In situ measurement of stress evolution in Sn-based solder joint under electromigration based on X-ray diffraction technique

The in-situ measurement of the stress evolution at the anode and cathode interfaces of the Cu/3.0Ag0.5Cu/Cu solder joints with current density of 4 × 10³A/cm² at room temperature by X-ray diffraction technique was investigated. The experimental results showed that the stress evolution at the interfaces was a very complicated process during current stressing, which owed to many influencing factors such as Joule heating effect, stress relaxation, electromigration force and so on. After current stressing, the whiskers and hillocks were formed at the interface of the anode side which was as a mode of relieving compressive stress. It was found that a uniform Cu₆Sn₅ intermetallic compound layer was formed at the anode interface after polishing the solder joint.