Intense Pulsed Light Soldering of Sn–3.0Ag–0.5Cu Ball Grid Array Component on Au/Pd(P)/Ni(P) Surface‐Finished Printed Circuit Board and Its Drop Impact Reliability

Intense pulsed light (IPL) soldering is investigated as an alternative soldering process to conventional reflow soldering. IPL soldering is suitable for achieving a carbon‐neutral society due to its low power consumption. In addition, it has several advantages in electronic device manufacturing, including low thermal damage, short processing time, and applicability to large‐area processes. Herein, an electroless‐nickel/electroless‐palladium/immersion‐gold surface finish and Sn–3.0Ag–0.5Cu solder are used. Three IPL parameters, pulse width, pulse number, and frequency, are considered in the soldering process. The microstructures of the interface and solder matrix are observed using a field‐emission scanning electron microscope equipped with an electron probe microanalyzer. Furthermore, board‐level drop impact tests are conducted to investigate the mechanical reliability of the joints. The results show that the compositions and morphologies of intermetallic compounds (IMCs) vary with the IPL parameters, which significantly affect the reliability. Specifically, the number of drops to failure increases ≈6.7 times under optimum IPL condition compared to reflow soldering. This is because cracks propagate through the solder matrix and discontinuous IMCs. Based on the obtained results, IPL‐based soldering is a promising alternative to reflow soldering. The microstructures and mechanical reliability of intense pulsed light (IPL)‐soldered joints are investigated for comparison with reflow‐soldered joints. Board‐level drop impact reliability is greatly improved by 6.7 times under optimum IPL condition. The cause is that the crack propagates along the discontinuous (Cu,Ni,Pd,Au)6Sn5 IMCs and the solder matrix between them.