Investigations On Quality Control Of Solder Joints Based On Selective Wave Soldering

Reviewing the development process of soldering technology in electronic industryrecently, we can see that more and more surface mount electronic components were appliedwidely in the high density electrical products along with the rapid development of SMT（surface mount technology）. However, some connectors, sensors and transformers and otherthrough-hole shield components are still used popularly. The selective wave soldering is aspecial wave soldering technology in order to meet the requirements of the development ofthe through-hole components. Selective wave soldering machine generally contains threemodules which are flux coating, preheating and soldering, and the machine can beprogrammed. The flux coating module can spray the flux to the selective areas, and afterpreheating by the preheating module, the soldering joints can be formed by the solderingmodule. The emergence of selective wave soldering make the high density and diversityproducts can be achieved easily; at the same time, it also contributed handed through-holemodule components into a wide use. But the quality of soldering joints cannot be overlookedin the product reliability. So it has become an important problem to achieve the overallwetting between the through-hole components and the pad of the PCB.Based on these problems, this dissertation will briefly introduce the selective solderingequipment architecture, soldering principles and techniques. Then, aiming at the problem ofthe ATCA-9301(Advanced Telecom Computing Architecture) products in selective wavesoldering, we prove up the effecting factor of the soldering joint qualities by the DOE method(design of experiment), and check and maintain the machine. Finally, we define the basicparameter settings by the selective wave soldering for ATCA-9301electronic products, andthe object of the quality control of the soldering joint is achieved.The experiment shows that the poor wetting of the solder joints in electronic productsduring the selective wave soldering can be improved by the DOE test method which canachieve a series of the optimization. As for ATCA-9301product, when the amount of flux is70%or the speed of flux spraying is5mm/s, the heating temperature of the top PCB is120℃and the actual temperature of the surface of PCB is105℃, the tin cylinder temperature is setfor290℃, the moving speed of nozzle is3mm/s, the wetting criterion of solder joints can beachieved the IPC-1-610-D, resulting in the high reliability of solder joints.