After soldering is completed, impurities remaining on the surface and surrounding areas of the solder ball will affect the performance and stability of electronic devices, and cleaning becomes a key link. The first step is to choose a suitable cleaning agent. Different types of impurities require targeted cleaning solutions. For common flux residues, water-soluble cleaners are the first choice due to their mild and efficient characteristics. This type of cleaner can quickly penetrate into the impurities and decompose them into water-soluble substances by chemically reacting with the flux components, laying the foundation for subsequent cleaning.
There are detailed considerations on the application method of the cleaner. Manual wiping is suitable for small or local welding scenarios. The operator uses a dust-free cloth to dip an appropriate amount of cleaning agent and gently wipes the surface and surrounding areas of the solder ball. The wiping process needs to control the intensity to ensure that the impurities are fully dissolved and removed, and not to damage the solder ball and surrounding fragile electronic components. For large-scale production of circuit boards, automated spray cleaning equipment plays an important role. The cleaning agent is sprayed on the surface of the circuit board in a uniform mist. With the precise control of the equipment, the cleaning agent is fully covered on every solder ball and the corner of the gap to ensure the thoroughness of the cleaning.
Ultrasonic cleaning technology shows unique advantages in the cleaning of solder balls. The circuit board coated with the cleaning agent is placed in an ultrasonic cleaning tank filled with cleaning liquid. The high-frequency vibration of the ultrasonic wave will produce countless tiny bubbles in the liquid. These bubbles will produce a strong impact when they burst instantly, like countless tiny "cleaning hammers", which can penetrate into the gaps and holes of the solder ball and peel off stubborn impurities from the surface. This physical action cooperates with the chemical action of the cleaning agent, and even impurities hidden at the bottom of the solder ball or in the gaps between components can be effectively removed.
The rinsing step is a necessary step to completely remove residual impurities and cleaning agents. Deionized water is used for rinsing. Deionized water is specially treated and does not contain conductive ions, which can avoid the risk of circuit short circuit caused by impurities in ordinary water. During the rinsing process, the direction and pressure of the water flow need to be precisely controlled. The appropriate water flow direction can follow the wiring of the circuit board and the arrangement of the solder ball, and smoothly take away the dissolved impurities and detergents; and the appropriate water pressure can ensure the strength of the flushing, ensure that the impurities are completely flushed, and will not cause impact damage to the solder ball and electronic components.
Drying is crucial to the consolidation of the solder ball cleaning effect. Although the natural drying method is simple, it takes a long time, and it is easy for the circuit board to absorb dust and other impurities again during the waiting process. Therefore, professional drying equipment is more popular. The hot air drying box blows out hot air at a constant temperature to quickly evaporate the moisture on the surface of the circuit board and the solder ball. The temperature and wind speed of the hot air are strictly set, which can achieve rapid drying without adversely affecting the solder ball and electronic components due to excessive temperature, ensuring that the cleaned circuit board is in a dry and clean state.
The detection of the cleaning effect is an important part of ensuring the quality of the solder ball cleaning process. With the help of precision testing instruments such as microscopes, technicians can zoom in and observe the details of the solder ball surface to check whether there are any impurities remaining. In addition, electrical performance tests will be conducted to detect whether the conductivity and insulation of the circuit board after cleaning are normal. Once it is found that the cleaning is not thorough or there are other problems, it will be cleaned again in time to avoid the hidden dangers of impurities remaining in the subsequent use of electronic equipment.
During the entire solder ball cleaning process, the control of the operating environment cannot be ignored. Cleaning work is usually carried out in a dust-free workshop. The air in the workshop is filtered at multiple levels to ensure that the content of pollutants such as dust and particles in the air is extremely low. Workers are also required to wear professional dust-proof clothing and gloves to prevent impurities they carry from contaminating the cleaned circuit boards and solder balls. At the same time, the temperature and humidity in the workshop are also kept in an appropriate range. Stable environmental conditions help the cleaning agent to achieve the best effect, ensure the smooth completion of the solder ball cleaning work, and provide a solid guarantee for the reliable operation of electronic devices.
