What are the reasons for the oxidation of PCB pads?
Solder pad oxidation refers to the formation of an oxide layer on the surface of the solder pad due to a chemical reaction between the pad and oxygen in the air. This layer hinders solder wetting, making it difficult for solder to form a good bond on the surface of the pad, resulting in poor soldering. The causes of solder pad oxidation can be summarized as follows:
- PCB material issues: Poor quality of PCB material, improper surface treatment, and long storage time can cause solder pad oxidation. For example, excessive moisture or other contaminants in the PCB material can promote oxidation.
- Environmental issues: Oxidation occurs when oxygen and other chemicals react at a certain temperature and humidity. Therefore, factors such as temperature, humidity, and oxygen concentration in the environment can affect the degree of solder pad oxidation. For example, a high-temperature and high-humidity environment is more likely to cause solder pad oxidation.
- Process issues: Improper process parameter settings for PCB assembly, such as high soldering temperature or duration, can cause solder pad oxidation. For example, a high soldering temperature can promote the oxidation reaction on the surface of the pad, aggravating the degree of solder pad oxidation.
To prevent solder pad oxidation from occurring, we can take the following measures:
- Choose high-quality PCB materials and ensure that their surface treatment is adequate to reduce the risk of solder pad oxidation.
- Control the temperature, humidity, oxygen concentration, and other factors of the PCB assembly environment to ensure that they are within an appropriate range.
- Reasonably set the process parameters for PCB assembly to avoid high soldering temperature and duration.
- Use some special soldering fluids during actual soldering to help remove the oxide layer on the surface of the solder pad and improve soldering reliability.
In summary, solder pad oxidation is a common issue during PCB assembly, and its causes are closely related to PCB materials, environment, and process factors. We can reduce the risk of solder pad oxidation and improve product quality and reliability by choosing high-quality materials, controlling environmental and process parameters, and using special soldering fluids.