Electronic products manufacturing industry to implement lead-free process to face the following problems: 1) lead-free solder; 2) components and PCB plate lead-free; 3) lead-free welding equipment
Lead free solder of 1)
So far, the world has reported nearly a hundred kinds of lead-free solder components, but the real is recognized and widely used in the industry is Sn-Ag-Cu three yuan, there are multiple alloys, add In, Bi, Zn and other components. Present international is the coexistence of a variety of lead-free solder alloys situation, to electronic product manufacturing costs increase, different customers for different solder and different process requirements, the development trend of the future will tend to uniform solder alloys.
(1) the melting point is high, about 30 degrees higher than the Sn-Pb;
(2) the ductility has declined, but there is no long-term deterioration;
(3) the welding time is about 4 seconds;
(4) the initial strength and late strength of the tensile strength are better than that of Sn-Pb.
(5) fatigue resistance.
(6) on the thermal stability of flux more demanding.
(7) high Sn content, high temperature of Fe has a strong solubility in view of the characteristics of lead-free solder determines the new lead-free soldering process and equipment
2) lead free components and PCB board
In lead-free soldering process, components and PCB plating lead-free technology is relatively complex, involving a wider area, which is an international environmental protection organization delayed lead-free process is one of the reasons, in a long period of time, the coexistence of lead-free solder and Sn Pb PCB plating, and bring the peel (Lift-Off) "and other welding defects, equipment manufacturers have to from the device and overcome this phenomenon. In addition to the PCB board production process requirements are relatively increased, PCB plate and components of the material requirements for better heat resistance.
Lead free welding equipment 3)
Due to the particularity of the lead-free solder, lead-free soldering process of lead-free welding equipment must be solved lead-free solder welding defects and solder on equipment influence, preheating / tin furnace temperature, nozzle structure, oxides, corrosion, welding after quench, flux coating, nitrogen protection.