When electronic manufacturers buy new wave soldering, whether it is a lead-free process or a lead-containing process, they must use tin bars
with relatively high purity, which is related to the welding quality of future products and the manufacturer's control of tin costs. Because the wave soldering furnace will corrode the copper and aluminum elements fused into the components and the wave soldering fixture in the tin furnace during the long-term use. In this way, the proportion of these impurities in the tin furnace will become larger and larger, so that the viscosity of the tin in the wave soldering furnace will become larger and larger.
One of the main reasons for the formation of lumpy slag (semi-molten bean curd slag tin lumps) is that the viscous force of the solder alloy in the molten state is large. Solder will produce tin powder in black powder state under normal working conditions. When the viscous force of the solder alloy in the molten state is large, the tin slag is wrapped around the tin slag during wave soldering to form a massive tin slag (tofu slag tin block). That's why we heat up the bulk dross to separate out a mostly intact solder alloy. In the same way, under working conditions, the solder with high viscous force is prone to defects such as sharpening and bridging. The harm of this semi-melted tofu slag tin block I think many people who have used wave soldering should know that this is one of the biggest wastes in wave soldering.
And if our new wave soldering furnace does not use pure wave soldering tin strips, the solder in the wave soldering furnace will soon produce a large number of semi-melted tin lumps like tofu slag in the neutralized state of the same aluminum. resulting in a lot of waste. At this time, we had to reluctantly replace the entire pot of tin.
First, if the lead-containing process is used, if it is a lead-containing wave soldering furnace, we must choose authentic 63A solder bars (sn63/pb37). 63A solder bars are the requirements of the national A-level standard. High fluidity and high welding fluidity prove that the tin bar has low viscosity, which has a certain maintenance effect on the new wave soldering furnace and will not produce tofu slag tin lumps.
Second, if the lead-free process is adopted, the wave soldering furnace generally uses more lead-free tin bars. Its main components are: sn99.3cu0.7. At present, there are many kinds of lead-free tin bars in the market. The lead-free tin bars are divided into Grade A and Grade B, Grade A is made of pure natural Yunnan tin material, and Grade B is smelted and manufactured from scrap tin. Most of the market is dominated by Grade B lead-free tin bars, which is mainly due to the low price. Green Times brand lead-free tin bars are mainly A-grade. For the new wave soldering furnace, adding grade A lead-free tin bar is the best choice, with high purity and less impurities, which plays a certain role in the maintenance of the later wave soldering. Electrolysis reduces impurities.