This chapter gives a complete survey of resistive network type BCI compact thermal models. Several benchmarks representing different package families are discussed, how exactly BCI models are generated via optimization starting from detailed models, including how the topology is selected, how the cost function is defined, what the level of accuracy is, what the differences are between various optimization techniques, and especially to which accuracy the compact models should be compared. The Chapter is closed with a discussion of papers from other than DELPHI sources.