Paul Rose European Electronics AE Manager LuxLive 2013 How to use Thermal Design Software

© 2013 Mentor Graphics Corp. Company Confidential Design Challenges in Electronics Design Overheating is the major reason for electronics failures There is a need to remove the heat generated by the electronic components. —Whether or not using mechanical means Figure 1 : Junction Life Statistics (Source : GEC Research) 2 PMR, Fast and Accurate Predictability of CFD Thermal Analysis for PCB Design, June 2010

© 2013 Mentor Graphics Corp. Company Confidential Design Challenges in Electronics Design Working against us… —Moore’s Law (increasing power) —Increased functionality —Reduce size —Reduce noise —Increase reliability —Constrictions of manufacture 3 PMR, Fast and Accurate Predictability of CFD Thermal Analysis for PCB Design, June 2010

© 2013 Mentor Graphics Corp. Company Confidential Design Challenges in Luminaire Design Junction temperature directly impacts light efficiency. Heat transfer paths have changed: Challenge is to ensure sufficient conduction to the environment. Light & Heat TJ = ˚C Heat Light TJ = ˚C

© 2013 Mentor Graphics Corp. Company Confidential Thermal analysis of Electronics Could employ physical testing —Cost of redesign / testing —Over engineer to avoid possibility of failure Use numerical computer based virtual testing which is where Computational Fluid Dynamics comes into play CAD Manufacture ConceptDetailingFinal DesignTesting Prototype 5 ConceptDetailingFinal DesignTesting Manufacture CAD CFD

© 2013 Mentor Graphics Corp. Company Confidential What is CFD? From a text book (Versteeg & Malalasekera, “An Introduction to Computational Fluid Dynamics: The Finite Volume Method”) “Computational Fluid Dynamics or CFD is the analysis of systems involving fluid flow, heat transfer and associated phenomena, such as chemical reactions by means of computer-based simulation”

© 2013 Mentor Graphics Corp. Company Confidential What is CFD? In Pictures…

© 2013 Mentor Graphics Corp. Company Confidential What is CFD? 18 th and 19 th Century many eminent scientists carried out research to mathematically describe the motion of Fluids: —Daniel Bernoulli (1700 – 1782) —Leonhard Euler (1707 – 1783 —Claude Louis Marie Henry Navier (1785 – 1836) and George Gabriel Stokes (1819 – 1903) Navier Stokes equations forms the basis of modern day CFD – based around conservation laws Late 20 th Century and beyond… —Research to create numerical methods to solve the basic equations —A number of general purpose codes developed and marketed —Computer power increasing allowing more accurate analysis to be performed

© 2013 Mentor Graphics Corp. Company Confidential Analysis Process Create geometry Create an analysis project

© 2013 Mentor Graphics Corp. Company Confidential Analysis Process Add thermal properties / heat sources / environmental conditions Look at the results….

© 2013 Mentor Graphics Corp. Company Confidential System Analysis

© 2013 Mentor Graphics Corp. Company Confidential System Analysis

© 2013 Mentor Graphics Corp. Company Confidential A System Level Problem Helpful to think in terms of ‘thermal headroom’ Heat sinkPCB LED Package Air Ambient temperature Max. Allowable Junction temperature Available Headroom Designer’s job is to decide how to split up the temperature rise from ambient to case System Designer Vendor

© 2013 Mentor Graphics Corp. Company Confidential “Thermal Head Room” Predicted LED Temperature = 65.1°C Available Headroom 4.9°C Acceptable LED Temperature = 70.0°C

© 2013 Mentor Graphics Corp. Company Confidential Design Challenge Heat flow from device to Heat Sink Heat flows within Heat sink to its surface Transfer from Surface into surrounding air

© 2013 Mentor Graphics Corp. Company Confidential Design Challenge Transfer from Surface into surrounding air Surface Area Aerodynamics Alter Number of Fins

© 2013 Mentor Graphics Corp. Company Confidential Heat Sink Design Changes

© 2013 Mentor Graphics Corp. Company Confidential Heat Sink Design Changes

© 2013 Mentor Graphics Corp. Company Confidential System-Level Thermal Management of LEDs John Parry & Paul Rose, 07 July 2009 What about the components Can use simulation to investigation component level thermal performance… …but also transient measurement techniques can accurately characterize the LED active layer to submount classical die attach (TIM1) solder/glue to MCPCB classical TIM to heat-sink (TIM2)

© 2013 Mentor Graphics Corp. Company Confidential Role of Physical Testing Combined thermal and radiometric characterization: T3Ster + TERALED

© 2013 Mentor Graphics Corp. Company Confidential Your Initials, Presentation Title, Month Year

© 2013 Mentor Graphics Corp. Company Confidential Completing the Circle Characterization of the LED from the physical test can be used in the simulation software…

© 2013 Mentor Graphics Corp. Company Confidential Final Thoughts… Thermal analysis should be an integrated part of the design process to: —Optimise thermal performance at the earliest possible stage —Prevent over engineering required to sort out problems that occur at a late stage of the design —Design a system that you know will work Stand G42 “FloEFD from Mentor helps us to understand and optimize headlamps. Even very complex geometries and test conditions can be investigated with a minimum of effort.“ Peter Jauernig, Head of Department Automotive Lighting

© 2013 Mentor Graphics Corp. Company Confidential