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Lead-free pure tin plating process is widely used in the electronic device pin plating , the launch of the process because the world is becoming more stringent limit of lead in electronic products , lead-free pure tin plating has low cost , the bath simple ingredients , easy operation and maintenance , ease of application and promotion , more and more domestic and foreign companies to use pure tin plating to replace tin-lead plating process . But the presence of lead-free pure tin plating process crystal tin whiskers , coating and easy to change , easy to muddy the bath , these issues will bring trouble and distress to the enterprise , will bring huge economic losses . This thesis focuses on the problem of lead-free pure tin plating coating and easy to change to study the use of electrochemical , chemical methods , lead-free pure tin plating process as the main object of study , in-depth analysis on the the coating discolored mechanism foundation , may cause plating discoloration of various factors, and passed the test method to verify the degree of influence of these factors on the coating discoloration , to find and easy to change control of the lead-free pure tin plating coating countermeasures . In this study, a systematic introduction of lead-free pure tin plating process and mechanism of coating discoloration , and provides the basis of the theory to solve the coating discoloration . This paper, through a large number of experimental data based on the mechanism of the plating process and coating discoloration , detailed study of the plating process from pre-processing , plating , coating discoloration after treatment , electroplating additives on coating discoloration . The paper on the basis of the factors that affect the coating discoloration found , through testing gives corresponding control measures to prevent Lead pure tin plating . After this study , through mass production verification has no obvious discoloration protect stored at room temperature conditions within the next year no obvious discoloration , dual 85% test 24H . Finally , in order to safeguard the effectiveness of countermeasures coating discoloration control , in order to improve the degree of automation of electroplating production , the paper designed an automated electroplating production line control system . Validation through large-scale production , the system is able to control the plating process , greatly improve the efficiency of production and electroplating process control level .
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