Issue link: https://resources.pcb.cadence.com/i/1541046
13. Keeping Height and Keep-In/Keep-Out Constraints Visible How To Implement 1. Gather mechanical and system data: f Obtain a 3D model (STEP/IGES) or mechanical drawings of the enclosure, mating assemblies, shields, or casework. f Identify all height restrictions: under shields, under heatsinks, under mounting bosses, at panel cutouts, and at board-to-board or connector mating areas. 2. Define height limits and keepouts in your EDA tool: f Use the mechanical layer to draw keep-in/keep-out zones for areas under 0 mm, 3 mm, 5 mm, or other specific height limits. f Apply region-specific rules for no-copper, no-component, and no-via zones (such as under heat sinks, metal can shields, or near press-fit connectors). f In your tool, set the maximum allowed part heights for each region of the board. 3. Assign accurate heights to all components: f Attach a 3D STEP model or at minimum set the "height" property, for every part in your layout tool's library. f Double-check tall parts (electrolytics, connectors, antennas, crystals, relays) against the mechanical BOM and real measured samples if available. 4. Perform a 3D collision check: f Use your EDA tool's 3D viewer to load the board and enclosure together or many PCB design and mechanical design solutions now support ECAD/MCAD bi-directional co design (ProSTEP - IDX). f Spin, pan, and zoom the model to check for part collisions with the lid, bosses, adjacent PCBs, or other modules. f Verify that connectors align to panel cutouts without interference. 5. Lock and document critical zones: f Mark keepouts and height limits in a dedicated mechanical drawing layer. Lock these objects in your CAD tool to prevent accidental moves. f Provide callouts and notes in your fabrication and assembly drawings describing all height-critical regions and keepout requirements. 6. Review after each placement or mechanical update: f After any significant part, enclosure, or system-level change, rerun the 3D collision and keepout checks. f Coordinate with mechanical and industrial design engineers for approval before final sign-off. Common Pitfalls, Their Impact, and How to Avoid Them Common Pitfall How to Avoid it Not assigning accurate heights to all components Relying on generic or default values can result in real-world collisions – Verify the maximum height of each component against current datasheets and import STEP models for 3D clearance checks. Forgetting about "hidden" obstacles Such as mounting bosses, screw heads, standoffs, thermal pads, or gaskets inside the enclosure – Import MCAD data of the enclosure early in the design process. Placing tall parts under shields or in airflow paths Blocks cooling or causes unantici- pated short circuits during vibration or drop – Consider mechanical constraints, thermal management, and manufacturability. Ignoring keepout rules for connectors and cable management Leads to cables that won't fit, or connectors that can't be mated – Run DRCs regularly throughout the design process.