Principle and purpose of reflow soldering

Reflow soldering is a soft solder that realizes the mechanical and electrical connection between the solder ends of surface mounted components or the pins and the printed board pads by remelting the paste-loaded solder that is pre-distributed on the printed board pads. weld.

Principle of reflow soldering

The circuit board with the mounted smt components is transported through the reflow oven guide rail, and passes through the preheating zone, heat preservation zone, welding zone and cooling zone of the reflow oven respectively point.

A. When the PCB enters the heating zone, the solvent and gas in the solder paste evaporate. At the same time, the flux in the solder paste wets the pads, component terminals and pins, and the solder paste softens, collapses, and covers the solder paste. plate to isolate pads and component pins from oxygen.

B. When the PCB enters the heat preservation area, the PCB and components are fully preheated to prevent the PCB from suddenly entering the high temperature area of welding and damaging the PCB and components.

C. When the PCB enters the soldering area, the temperature rises rapidly so that the solder paste reaches a molten state, and the liquid solder wets, diffuses, diffuses, or reflow the pads, component ends and pins of the PCB to form solder joints.

D. The PCB enters the cooling zone to solidify the solder joints; when the reflow soldering is completed.

Purpose of reflow soldering

"Reflow soldering" is because the gas circulates in the welding machine to generate high temperature to achieve the purpose of welding. It is to send the circuit board with the SMD components installed into the SMT reflow soldering chamber, and then put the solder paste used to solder the SMD components after high temperature. The process of forming a reflow temperature change through high temperature hot air melts, so that the patch components are combined with the pads on the circuit board, and then cooled and welded together. Overall summary The purpose of reflow soldering is to pass the SMT patch components of passive pins through Solder paste and circuit board are welded together to form a finished PCBA circuit board with certain electrical properties.