Design And Implementation Of Lead-free/Lead Assembly Compatibility Process Of Electronic Components

With the development of component packaging technology,surface mounting components will become smaller and smaller.Lead in solders used in traditional component pins and SMT assemblies can pollute the natural environment,so the lead-free process of civil electronic products began.The European Parliament passed legislation at the end of 2003.Since July 2006,electrical and electronic equipment sold in Europe must not contain lead and other harmful substances,and since then lead-free.Large scale components and lead-free solder have emerged.Because the solderability of lead components and solders is better than that of lead-free devices and solders,foreign military electronic products still use lead components and solders,but because of the backward basic technology of domestic component integration,many high-end components must rely on imports.About 70% of the high-end key components used in the aviation,aerospace and ordnance industries in China are imported.As there are many restrictions on the procurement of high-end military components in foreign countries,many of them are industrial grade and belong to lead-free components.This thesis mainly studies lead-free and lead-compatible assembly,including lead-free/lead-compatible welding,optimization of repair process parameters and process control of the whole welding process.Firstly,the overall scheme of the project is worked out,and the causes of void defects,the classification of voids and the basis of BGA solder joint inspection are analyzed in accordance with the technical difficulty of BGA voids.Then the BGA solder joint detection method and reliability verification test are given.Secondly,the lead-free/lead conversion process and lead-free BG are designed.A repairing and steel mesh opening research program;PCB and components selection was carried out through the design of the subject test program,and the validation items of each process sample were defined;then the research contents were studied and the test results were given according to the implementation path,including compatible assembly process parameters,lead-free / lead conversion parameters,BGA.Re-repair process and parameters,steel mesh design requirements,etc.Finally,through environmental tests,reliability analysis tests and other verify that the reliability of solder joints to meet the needs of military products.Through technical research,the problem of lead-free and lead-free assembly in the current production process of military electronics is solved,and the reliability of lead-free and lead-mixed assembly process is verified,so that many types of projects can be carried out smoothly.In addition to solving the compatibility problems,the research results of this project can also promote the further improvement of PCB design and fabrication,device quality control and other aspects.At the same time,the research results will be successfully applied in engineering projects.