IIB. Complete PCB Design Using OrCAD Capture and PCB Editor. Kraig Mitzner. ~»* ' AMSTERDAM BOSTON HEIDELBERG LONDON ^ i H

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1 Complete PCB Design Using OrCAD Capture and PCB Editor Kraig Mitzner IIB ~»* ' AMSTERDAM BOSTON HEIDELBERG LONDON ^ i H NEW YORK * OXFORD PARIS SAN DIEGO ШШЯтИ' ELSEVIER SAN FRANCISCO SINGAPORE SYDNEY TOKYO Newnes is an imprint of Elsevier NOWnQS

NEW YORK * OXFORD PARIS SAN DIEGO ШШЯтИ' ELSEVIER SAN

2 INTRODUCTION ACKNOWLEDGMENTS xi xv CHAPTER 1 Introduction to PCB Design and CAD 01 Computer-Aided Design and the OrCAD Design Suite 01 Printed Circuit Board Fabrication 02 PCB Cores and Layer Stack-Up 02 PCB Fabrication Process 04 Photolithography and Chemical Etching 05 Mechanical Milling 07 Layer Registration 07 Function of OrCAD PCB Editor in the PCB Design Process 09 Design Files Created by PCB Editor 12 PCB Editor Format Files 12 Artwork (Gerber) Files 12 PCB Assembly Layers and Files 13 CHAPTER 2 Introduction to the PCB Design Flow by Example 15 Overview of the Design Flow 15 Creating a Circuit Design with Capture 15 Designing the PCB with PCB Editor 22 The PCB Editor Window 22 Drawing the Board Outline 24 Placing Parts 25 Moving and Rotating Parts 25 Routing the Board 27 Creating Artwork for Manufacturing 31 CHAPTER 3 Project Structures and the PCB Editor Tool Set 33 Project Setup and Schematic Entry Details 33 Capture Projects Explained 33 Capture Part Libraries Explained 36 Understanding the PCB Editor Environment and Tool Set 38 Terminology 38 PCB Editor Windows and Tools 39 The Design Window 39 The Toolbar Groups 39 Control Panel with Foldable Window Panes 44 Command Window Pane 46

Created by PCB Editor 12 PCB Editor Format Files 12 Artwork (Gerber) Files 12 PCB Assembly Layers and Files 13 CHAPTER 2 Introduction to the PCB Design Flow by Example 15 Overview of the Design Flow

3 Contents WorldView Window Pane 47 Status Bar 47 Color and Visibility Dialog Box 48 Layout Cross Section (Layer Stack-Up) Dialog Box 48 Constraint Manager 48 Manufacturing Artwork and Drill Files 52 Understanding the Documentation Files 54 CHAPTER I* Introduction to Industry Standards 57 Introduction to the Standards Organizations 58 Institute for Printed Circuits (IPC Association Connecting Electronics Industries) 58 Electronic Industries Alliance (EIA) 58 Joint Electron Device Engineering Council (JEDEC) 59 International Engineering Consortium (IEC) 59 Military Standards 59 American National Standards Institute (ANSI) 59 Institute of Electrical and Electronics Engineers (IEEE) 60 Classes and Types of PCBs 60 Performance Classes 60 Producibility Levels 61 Fabrication Types and Assembly Subclasses 61 IPC Land Pattern Density Levels 62 Introduction to Standard Fabrication Allowances 62 Registration Tolerances 62 Breakout and Annular Ring Control 62 PCB Dimensions and Tolerances 63 Standard Panel Sizes 63 Tooling Area Allowances and Effective Panel Usage 64 Standard Finished PCB Thickness 64 Core Thickness 65 Prepreg Thickness 65 Copper Thickness for PTHs and Vias 66 Copper Cladding/Foil Thickness 66 Copper Trace and Etching Tolerances 67 Standard Hole Dimensions 68 Soldermask Tolerance 69 References 69 Suggested Reading 70 Other Items of Interest 70 CHAPTER 5 Introduction to Design for Manufacturing 71 Introduction to PCB Assembly and Soldering Processes 71 Assembly Processes 71 Soldering Processes 73

