Proposal of intense pulsed light soldering process for improving the drop impact reliability of Sn–3.0Ag–0.5Cu ball grid array package

Until now, electronic packages have been manufactured using the conventional convection reflow process. However, it is becoming challenging to apply the reflow process because it is time-consuming and produces thick intermetallic compounds (IMCs) at the joint interface. In addition, the reflow process consumes a lot of power because of the preheating required and the generation of waste heat, thereby interfering with carbon neutrality. To overcome these issues, the feasibility of intense pulsed light (IPL) radiation soldering for the ball grid array package assembly process was investigated in this study. A very thin IMC was formed at the IPL-soldered joint (IMC thickness = 1.2 μm) because of the short IPL process time. However, the IMC formed during the reflow process was 6.1 μm-thick. Thus, the drop impact reliability of the IPL-soldered joint (number of drops to failure = 277) substantially improved compared with that of the reflow-soldered joint (number of drops to failure = 103). In addition, the power consumption of the IPL radiation soldering process was 17.95 kWh, considerably lower than that of the conventional convection reflow process (29.50 kWh). Therefore, we suggest that IPL soldering has a high potential to reduce process time, IMC thickness (enhancing the drop impact reliability), and power consumption. © 2023