ENGG2800 / METR2800
Team Project II
PCB Design
ENGG2800 / METR2800
PCB Design: Tips, Guidelines, and Resources
by
Donald Cook
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ENGG2800 / METR2800
Team Project II
PCB Design
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Realistically, PCB design cannot be taught in a lecture. Instead, I have
created this set of slides to be used as reference material for you.
Altium provides fantastic tutorials that are well written and deliver all
the information you need. The very first tutorial is:
“Getting Started with PCB Design”
TU0117.pdf
ENGG2800 / METR2800
Team Project II
PCB Design
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Terms & Acronyms
PCB – Printed Circuit Board
Tracks – Form
components.
the
connections
between
Pads – Used to make connections between your
component and the track with solder.
Layers - Everything is drawn on a layer, layers can
have different physical properties. Example layers
are: Top layer, bottom layer, Top overlay, bottom
overlay, Mechanical 1, Keep Out.
Plated Through Holes (PTH) – Drilled holes that are
plated with conductive material (usually copper).
ENGG2800 / METR2800
Team Project II
PCB Design
Terms & Acronyms
Footprints – A collection of pads and outlines which
describe an individual component’s physical layout
on a PCB.
Design Rules – Rules specified by the designer to
ensure PCB integrity (more on this later).
Vias – Used to make connections between different
layers of the PCB.
Silkscreen – A protective layer over the top of the
board, makes soldering easier.
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ENGG2800 / METR2800
Team Project II
PCB Design
FAQ
1. Should I use metric or imperial?
2. Who manufactures my PCB?
3. What size drill-holes should I be using?
4. What size should my tracks be? What sort of clearance should I
have between tracks?
5. The tutors tell me Auto-route is the Devil, is this true?
6. Help! I can’t find a footprint for my component!
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ENGG2800 / METR2800
Team Project II
PCB Design
1. Should I use metric or imperial?
• Remember: Metric measurements are in (milli)meters,
imperial measurements are in thou (thousandths of an inch).
• For Team Project PCBs we have decided on the following
important rules.
• 1000mil/thou = 1 inch ≠ 1000mm
Drill Holes – USE METRIC!
Anything else – Either
(More on drill holes later)
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ENGG2800 / METR2800
Team Project II
PCB Design
2. Who manufactures my PCB?
• We currently use PCBfast (based in Melbourne)
• Website: www.pcbfast.com.au
• Most of our design requirements are copied directly from their
website; while a few design requirements are simply to speed up
turn-around time (for your benefit).
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ENGG2800 / METR2800
Team Project II
PCB Design
3. What size drill-holes should I be using?
• “Drill bits are available in tool sizes with 0.05mm
increments from 0.2mm to 3.0mm and 0.1mm increments
from 3.1mm to 6.3mm.” – PCBFast Website.
• “0.4mm – 6.00mm for PTH (Plated Through Hole).” –
PCBFast Website
BUT
• “15 tool sizes per standard manufacturing panel” - PCBFast
Website.
How does this affect me?
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Team Project II
PCB Design
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3. What size drill-holes should I be using?
• If a panel to be manufactured has more than 15 different
hole sizes, then the COST increases and possibly even the
LEADTIME. So try to use as few as possible (within reason).
Suggested Hole Sizes
(From the ENGG2800 Website)
Part
Suggested
Hole size
Vias
0.6mm
IC Legs, TO-92 Transistors, 1N4148 Diodes
0.9mm
Resistors/Capacitors/ and many other components
0.8mm
Diode Legs (1A, eg 1N4004), IDC connectors, TO-220 transistors
1.0mm
Diode Legs (3A, eg 1N5404), many connectors
1.25mm
ENGG2800 / METR2800
Team Project II
PCB Design
4. What size should my tracks be? What sort of clearance
should I have between tracks?
• A track should not be narrower than the minimum
manufacturing limit. However, it is recommended that for
simple designs you should stick to 12thou (0.3mm) as a
minimum.
“Minimum 8 thou track/space.” – PCBFast Website.
