Modelling guidelines and non-destructive analysis for thermal and mechanical behaviour of via-structures in organic boards

This paper proposes a new effective thermal material simulation model as well as a non-destructive failure analysis for multi-layer substrates with thermal vias to derive exact failure data to supplement existing lifetime models. An effective thermal material simulation model is derived which is validated in simulation and experiment in transient mode. The modelling is done for a test matrix of representative structures and results in a via structure class-dependent correction factor. Pulse IR thermography was chosen as non-destructing failure analytic method for crack detection in vias based on electrical and laser excitation, which also supports the observation of the transient behavior. The method shows that cracks are detectable unambiguously and shows its advantage over the electrical test. The electrical excitation correlate well with the FE-simulation for different crack length in the cylindrical via structure. There is also a good potential for large-scale screening using laser excitation as the board can stepwise be thermally excited and thermally screened in one go.