Leaching Behavior Of Solder Of Solder Alloys And Their Joints In Simulated Soid Salt Solutions

With the development of Electronic technology, more and more electronic product have been abandoning which also named electronics waste were mostly dealt with by landfill. Because various corrosive medium exist in soil, heavy metal elements will leach from solder alloy in electronics waste which resulting in environment pollution and groundwater contamination. The groundwater is the main source of drinking water, and the poisonous and harmful substances will finally enter human body with the water, causing harm to our health. Therefore, it is important for environment pollution management and human health protection to investigate leaching behavior of heavy metal elements from solder of electronics garbage.In this paper, Sn-0.75Cu, Sn-3.5Ag-0.75Cu and Sn-37Pb solder alloy and their joints which widely used in electronic packaging industry are investigated. The leaching and electrochemical corrosion behavior of solder alloys and their joints in the simulation 3.5%NaCl solution, NaCl-Na2SO4 solution, NaCl-Na2SO4-Na2CO3 solution have been summarized as follows:1,The leaching amount of heavy metal element from solder alloys and their joints in salt solution are increasing with the increasing leaching time. Furthermore, the leaching amount of heavy metal elecment from solder alloys in NaCl-Na2SO4-Na2CO3 mixed solution was the highest, in the other hand the leaching amount of heavy metal elecment from the joints in 3.5%NaCl solution were highest.2,The leaching amount of heavy metal elecment from solder alloys in 3.5%NaCl and NaCl-Na2SO4 solution are lower than that from their joints, but the result is opposite in the NaCl-Na2SO4-Na2CO3 mixed solution (Cu except), which is owning to two aspects:one is in connection with the occurrence of galvanic couple corrosion, the other is related to the morphology and structure of the surface corrosion product.3,The leaching amount of Sn and Pb from solder alloys in salt solutions is higher than that of Ag and Cu. However,in the case of solder joints, a lot of Sn,Pb and Cu element leach from the joints, while the leaching amount of Ag remains a little.4,The electrochemical property of solder alloys in 3.5% NaCl solution is the same as that in NaCl-Na2SO4 solution after the Potentiodynamic potential polarization. Sn-37Pb solder alloy presents the best corrosion resistance, but Sn-0.75Cu shows the worst. The Sn-3.5Ag-0.75Cu solder alloy in the NaCl-Na2SO4-Na2CO3 mixed solution presents the best corrosion resistance, and the corrosion resistance of solder alloys in NaCl-Na2SO4-Na2CO3 mixed solution is worse than the other two salt solutions.5,The leaching regular of solder alloys is consistent with the electrochemical behavior, which showing that the more Sn leaching amount of solder alloys in salt solutions after leached, the higher corresponding corrosion current density of solder alloys.6,The corrosion products on the surface of solder alloys after leached in 3.5% NaCl and NaCl-Na2SO4 solution remains a little, but a lot of thick surface corrosion products in the NaCl-Na2SO4-Na2CO3 mixed solution. However, In the case of solder joints, the morphology regular of corrosion products on the surface of the joints is opposite to that of solder alloys. The corrosion products of leaching behavior are mainly composed of Sn4(OH)6Cl2 phase. After potentiodynamic polarization of solder alloys in 3.5% NaCl and NaCl-Na2SO4 solution, a large and very dense corrosion products form on the surface which are mainly consist of Sn3O (OH)2Cl2 and Sn3OSO4 (OH)2 phase.