12-CRS-0106 REVISED 8 FEB 2013 Printed Circuit Board Design
IEEE Concordia Electronics Workshop Presented by Marc-Alexandre
Chan Concordia University, room EV 2.184 19 November 2014 Photo by
Christian Taube, CC-BY-SA 2.5.
Slide 2
12-CRS-0106 REVISED 8 FEB 2013 1. Why PCBs? 2. Background
Board, components & software 3. Design Process Component
selection, positioning, routing, power & ground, fabrication
Design your own! Positioning Routing Power & Ground Fabrication
considerations Make your own PCB! Why PCBs? Technology Comparison
Current Usage Absence in Coursework Technical Background Board
Materials Layer Structure Component Technologies Design Software
Design Process Component Selection Positioning Routing Techniques
Ground/Power Planes Fabrication Restrictions Advanced Design
External Connections High-Frequency Circuits Internal Layers
Workshop Overview
Slide 3
12-CRS-0106 REVISED 8 FEB 2013 Workshop Overview 1. Why PCBs?
2. Background Board, components & software 3. Design Process
Component selection, positioning, routing, power & ground,
fabrication Design your own! 4. Some advanced considerations
External connectors, multi-layer boards, high frequency
Slide 4
12-CRS-0106 REVISED 8 FEB 2013 PCB Basics
Slide 5
12-CRS-0106 REVISED 8 FEB 2013 Why PCBs? Limited alternatives
Breadboard, perfboard, chassis mount Custom designed for each
circuit High flexibility Compact (high density) Protective solder
mask 20+ layers possible Robots! (or cheap overseas labour) Photo
by Christian Taube, CC-BY-SA 2.5.
Slide 6
12-CRS-0106 REVISED 8 FEB 2013 Technical Background
Slide 7
12-CRS-0106 REVISED 8 FEB 2013 Board MaterialsLayer Structure
Most common: FR4 Epoxy and fibreglass Heat resistant, cheap
High-frequency boards Controlled impedance Usable at 1 GHz or more
Well-known: Rogers Corp. Copper layers Allows traces to cross More
heat dissipation More compact board Surface Layers Solder mask
Silkscreen printing Board Technologies
Slide 8
12-CRS-0106 REVISED 8 FEB 2013 Board Technologies Components,
solder mask, and silkscreen layers on a PCB. Photo by Christian
Taube, CC-BY-SA 2.5.
Slide 9
12-CRS-0106 REVISED 8 FEB 2013 Packages: Through-Hole Photo
credits: Abdullah Al Mamun, CC-BY-SA 2.5 Generic / Wikimedia
Commons; Nunikasi, CC-BY-SA 3.0 Unported / Wikimedia Commons;
Adafruit Industries, CC-BY-NC-SA, Flickr; Yves-Laurent Allaert,
CC-BY-SA 3.0 Unported / Wikimedia Commons; Kimmo Palosaari, public
domain / Wikimedia Commons; Common types of through-hole capacitors
(aluminium 4, ceramic 4) Axial lead resistorDiodes in DO-41 package
Inline packages: SIP and DIP (above); Plastic (PDIP, above),
ceramic (CDIP) TO (transistor outline): TO-220 (left), TO-92
(right), metal can, etc.
Slide 10
12-CRS-0106 REVISED 8 FEB 2013 SMD capacitors Resistors are
similar Sizes in photo: 1206, 1206, 0603, 0603 1210, 1206, 0805,
0805 1812, 1812, 1206, 1210 Packages: Surface Mount (1) Photo
credits: Shaddack, public domain / Wikimedia Commons.
Slide 11
12-CRS-0106 REVISED 8 FEB 2013 Packages: Surface Mount (2)
Photo credits: All images on this slide from Wikimedia Commons.
Leapfrog, public domain; Swift.Hg, CC-BY-SA3.0 Unported; SPHL,
CC-BY-SA 3.0 Unported; NobbiP, CC-BY-SA 3.0 Unported; NobbiP,
CC-BY-SA 3.0 Unported. SOT-23-3 (3-pin small-outline transistor 23)
QFP40 (40-pin quad flat pack) 0.65mm pitch SO-8 (SOIC family) (with
PDIP for comparison) Left to right: SOIC-14, SSOP16, QFN-28 BGA-16
(left, top and bottom of package), with SOT23-6
12-CRS-0106 REVISED 8 FEB 2013 Courses vs. real world Class:
100nF capacitor Real world: What?! Material; polarised? Maximum
voltage Physical size/package Heat capacity Error tolerance Cost!!
Digi-Key: 10HV23B104KN 100nF, 1kV, 10%, $70 ea. Component Selection
Photo by Megger Ltd. CC-BY 3.0. Photo by John Fader. CC-BY-SA
3.0.
Slide 15
12-CRS-0106 REVISED 8 FEB 2013 Balance of objectives Room for
traces Compactness (cost) Heat dissipation Design simplicity
Assembly (soldering) IC pin layouts Common sense atypical Dictated
by IC structure Deal with it Component Placement Photo by Nicholas
Wang (modified). CC-BY-SA 2.0.
Slide 16
12-CRS-0106 REVISED 8 FEB 2013 Component Pinout Example Yes,
you are reading the diagram correctly. The pinout uses order
A-D-B-C and A-B-C-D-E-G-F. From the CD4543BE datasheet (Texas
Instruments). Used for illustrative purposes.
Slide 17
12-CRS-0106 REVISED 8 FEB 2013 Like wires on a PCB Point A to
point B Angled lines Cant cross each other Usually CNC milled Avoid
right angles Avoid T junctions Classic PCB look Routing Techniques:
Traces Photo by Creativity103 (flickr). CC-BY 2.0.
