What is SMT patch wave soldering? Wave soldering means that the molten solder is sprayed by an electric pump or an electromagnetic pump into a solder wave peak required by the design, and it can also be formed by injecting nitrogen into the solder pool, so that the circuit board pre-installed with components passes through the solder wave peak. , to realize the soldering of the mechanical and electrical connection between the soldering end of the component or the pin and the pad of the circuit board. So, what is the control standard of SMT patch wave soldering process parameters?

1. Preheating temperature

The function of preheating is to fully volatilize the solvent in the flux, so as to avoid affecting the wetting of the circuit board and the formation of solder joints when the circuit board passes through the solder, so that the circuit board reaches a certain temperature before soldering, so as to avoid warping caused by thermal shock out of shape. Generally, the preheating temperature is controlled at 180~200C, and the preheating time is 1~3 minutes.

2. Orbit inclination

The influence of the orbital inclination on the welding effect is more obvious, especially when welding high-density SMT devices. When the inclination angle is too small, bridging is more likely to occur, especially in soldering, the shielded area of sMT devices is more prone to bridging, and the inclination angle is too large, although it is beneficial to the elimination of bridging, but the amount of tin in the solder joint is too small, and it is easy to produce virtual soldering. Therefore, the orbital indlination should be controlled between 5C and 7°C.

3. Peak height

The height of the wave crest will change due to the passage of soldering time. Appropriate corrections should be made during the soldering process to ensure the ideal height for soldering. The tinning depth is 1/2 - 1/3 of the PCB thickness.

4. Soldering temperature

Welding temperature is an important process parameter that affects welding quality. When the sc ldering temperature is too low, the expansion rate and wettability of the solder become poor, and due to insufficient wetting of the pad or component soldering end, defects such as virtual soldering, pulling, and bridging occur. When the soldering temperature is too high, It accelerates the oxidation of pads, component pins and solder, and is prone to false soldering. The welding temperature should be controlled at 250+5°C.