ELECTRONICS DESIGN
● Introduction to PCB Design ● Autodesk Eagle ● PCB Design ● Sample PCB using Eagle
ONE
Introduction to PCB Design
What is a PCB? PCB stands for Printed Circuit Board. It is a mechanical solution to an engineering problem. Green Solder Mask
What is a PCB? (Cont.) A professional and neat circuit with
A prototype circuit on breadboard
reliable connections and compact
with jumbled wires.
size.
With PCB design and
production
can be.
PCB Manufacturing Techniques Chemical Etching
An old technique used to etch the copper boards to make PCBs using special chemical material called Ferric Chloride. This technique is not safe for prototyping due to the hazards of the acidic material used for etching.
Printing
CNC Milling
One of the most commonly used techniques to make PCBS by milling/ engraving copper boards. This technique is safe and computerized which makes it more precise and convenient for fast prototyping and mass production.
One of the new techniques to make PCBs by printing the conductive traces and footprints on a ďŹ berglass (FR4) insulating material. Voltera V-One is one of the interesting machines for PCB printing. This technique is convenient for low current PCB circuitry fast prototyping due to conductivity limitation of the conductive ink.
Available at QBIC Fab Lab
PCB Types
Single Layer PCB
Double Layer PCB
Multi Layered PCB
Single copper layer.
Double sided copper layers
Multiple copper layers interconnected together.
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The top and bottom sides are covered with copper layers.
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as well as, other layers in between.
Traces on both sides and top and bottom are electrically connected
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Components can be mounted on the top and the bottom side.
different layers are electrically interconnected through vias.
through conductive vias. ●
Traces are on top and bottom layers;
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Components can be mounted only on the top and the bottom side.
PCB Design Process
Schematics Design Using CAD Software like
Main Step
PCB design is 90% Components placement and 10% routing!!
Components Placement
Iterating Steps
Traces Routing
Generate Gerbers
Fabrication!
TWO
Autodesk Eagle
Autodesk Eagle Autodesk EAGLE is an electronic design automation (EDA) software. It is one of the most widely used CAD software across the globe. Additionally, it is free, affordable, can be easily installed and can serve as an easy learning tool for PCB design. Schematic Design Schematic symbols for electrical components are used to map the circuit.
PCB Layout Components footprints are used to design a PCB.
Autodesk Eagle Cont. Eagle architecture can be summarized in the following chart. Terminology
Control Panel Project
â—?
Component Symbol: is the schematics icon of the component.
Schematics Capture
PCB Layout
â—?
Component Footprint: A footprint or land pattern is the arrangement
Symbol
Footprint
of pads used to physically attach and electrically connect a component to a PCB.
Library
Component print on a PCB.
IMPORTANT TERMS!! ●
Component Pattern → Component pattern defines the component number of pins and how they are mapped with respect to the center of the component.
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Component Package → Integrated circuits are put into protective packages to allow easy handling and assembly onto printed circuit boards and to protect the devices from damage.
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Component Datasheet → A datasheet, data sheet, or spec sheet is a document that summarizes the performance and other technical characteristics of an electronic component.
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DRC → Design Rule Check to check design rules.
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Hole → Hole to insert and solder components.
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Pad → Pad to solder surface mount components.
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Via → Hole/ Conductive channel to connect 2 layers of PCB together.
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Track → Copper line establishing connections between 2 parts equivalent to a wire of a circuit.
Autodesk Eagle Cont. In Eagle Software: Symbol + Footprint + Device Package = Component
Footprint
Symbol Device
Common Electronic Components Footprints and Packages Passive Components Resistors and Capacitors
Integrated Circuits (ICs)
THREE
PCB Design
Single Sided PCB Design To design a single sided PCB follow the steps below: ●
Before using Eagle, start with a sketch/ schematics diagram on paper.
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In Eagle, create a “New Project” ○
Create a new “Schematics” ■
Find parts
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Check PCB footprints while choosing the parts/ components.
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Consider power connections (e.g. ports or connectors). ●
■ ○
Connect all grounds together.
Join parts to make a proper circuit schematics.
After finishing with schematics, “Switch to Board” while following schematics guide. ■
Map/ orient the parts properly.
■
Route the traces.
■
Check errors and design rules with DRC.
Important PCB Design Rules
Rules considered as errors by the software (DRC)
Overlap between traces or traces and pads.
Rules to be considered by the designer and cannot be detected by the software
Thick Traces width. Clearance
Unrouted networks.
Avoid sharp edges (90 degrees) as they tend to accumulate the current.
Rules to be considered by the designer and cannot be detected by the software cont. -
Solder Pad to Trace Connections: Asymmetry should be avoided in the trace and connected solder pads.The ďŹ gure below shows the symmetric and asymmetric traces. Traces should start exactly at the center of the solder pads.
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The trace should not overlap the pad and the trace width should be reduced at the point of contact.
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For two adjacent traces, the connection should be as follows:
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To ensure a strong connection between a trace and hole the following designs are recommended.
FOUR
Sample PCB Using Eagle Punk Console Circuit
Punk Console Circuit Punk console circuit is an example for sound generating circuits or logic noise circuits. It is mainly designed using two 555 timers and the sound pitch is controlled using potentiometers/ variable resistors. Refer to schematics design and circuit description HERE and simulation HERE. Using Eagle software the schematics and PCB layout can look as follows. Schematics
PCB Layout
Thank you :)