I believe you are referring to “wave soldering,” a widely used soldering process in electronics manufacturing. Wave soldering is a technique used to solder electronic components onto a printed circuit board (PCB) efficiently and consistently. It is especially common for through-hole components, which have wire leads that pass through holes in the PCB.
Here’s an overview of how wave soldering works:
1. PCB Preparation: Before the soldering process begins, the PCB is prepared by inserting the through-hole electronic components into their designated positions on the board. These components typically have leads or pins that protrude through the PCB.
2. Flux Application: A flux is applied to the PCB, either by spraying or foam application. Flux serves several purposes in the soldering process, including cleaning the metal surfaces, preventing oxidation, and improving solder wetting (the ability of solder to flow and adhere to the metal surfaces).
3. Preheating: The PCB is preheated in a conveyorized oven. Preheating is essential to bring the entire assembly up to a uniform temperature, which helps prevent thermal shock and promotes better soldering results.
4. Solder Wave: The key feature of wave soldering is the use of a “solder wave.” This wave consists of molten solder (typically a tin-lead alloy) maintained at a controlled temperature. The solder wave is generated by a pump and nozzle system.
5. Solder Contact: The PCB is then passed over the solder wave. As it does so, the solder wave wets the exposed metal surfaces of the component leads and the PCB pads, creating a strong, conductive bond.
6. Solder Cooling: After passing over the solder wave, the soldered assembly moves through a cooling zone. This rapidly cools the solder, solidifying it and ensuring the components stay in place.
7. Inspection: The soldered PCB is inspected for defects, such as solder bridges (unwanted connections between adjacent pads), insufficient solder, or cold solder joints (improperly formed joints). Any defects are identified and corrected if necessary.
8. Cleaning: Depending on the application and the type of flux used, the PCB may undergo a cleaning process to remove any remaining flux residues. This step is crucial to ensure the long-term reliability of the assembly.
Wave soldering is particularly suited for high-volume production because it allows for the simultaneous soldering of multiple components on a PCB. It’s an efficient and reliable process for through-hole component assembly. However, it’s worth noting that with the increasing use of surface mount technology (SMT), which uses different soldering methods, wave soldering is less commonly used for modern electronic devices that primarily consist of SMT components. SMT components are typically smaller and soldered using reflow soldering techniques.