Process Parameters in Resistance Projection Welding for Optical Transmission Device Package

The effects of main process parameters and electrode materials on joint quality (charging voltage and operating force) were investigated using detailed metallurgical examination and the helium leak test. The electrode materials used for resistance projection welding were brass and Cr-Cu alloy. The TO-Can components (cap and header) were nickel-coated SPCC steel. The results indicated that when the operating pressure increased, the electrode displacement increased, causing expulsion and distortion of the welds. The nugget area increased with the increase of charging voltage; however, it decreased with the increase of operating pressure. Results from the optical microscopy analysis showed that a larger acceptable welding range was achieved by using Cr-Cu electrodes. TO-Can in the acceptable and expulsion range successfully passed the helium leak rate of less than 5 × 10⁻⁸ mbar L/s. For commercial purposes, where dimensions have to be exact and without deformation, the TO-Can components produced in the expulsion zone cannot be used.