Slide 18
12-CRS-0106 REVISED 8 FEB 2013 Connect layers All: Straight
through Some: Buried/blind vias Difficult and expensive Allows
trace tunnels Pass under another trace Tips for vias Through hole
pads = vias! Allow for extra space High current: more vias Routing
Techniques: Vias Photo by Karl-Ludwig G. Poggemann. CC-BY 2.0.
Slide 19
12-CRS-0106 REVISED 8 FEB 2013 Large area of copper High
thermal capacity Large current capacity Obstacle for traces Obvious
light colour Copper pour tips Might need thermals Can have vias in
them Island/deadzone removal Software priority order Routing
Techniques: Copper Pour Photo by t0msk (flickr). CC-BY-NC-SA
2.0.
Slide 20
12-CRS-0106 REVISED 8 FEB 2013 Ground/power planes Pours cover
whole layer Common in 4+ layer PCB Lowest priority Many and/or
larger vias Can use several pours Battery/supply voltage Regulated
voltage Logic level voltage Multiple grounds Routing components
Take advantage of mask! Traces between pins Traces under SMD pads
Fabrication constraints DRC limits Trace-trace clearance Board edge
clearance Trace-pad clearance Real-world drill sizes Practical
Strategies
12-CRS-0106 REVISED 8 FEB 2013 Connector Examples Photo credits
(clockwise from top left): oomlout (flickr), CC-BY-SA 3.0;
Appaloosa, CC-BY-SA 3.0 / Wikimedia Commons; M7, public domain /
Wikimedia Commons; Mike1024, public domain / Wikimedia Commons
Slide 23
12-CRS-0106 REVISED 8 FEB 2013 High-FrequencyMultilayer Design
Board RF Behavior Transmission line effects Digital circuit
switching Intentional antennas Unintentional antennas Controlled
Impedance Simulation / fabrication Problems Alleviated Ground loops
Traces to ground have impedance in real world! Crosstalk Internal
Planes Free capacitor Buried/blind vias High-Frequency
Considerations
Slide 24
12-CRS-0106 REVISED 8 FEB 2013 Design Walkthrough Activity
Design a PCB from start to finish! Link to PCB software:
http://ieee.concordia.ca/go/pcb Photo by Windell Oskay. CC-BY
2.0.
Slide 25
12-CRS-0106 REVISED 8 FEB 2013 Alarm/Buzzer Module Schematic:
Alarm/buzzer module
Slide 26
12-CRS-0106 REVISED 8 FEB 2013 Alarm/Buzzer Module How it
works: When TRIG is LO (0V):nothing happens (low power) When TRIG
is HI (5V):buzzer sounds (higher power) TRIG short circuit to
ground same as LOW TRIG open circuit same as HI (pull-up resistor)
Ideas for the module Plug a switch in between TRIG and GND Use reed
switch on a door frame and a magnet on door! Make a microcontroller
module to control the alarm Arm/disarm, intruder detection, alarm
patterns, etc.
Slide 27
12-CRS-0106 REVISED 8 FEB 2013 Basic schematic capture Choose
components Connect with wires Custom components LM555CN Custom
symbol (pins) Standard DIP8 pattern Speaker custom symbol and
pattern Convert to PCB Create board outline Target size: 5cm 8cm
Pre-place components Verify packages and sizes Routing the board
Ground and power planes Traces for programming Check drill sizes
Prepare for manufacturing To Do List
Slide 28
12-CRS-0106 REVISED 8 FEB 2013 Board Layout Sample PCB layout:
top layer (left) and bottom layer (right)
Slide 29
12-CRS-0106 REVISED 8 FEB 2013 Ready for Manufacturing Sample
PCB Gerber file (bottom layer traces)
Slide 30
12-CRS-0106 REVISED 8 FEB 2013 Ready for Manufacturing How can
you manufacture your design? Do it yourself with traditional
methods Photosensitive two-sided copper boards Regular copper board
+ a laser printer + glossy paper In all cases: ferric chloride to
eat away unwanted copper Get a fab house to do it Many companies
can do prototypes/small orders for cheap APCircuit (Alberta,
http://www.apcircuits.com)http://www.apcircuits.com Advanced
Circuits (US, http://www.4pcb.com)http://www.4pcb.com ITEAD (China,
http://iteadstudio.com)http://iteadstudio.com SeeedStudio (China,
http://www.seeedstudio.com)http://www.seeedstudio.com OSHPark (US,
https://oshpark.com)https://oshpark.com
Slide 31
12-CRS-0106 REVISED 8 FEB 2013 Want to learn more? More details
and good practices for PCBs?
http://alternatezone.com/electronics/files/
PCBDesignTutorialRevA.pdfhttp://alternatezone.com/electronics/files/
PCBDesignTutorialRevA.pdf Want to start getting into advanced PCB
design? High power and high current design Copper thickness
(weight: standard is 1 oz) Maximum current through a trace
Isolation slots, circuit isolation High frequency design (100MHz to
many GHz) Transmission line effects, microstrip design
(ELEC351/353/453) Cross-talk, resonant circuit layout, etc.
Slide 32
12-CRS-0106 REVISED 8 FEB 2013 Thank you for participating in
this workshop! Questions? [email protected]
http://ieee.concordia.ca This work is licensed under the Creative
Commons BY-NC-SA 3.0 Unported License. To view a copy of this
license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/ or
send a letter to Creative Commons, 444 Castro Street, Suite 900,
Mountain View, California, 94041, USA. Copyright 2013-2014 the
Institute of Electrical and Electronics Engineers, Inc.
Contributors: Marc-Alexandre Chan, Ryan Desgroseilliers.