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1 Electrothermal Mechanical Stress Reference Design Flow for Printed Circuit Boards and Electronic Packages // Electrothermal Mechanical Stress Reference Design Flow for Printed Circuit Boards and Electronic Packages Aligned with this paper is a collection of YouTube training videos on the ANSYS Electronics Channel that demonstrate in detail all the steps for performing the electrothermal and structural analyses of a modern PCB from the consumer electronics industry. The videos are available under the playlist: ANSYS Electronics: Electrothermal Mechanical Stress Reference Design Flow for Printed Circuit Boards and Electronic Packages If you follow our reference design flow, you can: 1. Translate ECAD geometry to ANSYS solutions 2. Review schematics 3. Analyze power integrity and DCIR in ANSYS SIwave 4. Perform automated and iterative thermal analysis 5. Perform temperature post-processing in ANSYS Icepak 6. Generate temperature profiles for the board in Icepak 7. Prepare a PCB for use in ANSYS Mechanical 8. Assemble the project in ANSYS Workbench 9. Import layer metallization on the board using the "Trace Mapping Technique" 10. Transfer temperatures from Icepak to the board in Mechanical 11. Simulate the board for thermal stress, deformation and elastic strain. The multiphysics analyses also let you build "what-if" scenarios where you can make modifications to your design. For example, you can determine mitigation measures to minimize power losses and study cooling techniques (like adding heat sinks) to ensure board and IC temperatures are safe to operate. The "what-if" tests also let you try out different material properties for minimizing thermal stress. This comprehensive reference design flow will give you a general guideline for performing electrothermal and structural analysis for any printed circuit board or ECAD. This paper presents a reference design flow for solving the electrical, thermal and mechanical challenges of a printed circuit board (PCB) using simulation tools from ANSYS. This approach can be utilized for all electrical CAD (ECAD) types such as IC packages, touch panel displays, and glass and silicon interposers. The authors followed this reference design flow for analyzing a PCB virtual prototype used in the consumer electronics industry. The design flow details nearly all aspects of the modeling technique from studying electrical connections in a schematic and setting up the PCB to analyzing the electrical, thermal and mechanical characteristics of the board — all using ANSYS tools. The multiphysics simulation yields power losses across the entire board and its objects, determines whether the integrated circuit (IC) and overall board temperatures lie within safe operating limits and predicts overall PCB reliability, taking into account all its components and heat sinks. WHITE PAPER / Motivation for Electrothermal and Structural Reliability A PCB is composed of successive layers of different materials laminated together. Prepreg and inner layer cores are sandwiched between copper layers with varying thicknesses. The PCB forms the base to mechanically support and electrically connect the components that are mounted on it. Considering the structural composition of a PCB with mismatched coefficients of thermal expansion (CTEs) for the different materials, mechanical and electrical difficulties are typical for a PCB. PCB problems can be broadly classified as electrical, thermal and mechanical. Electrical problems include signal integrity, crosstalk and electromagnetic interference. Current flow in a PCB and through the electronic components causes power losses across the board and leads to power dissipation in the Figure 1. PCB fabrication view

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