Surface Mount Technology And Printed Circuit Board Electrical Interconnection Reliability Research

The reliability of electric connection in surface welding dot of packaging is studied in this paper. This paper researches this issue from two aspects: firstly thermal analysis is conducted on the whole system with assistance of FLOTHERM Software, secondly research is focused on outlook and status of Pb63-Sn37 welding dot in BGA packaging and its influence on reliability of welding dot.System research is carried out on connection progress between PRO-E and ANSYS. And problems in interface are resolved, which plays a very import role in follow-up research.Thermal analysis is carried out on model of the whole system by FOLTHERM to get temperature in different chips. The analysis results play an instrumental role in other analysis work of this paper.Model on composite Pb63-Sn37 welding dot in BGA is established. By ANSYS software, composite welding dot model is studied based on simulation by finite element method. Relationship between parameters and stress of the welding spot is found, and optimum values of the welding dot size and material parameter bonding pad are obtained by the optimal designing method.Simulation via Coffin-Manson model discloses close relationship between life spam of thermal circulation and pad material as well as size of welding dot. Changes on pad material and size of welding dot are considered as good solution on increase the reliability of welding dot. Change of stress in thermal circulation in Pb63-Sn37 welding dot can be simulated via ANSYS and the largest stress in outboard of pad material and pad is observed, so the area is the most one. It is helpful to make forecast life spam of thermal circulation of welding dot. Relationship between design variables and displacement, stress and strain of the welding dot is obtained by sensitivity analysis basing on Monte Carlo method.