Abstract: Objective This study aimed to solve the problems of insufficient solder penetration rate and void ratio in through-hole solder joints on thick plates. Methods A dual-layer synchronous focused induction heating device was used to explore the soldering process for through-hole solder joints on 3 mm, 4 mm, and 5 mm thick plates. The effects of soldering time, heating power and different plate thicknesses on solder joint morphology and solder penetration rate was analyzed, and optimal process for through-hole solder joints on 3 mm, 4 mm and 5 mm thick plates was determined. Results Solder joints obtained using the optimal process had complete morphology with no obvious defects, and no burnt or overheated defects were found on printed circuit board. The pull-out strength of through-hole solder joints was higher than that of pin material, and all solder joints showed good electrical conductivity. The solder penetration rate of through-hole solder joints on thick plates reached 100%. Scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX) analyses were performed on solder joints. The results showed that solder wetted and spread along both sides of the pads, forming a skirt-shaped solder joint structure at upper and lower pads. A dense intermatallic counpound (ICM) was formed at the interface interconnection between Cu pads and SAC305, with an IMC thickness between 1 and 3 μm. Temperature cycling tests were conducted on the solder joints. After 500 temperature cycles, the solder joint surface was bright, without cracks, pinholes, or desoldering. Pull-out tests showed that the pins broke, but the solder joints remained unaffected. The circuits at all solder joints remained conductive, and the solder penetration rate remained 100%. Conclusion Dual-layer synchronous focused induction heating soldering can achieved through-hole solder joint interconnection on thick plates of varying thicknesses. The resulting solder joints exhibited good mechanical properties and reliability, providing an effective solution for through-hole solder joint interconnection on thick plates.