Electronics Industries) 58 Electronic Industries Alliance (EIA) 58 Joint Electron Device Engineering Council (JEDEC) 59 International Engineering Consortium (IEC) 59 Military Standards 59 American

4 Component Placement and Orientation Guide 77 Component Spacing for Through-Hole Devices 78 Component Spacing for Surface-Mounted Devices 78 Mixed THD and SMD Spacing Requirements 82 Footprint and Padstack Design for PCB Manufacturability 82 Land Patterns for Surface-Mounted Devices 84 Land Patterns for Through-Hole Devices 90 References 96 PCB Design for Signal Integrity 97 Circuit Design Issues Not Related to PCB Layout 97 Noise 97 Distortion 98 Frequency Response 99 Issues Related to PCB Layout 99 Electromagnetic Interference and Cross Talk 99 Magnetic Fields and Inductive Coupling 100 Loop Inductance 103 Electric Fields and Capacitive Coupling 105 Ground Planes and Ground Bounce 106 What Ground Is and What It Is Not 106 Ground (Return] Planes 110 Ground Bounce and Rail Collapse 110 Split Power and Ground Planes 112 PCB Electrical Characteristics 114 Characteristic Impedance 114 Reflections 119 Ringing 124 Electrically Long Traces 125 Critical Length 129 Transmission Line Terminations 129 PCB Routing Topics 132 Parts Placement for Electrical Considerations 132 PCB Layer Stack-Up 133 Bypass Capacitors and Fan-Out 137 Trace Width for Current-Carrying Capability 138 Trace Width for Controlled Impedance 139 Trace Spacing for Voltage Withstanding 149 Trace Spacing to Minimize Cross Talk (3w Rule) 149 Traces with Acute and 90 Angles 150 Using PSpice to Simulate Transmission Lines 152 Simulating Digital Transmission Lines 153 Simulating Analog Signals 156 References 156 Numbered References 157

Issues Not Related to PCB Layout 97 Noise 97 Distortion 98 Frequency Response 99 Issues Related to PCB Layout 99 Electromagnetic Interference and Cross Talk 99 Magnetic Fields and Inductive Coupling

5 Contents CHAPTER7 Making and Editing Capture Parts 159 The Capture Part Libraries 159 Types of Packaging 160 Homogeneous Parts 160 Heterogeneous Parts 160 Pins 161 Part Editing Tools 162 The Select Tool and Settings 162 The Pin Tools 162 The Graphics Tools 163 The Zoom Tools 163 Methods of Constructing Capture Parts 164 Method 1. Constructing Parts Using the New Part Option (Design Menu) 164 Method 2. Constructing Parts with Capture Using the Design Spreadsheet 176 Method 3. Constructing Parts Using Generate Part from the Tools Menu 179 Method 4. Generating Parts with the PSpice Model Editor 180 Constructing Capture Symbols 194 CHAPTER 8 Making and Editing Footprints 197 Introduction to PCB Editor's Symbols Library 197 Symbol Types 198 Composition of a Footprint 199 Padstacks 200 Graphical Objects 201 Text 202 Minimum Footprint Requirements 202 Optional Footprint Objects 202 Introduction to the Padstack Designer 203 Padstack Designer Parameters Tab 203 Padstack Designer Layers Tab 204 Footprint Design Examples 205 Example 1. Design of a Through-Hole Device from Scratch 206 Example 2. Design of Surface-Mount Device from an Existing Symbol 212 Example 3. PGA Design Using the Symbol Wizard 216 Flash Symbols for Thermal Reliefs 219 Mechanical Symbols 222 Mounting Holes 223 Creating Mechanical Drawings 225 Placing Mechanical Symbols on a Board Design 226 Blind, Buried, and Microvias 227 Using the IPC-7351 Land Pattern Viewer 229 References 232

Constructing Parts Using the New Part Option (Design Menu) 164 Method 2. Constructing Parts with Capture Using the Design Spreadsheet 176 Method 3.

