Causes and solutions of fake welding in PCBA processing

Fake soldering is a common phenomenon in PCBA processing . Fake soldering is actually the SMT chip components that seem to be soldered to the pads, etc., which have not actually reached the point of complete integration, or it is possible. The intermediate unstable state that may be blocked will affect the circuit characteristics and may cause the multilayer PCB board to be unqualified or scrapped. Therefore, we must pay attention to the phenomenon of PCBA fake soldering. The reasons and solutions for PCBA soldering are introduced below.
 

 

The reasons for PCBA solder joints are as follows:
1. Oxidation of pads and component pins: Oxidation of pads and component pins can easily cause the solder paste to be liquefied during reflow soldering, and the solder pads cannot be fully wetted, and the solder is crawled, resulting in fake Welding.
2. Less tin: In the solder paste printing process, due to the small opening of the stencil or the too small pressure of the squeegee, there is less tin. As a result, the amount of solder paste is insufficient during soldering, and the components cannot be fully soldered, resulting in fake soldering.
3. Too high or too low temperature: In addition to low temperature, it will cause fake welding, and the temperature should not be too high. Because the temperature is too high, not only the soldering tin will flow, but also the surface oxidation speed will be aggravated, which may result in fake soldering or failure of soldering.
4. Low melting point of solder paste: For some low temperature solder pastes, the melting point is relatively low, and the component pins and the board materials of the fixed components are different, and their thermal expansion coefficients are different. Under the force of shrinkage, fake welding will occur.
5. The quality of solder paste: The quality of solder paste is not good, the solder paste is easily oxidized, and the flux loss will directly affect the soldering performance of the solder paste, leading to fake soldering.
 
In general, the situation of PCBA's fake soldering is complicated, and strict process control in production is required to optimize the process flow.
 
Methods to solve PCBA fake soldering:
PCBA fake welding can reduce the occurrence of virtual welding through the pre-material storage, post-processing and other links. This requires our electronic processing companies to strictly standardize the production management process. The specific measures are as follows:
1. The components must be stored in moisture-proof;
2. The in-line electrical appliances can be slightly polished;
3. When soldering, you can use solder paste and flux, it is best to use a reflow soldering machine, manual soldering requires good technology;
4. Reasonably choose a good PCB substrate material.

In the process of PCBA manufacturing processing, fake soldering is an important reason that affects the quality of the circuit board. Once the fake soldering phenomenon occurs, it needs to be reworked, which not only increases labor pressure, but also reduces production efficiency and causes losses to the enterprise. The POE PCBA processing plant will strictly control each link, do a good job of inspection, and complete each customer's order with quality and quantity.