A microstructural study of creep and thermal fatigue deformation in 60Sn-40Pb solder joints
Thermal fatigue failures of solder joints in electronic devices often arise from cyclic shear strains imposed by the mismatched thermal expansion coefficients of the materials that bind the joint as temperature changes are encountered. Increased solder joint reliability demands a fundamental understanding of the metallurigical mechanisms that control the fatigue to design accurate accelerated probative tests and new, more fatigue resistant solder alloys. The high temperatures and slow strain rates that pertain to thermal fatigue imply that creep is an important deformation mode in the thermal fatigue cycle. In this work, the creep behaviour of a solder joint is studied to determine the solder's microstructural response to this type of deformation and to relate this to the more complex problem of thermal fatigue. It is shown that creep failures arise from the inherent inhomogeneity and instability of the solder microstructure and suggest that small compositional changes of the binary near-eutectic Pn-Sn alloy may defeat the observed failure mechanisms. This work presents creep and thermal fatigue data for several near-eutectic Pb-Sn solder compositions and concludes that a 58Sn-40Pb-2In and a 58Sn-40Pb-2Cd alloy show significantly enhanced fatigue resistance over that of the simple binary material. 80 refs., 33 figs., 1 tab.
- Research Organization:
- Lawrence Berkeley Lab., CA (USA)
- Sponsoring Organization:
- DOE/ER
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 6292501
- Report Number(s):
- LBL-29018; ON: DE91005404
- Country of Publication:
- United States
- Language:
- English
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Time-dependent deformation behavior of near-eutectic 60Sn-40Pb solder
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Related Subjects
360102 -- Metals & Alloys-- Structure & Phase Studies
360103* -- Metals & Alloys-- Mechanical Properties
ALLOY SYSTEMS
ALLOYS
CADMIUM ALLOYS
CREEP
CRYSTAL STRUCTURE
DEFORMATION
EUTECTICS
FATIGUE
INDIUM ALLOYS
JOINTS
LEAD ALLOYS
MECHANICAL PROPERTIES
MICROSTRUCTURE
SOLDERED JOINTS
TERNARY ALLOY SYSTEMS
TIN ALLOYS
TIN BASE ALLOYS