Cleaning after SMT soldering is a normal PCBA quality control process, and ultrasonic cleaning is commonly used. So, what issues should be paid attention to in the cleaning after SMT PCB assembly welding? Let me share with you:
1. The principle of ultrasonic cleaning
The cleaning agent produces cavitation and diffusion under the action of ultrasonic waves. When the holes are generated, a strong impact force is generated, which frees the contaminants adhering to the surface of the object to be cleaned: the vibration of the ultrasonic wave causes the liquid particles of the cleaning agent to diffuse and accelerates the dissolution rate of the cleaning agent to the contaminants. Therefore, contaminants in the bottom of the components, between components and in small gaps can be cleaned.
2. The selection principle of cleaning agent
① It has good wettability and low surface tension, so that the contaminants on the surface of the assembled board are fully wetted and dissolved.
②The capillary action is moderate, which can penetrate into the seams of the laundry and is easy to discharge.
③High density, which can slow down the volatilization rate of solvents and reduce environmental pollution.
④The boiling point is high, which is conducive to vapor condensation, and the cleaning efficiency can be improved by raising the temperature.
⑤Strong dissolving ability. The dissolving ability is also called the KB value. The larger the KB value, the stronger the ability to dissolve pollutants.
⑥Small corrosive (corrosive). It does not corrode the package body of the components, the printed board and the solder joints.
⑦It is harmless to human body and has little environmental pollution.
⑧ Good safety, non-flammable and explosive.
⑨ Low cost.
The above are the two issues that should be paid attention to in the cleaning after SMT PCB board soldering. I believe it will be helpful to you.