The four factors affecting the stability of PCBA cleaning process were reviewed

For a long time, the industry's understanding of the cleaning process was not sufficient. Mainly because the previous PCBA assembly density is low, the adverse effects of pollutants such as flux residues on electrical performance are not easy to be detected. Nowadays, with the development of the design of PCBA to miniaturization, the device size and the spacing between the devices have become smaller, and the short-circuit and electrochemical migration caused by small particle residues have attracted widespread attention. In order to adapt to market trends and improve product reliability, more and more SMT manufacturers have started a journey of learning about the cleaning process. The cleaning process is a process that combines the static cleaning force of the cleaning agent and the dynamic cleaning force of the cleaning equipment to finally remove the pollutants. PCBA cleaning is divided into SMT (SMT) and plug-in (THT) two stages, through cleaning can remove the accumulation of surface pollutants during the processing of products, reduce the risk of surface contamination and reduce reliability of products. In the electronics manufacturing and semiconductor processing industries, choosing the right cleaning agent with the right cleaning equipment is very important. The factors that affect the stability of PCBA cleaning process mainly include: cleaning object, cleaning equipment, cleaning agent and process control. Under normal circumstances, the cleaning object is the solder paste and flux residue, which will cause electrochemical migration, corrosion and short circuit, which brings a great threat to the reliability of the product, but it does not exclude large particle pollution, oil stains and sweat stains on the surface of the circuit board. The material properties and surface conditions of different PCBA are also different. The ZESTRON Technical Center conducts free cleaning tests every day, and in many cases the customer's product cannot be flooded and therefore is not suitable for the immersion cleaning process! In addition, some components are made of sensitive metals, which are very fragile and cannot be cleaned using ultrasonic waves, otherwise those bubbles will shatter the components when they explode. There are also some components that must be treated "gently" with a pH neutral cleaning solution! Usually the surface of the circuit board has a very complex geometric structure, and the integrated density is also very high. When the distance between the device and the substrate is very small, the water droplets of deionized water can not drill into the small gap, and it is unable to remove the pollutants at the bottom of the device, and chemical cleaning agents are needed to help. Cleaning agent Choosing a special cleaning agent is very important. The ZESTRON database stores more than 2,500 formulations and related raw materials, with a rich portfolio of water-based, semi-water-based and solvent-based products designed for different contaminants. Material compatibility is often overlooked but vital part of the cleaning process, such as: the power module package has a variety of metal materials such as copper, nickel or aluminum, improper cleaning process can easily lead to corrosion or oxidation of the surface of aluminum chips and copper, and some characters fall off. Therefore, the material incompatibility between the cleaning agent and the cleaning object, and between the cleaning agent and the cleaning equipment may lead to product scrap, or cause the blockage of the equipment pipeline. As a chemical used in the production line and may directly contact the human body, improper operation may cause personal injury and economic loss. ZESTRON has been a green and safe cleaning product since 1989, when it developed the first alternative to CFCS. At all times, ZESTRON is committed to compliance with REACH, the RoHS Directive and the WEEE Directive. ZESTRON cleaning agent does not contain ODS ozone layer destroying components and VOC content meets national standards. Cleaning equipment A complete cleaning process usually includes cleaning, rinsing and drying these three processes, in the cleaning process, cleaning agent and pollutants contact each other, cleaning agent will separate the pollutants from the surface of the cleaning object; The rinsing and drying process is mainly to further remove contaminants, but also to ensure that there is no residue of cleaning agent on the surface of the components. The ZESTRON Technical Center houses more than 100 cleaning equipment from the world's leading cleaning equipment manufacturers. From off-line batch cleaning equipment, such as ultrasonic cleaning equipment, submerged cleaning equipment, centrifugal cleaning equipment, to online spray equipment, customers can choose from a variety of common cleaning mechanics. ZESTRON can test your products under real production conditions and evaluate cleaning applications, cleaning equipment, and cleaning agents according to customer requirements. Cleaning process control With the increase of cleaning time, the continuous entry of pollutants in the cleaning solution will have a negative impact on the cleaning efficiency. When should I change the fluid? When is the latest fluid change? How to adjust the cleaning parameters when the environment/product changes? These questions are directly related to the customer's cost and output, and the key to finding answers lies in the collection of cleaning data, including: time, movement, concentration and temperature. Among them, the cleaning solution will be affected by many factors in the process of use, such as: residue in the liquid, the evaporation of the liquid, the addition of deionized water, etc., and its concentration will often fluctuate. Therefore, in the circuit cleaning process, the concentration monitoring is directly related to the stability of the cleaning effect.