Solder Joint Reliability

Solder joint reliability is the ability of solder joints to function under given conditions and to remain in conformance to both mechanical and electrical specifications for a specified period of time (without failing within the intended operating time).In general, a particular failure mode is the result of certain failure mechanisms in which certain specific combinations of material properties and the surrounding environment act simultaneously. Many different factors have to be considered when assessing the reliability performance of a solder joint structure, such as stress distribution, strain amplitude, strain rate, the cyclic nature of the stress (mechanical, thermal, and thermomechanical), temperature, and many other environmental factors (corrosion, vibration, and so on). Apart from these, the metallurgical and physical behavior of the solder and the solder joint are also very important to take into account, since these also highly affect the reliability behavior of the solder joint.The aim of this chapter is to increase the knowledge regarding reliability and failure of lead-free solder alloys/joints. This chapter gives an insight into how the microstructure of some lead-free solders is built its stability and some interfacial reactions. An introduction is also given to the failure mechanisms of solder joints, including fatigue failure, which is one of the most significant threats to the integrity of solder joints. Both the effect of second-level solder interconnection and some common standards used when testing solder joint reliability are also mentioned in this chapter.