Reliability of solder joints in 'under the hood' automotive electronic packages - how represent standard test profiles the effect of real use conditions

摘要

Failure of solder joints by low cycle fatigue is an important problem in automotive electronic packages for Under the Hood applications. A typical product are electronic control units (ECU) which must be mounted very close to the engine. In order to assess the reliability of the assembly Magneti Marelli initiated a study including a meteorological research of Europe, analysis of hot spots inside the ECU package, measurement of operational temperature profiles during an actual test ride, derivation of non standard thermal cycling tests, FEM simulations of mechanical strains and stresses inside the solder joints. The paper will present the results of investigations about the reliability of solder joints in "Under the Hood" automotive electronic packages. A brief of mode and magnitude of mechanical stress inside the solder joints is given as a comparison between actual operation, standard test and non standard test. The various damage on solder joints induced at different test conditions are correlated with the results of the FEM simulations. Recommendations regarding the loading profile of thermal cycling tests for reliability assessment of automotive electronic packages are given.