High-temperature superconducting (HTS) tapes are now commercially available for various magnet applications. Their higher tensile strength enhances strain tolerance, allowing for the winding of smaller diameter coils. The most crucial component in a double pancake winding of a coil is the fabrication of inter-double pancake joints with minimal electrical resistance. This is due to the structural design of REBCO (RE—rare earth) tape, which consists of very thin layers of materials prone to deterioration when exposed to temperatures exceeding the recommended value, optimal joint overlap length, and the selection of solder materials. In this study, we investigated the effects of tape overlap lengths, solder materials, and soldering temperatures on joint resistance. The lowest joint resistance recorded was 18 nΩ, achieved with an overlap length of 150 mm at 4.2 K in a self-field, as reported in this paper for a 3.5 T REBCO coil winding pack.