Reliability of Pb-free solders for harsh environment electronic assemblies

Abstract

Since 2006 and the implementation of environmental regulations, the electronic industry has moved to Pb-free solders. Harsh environment industries that were exempted from the regulations will soon have to follow suit. However, a suitable replacement solder for use in harsh environments still has to be validated and reliability models are yet to be established. In this review, research that led to the selection of currently used Pb-free alloys and the continuing search for high reliability alloys are described. Sn pest and Sn whiskers, potential major threats for electronics operating in harsh environments, are highlighted. This review also focuses on the microstructure, mechanical properties and deformation mechanisms of Pb-free alloys. Emphasis is placed on Sn–Ag–Cu alloys, now considered to be the alloys of choice for replacement of Sn–Pb solders. The reliability of Pb-free electronic assemblies is studied, focusing on thermal fatigue, believed to be the main source of failure through creep–fatigue mechanisms. The validity of models for Pb-free solder joints life time prediction is assessed and the lack of cohesiveness among the available reliability data is examined.

Effects of Gaseous and Particulate Contaminants on Information Technology Equipment Reliability—A Review

“…The atmospheric corrosion mechanism of electronic materials and other cases of atmospheric corrosion are similar, as they are all affected by synergies between relative humidity [81][82][83][84], temperature [85,86], contaminants (Cl À , H 2 S, SO 2 ; and NO x ) [87][88][89][90][91][92][93] among others. The increase in creep corrosion due to the electronic industry moving away from Pb-free solders has been reported by several authors [94][95][96]. These studies mainly addressed that a move to ImAg and organic solderability preservatives (OSP) board finishes would dramatically increase early life failure in computer PCBs due to copper creep corrosion, especially in high sulfur environments.…”

Drop Reliability of Epoxy-contained Sn-58 wt.%Bi Solder Joint with ENIG and ENEPIG Surface Finish Under Temperature and Humidity Test

“…17,18 Also, designing for enhanced solder joint reliability is critical to long-lifetime electronic packages, because solder joints are prone to failure in the electronic package under various environmental conditions such as temperature, humidity, dust, shock, and vibration, making it important to evaluate solder joint reliability under harsh environmental conditions. 19,20 In this work, we demonstrate the effects of two surface finishes, namely electroless nickel immersion gold (ENIG) and electroless nickel electroless palladium immersion gold (ENEPIG), on epoxyenhanced Sn-58 wt.%Bi solder by means of boardlevel drop tests to evaluate the mechanical properties of the solder joints under constant temperature-humidity testing.…”