Amber PCB Blog

pcb industry technology development process, a clear trend reflow technology. In principle, the traditional plug pieces can also be used reflow process, which is commonly referred to as through-hole reflow. The advantage is possible at the same time to complete all the solder joints, so that production costs to a minimum. However, it limits the temperature-sensitive components of the application of reflow soldering, both cartridge cases or SMD. Then people turn select welding. Most applications can be used in the selection after reflow soldering welding. This will become an economic and efficient completion of the remaining parts of the welding cartridge, but also in the future lead-free solder compatible.

Characteristics of selective soldering process

By comparison with the wave soldering process to understand the characteristics of selectivity. The most obvious difference between the two is the lower part of the wave soldering PCB completely immersed in liquid solder, soldering in the selective, only some specific regions with the solder wave exposure. As the PCB itself is a bad heat conduction medium, so that it does not heat melt welding components and PCB area adjacent joints. Prior to soldering flux must be pre-coating. Compared with the wave soldering flux coating only the lower part of the PCB area to be welded, rather than the entire PCB. Other selective soldering components only for plug welding. Selective soldering is a new approach, a thorough understanding of welding and selective soldering equipment is necessary for success.

Selective soldering process

Selective soldering process typically includes: the flux coating, PCB preheat, dip soldering and drag soldering.

Flux Coating Process

In selective soldering, the flux coating process plays an important role. Welding heat and weld end of the active flux should be sufficient to prevent bridging and to prevent the formation PCB produce oxidation. Spray flux from the X / Y PCB manipulator carrying the nozzle through the flux above the flux coating to the PCB to be soldered position. Flux with a single spray nozzle, micro jet, simultaneous multi-point / graphics spray a variety of ways. Peak reflow process after the election microwave welding, the most important thing is accurate spray flux. Micro jet solder joints will not soiled beyond the region. Micro-point spray flux point graphics diameter greater than the minimum 2mm, so spray deposition flux on the PCB location accuracy of ± 0.5mm, can guarantee the flux is always covered in the welded parts of the above, the tolerance dose of spray welding provided by the supplier, technical specifications should provide for the use of flux, usually 100% of the proposed safety tolerances.

Preheating process

In the selective soldering process is not the main purpose of preheating to reduce heat stress, but to remove the solvent pre-drying flux, before entering the solder wave so that the correct viscosity flux. In welding, preheat the heat brought on the welding quality is not a key factor, PCB thickness, device packaging requirements and the type of flux preheat temperature settings. In selective soldering, there are different theories on the interpretation of preheating: Some process engineers that the PCB flux spray should be carried out before preheating; another point of view directly without preheating welding. Users can be arranged according to the specific situation of selective soldering process.

Welding Technology

Selective soldering process, there are two different processes: drag welding process and dip soldering process.

Selective soldering process is dragging on a single small welding done on wave solder nozzle.

pcb circuit board industry technology development process, a clear trend reflow technology. In principle, the traditional plug pieces can also be used reflow process, which is commonly referred to as through-hole reflow. The advantage is possible at the same time to complete all the solder joints, so that production costs to a minimum. However, it limits the temperature-sensitive components of the application of reflow soldering, both cartridge cases or SMD. Then people turn select welding. Most applications can be used in the selection after reflow soldering welding. This will become an economic and efficient completion of the remaining parts of the welding cartridge, but also in the future lead-free solder compatible.

Characteristics of selective soldering process

By comparison with the wave soldering process to understand the characteristics of selectivity. The most obvious difference between the two is the lower part of the wave soldering PCB completely immersed in liquid solder, soldering in the selective, only some specific regions with the solder wave exposure. As the PCB itself is a bad heat conduction medium, so that it does not heat melt welding components and PCB area adjacent joints. Prior to soldering flux must be pre-coating. Compared with the wave soldering flux coating only the lower part of the PCB area to be welded, rather than the entire PCB. Other selective soldering components only for plug welding. Selective soldering is a new approach, a thorough understanding of welding and selective soldering equipment is necessary for success.

Selective soldering process

Selective soldering process typically includes: the flux coating, PCB preheat, dip soldering and drag soldering.

Flux Coating Process

In selective soldering, the flux coating process plays an important role. Welding heat and weld end of the active flux should be sufficient to prevent bridging and to prevent the formation PCB produce oxidation. Spray flux from the X / Y PCB manipulator carrying the nozzle through the flux above the flux coating to the PCB to be soldered position. Flux with a single spray nozzle, micro jet, simultaneous multi-point / graphics spray a variety of ways. Peak reflow process after the election microwave welding, the most important thing is accurate spray flux. Micro jet solder joints will not soiled beyond the region. Micro-point spray flux point graphics diameter greater than the minimum 2mm, so spray deposition flux on the PCB location accuracy of ± 0.5mm, can guarantee the flux is always covered in the welded parts of the above, the tolerance dose of spray welding provided by the supplier, technical specifications should provide for the use of flux, usually 100% of the proposed safety tolerances.

Preheating process

In the selective soldering process is not the main purpose of preheating to reduce heat stress, but to remove the solvent pre-drying flux, before entering the solder wave so that the correct viscosity flux. In welding, preheat the heat brought on the welding quality is not a key factor, PCB thickness, device packaging requirements and the type of flux preheat temperature settings. In selective soldering, there are different theories on the interpretation of preheating: Some process engineers that the PCB flux spray should be carried out before preheating; another point of view directly without preheating welding. Users can be arranged according to the specific situation of selective soldering process.

Welding Technology

Selective soldering process, there are two different processes: drag welding process and dip soldering process.