Solder balls refer to small spherical substances formed when solder is extruded between the solder pad and component lead during the wave soldering process. Silman Tech here shares with you the reasons for solder ball formation in wave soldering and preventive measures.
Firstly, the reasons for solder ball formation are as follows:
- Excessive soldering temperature: Solder has good thermal conductivity. If the temperature exceeds the solder’s melting point during soldering, it will cause solder melting and flow, ultimately forming solder balls.
- Influence of flux: Flux contains certain substances such as antimony, bismuth, etc., which promote solder flow and increase solder ball formation.
- Condition of the printed circuit board (PCB) surface: If the PCB surface contains oxides or other impurities, these substances react with solder during wave soldering, leading to solder ball formation.
To prevent solder ball formation, we can take the following preventive measures:
- Control soldering temperature: Choose the appropriate soldering temperature based on the size and shape of components, typically not exceeding 300°C.
- Choose appropriate flux: Use flux without substances such as antimony and bismuth.
- Maintain cleanliness of the PCB surface: Clean the PCB surface with alcohol or other cleaning agents.
- Use anti-solder ball flux: Some fluxes contain anti-solder ball components, which can be applied to the PCB before wave soldering to reduce solder ball formation.
- Choose appropriate solder resist film: Smooth solder resist film surfaces are relatively prone to solder ball formation.
- Increase the surface roughness of the PCB: Decrease the contact area between solder balls and the PCB surface, facilitating solder ball return to the solder pot.
- Preheat the PCB before soldering.
For cleaning solder balls, we can use the following method:
Use Silman Tech PCBA brush cleaning machine for cleaning. The DEZ-C758 is mainly used for cleaning various types and large quantities of PCBA circuit boards with single-side solder joints, coating products, and high-end precision products in military, aerospace, medical, automotive new energy, and other industries, effectively cleaning organic and inorganic contaminants such as flux residues on the surface of PCBA boards after DIP/THT soldering…
By implementing the above preventive measures, we can effectively reduce solder ball formation during the wave soldering process and improve soldering quality.
