Soldering
Wave or reflow soldering is used for the fully-automatic or semi-automatic soldering of components to circuit boards and flat modules.
In wave soldering, after the circuit board has been assembled, it is heated and then passed over a solder wave. In this process, hot fluid solder is pumped through a gap (chip and delta wave) or, for example, through holes in a perforated plate (Wörthmann wave). The component?s solder pins take up the solder, which results in a perfect solder connection after the solder has cooled.
In reflow soldering, soldering paste is applied under pressure to the circuit board. As the applied solder has adhesive properties, the circuit board can be assembled without any further fixation, and can then pass through the furnace. After a pre-heating phase, the solder is heated to fusion temperature during the soldering phase. At this temperature, the solder becomes liquid, and this creates a bond between the component and circuit board. The result is a fault-free solder connection after the solder has cooled.
The soldering process consists of the following four main phases:
1. Preparation: In the wave soldering process, first the components are mounted on the circuit board. In reflow soldering, by contrast, first the soldering paste is applied, and then the components are mounted.
2. Preheating: During this phase, the assembled circuit boards are brought to a preheat temperature ? there are different processes for this purpose. The preheating method prevents deformation of the circuit board or its components and other damage.
3. Soldering: In wave soldering, the preheated circuit board passes over a solder wave. In reflow soldering, the entire circuit board is heated to the soldering temperature. The soldering time must be carefully selected to ensure that there is no damage to the circuit board or its heat-sensitive components.
4. Cooling: The circuit board components should be cooled under supervision immediately after soldering. This minimises thermal stress on the circuit board and its components.
Below we recommend the soldering temperature profiles for the various soldering processes. Please note that these are only recommended profiles, because it is not possible to list general parameters for different procedures, circuit boards and components. A soldering profile which produces optimal results must be calculated on an individual basis.
