Lead-free Reliability Introduction
With the implementation of the RoHS directive that took effect on July 1 of 2006, the usage of the traditional tin/lead solder for over 50 years is being changed to lead-free solder. Currently, tin, silver, and copper (Sn-Ag-Cu, aka SAC) alloys are used on the market. However, the melting temperature of SAC solder is around 217℃~220℃, which is higher than the temperature of traditional Pb Alloy 63/67 being 183℃. Consequently, SMT processing has entered a high temperature components era. Due to this 40℃ difference, high temperature processing will directly impact the products' quality and reliability, especially on the components and PCBs with complex PCBA production process, such as issues with PCB cracks and IC delaminations.
Under good SMT assembly conditions, studies showed that lead-free soldering can withstand better pull and shear but lack in performance in the Board Bending Test, showing lead-free soldering joints are weaker. Therefore precautions must be taken to avoid solder joint deterioration caused by improper force exertion, e.g. “In Circuit Test-Probe Forces”, during the test procedure.
Problems derived from lead-free solder assembly include IC/PCB Delamination, Solder Crack, PCB Warpage, short resulting from Tin Whisker, PCB Migration, Heat Damage of parts, excessive Voids, Cold solder, Poor rework, and process Contamination.
We have performed more than 500 lead-free process reliability validation and failure analyses for domestic and international customers over versatile products since 2004, the accumulation of practical know how enables us to assist customers by providing test analyses and improvement suggestions.
We are capable of providing turnkey lead-free qualification including Lead-free parts/PCB reliability analysis, Lead-free process parameters optimization (Process DoE) → Assembly Inspection→Reliability Test → Physical / electrical failure analyses, etc.