Download ppt - Printed Circuit Board Design

Printed Circuit Board DesignPrinted Circuit Board Design

Sung Yeul ParkSung Yeul Park

Dept. of Electrical and Computer EngDept. of Electrical and Computer Eng

University of ConnecticutUniversity of Connecticut

September 24, 2014September 24, 2014

What can you see from an electrical What can you see from an electrical engineering perspective?engineering perspective?

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Three Elements to be consideredThree Elements to be considered

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Components : Components :

- How to select components?- How to select components?

- What values are needed?- What values are needed?

- What kind of package will be?- What kind of package will be? Printed Circuit Board :Printed Circuit Board :

- Schematic Design- Schematic Design

- PCB Layout Design- PCB Layout Design

- Prototype board- Prototype board Case or Box for the prototype board :Case or Box for the prototype board :

- Purchase - Purchase or build by yourselfor build by yourself

Printed Circuit Board ?Printed Circuit Board ?

A printed circuit board (PCB) mechanically supports and electrically A printed circuit board (PCB) mechanically supports and electrically

connects electronic components using conductive tracks, pads and other connects electronic components using conductive tracks, pads and other

features etched from copper sheets laminated onto a non-features etched from copper sheets laminated onto a non-

conductive substrate. conductive substrate.

PCBs can be single sided (one copper layer),double sided (two copper PCBs can be single sided (one copper layer),double sided (two copper

layers) or multi-layer. layers) or multi-layer.

Conductors on different layers are connected with plated-through holes Conductors on different layers are connected with plated-through holes

called vias. called vias.

Advanced PCBs may contain components - capacitors, resistors or Advanced PCBs may contain components - capacitors, resistors or

active devices - embedded in the substrate.active devices - embedded in the substrate.


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A PCB as a design on a computer (left) and realized as a board assembly populated with components (right). The board is double sided, with through-hole plating, green solder resist and a white legend. Both surface mount and through-hole components have been used.


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Schematic Design

PCB Layout

Key terms for PCB designKey terms for PCB design Pads are where the components are soldered Pads are where the components are soldered

to the PCB. to the PCB.

Traces are the copper tracks that Traces are the copper tracks that connect pads together.connect pads together.

Via are small holes through the board Via are small holes through the board that link a bottom and top trace that link a bottom and top trace together electrically. Traces on the together electrically. Traces on the same layer cannot cross, so often, same layer cannot cross, so often, when you are laying out a PCB, you when you are laying out a PCB, you need to a signal to jump from one need to a signal to jump from one layer to another.layer to another.

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Key terms for PCB designKey terms for PCB design

Silk-screen refers to any lettering that Silk-screen refers to any lettering that will appear on the final board.will appear on the final board.

Solder-mask is a layer of insulating Solder-mask is a layer of insulating lacquer that covers both sides of the lacquer that covers both sides of the board except where there are pads.board except where there are pads.

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Multi-layer PCB designMulti-layer PCB design 2 Layer PCB design: Top layer and bottom layer2 Layer PCB design: Top layer and bottom layer

4 Layer PCB design: Top, Bottom, and two middle layers.4 Layer PCB design: Top, Bottom, and two middle layers.

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PCB design procedurePCB design procedure Design specificationDesign specification Circuit diagramCircuit diagram Schematic design Schematic design Select components Select components

Check the dimension Check the dimension Build a footprint Build a footprint Make a PCB library Make a PCB library Add parts Add parts

Export schematic design to layout designExport schematic design to layout design Route all connectionRoute all connection Design rule checkDesign rule check Generate Gerber files and drill file and zip themGenerate Gerber files and drill file and zip them Upload zip file to PCB order websiteUpload zip file to PCB order website

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PCB Library designPCB Library design

Are you Ready to build a library?Are you Ready to build a library? Component datasheetComponent datasheet Dimension: mil (imperial unit) vs mm (metric)Dimension: mil (imperial unit) vs mm (metric)

1 inch =1000 mil, 1 mil = 0.0254 mm1 inch =1000 mil, 1 mil = 0.0254 mm

1 mm = 39.3700787 mil1 mm = 39.3700787 mil

DIP component and connector: 100 mil or 2.54 mmDIP component and connector: 100 mil or 2.54 mm Symbol in schematic vs Exact dimension in LayoutSymbol in schematic vs Exact dimension in Layout Pad number should be matched in schematic symbol Pad number should be matched in schematic symbol

and layout footprintand layout footprint

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PCB Library dimension examplePCB Library dimension example

Male headerMale header

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PCB manufacturing procedurePCB manufacturing procedure

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http://www.pa-international.com/images/stories/Multi-layer%20Metal%20Plate%20PCB%20Process%20Flow%20Chart.JPG

Tips for PCB designTips for PCB design Keep traces straight,Keep traces straight,

Try to avoid 90Try to avoid 90oo turns use two 45 turns use two 45oo’s.’s.

Double, even triple check layout,Double, even triple check layout, Having a fresh pair of eyes look it over,Having a fresh pair of eyes look it over, ““measure twice, cut once” idea.measure twice, cut once” idea.

Trace thickness & spacingTrace thickness & spacing Spacing of at least .010”,Spacing of at least .010”,

0.030” for In-house0.030” for In-house ~0.025” per 1 Amp carrying lines,~0.025” per 1 Amp carrying lines, Don’t use anything smaller than 0.010” for traces,Don’t use anything smaller than 0.010” for traces,

0.030” for In-house milling.0.030” for In-house milling.

Try to keep all connections on one side of PCBTry to keep all connections on one side of PCB Take into account component package Take into account component package

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Free PCB design programFree PCB design program EAGLE PCB Design Software:EAGLE PCB Design Software:

http://www.cadsoftusa.com/download-eagle/freeware/ http://www.cadsoftusa.com/download-eagle/freeware/

Express PCB:Express PCB:

http://www.expresspcb.com/expresspcbhtm/download.htm http://www.expresspcb.com/expresspcbhtm/download.htm

Free PCB:Free PCB:

http://www.freepcb.com/ http://www.freepcb.com/

Advanced Circuits:Advanced Circuits:

http://www.4pcb.com/free-pcb-layout-software/http://www.4pcb.com/free-pcb-layout-software/

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Making PCBsMaking PCBs

Layout your circuit / circuitsLayout your circuit / circuits Check out Check out http://www.expressPCB.comhttp://www.expressPCB.com for some for some

great tips on component layout and power great tips on component layout and power distribution.distribution.

Layout is more of an art.Layout is more of an art. Tight spacesTight spaces Lots of connectionsLots of connections Make a 2 level board into a 3 level with viasMake a 2 level board into a 3 level with vias

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PCB Design ExamplePCB Design Example

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Top and Bottom LayerTop and Bottom Layer

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Middle Layers(2Middle Layers(2ndnd & 3 & 3rdrd))

2020 DC-DC ConverterDC-AC Inverter

DS

P

Board

PCB Design AssignmentPCB Design Assignment

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Every senior design team need to design one printed circuit board Every senior design team need to design one printed circuit board

during fall semester.during fall semester.

The number of components should be more than 10 components The number of components should be more than 10 components

with connectors, surface mount components, through-hole with connectors, surface mount components, through-hole

components, and ICs.components, and ICs.

The number of layers should be 2 or more.The number of layers should be 2 or more.

Report due date is November 19Report due date is November 19thth 2014 2014

Report: Schematic, Layout, and Free dfm Check resultReport: Schematic, Layout, and Free dfm Check result

https://www.my4pcb.com/net35/FreeDFMNet/FreeDFMHome.aspx