A short neck can consume a large share of resistanceThe 80 mm main route and 10 mm neck have equal resistance in this simple series model. Local temperature still depends on thermal spreading and boundary conditions.A short neck can consume a large share of resistanceIllustrative 175 µm copper; all sections at the same temperature.80 mm × 8 mm10 mm × 1 mm10 mm × 8 mmL / w: 10 + 10 + 1.25 = 21.25 squaresThe neck: 47.1% of resistance, over only 10% of length.³Ô¹Ïtv engineering illustration · conceptual, not to scale · examples are not acceptance limits