Issue link: https://iconnect007.uberflip.com/i/1533085
40 DESIGN007 MAGAZINE I MARCH 2025 • Copper balancing (addressing thermal and board warping concerns) • Solder mask clearances • Drill-to-copper distances Collaborating with the fabricator to establish these design rules up front can save significant time and avoid costly iterations. e industry best practice is to perform a DFM analysis as early in the design process as possible. e goal is to design quality into your product, not sim- ply check for DFM issues/concerns at the end of design creation—which has the potential to be time-consuming and very costly to address aer the fact. Plus, time to market is extremely important when you consider the window of opportunity potentially being a small moving target. It's important to understand whether the designer is being proactive throughout the design process as opposed to being reac- tive based on a manufacturer inquiry (TQ). Whether you perform the DFM task or have your supplier do it, the key to downstream success is that the DFM task/step is not passed over, neglected, or skipped. 3. Material and finish selection: Fabricators need precise information about materials and fin- ishes, as these affect performance, reliability, and cost. Designers should specify: • Substrate material (e.g., FR-4, Rogers, polyimide) and its thickness • Copper weight • Surface finish (e.g., HASL, ENIG, OSP, etc.) Consulting with the fabricator on material availability, cost, and lead times before finaliz- ing the design can prevent delays. 4. Dimensional tolerances: Designers must spec- ify tolerances that balance precision and man- ufacturability, which is why identifying the PCB performance-class is important. Overly tight tolerances increase costs and may be unnecessar y for the application. Key consid- erations include: • Hole size tolerances • Outline milling accuracy • Impedance control tolerances for RF and high-speed designs 5. Impedance and signal integrity requirements: For high-speed and RF designs, designers should provide detailed impedance require- ments, including: • Impedance types and values • Trace width and spacing calculations • Trace length/delays requirements • Layer stackup and dielectric constant Completing and sharing simulation results or working with the fabricator's engineering team can help fine-tune these parameters. Correct by construction is key to achieving success. 6. Panelization details (optional): If the design will be panelized, the designer should provide the following or coordinate them with both fabrication and assembly: • Panel dimensions and arrangement • Fiducial marks for assembly • Breakaway tab or scoring preferences