The reliability and mechanical performance of an electronic integrated circuit is studied based on finite element analysis.

The flip flop on board (FCOB) package – one of the current plastic encapsulated packages consists of a die, solders, PCB & underfill resin encapsulated between the die and the PCB, which is subjected to a typical thermal cycle experienced during the manufacturing process.

The effects of viscoelastic properties of underfill resin on mechanical responses and residual stresses of FCOB packages are specifically studied and the results are compared with those obtained for a thermoelastic underfill resin.

The viscoelastic properties of the underfill resin are characterized using time – temperature superposition technique.

The viscoelastic nature of underfill material should be properly taken into account if the failure of solder joints and the lifetime of the package are to be accurately estimated.