ReflowLötverfahren

ReflowLötverfahren, also known as reflow soldering, is a soldering process used in the electronics industry to create a permanent electrical connection between electronic components and a printed circuit board (PCB). It is a widely adopted technique, especially for surface-mount technology (SMT) components.

The process begins with the application of solder paste, a mixture of solder powder and flux, to the solder pads on the PCB. This paste is precisely deposited using stencils or dispensing machines. Once the components are placed onto the solder paste on the PCB, the assembly is moved into a reflow oven. The oven employs a carefully controlled temperature profile. This profile typically involves several zones: a preheat zone to gradually raise the temperature and drive off volatile solvents in the paste, a soak zone to ensure uniform temperature across the assembly and activate the flux, and finally, a reflow zone where the temperature exceeds the melting point of the solder.

In the reflow zone, the solder paste melts, forming a molten solder joint that wets the component leads and the PCB pads. As the assembly passes through the cooling zone, the solder solidifies, creating a robust electrical and mechanical connection. The flux within the solder paste plays a crucial role by cleaning the surfaces to be soldered, preventing oxidation, and promoting good solder wetting. The precise temperature control is critical to prevent damage to sensitive electronic components and ensure the formation of high-quality solder joints free from defects.