Ultrafast Photonic Soldering with Sn–58Bi Using Intense Pulsed Light Energy

Solders, which are the most commonly used materials in electronic packaging, have been widely used for electrical interconnections. When producing a solder joint, a layer is formed on the contact pad, followed by a reflow process conducted using infrared or thermal energy. This process requires a high‐temperature environment and long heating time. Herein, an advanced approach involving photonic soldering using intense pulsed light (IPL) energy is examined thoroughly. In particular, the relation between the bonding characteristics and pulse conditions, such as the energy, frequency, and number, for the development of ultrafast, low‐damage, and large‐area bonding technology is studied. Compared with the conventional reflow, IPL soldering requires a process time of only ≈2.5% and can improve the strength by 40%. Fracture micrographs after the die shear test indicate an interfacial fracture after conventional reflow and a mixed fracture after IPL soldering; this results in the consumption of the Cu layer after the time‐consuming reaction in the reflow and the formation of an extremely refined region in the solder joint after irradiation with IPL energy. Because of its improvement with respect to the process and bonding characteristics, IPL soldering can be a candidate for innovative interconnections in microelectronics.