During the PCBA manufacturing process, residues of solder paste and flux are inevitable. Over time, these residues can solidify, forming corrosion substances such as metal halides, which can adversely affect the stability and lifespan of the PCB. Therefore, it’s essential to thoroughly remove residual solder paste, flux, and other contaminants from the surface of PCBA boards after manufacturing to maintain cleanliness and integrity. There are various types of solvents for cleaning PCBA circuit board surfaces available in the market. Here’s how to choose the right one:
- Solvent-based Cleaning Agents: Solvent-based cleaning agents can be categorized into hydrocarbon solvents, halogenated solvents, and fluorinated solvents. Solvent-based cleaning agents are self-cleaning and have low residues. However, they are prone to evaporation and volatility, requiring special attention in storage due to environmental protection policies. In recent years, the use of halogenated and fluorinated solvents has decreased due to environmental regulations. When using hydrocarbon solvents, fire prevention measures for equipment and environment should be taken into account. Additionally, measures to prevent leakage of volatile organic compounds must be considered. Hydrocarbon solvent-based cleaning agents are effective for removing residues of some rosin-based and no-clean fluxes, oils, and dirt, especially in small-scale PCBA prototyping.
- Water-based Cleaning Solutions: Water-based cleaning solutions can be used in most scenarios. However, when selecting water-based cleaning solutions, considerations should be made for surface compatibility with the PCB, metallization, and components, including compatibility with reaction products of lead oxide, white metals, yellow metals, ink markings, and coating materials. Factors such as the size, spacing, and complexity of assembly components should also be considered. Different types of flux residues have different compositions, and the cleaning materials in water-based cleaning solutions have varying capabilities to remove soldering residues. Water-based cleaning processes include ultrasonic cleaning and spray cleaning. In spray cleaning, there is lower tolerance for foam, requiring foam-free or minimally foaming solutions that dissipate quickly.
Understanding the composition of residues on PCBA circuit boards allows for choosing between solvent-based cleaning agents and water-based cleaning solutions based on specific needs while considering environmental pollution concerns. For large-scale cleaning, professional PCBA cleaning equipment like Silman Tech can effectively remove organic and inorganic contaminants left on PCBA boards after soldering, especially for DIP/THT assemblies.