PCB Thermal Simulation - RTP Designers Council

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34 Detail leads to accuracy? “A detailed PCB representation will increase my results accuracy” A true statement but caution is required Increased detail will lead to longer simulation solution times So, when is a detailed PCB representation necessary? — When the critical heat flow path is through the board – Natural convection or conduction cooled environments – Small high powered surface mount actives where the local PCB copper acts as a heatspreader So, when should a simpler PCB representation be used? — When the board is not on the critical heat flow path – Forced convection cooled environments — When your component representation is not detailed enough – Why model the PCB Cu content in detail when all components are modelled as simple blocks? © 2010 Mentor Graphics Corp. Company Confidential www.mentor.com
35 A final word on Accuracy “How accurate is the thermal simulation?”, a common question for obvious reasons Sources of error fall into three categories: 1. Data availability – Dictates both component and PCB modeling approaches 2. Data accuracy – If there are just 3 inputs to define accurately then they are power dissipation, power dissipation and power dissipation 3. Numerical modelling – CFD grid not fine enough on the air side around components and/or in the board just under components – Incorrect assumption made about the environment the PCB is placed in A good model(er) that is aware of the above 3 issues should produce T j – T a results within 10% of experimental © 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 and 16: 17 The grail of T j and T c modelin
Page 17 and 18: 19 From source to ambient: Modeling
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: 33 Application Example: JCI PCB Re
Page 35: 37 www. mentor. com © 2010 Mentor

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