Webinar: Thermal simulation helps in choosing the right thermal management concept Würth Elektronik Circuit Board Technology www.we-online.com/thermal_management Page 1 06.11.2014 Basics Drivers for ever more effective thermal management concepts Further miniaturisation of components Increasingly powerful components Thermal dissipation per unit area is rising Higher clock frequencies, higher packaging densities Installation of populated PCBs on warm assembly units and machine parts or in hermetically sealed housing The need for circuit carriers with carefully planned thermal management is increasing The temperature resistance of LED applications is especially limited Change in light and colour properties / Reduction in working life www.we-online.com/thermal_management Page 2 06.11.2014 Basics Over 50 % of electronic system failures are caused by increased temperatures Heat dissipation influences the system efficiency Sufficient cooling is essential for an improved reliability and lifetime. Humidity 19% Temperature 55% Dust 6% Vibrations 20% Source::US Air Force Avionics Integrity Program (AVIP) PCBs play an important role in the development of efficient thermal management www.we-online.com/thermal_management Page 3 06.11.2014 Basics Length of thermal path thermal resistance Rth d = thermal conductivity λ * cross section of thermal path A GOAL: Reduction of thermal resistance Layer thickness d reduced by thinner circuit board thinner isolation layers Thermal conductivity λ increased by higher copper content parallel thermal vias in the z - axis Cross section of thermal path A increased by min. 25µm copper in the barrel ! parallel thermal vias large copper area for heat distribution (x/y) large contact surface area of copper / heat sink www.we-online.com/thermal_management Page 4 06.11.2014 Basics Types of heat dissipation Radiation: Emission of photons Convection: heat transfer through gases or fluids Conduction: Heat dissipation via solid objects Vertical: Thermal via / microvia / buried via Horizontal: Copper foil heat distribution/heatsink www.we-online.com/thermal_management Page 5 06.11.2014 Layout www.we-online.com/thermal_management Page 6 06.11.2014 Boundary conditions simulation Size of the pcb 45 x 45 mm Power loss of the LED 3W Ambient temperature 20 °C Pcb vertical free-standing in laboratory Heat transfer to the air 12 W/m²K www.we-online.com/thermal_management Page 7 06.11.2014 Thermal simulation Variant 1 Layout Copper layer: 50µm FR4: 1550µm www.we-online.com/thermal_management Page 8 06.11.2014 Thermal simulation Variant 1 www.we-online.com/thermal_management Page 9 06.11.2014 Thermal simulation Variant 2 Improved Layout Copper layer: 50µm FR4: 1550µm www.we-online.com/thermal_management Page 10 06.11.2014 Thermal simulation Variant 1 Copper plane Thereby spread of heat Reduction in temperature of LED from 552°C to 170°C Variant 2 www.we-online.com/thermal_management Page 11 06.11.2014 Thermal simulation Variant 3 Copper layer: each 50µm FR4: 1550µm www.we-online.com/thermal_management Page 12 Improved Layout Additional copper layer BOTTOM 06.11.2014 Thermal simulation Variant 2 Additional copper layer BOTTOM Reduction in temperature of LED from 170°C to 144°C Variant 3 www.we-online.com/thermal_management Page 13 06.11.2014 Thermal simulation Variant 4 Copper layer: each 50µm FR4: 1550µm Thermovia hole 25 µm copper www.we-online.com/thermal_management Page 14 Improved Layout Additional copper layer BOTTOM Thermovia from 1 to 2 06.11.2014 Thermal simulation Variant 2 Variant 3 Variant 4 www.we-online.com/thermal_management 2 layer and Thermovia Reduction in temperature of LED from 170°C to 113°C Page 15 06.11.2014 Thermal simulation Variant 5 Copper layer: each 50µm Reduced FR4 thickness: 1550µm Thermovia hole 25 µm copper Aluminum heatsink: 1000µm www.we-online.com/thermal_management Page 16 Improved Layout Additional copper layer BOTTOM Thermovia from 1 to 2 06.11.2014 Thermal simulation Variant 2 Variant 3 Variant 5 www.we-online.com/thermal_management 2 layer, Thermovia and heatsink Reduction temperature LED from 170°C to 89°C Page 17 06.11.2014 Thermal simulation - conclusion Sufficient cooling is not given in the variants 1, 2 and 3. The variant 4 is located in the limit area. If we consider that in the LED itself, a temperature increase of 4-6 degrees takes place, the allowable junction temperature may have already been exceeded. With the use of Thermovia and Heatsink in variant 5, a reliable heat dissipation of the LED can be guaranteed. www.we-online.com/thermal_management Page 18 06.11.2014 Thermal simulation Copper layer 2: each 50µm Reduced FR4 thickness: 500µm Thermovia barrel 25µm copper Aluminum heatsink: 1000µm Heatsink 15mm larger all around www.we-online.com/thermal_management Page 19 06.11.2014