PCB Thermal Simulation - RTP Designers Council

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18 Component Representation θ ja <strong>Thermal</strong> resistance from junction to ambient metric Good for comparative purposes only, NOT predictive Various methods of component representation exist Choice most often based on data availability rather than simulation intent! k=? Simple block model Good for ‘typical’ case temperature prediction at best Case (top) Junction Board Top Inner Top Outer Side Junction Leads Bottom Outer Bottom Inner <strong>Thermal</strong> Resistor Network model “2-Resistor” and “DELPHI” types Capable of Tj and Tc prediction Generally DELPHI models are better than 2-Resistor Results as good as the derivation of the characteristic thermal resistances Increasing T j and T c predictive accuracy Detailed model Explicit representation of internal construction geometry, materials, die size etc. Capable of Tj and Tc prediction Most accurate model type available © 2010 Mentor Graphics Corp. Company Confidential www.mentor.com
19 From source to ambient: Modeling heat flow paths Heat is dissipated in the component and travels to a (colder) ambient From a design perspective it’s important to get the heat out easily/quickly (choose your analogy), conversely get the cold in easily/quickly Similarly, from a simulation perspective, it’s important to model the critical heat flow paths accurately — In terms of the thermal resistances the heat experiences as it leaves by: – Convection (heat removal by air) – Conduction (heat removal through solid) – Radiation (heat removal by em radiative transfer from solid to solid surface) Only a full 3D CFD simulation captures all modes of heat transfer accurately © 2010 Mentor Graphics Corp. Company Confidential www.mentor.com
Page 1 and 2: PCB Thermal Simulation - The State
Page 3 and 4: 3 About the Mentor Graphics Mechani
Page 5 and 6: 7 Typical Design Constraints Opera
Page 7 and 8: 9 Causes of Electronic Failure Num
Page 9 and 10: 11 Heat Transfer 101 Heat transfer
Page 11 and 12: 13 The Thermal Budget A useful des
Page 13 and 14: 15 In the beginning… 20 years ag
Page 15: 17 The grail of T j and T c modelin
Page 19 and 20: 21 The fully lumped approximation
Page 21 and 22: 23 The fully lumped approximation
Page 23 and 24: 25 Discrete layer representation N
Page 25 and 26: 27 Full Metallic Distribution Repre
Page 27 and 28: 29 Full Metallic Distribution Repre
Page 29 and 30: 31 Application Example: JCI PCB Bot
Page 31 and 32: 33 Application Example: JCI PCB Re
Page 33 and 34: 35 A final word on Accuracy “How
Page 35: 37 www. mentor. com © 2010 Mentor

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