Issue link: https://iconnect007.uberflip.com/i/1537388
F E AT U R E Q & A w i t h K r i s M oye r, G l o b a l E l e ct ro n i c s As s o c i a t i o n M ost designers learn how to set their design constraints through trial and error. EDA vendors' guidelines explain how to use their par- ticular tools' constraints, and IPC standards offer a roadmap, but PCB designers usually develop their own unique styles for setting constraints. Is there a set of best practices for setting con- straints? That's what we asked Global Electronics Association design instructor Kris Moyer, who covers design constraints in his classes. In this interview, Kris discusses how to identify PCB design requirements and set design constraints tightly enough for performance but flexible enough for manufacturing limitations. Creating a Design Constraint Strategy What pre-layout analysis should be performed before you begin setting constraints? Kris Moyer: There are several analyses that should be completed before setting constraints. These include the following: • Timing/signal integrity: Used to set controlled impedance, termination, length matching and max length, and layer restrictions for digital signals. • SPICE/power integrity analysis: Used to define the power distribution network (PDN) limits, the current requirements (trace widths), and voltage clearance requirements (Cu-Cu clearance). • Thermal analysis: Used to determine how many plane layers, the copper weight of the plane lay- ers, temperature rise of the traces (also used to define trace width), and any heat-sinking needed. • Structural/mechanical analysis: This is the vibration, shock, and other environmental impacts to the design. It's used to trade off between how many copper layers vs. board thickness for the stackup, and it is also used to evaluate the number and locations of mount holes or other support structures for the board. This analysis also leads to placement restric- tions, such as specific placement of tall parts due to the design of the enclosure, or heavy/ high mass parts due to special support struc- tures designed into the housing, etc. 8 DESIGN007 MAGAZINE I JULY 2025