Deformation and damage of solder joints in electronic components

• Research unit: COST
• Project number: C00.0102

Key words (English)

Solder joints; thermomechanical loads; nonlinear deformation; fatigue; fracture; reliability

Research programs (English)

COST-Action P4 - Non-linear dynamics in mechanical processing

Short description (English)

See abstract

Further information (English)

Full name of research-institution/enterprise: EPF Lausanne Laboratoire de mécanique appliquée et d'analyse de fiabilité LMAF STI-I2S-LMAF

Partners and International Organizations (English)

CZ, DK, F, D, GR, H, IRL, I, NL, PL, SI, E, S, CH, GB

Abstract (English)

The effects of mechanical loads on deformation, damage and fracture of standard solder alloy (Sn63/Pb37) copper joints are characterized in uniaxial tension specimens. The specimens are made of two copper plates and one layer of solder alloy in between. Macroscopic observations demonstrate that the specimens fail at the interface between the copper and the inter-metallic layer at approximately the maximum load supported by the specimen. Finite element simulations have been performed to characterize the stress-strain state in the solder joint using an elasto - visco - plastic constitutive law and appropriate material properties. The results of the simulations describe the macroscopic behavior of the joint. Quantitative damage analysis, using electron microscopy, of polished specimens has been carried out at different load levels and the load induced damage is measured using standard procedures. Experimental data on damage (voids and microcracks) at different load levels are correlated with the corresponding irreversible equivalent strains calculated by means of the numerical model. The results show that while damage increases with inelastic strain, its rate of growth decreases suggesting a saturation of damage at crack initiation. Simultaneously, experiments on similar specimen with a Pb-free alloy, (Sn95.5Ag4Cu0.5), have been performed in order to compare their damage and mechanical characteristics with the (Sn63/Pb37) joints. The main geometrical parameter is the thickness of the solder layer. The comparisons aim at establishing experimental procedures for developing Pb-free solders joints with mechanical properties relevant to the microelectronics packaging.

References in databases (English)

Swiss Database: COST-DB of the State Secretariat for Education and Research Hallwylstrasse 4 CH-3003 Berne, Switzerland Tel. [phone] Swiss Project-Number: C00.0102