARIES
MATERIALS TESTING
MICROSTRUCTURE
SOLDERED JOINTS
STRAINS
STRESSES
ALLOYS
CRYSTAL STRUCTURE
FATIGUE
JOINTS
MECHANICAL PROPERTIES
TESTING
360103* - Metals & Alloys- Mechanical Properties
420500 - Engineering- Materials Testing