[Show abstract][Hide abstract] ABSTRACT: As flexible electronic applications gain more and more research interests, the thermal management issues related to these become more critical. This paper quantifies the thermal resistance of flip chip interconnection on flexible substrate by both simulation and experimental measurements. For the simulation, both finite element method (FEM) and computational fluid dynamics (CFD) are used. Measurements are employed in both steady state and transient state conditions. Results reveal that thinner flex substrate is a poor thermal conductor and one of the key factors in improving thermal performance is the amount of copper in the substrate, as this acts as a heat spreader to remove heat over a larger area. The module without backside metallization has a significant amount of heat conduction through the copper tracks, while for the module having backside metallization, the main portion of heat is spread over the backside metallization. Thermal resistance is also boundary-dependent: it is smaller in cold-plate condition, while 5-15 times higher at natural convection condition. The backside copper metallization plays an important role under natural convection condition, while this influence is not pronounced under cold-plate conditions
[Show abstract][Hide abstract] ABSTRACT: This paper summarises the thermal and mechanical characterisation embedded chips in flex and rigid substrates. Besides the technical integration issues, both technologies are also coping with thermal and mechanical issues. From thermal point of view, it is important to have a good thermal conductive path to conduct the heat towards the environment. From mechanical point of view, the thermo-mechanically induced stresses can become very high. In case of flex, also bending can add additional stresses. Therefore, simulation is very useful as a first virtual prototyping tool to analyse and finally optimise the structural design in order to have a low thermal resistance and sufficiently high reliability. The thermal simulation results are validated by experimental results.