Creep deformation behavior in eutectic Sn-Ag solder joints using a novel mapping technique

Abstract

Creep deformation behavior was measured for 60-100 µm thick solder joints. The solder joints investigated consisted of: (a) non-composite solder joints made with eutectic Sn-Ag solder, and (b) composite solder joints with eutectic Sn-Ag solder containing 20 vol.%, 5 µm diameter in-situ Cu 6 Sn 5 intermetallic reinforcements. All creep testing in this study was carried out at room temperature. Qualitative and quantitative assessment of creep deformation was characterized on the solder joints. Creep deformation was analyzed using a novel mapping technique where a geometrical-regular line pattern was etched over the entire solder joint using excimer laser ablation. During creep, the laser-ablation (LA) pattern becomes distorted due to deformation in the solder joint. By imaging the distortion of laser-ablation patterns using the SEM, actual deformation mapping for the entire solder joint is revealed. The technique involves sequential optical/ digital imaging of the deformation versus time history during creep. By tracing and recording the deformation of the LA patterns on the solder over intervals of time, local creep data are obtained in many locations in the joint. This analysis enables global and localized creep shear strains and strain rate to be determined.

Study on Cu particles-enhanced SnPb composite solder

“…The intermetallic compounds also help Cu particles to uniformly distribute in the composite solder. The average nearest particles spacing, λ 0 , is estimated from 18 (2) where A is the area measured, and N is the number of Cu particles in the area measured. Based on the statistical measurement, the s average nearestparticles spacings of 5vol.%Cu and 10vol.%Cu particles-enhanced SnPb-based composite solder are 13.1 µm and 6.5 µm, respectively.…”

“…1 Lucas et al 2 compared the creep behavior of the Sn-3.5Ag solder using small, single shear-lap soldered joints with in-situ reinforcements. It is found that the global creep-strain rate was decreased in composite solder joints.…”

Creep properties of eutectic Sn-3.5Ag solder joints reinforced with mechanically incorporated Ni particles

“…Since eutectic Sn-3.5Ag solder is considered as a leading candidate of Pbbearing solders, several approaches have been used to improve its comprehensive properties such as creep resistance, thermomechanical fatigue resistance, mechanical strength, and solder joint reliability. [15][16][17][18][19][20][21][22][23][24][25][26][27] Among these approaches, the composite approach was designed mainly to improve its service performance, including service temperature capability. Composite solders, whether tested as bulk or as joint specimens, generally showed improved properties.…”

Effects of intermetallic morphology at the metallic particle/solder interface on mechanical properties of Sn-Ag-based solder joints

“…Creep testing was carried out on these solder joints, marked with a laser pattern or a scratch, 14 using dead-weight loading on a miniature creeptesting frame fixed on an optical microscope. The de formation of the polished side of the solder joint was monitored using a Kodak (Rochester, NY) chargecouple device camera connected to a microscope and a computer.…”