The manufacture and assembly of printed circuit boards requires a high-quality solder paste to connect the components to the board. The type of solder used will depend on the manufacturing process or technique being used. Liquid solder for electronics is ideal for the wave soldering method and applications that require low temperature soldering. Liquid solder is a heavy-duty, water-resistant, and strong adhesive that will keep the components properly bonded to the board. Like solder pastes, liquid solder for circuit boards contain metals that will help create a conductive joint between metal surfaces to establish an electrical connection.
There are different types of liquid solders, and the right product will depend on your assembly process. High-quality liquid solder for electronics are high-solid, no-clean, rosin-bearing, and alcohol-based dulling flux formulated to provide excellent solderability and electrical reliability in either tin-lead or lead-free wave soldering processes. Regardless of the product you will choose, make sure that it will comply with every major international requirement for SIR (surface insulation resistance) and EM (electromigration).
You will find that some types of liquid solder for circuit boards are practical for topside hole-fill applications with their superior resistance to connector bridging and micro-solderballing. Likewise, they can resist bridging, which can occur on the bottom side of SMT components, including the fine-pitch QFPs. Just make sure that they provide superb flux action for defect-free results and excellent electrical reliability in the long run.
A high-quality and specially formulated liquid solder for electronics will spread evenly and uniformly, with a non-tacky and clear residue on the solder mask. Flux dulls on its own to minimize glare on the solder joints, and this can be helpful when you conduct visual inspections. The solder may be applied via foaming or spraying, depending on your preferred process. Some manufacturers have created environmentally friendly liquid solder for circuit boards, such as the alcohol-based and water-based products that provide virtually defect-free soldering and excellent wetting properties.
Water-based fluxes are non-flammable, easily removable, and do not contain organic solvents. Moreover, they are formulated to meet the current and upcoming VOC (volatile organic compound) emission regulations. Non-flammability is an important feature in liquid solder, as it reduces the risk of overheating and fire during the wave soldering processes.