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SMT pcb assembly welding process and equipment introduction

 

In SMT PCB assembly, welding is the main process technology in surface assembly technology. It is the link to complete the electrical connection of components. It is directly related to the reliability of the product. It is also one of the key factors affecting the pass rate of the whole process. Currently the main methods in smt welding process are reflow soldering and wave soldering. Wave soldering is mainly used in the traditional through-hole insertion process, as well as the mixing process of surface assembly and through-hole components. Surface mount components for wave soldering include rectangular and cylindrical chip components, SOTs, and smaller SOP devices. With the development of ultra-small chip components and multi-pin fine pitch devices, especially the development of BGA devices, wave soldering has not been able to meet the soldering requirements, so the SMT pcb assembly manufacturing process is mainly based on reflow soldering.

SMT pcb assembly welding process and equipment introduction

SMT pcb assembly welding process and equipment introduction

Reflow soldering is a process in which a spherical powdered solder in a region where solder paste is applied is melted and aggregated by heating, and is filled into a weld seam by surface adsorption and capillary action to achieve metallurgical joining. As the PCB mounting method is changed from the traditional through-hole mounting (THT) method to the surface mounting (SMT) method, the reflow soldering method is rapidly becoming one of the mainstream technologies for modern electronic equipment automation soldering (hereinafter referred to as soldering). .

 

Reflow soldering principle

Reflow soldering is apply a proper amount solder in PCB soldering part, and then the surface mount components are mounted, and then the external heat source is used to reach soldering purpose in form of group or point by point. The reflow soldering process is the last process of smt pcb assembly, which is the link to complete the electrical connection of components, directly related to product reliability. The basic process flow for reflow soldering is shown in the figure. Among them, the temperature profile is the most important factor affecting the results of reflow soldering.

 

Reflow soldering process→welding preparation→setting parameter→test temperature profile→reflow welding→(1.inspect rework  2.defect analysis  3.process conclusion)

 

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