Despite the controversy over the technological need for lead-free soldering, consumer and legislature requirements for lead-free products are clear. The main disadvantage of lead-free solders is the higher cost than traditional tin-lead solders, but whether you like it or not, it is clear that manufacturers have to use lead-free processes in all of their production. After all, the way to reduce costs is always there.
Despite the appearance of surface mount components, wave soldering developed specifically to handle through-hole components remains alive and a key part of any production line.
The following four process technologies form several aspects that are economically tightly coupled, thereby saving the cost of lead-free soldering:
1. The design of the preheater. Most wave soldering machines are equipped with different preheaters. However, the optimum design for a preheating system should include more than one type of heater, for example, a combination of a black body IR heating plate at the bottom and a powerful air convection heater above.
2. Type of preheater. Wave soldering equipment manufacturers use different types of heating methods: quartz lamps, infrared (IR) tubes and Calrod ceramic components, all operating at high temperatures (1300 to 2000 °F), so that the top surface of the PCB reaches 190 to 240 before entering the peak. The optimum temperature of °F. Obviously, such a high Δt makes energy utilization very low. Moreover, it is not possible for components to absorb as much heat emitted by these heat sources. The use of such a high temperature heat source attempts to bring the PCB surface to a relatively low temperature, which greatly increases the possibility of flux overburning.
In contrast, the use of a low Watt dense black body IR heating plate is the most efficient way to heat the PCB. These heating elements emit long wavelength IR and are easily absorbed by the PCB. Therefore, the Δt between the heat source and the PCB is much smaller than the Δt produced by the heating elements such as quartz lamps and infrared tubes.
3. Solder recovery and regeneration. The use of a solder recycling system maximizes cost savings. During the welding operation, up to 75% (depending on the pump design) the solder will oxidize to become scum, the main component of the scum is pure solder.
4. Control of lead-free processes. People use more expensive solders, and naturally it is desirable to have fewer soldering defects. One of the main causes of soldering defects such as bridging, tipping, and inadequate top surface welds is insufficient heating of the printed circuit board (PCB) assembly during the warm-up phase. However, it is too insufficiency, too much heating and insufficient heating, especially for lead-free processes. In fact, preheating requirements are more stringent in lead-free applications because it requires higher temperatures: some lead-free solders have melting temperatures close to 700 °F.
The physical design of the preheater is another major factor in the uniform and gradual heating of the plate. For example, if there is a gap between the end of the preheater and the beginning of the peak, the plate will cool. Similarly, when the plate is run on the transport mechanism, the distance between it and the heat source also has an important effect on the plate heating process. The ideal design is to get closer to the heat source when the plate is near the peak. In addition, since lead-free solder will be at a higher temperature as the PCB enters the wave bath, it is naturally expected that the most efficient preheating system will minimize defects and rework and rework costs when continuously produced to meet high production requirements. .
Among our products, the standard 300 series lead-free double wave soldering (computer / touch screen / button) V-300C/V-300M/V-300A is a powerful and stable performance developed in combination with the above process characteristics. New product.