6 Contents CHAPTER 9 PCB Design Examples 233 Introduction 233 Overview of the Design Flow 234 Example 1. Dual Power Supply, Analog Design 236 Initial Design Concept and Preparation 237 Setting Up the Project in Capture 238 Preparing the Design for PCB Editor 245 Setting Up the Board 253 Design Rule Check and Status 276 Defining the Layer Stack-Up 278 Pouring Copper Planes 282 Verifying Connectivity between Pins and Planes 285 Defining Trace Width and Spacing Rules 289 Prerouting the Board 292 Manually Routing Traces 295 Finalizing the Design 298 Example 2. Mixed Analog/Digital Design Using Split Power, Ground Planes 304 Mixed-Signal Circuit Design in Capture 304 Defining the Layer Stack-Up for Split Planes 310 Setting Up Routing Constraints 316 Adding Ground Planes to Routing Layers 322 Example 3. Multipage, Multipower, and Multiground Mixed A/D PCB Design with PSpice 326 Introduction 326 Multiplane Layer Methodologies 327 Capture Project Setup for PSpice Simulation and Board Design Designing the Board with PCB Editor 340 Assigning Vias to Nets 348 Alternate Methods of Connecting Separate Ground Planes 354 Example 4. High-Speed Digital Design 358 Layer Setup for Microstrip Transmission Lines 360 Constructing a Heat Spreader with Copper Pours and Vias 362 Determining Critical Trace Length of Transmission Lines 369 Moated Ground Areas for Clock Circuits 373 Gate and Pin Swapping 375 Using Swap Options 377 Using the Autoswap Option 380 Positive Planes 383 Positive Plane Artwork Production 389 Positive vs. Negative Plane File Sizes 389 Pros and Cons of Using Positive vs. Negative Planes 389 Design Templates 391 Making a Custom Capture Template 391 Making a Custom PCB Editor Board Template 391 Making a Custom PCB Editor Technology Template 392

Check and Status 276 Defining the Layer Stack-Up 278 Pouring Copper Planes 282 Verifying Connectivity between Pins and Planes 285 Defining Trace Width and Spacing Rules 289 Prerouting the Board 292

7 Using the Board Wizard 393 Moving on to Manufacturing 396 References 396 CHAPTER IO Artwork Development and Board Fabrication 399 Schematic Design in Capture 399 The Board Design with PCB Editor 400 Routing the Board 400 Placing Mechanical Symbols 402 Generating Manufacturing Data 405 Generating the Artwork Files 405 Generating Drill Files 415 Generating Route Path Files 417 Generating the Route File 419 Verifying the Artwork 420 Using CAD Tools to 3-D Model the PCB Design 421 Fabricating the Board 423 Receipt Inspection and Testing 425 Generating Pick and Place Files 425 References 428 APPENDICES 429 APPENDIX A List of Design Standards 431 APPENDIX В Partial List of Packages and Footprints and Some of the Footprints Included in OrCAD Layout 433 APPENDIX С Rise and Fall Times for Various Logic Families 447 APPENDIX D Drill and Screw Dimensions 449 APPENDIX E References by Subject 451 INDEX 467 is

File 419 Verifying the Artwork 420 Using CAD Tools to 3-D Model the PCB Design 421 Fabricating the Board 423 Receipt Inspection and Testing 425 Generating Pick and Place Files 425 References 428

Executive Summary. Table of Contents

Executive Summary. Table of Contents Executive Summary How to Create a Printed Circuit Board (PCB) Department of Electrical & Computer Engineering Michigan State University Prepared by: John Kelley Revision: 4/06/00 This application note