Issue link: https://resources.pcb.cadence.com/i/1532919
Contents Part 2 - Standard Constraints ..................................................... 3 Physical and Spacing Constraints .............................................. 3 Trace Width: Minimum and Maximum Width for Signal And Power Traces. .................................................................. 3 Via Size: Diameter and pad size for vias, including microvias and blind/buried vias. ........................................ 6 Differential Pairs (Basic Setup) ...........................................8 Creating a Diff Pair................................................................. 11 Spacing Constraints ..................................................................... 12 Creepage and Clearance: Minimum Distances Between Conductive Elements to Prevent Electrical Arcing ....................................................................................... 12 Component Spacing: Minimum Distances Between Components to Avoid Interference and Facilitate Cooling ..................................................................................... 15 Manufacturing Constraints ........................................................23 Fabrication Tolerances: Allowable Variations in Dimensions for Manufacturing .........................................23 Board Outline Dimensions: Tolerances for Overall Board Size and Shape .........................................................23 Trace Width for Manufacturing: Minimum Copper Width for Traces ....................................................................23 Trace Spacing: Minimum Distance Between Copper Features ..................................................................................24 Annular Ring: Minimum Width of Copper Surrounding a Hole ........................................................................................26 Drill to Copper Spacing ...................................................... 28 Teardrops (Fillets) ................................................................. 31 Pad To Mounting Hole Spacing: Minimum Distance Between Pads and Mounting Holes ................................ 31 Acid Traps: Avoiding Acute Angles in Copper Features That Can Trap Etching Chemicals ................................... 33 Minimum Copper Area: Smallest Allowable Area of Isolated Copper Features .................................................. 34 Assembly Constraints: Rules for Component Placement, Orientation, and Soldering ......................................................... 35 Outlines and Cut Outs ........................................................ 35 Where to Apply the Constraint Set .......................................... 36 Package to Package Spacing ........................................... 36 Component Spacing to PCB Features........................... 36 Pastemask ............................................................................. 36 Silkscreen and Solder Mask: Specifications for Text and Mask Application on The PCB. ................................. 38 Design for Test (DFT) Constraints ........................................... 40 Test Points: Placement and Minimum Distances From Other Test Points and Components ............................... 40 3D Constraints ................................................................................ 41 Rigid Flex PCB Constraints ........................................................ 43 Teardrops (Fillets) ................................................................ 43 Component to Flex PCB..................................................... 43 Conclusion ...................................................................................... 45 2 www.cadence.com OrCAD X Constraint Management Guide