Produce Your Own PCB BoardJack OuEngineering ScienceSonoma State University
Four-Bit Adder-Subtractor (4 bit ripple adder)
A Four-Bit Adder/Subtractor on Breadboard Problem: too many wires!
Tips • Double click to terminate a wire
Add Junction to the Schematic Add junction to the schematic.
Add Power and Gnd of Each IC Chip to the schematic 1. Right click on a part (74LS08N in this example) 2. Click on Invoke
Invoke a Part Select PWRN, Press OK.
Move • Use the Move button to alter any component’s location Click on + to move a part
Display Net Name 1. Enter a net name 2. Display the netname
ERC error Use ERC to check connectivity of the wire.
Board Editor If you keep both windows open, changes made on the schematic window will be reflected in the layout window.
Rearrange the Comopnents (Right-Click to rotate a component) (The smaller the board, the more economical)
Click on Route to Start Wiring Up the Circuit (Left click to select air wire to route) Double click To remove wire
Routing Menu Add angel to the wiring (Width of a wire) (Two Metal Layers) You should select the width of the wire to be 0.04 inches (40 mils) or greater.
Reduce the Active Area Hieight is 2.5 inches
Auto Router Click this option to start autoroute
Result of Auto Route 2 metal layers used Not area efficient
Header Termination Terminate the traces going to the header at the bottom metal layer Reason: this is where the IC will be soldered. Header terminates at the top metal layer—not a good practice
How to Change Metal Layer Step 1: Click on ripup, double click a wire to delete.
How to Change Metal Layer Step 2: Move the wires to create sapce
How to Change Metal Layer Step 3: Route wire. Start routing at the top metal level. Step 4: Click once to place the wire in an empty area. Step 5: Switch to the bottom layer Step 6: Make contact with the pad at the bottom layer
A Sample Eagle Layout Clean up the metal layer
Jumpers • You will need to use physical wires as jumpers in places where you can’t route across existing copper trace.
Add Vias • Add Vias • Drill 0.03149 (Assumptions: 1. drill bit is approximately 31 mils in diameter 2. wire size is 29 mils) • Diameter 0.056 (56 mils)
Provide Connection Via Jumper (Right click to bend the wire by 45 degrees)
Print Only Necessary Metal Layers (Show Bottom trace, pads, and via)