During the Dip Soldering process, the surface of the solder pot is continuously exposed to high-temperature air, and oxidation of the molten solder is an unavoidable physical phenomenon. However, differences in oxidation rate directly determine the morphology, thickness, and removal difficulty of dross. We found that when using ordinary Solder Bars, the dross is loose, porous, and easily crumbles, while the oxide film formed by JJY solder bars is dense, uniform, and strongly adherent, causing the dross to float on the liquid surface in sheet-like form. This not only facilitates one-time scraping but also significantly reduces the risk of fine solder ash re-mixing into solder joints.

The oxidation resistance of solder bars does not rely solely on tin purity; the key lies in the synergistic effect of trace elements copper and nickel. A copper content controlled at 0.7%±0.05% can effectively inhibit abnormal grain growth of SnO₂, while nickel participates in grain boundary segregation in the range of 0.03% to 0.045%. Together, they slow down the diffusion rate of oxygen into the molten solder. Meanwhile, JJY introduces trace lanthanide rare earth elements during the smelting stage, reducing the surface tension of the molten solder by approximately 12%, further reducing local severe oxidation caused by splashing and air entrainment.

Actual production line verification shows that when the dip soldering temperature is set to 258°C, wave height to 5.2mm, and conveyor speed to 1.3m/min, after using JJY solder bars, the frequency of manual dross removal from the solder pot is extended from once every 2.5 hours to once every 5.8 hours. The daily average solder bar replenishment amount decreases from 3.6kg to 1.9kg, and the tin content in the dross remains stable at 68% to 71%, far higher than the industry common range of 52% to 58%, indicating that the oxidation reaction is effectively inhibited rather than simply covered.

Analysis of dross composition shows that SnO₂ accounts for 39% in ordinary solder bar dross, while it is only 22% in JJY batches. The remainder is mainly SnO and trace Sn₃O₄ composite phases. These lower-order oxides are more easily re-dissolved back into the molten solder under reducing atmosphere. Therefore, in semi-enclosed dip soldering equipment where the nitrogen protection concentration is maintained below 800ppm, the molten solder life can still be stably maintained at over 120 hours.

It is necessary to simultaneously adjust the Flux spray volume and preheating temperature for matching. If insufficient preheating causes the PCB to carry moisture into the solder pot, even using JJY solder bars will induce interfacial micro-explosions and accelerate local oxidation. We recommend increasing the peak preheating temperature to 105°C±3°C, with the temperature fluctuation at the board bottom measurement point not exceeding ±2°C, so that the oxidation resistance advantage can truly be translated into a substantial reduction in dross loss.