Advantages of through hole reflow soldering process

The key problem of through-hole reflow soldering technology is that the amount of solder paste required by the through-hole solder joint is larger than that required by a surface mount solder joint. However, the traditional reflow solder printing method can’t apply an appropriate amount of solder paste to through-hole components and surface mount components at the same time. The solder amount of through-hole solder joint is usually insufficient, so the solder joint strength will be reduced.

This article will introduce you from the following points: process principle of through hole reflow soldering, advantages of through hole reflow soldering process.

 (1) Process principle of through hole reflow soldering

Through hole reflow soldering technology is to use reflow soldering technology to assemble through hole components and special-shaped components. The manufacturing process for assembling printed circuit board (PCBs) mainly depends on the special components used in the assembly. Due to the increasing emphasis on miniaturization, increasing functions and increasing component density, many single and double side boards are mainly surface mount components (SMC). Through hole reflow, sometimes called classified component reflow, is gradually emerging. It can remove the wave soldering link and become a process link in PCB mixed assembly technology. A big advantage is that the advantages of the SMT manufacturing process can be brought into play, and the through-hole plug-in can be used to obtain better mechanical connection strength. For large size PCB, the flatness can’t make all the pins of surface mount components contact with pads.

(2) Advantages of through hole reflow soldering process

1. The existing SMT equipment can be used to group THC/THD, which can save cost and investment.

2. At present, the automatic multi-function mounting equipment can be installed with THC/THD. Using through hole reflow on PCB with a surface mount as the main part, the traditional wave peak welding technology and manual plug-in process are abandoned. The single SMT production line can complete the assembly of all PCBs.

3. Various operations are simplified into a comprehensive process.

4. Less equipment, materials and personnel are required.

5. It can reduce production costs and shorten the production cycle.

6. It can reduce the high defect rate caused by wave soldering.

7. One or more heat treatment steps can be omitted to improve the weldability and reliability of electronic components. Through hole reflow has special requirements for the temperature resistance of components, the design of through hole welding plate, the design of the template, solder paste printing and reflow welding.

The key to the success of through hole reflow soldering process is to accurately calculate the amount of solder paste needed for printing. The solder paste volume calculation should first use the ideal solid metal solder joint, the so-called ideal solder joint. Due to the changes of metallurgical methods, pin conditions, reflow characteristics and other factors, the arc method can accurately predict the shape of welding fillet. It is an appropriate and simple approximate method to use arc to describe the leg, and then rotate the leg area to determine the volume of the solid solder joint.