QUALITY AND RELIABILITY TESTING OF CIRCUIT BOARDS ASSEMBLED WITH LEAD FREE COMPONENTS, FINISHES, SOLDERING MATERIALS AND PROCESSES IN SIMULATED PRODUCTION CONDITIONS

摘要

The New England Lead-free Electronics Consortium is arncollaborative effort of New England companies spanningrnthe electronics supply chain, created by the University ofrnMassachusetts Lowell in 1999 and sponsored by the ToxicsrnUse Reduction Institute and the U.S. EPA. The consortiumrnhas completed and published the results of three phases ofrnmanufacturing and testing of lead-free Printed WiringrnBoards (PWBs) with the goal of achieving zero-defect leadfreernsoldering processes with comparable or superiorrnreliability to that of leaded solder processes.rnIn this fourth phase of testing, which began in 2007, severalrnsimulated conditions of assembly and rework processesrnwere evaluated in a matrix of multiple levels of components,rnPWB lead free surface finishes and solders, and comparedrnto a baseline of leaded equivalent materials and processes.rnBoth Through Hole (THT) and Surface Mount (SMT)rnTechnologies were evaluated. The assembly portion of therntesting and rework is completed and the long term reliabilityrnand vibration is ongoing.rnAll quality and reliability testing was performed withrnindustry standard methodologies, using specially trainedrnproduction inspectors for the quality evaluation, andrnextreme thermal cycling for reliability testing.rnOur results indicate that with proper selection of currentlyrnavailable (2008) materials and finishes and careful controlrnof the assembly processes, successful lead free assemblyrnand rework can be achieved. Comparison of differentrnstrategies for rework, and recommendations for least copperrndissolution for THT technology processes are discussed inrnthe published book by the paper authors. Reliability testingrnto date showed interesting inflection points for leadedrnversus lead free reliability that has to be resolved byrnadditional thermal cycling, to be published when completedrnin 2009, together with vibration testing.