Further refinements and optimizations have been made to the scaled-down aluminum alloy spot-welding pen developed by Brother Er.

               The modifications are as follows:

              The upper shell has been redesigned to provide extra lateral clearance for accommodating the aluminum busbar, thereby eliminating slippage and jamming caused by assembly and material tolerances.

              The 3.5 mm headphone jack stop has been adjusted to accommodate headphone plugs of varying outer diameters.
              Chamfers have been added to the pressure spring assembly to facilitate installation and reduce assembly difficulty.
              The PCB slider baseplate area has been lowered by 0.2 mm to reduce assembly clearance, addressing issues where component shrinkage or flow irregularities prevent proper assembly.
              The PCB locking mechanism has been changed to an M2×4 mm self-tapping screw, with an increased outer diameter to enhance structural strength.

All of the above modifications have been thoroughly tested and deliver a smoother, more user-friendly experience.