Issue link: https://resources.pcb.cadence.com/i/1526746
Types of Constraints In PCB design, constraints are crucial for ensuring the final product's functionality, reliability, and manufacturability. The main types of constraints are electrical, physical, spacing, manufacturing, and high-speed design constraints. Each domain addresses specific aspects of PCB design and often interrelates with others. Let's explore these domains and their impor- tance: Electrical Constraints Electrical constraints focus on maintaining signal integrity, controlling impedance, and managing power distribution. These constraints are vital for ensuring proper circuit functionality and preventing issues like signal degradation or electromagnetic interference. Some key areas managed by electrical constraints include: f Wiring topology (e.g., for DDR3 or T-branch configurations) f Impedance control f Signal timing and propagation delays f EMI management f Power integrity Physical Constraints Physical constraints deal with the tangible aspects of PCB design, including component placement, board dimensions, and layer stack-up. These constraints ensure that the PCB can be physically manufactured and assembled while meeting perfor- mance requirements. Examples of physical constraints include: f Board outline and dimensions f Component placement rules f Layer stack-up definition f Differential pair geometry f Via types and usage Spacing Constraints Spacing constraints define the minimum distances between various elements on the PCB, such as traces, components, and board edges. These constraints are crucial for preventing short circuits, reducing electromagnetic interference, and ensuring manufacturability. Key spacing constraints may include: f Trace-to-trace clearance f Component-to-component clearance f Trace-to-board edge clearance f Pad-to-pad spacing Manufacturing Constraints Manufacturing constraints ensure that the PCB design can be produced using available manufacturing technologies. These constraints help prevent issues during fabrication and assembly, reducing costs and improving yield. Some manufacturing constraints include: f Minimum trace width and spacing f Drill sizes and tolerances f Solder mask and silkscreen clearances f Copper pour rules 7 www.cadence.com Part 1 of 5