Printed Circuit BoardElectronic Board that connects circuit componentsPCB populated with electronic components is a printed circuit assembly (PCA)PCBs are rugged, inexpensive, and can be highly reliableMass manufacturingProfessional
Components Pads TracesVias Top Metal LayerIntermediate Layers Bottom Metal LayerLocation that components connect to.You will solder components to the pads on the PCB. Pads will connect to traces. Pads have an inner diameter and outer diameter.Traces connect pads together. Traces are essentially the wiring of the PCB.Equivalent to wire for conducting signalsTraces sometimes connect to vias. High current traces should be wide.Signal traces usually narrower than power or ground tracesPad with a plated hole connecting traces from one layer of board to other layers. Attempt to minimize via use in your PCBs. Some component leads can be used as vias.
Not just physical layout and routingComponent SizeHeat DissipationInput and OutputMounting PointsSeries InductanceShunt CapacitanceInductive CouplingCapacitive Coupling
Most of us start hereComponents are the actual devices used in the circuit.This includes input/output connections.I/O ports, including power supply connections, are also important in the PCB design.Libraries may be eagle libs or previous designsConnections are not only on board, but off boardDon’t forget the dimensions!
Avoid changing the grid unless absolutely necessary.Free Eagle version does not allow “sheets”.Free Eagle version requires that schematic drives the layout ... not vice-versa.Groups, Info, and Layers icons are useful.Pan, zoom, niceties easy to use.Really care about that “net”? Label it.Keep it clean - don’t be lazy.Document!Networks are key if you are doing ground plane flooding
Passives - 0805 means 0.08” by 0.05”Connectors - beware of physical fitActives - lots of packaging alternativesThink about buildability, testability and troubleshooting
Are your Design Rules setup correctly?Run the Design Rule Check (DRC) often.Run the Electrical Rule Check (ERC) often.Save a snapshot of your placement file.Take your time.Untangle flight lines.Think about planes.Consider testability.Mechanical Fit?Hard stuff first.Keep silkscreen.Think hard about components on 2-sides.
Time to wire it upThink about how many layers you have. Stick to tone. Let it slip to two. If you can afford 4, what are you doing listening to me?You want to route, not wire.You want to ripup, not delete nets.Are you on the top or the bottom?Vias are on top and bottom. Easy to add.DRC often!Iterate like mad.
From Idea to ImplementationCreating Circuit Boards Using EaglePCBBob Bownes KI2Lbownes@web9.com
From Idea to Implementation• Idea• Block Diagram• Schematic• Prototype• PCB Outline & Place• PCB Routing• Enclosure Selection• Build• Correct• Mass Produce
What is a PCB?A Mechanical Solution to an Electrical Problem3
What is a PCB?Layers, Pads, Traces, Planes, and Vias ... oh my!4
Schematic CaptureCreating a New Schematic• File -> New -> Schematic• Save it with a new name!• Don‟t go creating a Board justyet.• Keep the defaults.
Schematic CaptureAdding Components• Click the Add icon• Find the component in thelibrary• Set values or take defaults.• Don‟t see the library? Try Use -> Library
Schematic CaptureAdding Power, Ground, etc• Click the Add icon• Find the global symbol in thelibrary (supply1)• Place as if it were a component• Place power and ground forevery powered component• Make a row for bypass caps• Place a few spares in a corral
Schematic CaptureConnect The dots!• Click the Wire icon• Connect component endpoints• Use the Junction icon• Additional Features• Buss wires• Networks
Libraries• Internal• CadSoft Web Site > 100 libs– Cadsoftusa.com/downloads• SparkFun• Manufacturer websites
Board Layout• Create your board• From the schematic,choose File -> Switchto Board.• “Create From Schematic”?• Of Course!• Board window automaticallyopens.• Create an outline of thephysical board• Parts at lower left
Place Components• Select Move icon toreposition.• Click on component,drag to new location• Lather, rinse, repeat• Use the Rotate icon torotate a component• Use Mirror icon to flipa component17
Board Layout• DRC is your Friend!• Save often, save revisions.20
Route• Click the Route icon• Pick the end of an airwire• Drag, click, drag, doubleclick endpoint• Right click on anendpoint or via, setsignal name
Route – The Auto Router• Tools Auto or cmd line„auto;‟• May take a while forcomplex designs• Will use all availablelayers• Will probably notcomplete• Leaves you the hard work22
Route – Auto Router Hints• Work in small patches• Use components as jumpers• Rotate components• Rip up single wires• Use rip; to rip up everything• Rip up groups• Manual wire and via placement• Only sadists put the DIPs inmultiple orientations!23
EagleUp• Eagle meets Google SketchUp• Plug-in (ULP)
G-Code• Numerical Control (NC) Programming Language• MIT Origin• AKA ISO 6983 / RS274D / GERBER_RS_274• Full programming language with loops,conditionals, variables, etc.• Basic operations– Start, stop, position, move in straight line or arc– Set tool information, coordinate systems, internalcontrol
G-Code Generation• PCB-Gcode• Eagle Plug in• Generates g-gode from board layout• Many options• Support for multiple consumers