Measurement and simulation of packaging induced stress on sensors

Evaluation of encapsulation induced stresses has been performed with embedded fiber Bragg gratings and coupling between 3D structural and fluidic simulation tools. Strains due to drag forces on electronic components during injection of transfer mold material have been measured online as well as strains during material polymerisation, shrinkage and cooling. The strains could be transferred into stresses inside the electronic components and joints by means of FEA. Assisted by tensile tests we analysed the most important rapid prototyping processes like stereolithography and vacuum casting as well as the bonding behaviour between fiber and polymer matrix. The process analysis was followed by structural health monitoring of encapsulated electronics during thermal loading. We could detect delaminations and cracks by non-destructive means during the very first temperature cycles. Material degradation could be observed.