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52 DESIGN007 MAGAZINE I AUGUST 2025 Plan for accessible test points early in the design process for debugging and in-circuit testing. It can be very costly in both time and money when add- ing them after the design is 100% complete. Ensure space for fiducial marks for automated assembly equipment. The Floor Planning Process: An Iterative Approach No design is perfect on the first pass. Floor plan- ning evolves as the design matures. 1. Gather requirements: Understand the system architecture, critical signals, mechanical con- straints, and environmental factors. 2. Place fixed components: Start with connectors, mounting holes, tooling holes, heat sinks, and any components dictated by the enclosure. 3. Identify critical components: Place major ICs (CPU, FPGA, memory), power management units, and high-speed interfaces. 4. Define functional blocks: Group related com- ponents into logical blocks. 5. Rough placement: Arrange the functional blocks on the board, considering signal flow and major interfaces between blocks. 6. Refine and optimize: Adjust placement based on signal integrity needs (shortening critical traces). Address thermal concerns (spread- ing heat, adding thermal relief). Incorporate decoupling capacitors close to ICs. Ensure manufacturability guidelines are met. Review for EMI/EMC issues. 7. Iterate: Floor planning is rarely a one-shot pro- cess. It often involves multiple iterations, mov- ing components, and re-evaluating until an optimal balance of all constraints is achieved. Tools and Techniques Modern EDA tools make floor planning easy by providing the best tools for the job. Today's tools enable users to group and move components together. Design rule checking (DRC) automatically checks for spacing, trace width, and other rules. Modern length matching, thermal analysis, and 3D visualization tools will help accelerate the floor planning and design cycles. Conclusion PCB floor planning is science and art, requiring a blend of technical knowledge and system-level thinking. It blends engineering principles with spa- tial reasoning. It's a foundational step that, when executed meticulously, can significantly reduce design iterations, improve product performance, and streamline the manufacturing process. It's where design intent meets physical reality, and it sets the tone for everything that follows in layout, routing, and manufacturing. Investing time and effort in robust floor plan- ning at the outset of a PCB design project is not merely an industry best practice, it's a non-nego- tiable step on the path to first-pass success, and it's a prerequisite for achieving overall success in PCB design. DESIGN007 Stephen V. Chavez is the principal technical product marketing manager for Siemens EDA and chair of PCEA.