1. the use of solder paste is different

        The biggest feature of no-clean solder paste is that it can be free from cleaning. After the circuit board is soldered with no-clean solder paste, it can proceed to the next step of testing and assembly without cleaning. After SMT manufacturers use solder paste for soldering, the surface of the circuit board is relatively clean, and the volatilized residue after the solder paste is melted is relatively small. The circuit board can pass the inspection of various electrical performance indicators, and does not need to use the secondary cleaning technology. The flux residue of the no-clean solder paste is not easy to combine with the water vapor in the air to cause the circuit board to become damp, so in the general use environment, the products produced by SMT manufacturers using this lead-free solder paste will not Short circuit and corrosion phenomena occur. The biggest advantage of using no-clean cleaning is that it can be freed from cleaning. SMT manufacturers can save a lot of labor by using this solder paste. In the entire electronic soldering industry, saving labor is saving money. Using this lead-free solder paste can save a lot of money for SMT manufacturers. The water-washed solder paste needs to be cleaned with water after use, which greatly wastes the labor cost of the manufacturer. The biggest difference between the two lead-free solder pastes is whether the SMT manufacturer needs to use water for cleaning after the soldering is completed.

2. Different solder paste residues

        The reason why the water-washed solder paste needs to be cleaned with water after the soldering is completed is because the components in the flux added by the solder paste manufacturer during the production process may corrode the circuit board after the soldering is completed, and water needs to be used. to clean. After the water-washed solder paste is soldered, it is necessary to soak the soldered circuit board in water or alcohol for about 5 to 10 minutes. It is also necessary to use a brush to clean the residue after the water-washed solder paste is soldered, and then rinse it again. Only then can the above lead-free solder paste residue be removed. After the circuit board is cleaned, it needs to use hot air of about 60~80 degrees to dry the circuit board or wait for it to dry naturally. After the circuit board is dried, the whole welding process is completed, and the next step of testing and assembly can be performed. No-clean solder paste does not require the entire cleaning process. After the soldering is completed, the circuit board can be directly tested and assembled in the next step. The two lead-free solder pastes are used differently because of the different residues after soldering.

3. The use environment of solder paste is different

        In another process of washing solder paste, SMT chip manufacturers have time requirements for the process of washing the circuit board after using the solder paste. The general requirement is that it must be cleaned within 4 hours, otherwise the above Residues will be dangerous to the board, possibly corroding the board. The white powder remaining after soldering of these lead-free solder pastes is very dangerous. If it is not cleaned in time, it will cause great damage to the circuit board. Solder paste manufacturers recommend that after the circuit board is soldered, the soldering residue of the above water-washed solder paste must be cleaned within 4 hours. Lead-free solder paste manufacturers believe that there is no major problem in cleaning the no-clean solder paste solder residue on the circuit board within 4 hours. Through cleaning, the solder joints of the circuit board will be very bright, and will also become very clean due to cleaning. The general cleaning process is first to use tap water to warm and rinse, rinse with water at the point of use, and finally use a hot air knife to blow the entire cleaned circuit board clean, and the entire SMT lead-free solder paste soldering process is completed.