What are the cleaning solvents for PCBA circuit board surface?

During the PCBA processing, the use of solder paste and flux will produce residual substances. The flux residue will gradually harden over time and form corrosive substances such as metal halides, which will have an adverse effect on the reliability and service life of the PCB board. Therefore, after the PCBA processing is completed, the residual flux, solder and other contaminants on the PCB board need to be thoroughly removed to keep the surface of the PCBA board clean and tidy. There are many types of PCBA circuit board surface cleaning solvents on the market, so how should we choose? 

1. Solvent cleaning agent

Solvent cleaning agents can be divided into hydrocarbon solvents, halogenated solvents, and fluorinated solvents. Solvent-based cleaning agents are self-cleaning and low-residue cleaning agents. The disadvantage is that they are easy to evaporate and volatilize, and special attention needs to be paid to storage. Due to the requirements of environmental protection policies, halogenated solvents and fluorinated solvents have been used less in recent years. When using hydrocarbon cleaning agents, attention should be paid to fire prevention measures on machines and the environment, and leakage prevention of volatile organic compounds should also be considered. Only when these situations are handled well can hydrocarbon solvent cleaning agents be used in small batch PCBA proofing. Hydrocarbon cleaning agents have better effects on some rosin-type and some no-clean flux residues, oil stains, and dirt.

2. Water-based cleaning agents

Water-based cleaning agents can be used in most scenarios, but when choosing water-based cleaning agents, the limitations of circuit board surface, metallization, and compatibility should be considered, including the compatibility of lead oxide reactants, white metals, yellow metals, ink markings, and coating materials, followed by the size, spacing, and complexity of the assembly. Different types of flux residues have different components, and the cleaning materials of water-based cleaning agents have different abilities to remove solder residues. At the same time, the cleaning process of water-based cleaning agents also includes ultrasonic cleaning process and spray cleaning process. In spray cleaning, the tolerance for foam is lower, requiring no foam or very small foam that can dissipate quickly.

When we know the composition of the residues remaining on the PCBA circuit board, we can choose whether to use solvent cleaning agents or water-based cleaning agents according to actual needs. When the cleaning conditions are met, we also need to consider environmental protection issues.