Wave soldering is a manufacturing process used in the assembly of printed circuit boards (PCBs). It is primarily employed for soldering through-hole components to the PCB. The process involves creating a wave of molten solder, which components are passed through to create solder joints on the PCB.
Here’s a basic overview of how wave soldering works:
- Component Placement: Through-hole electronic components (components with wire leads) are placed onto the PCB. These components are positioned in their designated locations, and the leads extend through the holes in the PCB.
- Flux application: This is sprayed on to the underside of the PCB and serves to clean and prepare the PCB pads and component leads to be soldered. The cleaning ensures that a good solder joint is achieved.
- Preheat: The PCB with the components is preheated in a preheating zone. This step helps to gradually raise the temperature of the assembly, which can help prevent thermal shock to the components. It also flashes off the flux volatiles, which is important to avoid fires later in the process.
- Wave Soldering: The preheated PCB is then passed over a wave of molten solder on a conveyor. The solder wave is typically made of a lead-based or lead-free solder alloy (Active EMS only use lead-free solder). As the PCB passes over the wave, the molten solder makes contact with the exposed leads of the components. The flux in the solder paste helps ensure good solder wetting, forming strong and reliable solder
- Cooling and Solidification: After passing over the solder wave, the PCB is cooled to solidify the solder This can be achieved through various means, such as cooling fans or conveyor systems.
- Inspection: Once the solder joints have solidified, the PCB is typically inspected to ensure the quality of the solder Any defects, like solder bridges or insufficient solder, may be addressed.
Wave soldering is an efficient and relatively quick method for soldering through-hole components in mass production. It’s suitable for components that can withstand the high temperatures involved in the soldering process. However, because of the high temperatures and the use of flux, proper control and cleanliness are essential to ensure the quality and reliability of solder joints. Additionally, environmental concerns related to the use of lead-based solder have led to the development and adoption of the lead-free solder alloys used by Active EMS.