Choosing the right thermal conductivity is critical when designing an Insulated Metal Substrate (IMS) PCB for high-power electronics. This engineering guide compares 3W/m·K, 5W/m·K, and 8W/m·K IMS materials, explaining how thermal conductivity, dielectric thickness, copper thickness, metal-base selection, and overall thermal resistance affect PCB performance. Based on practical IMS design considerations, ChengYue helps engineers understand when higher thermal conductivity is truly necessary and how to select the most suitable IMS structure for LED lighting, automotive electronics, power modules, EV systems, and other thermal-critical applications.