Webinar: Thermal simulation helps in choosing the right thermal management concept Würth Elektronik Circuit Board Technology

Transcription

1 Webinar: Thermal simulation helps in choosing the right thermal management concept Würth Elektronik Circuit Board Technology Page

2 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 Page

3 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 Page

4 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 Page

5 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 Page

6 Layout Page

7 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 Page

8 Variant 1 Copper layer: 50µm FR4: 1550µm Layout Page

9 Variant 1 Page

10 Variant 2 Copper layer: 50µm FR4: 1550µm Improved Layout Page

11 Variant 1 Copper plane Thereby spread of heat Reduction in temperature of LED from 552 C to 170 C Variant 2 Page

12 Variant 3 Copper layer: each 50µm FR4: 1550µm Improved Layout Additional copper layer BOTTOM Page

13 Variant 2 Additional copper layer BOTTOM Reduction in temperature of LED from 170 C to 144 C Variant 3 Page

14 Variant 4 Copper layer: each 50µm FR4: 1550µm Thermovia hole 25 µm copper Improved Layout Additional copper layer BOTTOM Thermovia from 1 to 2 Page

15 Variant 2 Variant 3 Variant 4 2 layer and Thermovia Reduction in temperature of LED from 170 C to 113 C Page

16 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 Page

17 Variant 2 Variant 3 Variant 5 2 layer, Thermovia and heatsink Reduction temperature LED from 170 C to 89 C Page

18 - 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. Page

19 Copper layer 2: each 50µm Reduced FR4 thickness: 500µm Thermovia barrel 25µm copper Aluminum heatsink: 1000µm Heatsink 15mm larger all around Page