• Thicker tracks are needed if you want to carry significant
current. Thin tracks will get hot, and cause voltage drops if
significant current flows.
• For your projects, there’s no harm in using larger tracks.
See the website for track width recommendations.
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ENGG2800 / METR2800
Team Project II
PCB Design
5. The tutors tell me Autoroute is the devil!
• Using Autoroute is a design decision of your own to make.
• Using Autoroute is a lazy option (you should be spending
more time learning how to create PCBs, not less).
“Would you trust Microsoft Word to automatically format
your reports?” – Donald Cook.
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ENGG2800 / METR2800
Team Project II
PCB Design
6. Help! I can’t find a footprint for my component!
MAKE YOUR OWN
(More on this soon)
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Team Project II
PCB Design
General PCB Design Tips
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Team Project II
PCB Design
PCB Design Tip 1: LABEL YOUR PCB
•
•
Include your TEAM NUMBER & COURSE CODE
Put it on Top Overlay
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Team Project II
PCB Design
PCB Design Tip 2: Be careful with your power nets
•
Place decoupling caps near microcontrollers and other ICs, to
help reduce noise on your power-supply line. How much
capacitance? If the datasheet don’t specify an amount, start
with 10-100nF, then measure your supply-line using a CRO.
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Team Project II
PCB Design
PCB Design Tip 3: Orientate polarised components sensibly
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Team Project II
PCB Design
PCB Design Tip 4: Where did that component go?
Make use of the PCB filter
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Team Project II
PCB Design
PCB Design Tip 5: Make sure you draw a PCB border on
Mechanical Layer 1
OTHERWISE YOUR PCB MAY BE
REJECTED!
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Team Project II
PCB Design
PCB Design Tip 6: Make sure you turn on all USED layers when
you submit your PCB for manufacturing!
OTHERWISE YOUR PCB MAY NOT BE MANUFACTURED
CORRECTLY (MISSING VIAS, TRACKS, ETC)
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Team Project II
PCB Design
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PCB Design Tip 7: Don’t use tracks at right angles, they are a
common point of failure when the board is being routed.
Bad!
Good!
ENGG2800 / METR2800
Team Project II
PCB Design
PCB Design Tip 8: If you make mistakes on your board, it is
possible to correct them with PCB hacks.
• Cut tracks with a sharp knife.
• Bridge tracks/pads with fly-wire.
• File/cut your board down to size. Wear a mask.
• Drill new mounting holes (if you forgot them!).
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Team Project II
PCB Design
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PCB Design Tip 9: Use oval shaped solder pads instead of circular
pads.
Difficult to
solder!
Easy
to solder!
ENGG2800 / METR2800
Team Project II
PCB Design
PCB Design Tip 10: Use long solder pads for surface mount
devices.
Difficult to
solder!
Easy
to solder!
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ENGG2800 / METR2800
Team Project II
PCB Design
PCB Design Tip 11: Learn how to use the Bill of Materials tool!
You can keep track component details such as:
• Part Manufacturer
• Supplier (and cost)
• Supplier order number
• Datasheet URL
• etc
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ENGG2800 / METR2800
Team Project II
PCB Design
PCB Design Tip 12: Spend lots of time setting up your PCB rules!
Eg
• Set your Power Nets to have a minimum track
width of 18mil.
• Set your ground plane to have a larger
clearance constraint than usual.
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ENGG2800 / METR2800
Team Project II
PCB Design
PCB Design Tip 13: Make sure you check the PCB manufacturing
rules!
Or your board will not be manufactured!
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ENGG2800 / METR2800
Team Project II
PCB Design
PCB Design Tips
•
Use a sensible number of drill-hole sizes. (Consolidate with
other teams).
•
Don’t forget mounting holes!
•
If your PCB has a background layer, delete it!
•
Take your time (and allocate a lot of it). You can’t do a PCB
design the night before a batch is due.
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ENGG2800 / METR2800
Team Project II
PCB Design
NUMBER ONE PCB DESIGN TIP
PRINT YOUR PCB TO SCALE AND
PLACE COMPONENTS ON TOP OF
YOUR PRINTED PCB.
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