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 Humidity 19% Dust 6% Vibrations 20% Heat dissipation influences the system efficiency Sufficient cooling is essential for an improved reliability and lifetime. Temperature 55% 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 thermal resistance Rth = Length of thermal path 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: Convection: Emission of photons 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
Variant 1 Copper layer: 50µm FR4: 1550µm Layout www.we-online.com/thermal_management Page 8 06.11.2014
Variant 1 www.we-online.com/thermal_management Page 9 06.11.2014
Variant 2 Copper layer: 50µm FR4: 1550µm Improved Layout www.we-online.com/thermal_management Page 10 06.11.2014
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
Variant 3 Copper layer: each 50µm FR4: 1550µm Improved Layout Additional copper layer BOTTOM www.we-online.com/thermal_management Page 12 06.11.2014
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
Variant 4 Copper layer: each 50µm FR4: 1550µm Thermovia hole 25 µm copper Improved Layout Additional copper layer BOTTOM Thermovia from 1 to 2 www.we-online.com/thermal_management Page 14 06.11.2014
Variant 2 Variant 3 Variant 4 2 layer and Thermovia Reduction in temperature of LED from 170 C to 113 C www.we-online.com/thermal_management Page 15 06.11.2014
Variant 5 Copper layer: each 50µm Reduced FR4 thickness: 1550µm Thermovia hole 25 µm copper Aluminum heatsink: 1000µm Improved Layout Additional copper layer BOTTOM Thermovia from 1 to 2 www.we-online.com/thermal_management Page 16 06.11.2014
Variant 2 Variant 3 Variant 5 2 layer, Thermovia and heatsink Reduction temperature LED from 170 C to 89 C www.we-online.com/thermal_management Page 17 06.11.2014
- 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
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