Shear Force Of Solder Joints Research Articles

Fatigue life evaluation of gold wire bonding solder joints in MEMS pressure sensors

The failure of the gold wire bonding solder joint of a MEMS pressure sensor caused by the thermal cycling test was investigated with thermal cycling experiments and fatigue simulations. The results show that the maximum stress and strain occurred at the root of the solder joint on the substrate. With the accumulation of strain caused by thermal cycles, the bonding area of solder joint became smaller and the shear force of solder joints reduced to 22.3% after 1600 thermal cycles. The solder joints on the substrate failed after 1940 thermal cycles in plastic fatigue simulations and 3.16 × 108 thermal cycles in creep fatigue simulations. Plastic fatigue is the major factor for thermal failure of gold wire bonding.

Three-dimensional interface and property of SnPb solder joint under extreme thermal shocking

To meet the demand of cryogenic reliability on the electronic packaging for deep space satellite, the three-dimensional interfacial morphology and property of eutectic SnPb solder joint under an extreme thermal shocking of 77–423 K were investigated. After thermal shocking, Cu-Sn IMC layers coarsened in the cross-sectional observation and micro-cracks formed in Cu6Sn5 layer. The rough Cu6Sn5 layer in the top view gradually smoothed, with broken Cu6Sn5 particles and exposed Cu3Sn. In the bottom-view observation, the Cu6Sn5 layer of as-soldered joint was overlapped by Cu3Sn layer. But no defects were generated in Cu3Sn layer. The shear force of solder joint was greatly reduced due to broken Cu6Sn5 with the changing fracture characteristics from the solder-controlled mode to the solder/IMC mixed mode.

Comparative study on the reliability of SnPbSb solder joint under common thermal cycling and extreme thermal shocking

The increasingly severe temperature has always been a problem for the solder joint applied in the future novel electrical devices. The reliability evolution of solder joint in these conditions is necessary for the design of electrical packaging materials. In this paper, a common thermal cycling test of − 65 to 150 ℃ and an extreme thermal shocking test of − 196 to 150 ℃ were carried out on Sn50Pb49Sb1/Cu solder joint. The interfacial behavior of the solder joint, as well as the corresponding mechanical performance, was analyzed. In the thermal cycling test, the coarsening behavior of Cu6Sn5 layer and the formation of a new Cu3Sn layer were detected. After 400 cycles of thermal cycling, the shear force of solder joint was decreased by 31.55%, but the ductile fracture was hardly changed. The reliability of solder joint was more sensitive to the extreme thermal shocking. Besides the coarsening behavior of IMC layer, the micro-crack formation induced by thermal stress was obtained in Cu6Sn5 layer. These micro-cracks became the crack source and gave a further decrement of the shear strength. After 400 cycles of extreme thermal shocking, the shear force of solder joint was reduced by 50.43%, giving a ductile/brittle mixed fracture.

Effect of extreme thermal shocking on the reliability of Sn50Pb49Sb1/Cu solder joint

The cosmic extreme temperature is deemed to be an enormous problem for the electronic devices and solder joints of on-orbit satellite. In this paper, an extreme thermal shocking test from 77 to 423 K was carried out to partly simulate the space temperature environment. The extreme thermal shocking effect on the microstructure, shear force and fracture behavior of Sn50Pb49Sb1/Cu solder joint was investigated to try to clarify the reliability evolution of solder joint. It was found that after the thermal shocking, Cu6Sn5 layer thickened significantly with the formation of micro-cracks. The columnar shape of Cu6Sn5 layer in as-soldered joint was changed to plane shape due to its excessive growth. The Cu3Sn layer formed and coarsened during the thermal shocking process, but no defects were observed. Owing to the growing interfacial layers and prolonging cracks, the shear force of solder joint was reduced with the increasing shock cycles. The fracture of solder joint was also transformed from solder-controlled mode to a mixed mode of solder and intermetallic compound, giving a different fracture location and lower ductility.

Analysis of high-temperature aging and microstructure of FC LED solder joints of a silver conductive layer bonded using SAC solder

Flip-chip (FC) light-emitting diode (LED) filaments with a silver conductive layer are impeded by heat dissipation, with the flip-chip junction temperature of reaching up to 423.15 K. To overcome this problem, we simulated aging of SAC305 solder joints at a high temperature of 433.15 K. Scanning electron microscopy was performed to analyze the changes in the microstructure of the solder joints with aging time. Moreover, energy-dispersive X-ray spectroscopy was performed to analyze changes in the element content of the solder joints with aging time. The shear force of solder joints was measured using a strength tester. Results revealed that the Ag/Au content of the solder joints increased under the high-temperature conditions, resulting in the formation of cracks and holes in the solder joints. Furthermore, the reliability of the FC LED filaments was affected by the maximum shear stress that can be tolerated by the solder joints.

Mechanical reliability of solder joints in PCBs assembled in surface mount technology

Purpose – The purpose of this paper is to determine the dependence of mechanical strength of solder joints on printed circuit boards from the soldering process parameters and operating conditions of the electronic device. Design/methodology/approach – The research was performed using the Taguchi method of planning of experiments. Evaluation of the quality of solder joints was made on the basis of microscopic observations, X-ray analysis and measurements of shear force of solder joints. Findings – The carried out research has shown the influence of the individual parameters of the soldering process on the mechanical strength of solder joints and the mechanism of damage of solder joints under the influence of shear force. Originality/value – The authors present results of their research using advanced techniques of experimental design and analysis of results. In this study, original approach was used to simulate the operational conditions of electronic devices including thermal imaging technology.