Characteristics and properties of lead-free reflow soldering

Lead free reflow soldering is to use the same process as tin lead soldering temperature to treat lead-free. This practice has many advantages due to the low temperature. For example, the equipment needs to be replaced, the power consumption is less, and the risk of device damage is small. However, this process has high requirements for DFM and reflow soldering process. It is necessary for users to have a good grasp of the adjustment principle of reflow soldering process and the compensation for errors. Jeenoce electronics shares the characteristics and performance of lead-free reflow soldering.

Difference between lead-free reflow soldering and lead reflow soldering

There is little difference between SMT lead-free reflow soldering and lead reflow soldering. They are still: steel plate printing solder paste, device installation (including high-speed mounting of sheet shaped forced components and active placement of large components with special-shaped parts), hot air reflow soldering, cleaning and quality inspection. The difference is that the melting point of lead-free solder paste rises, the solderability becomes poor, the number of empty monuments increases, the plates are easy to explode, and the humidity sensitive seals are more vulnerable. It is necessary to change the concept and face it from scratch. In fact, according to years of mass production experience, the reasons that affect the quality of reflow soldering only need four key points: solder paste itself, printing parameters, reflow furnace quality and reflow soldering curve selection. Most problems can be solved by those who have a good grasp of them.

Lead free reflow soldering has the following advantages

1. high precision: temperature control precision of lead-free reflow soldering ± 2 ℃.

2. powerful functions: circuit board preheater, lead-free welding, chip aging and red glue curing.

3. inner and outer arc design: lead-free reflow soldering helps the uniform flow of hot air and makes the process curve more standard.

4. process automation: lead-free reflow soldering realizes full-automatic precision lead-free soldering; The whole process curve is automatically controlled, and lead-free reflow soldering can complete the double-sided mounting or mixed mounting welding process.

Lead free reflow soldering skills

After lead-free soldering, the flux pollution is particularly significant due to the impact of high-temperature oxidation. Generally, the lead reflow soldering equipment is equipped with a flux management system to prevent the high-temperature airflow of many flux from entering the cooling area and condensing in the heat sink and furnace, reducing the cooling efficiency and polluting the equipment.

The lead-free reflow soldering system is to extract the high-temperature gas flow containing a lot of flux from the front of the preheating zone, the reflow zone and the cooling zone, and then send the clean gas back to the furnace after the external cooling filtration system. Another benefit of this is to form a closed cycle during nitrogen maintenance to avoid nitrogen consumption. This system has been greatly modified, which is generally difficult to increase. If the production capacity is not large and the flux pollution is small, it can be cleaned up on time without replacement. Vacuum nitrogen furnace

Lead free reflow soldering belongs to reflow soldering. In the early years, the solder for reflow soldering was made of lead containing materials. With the deepening of environmental protection thought, people pay more and more attention to lead-free skills (i.e. lead reflow soldering nowadays). Great changes have been made in materials, especially in solder. In terms of process, the welding process has a great impact. This is mainly caused by the characteristics of solder alloys and the difference of corresponding fluxes.