Research On Lead-free Electronic Assembly Technology

As a kind of poisoned substance to human health, lead, owns strong affinity to thehuman body. It mainly through harming the people’s nervous system、 hematopoieticsystem and the digestive system to damage human health. Lead poisoning is also thefinal killer of leukemia、kidney disease、heart disease and spirit unusual. With therequirements of environment protection and the promotion of ISO14000, most countriesin the world banned the use of lead composition in welding materials, in order toachieve the lead-free solder.Spread lead-free welding materials have a serious of effects on welding technology.Therefore, in the development of lead-free soldering process，welding process must beoptimized in all relevant aspects. Currently，there are a lot of information based onlead-free welding materials and lead-free welding process. It is important for thesefactories need for developing of lead-free craft to carefully screening these information，with the purpose of organically combined them. To develop a sound， high qualified oflead-free welding line， they must to make plan carefully， and conscientiouslyimplement the plan. In addition， because lead-free has changed many aspects ofmaterials，equipment and welding technology， they must to establish a strict processcontrol system to ensure the quality of the products and make process under controlled.This paper made lead-free electronic assembly technology as the research object.We mainly researched the application situation of lead-free materials, and discussedwhere should be noticed and improved in several key technologies and equipmentsinvolved electronic assembly in order to adapt to the lead-free. Finally，we researchedthe reliability problems of lead-free solder joints. Then, we made PCBA sample oflead-free soldering in three ways of reflow soldering，wave soldering and manualwelding. Through the reliability testing of those PCBA sample，we found weldingtechnology conditions that meet lead-free soldering PCBA technical indexes required.The research results of this thesis have guidance and reference significance tolead-free materials selection，and lead-free electronics assembly and production.