What is the difference between using a pressure tank or water pressure for flux supply in wave soldering?

What is the difference between using a pressure tank or water pressure for flux supply in wave soldering?

A wave soldering system consists of a conveyor, spray system, preheating system, wave soldering system, and cooling system. Among these, the spray system is a critical component for ensuring the quality of the soldered product. An unstable spray system can lead to issues such as cold solder joints, bridging, solder spikes, and insufficient solder coverage.

The flux supply device in the wave soldering spray system is crucial for ensuring the uniformity and stability of flux application through the nozzle. Currently, most wave soldering systems on the market use either a water tank or a pressure tank to supply flux to the nozzle. The water tank is made of 316 stainless steel and uses the high water level in the tank to supply flux to the low water level at the nozzle. This is the standard flux supply method used in most wave soldering machines on the market, which can basically meet the requirements of PCB welding processes. It has the advantages of low cost and easy maintenance. However, it is not practical for products with strict requirements for solder penetration to the board surface. Its drawback is that the spray is affected by water pressure, resulting in lower overall spray uniformity compared to pressure tank supply. Additionally, when the solder flux level in the water tank is low, the water pressure decreases, and insufficient pressure may cause intermittent or no spray. Furthermore, the sealing performance of the water tank lid cannot be compared to the fully welded sealed pressure tank, Gaps between the tank body and lid can cause flux evaporation, affecting flux composition. Therefore, when using a water tank for liquid supply, it is recommended to use up the flux within the tank within one day. Any remaining flux should be poured into a dedicated sealed container for reuse the next day and should not be returned to the original flux container.

Pressure tanks are also made of 316 stainless steel, with the entire structure welded and sealed. Flux is injected through a ball valve, the valve is closed, and dried air pressure is added. The air pressure forces the flux to the nozzle, ensuring stable and uniform fluid supply. This significantly aids in the penetration of flux into the solder pads, which is critical for subsequent wave soldering to ensure tin penetration to the PCB surface. If the flux does not penetrate from the component leads into the pad holes, the solder cannot climb to the PCB surface. The drawbacks include higher costs and more challenging maintenance, requiring engineers to have a certain level of operational expertise.