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Printed Circuit Board Schematic and

Layout Design

Li-Shian Chen

April 2nd

2010

Executive Summary

Printed circuit boards are widely used on almost every electronic product, due to the

fact that it has advantages such as large scale with low price manufacturing, high

quality, and space saving for the project.

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Table of Contents

1. Introduction …………………………………………………………………page 3

2. Objective …………………………………………………………………page 3

3. Implementation ……………………………………………………………page 4

4. Results ………………………………………………………………………page11

5. Recommendations & Conclusion ………………………………………page11

6. References …………………………………………………………………page12

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1. Instruction

Printed circuit board, also know as PCB, are highly use in all kinds of electronic

designs in industries. PCB’s history begins with “printed wired” in 1903 to

multi-layer in 1980s. PCB is usually coated in a color of green, blue, or red with

solder mask. The conducting layouts are typically made with copper foil. Currently,

there are no standard PCB. Each PCB is unique and has its own function for the

product. The PCB designer will use computer-aided design software to design the

board. Figure1. is an example of a final version 2 layer PCB.

Figure1. – Two Layer Printed Circuit Board with solder mask

2. Objective

The purpose of this application note is to instruct how to use CAD software tool.

This document will explain how to draw the schematic of the circuits, design the

printed circuit board layout of the project for the PCB manufacturing.

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3. Implementation

There are lots of free CAD software available online for designer to download

such as Orcad, Cadence, ExpressPCB, etc. For this document, I will use Eagle CAD

software as an example to do a simple design demonstrate.

Step1. Open the software and create a new project. Inside the project create a

new schematic file.

Figure2.

Step2. Add the components from the library (Figure3b.) to the schematic window

(Figure 3a.). If some of the components are not in the library, user can download

online and add into the library folder or the designer can design their own

components.

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Figure3a. – Add components by clicking the “Add” button on the left hand side tool

bar and use “Move” button to place components on the desire position

Figure3b. – Components library will pop-up after the user click the “Add” button

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Step3. Connect all the wire to the components (Figure4.). In order to do that, we

click the “Wire” button and connect the components node by node and if we have

more than 1 connection, we can label nodes on the schematic by clicking the

“Junction” button.

Figure4. – Wire all components

Step4. Create a board file (.brd) (Figure5b.) by clicking FileSwitch to board

(Figure5a.).

Figure5a. – Create board file

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Figure5. – Open the board file (.brd) by clicking the “Board” button on top of the

schematic file

Step5. Position all the components to the desire place (Figure6.). Use the

“Move” button we did in Step2. Figure3a. and place on the desire position.

Figure6. – Place components on the desire position

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Step6. Route all the traces (Figure7.). Click the route button and route the

component like we wire components in the schematic file.

Figure7. – Route all the trace (1.27mm wide) by clicking the “Route” button on the

tool bar. We also can change the trace direction by click right button on the mouse

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Step7. Copper pour

Figure8. – Click the “Polygon” button and line on the edge of the board for top and

bottom layer

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4. Results

After complete the PCB design, the designer can submit the .sch file (schematic

file) and .brd (PCB layout file) to the PCB manufacture for the quote and order.

Figure9. – Schematic file (.sch) of Microphone Pre-Amp for SAiNT preject

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Figure10. – PCB Board file (.brd) of the Microphone Pre-Amp for SAiNT project

Figure11. – Custom library file (.lib) for SAiNT project

5. Recommendations & Conclusion

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CAD software is a very powerful tool for the PCB design. Although the

designer can start the design without schematic, start with the schematic is highly

recommended for the beginner. The disadvantage is that some of the CAD software

are powerful than the free one, but it cost

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6. References

Grover, D.. "Prototyping Techniques". April 3, 2010

<http://www.egr.msu.edu/classes/ece480/goodman/Prototyping_v2.sxw.pdf>.

Unknown, Unknown. "Manufacturer of Printed Circuit Boards (PCB)". Electronic

Interconnect. April 3, 2010 <http://www.eiconnect.com/default.aspx>.

Unknown, Unknown. "Printed Circuit Board". Wikipedia. April 3, 2010

<http://en.wikipedia.org/wiki/Printed_circuit_board>.

Unknown, Jason. "rpcelectronics". April 3, 2010

<http://www.youtube.com/user/rpcelectronics>.