introduction to pcb designing with orcad 9

8/13/2019 Introduction to PCB Designing With OrCAD 9

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Introduction to PCB Designing with orCAD v.9.2+

orCAD Family Release 9.2 (by Cadence) is a collection of several CAD software.

e.g.

Capture

and

Capture

CIS

–

for

schematic

drawings

Pspise – for simulation

Layout Plus and Layout Engineer’s Edition – for PCB designing

Here, we use Capture CIS and Layout Plus for our PCB designing purposes. Here are the steps;

1) Creating a new project for the schematic drawing Open Capture CIS (i.e. not Capture) from the Start menu and File>New>Project

Give a Project Name and select the Location where your project to be saved.

Make sure if the radio button PC Board Wizard is selected before hit on Ok.

Simply go Next>Finish, if a project simulation message is displayed.

2) Being familiar If the work space (a white space with a grid with the default name SCHEMATIC1: PAGE1)

is not opened automatically, expand the tree under project_name.dsn (i.e.my_pcb.dsn)

from your

project

window

that

is

normally

appeared

in

the

left

corner(perhaps

project

window might be minimized in the left‐bottom corner). Then click on PAGE1.

i.e. Observe the difference occur in the menu bar when the PAGE1 is selected and not

selected!

If the Tool Palette on the right side of the window is not visible click on the white grid

space(i.e.your page). If the Tool Palette is still not visible, go View>Palette



3) Adding Libraries in order to place components Click on Place Part (component select tool from the Tool Palette) and then Add Libraries.

Select all (i.e. select a file and then press Ctrl+a) the .olb files in

C>Program Files>orCAD>Capture>Library and Open. In the same manner add all the libraries in

C>Program

Files>orCAD>Capture>Library>Pspice

I.e. Libraries are where the details of the components (i.e. diodes,resistors,etc) are

written!

4) Placing components You will see, under each library different components are available. But it is pretty

confusable to precisely find the library that contains the component that you want to

pick. Examine the names of the libraries well, and then you’ll feel bit comfort. However,

it is the practice to pick the correct one quickly! Whenever you select a component from

Part List, click OK (or enter key) and then place it on your workspace by left‐clicking. A

copy of the component will appear. Hit the escape key or right ‐click>end mode.

*Note: Always try to add components that have the PCB Layout Footprint (i.e. see the figure). If you select a component which does not have the layout footprint, you may

have to type it manually (i.e. more explanation is ahead). The layout footprint of a

component describes its dimensions: pin width, pin distance, radius of the component,

etc.



*Hint: To find components easily

Select all (crtl+a) the libraries under Libraries: in the Place Part window. Then, under

Part: type;

R – for resistors, C – for capacitors, R_var – for variable resistors, C_elect – for

electrolytic caps, L – for inductor , Conn – for connectors, LED – for LEDs,

Or if you want to find an IC or a Transistor type its name as LM741,etc.

e.g. If you just type “R”, you’ll get a resistor that has no layout footprint. Then, just scroll

down a bit (hit arrow key), you’ll surely find a resistor that has its layout footprint.

5) Editing Footprints Go

back

to

the

workspace.

Select all the components that you have placed (drag the mouse pointer over the

workspace keeping the left mouse button clicked – selecting the area ). Press ctrl+e or

right click and go to Edit Properties.



Type the footprint under PCB Footprint and close the Property Editor window. You kan

find the relevant footprints from a book (download from

http://orcadlayout.tripod.com/sitebuildercontent/sitebuilderfiles/orcadlayou.pdf ).

For an example: If you want to find the footprint for DB25 parallel port, refer the book

and

you’ll

find

it

as

DSUB/RP.318/TM/25

.

Just

type

it

in

front

of

the

relevant

part

under

the PCB Footprint column. In the figure shown below I have to find and type the foot

prints for J1 connector and Q1 transistor.

6) Wiring Connect the components using the wiring tool in the Tool Palette. To connect first click

the wiring tool (i.e. mouse pointer will be changed into a cross ): then click on a little box

appearing in terminals of the component and mach it to another little box.

Move the components as you wish(i.e. this component arrangement will not be that

appears in the final PCB). Connect all the wires.



7) Creating the Netlist

Click on project_name.dsn (i.e. here my_pcb.dsn) . Then go to Tools>Create Netlist and

select the Layout tab.

Under Netlist File: , define the location where the netlist is to be save and click ok . If the

program asks to save the design file, click ok. The netlist will be save with the extension

.MNL. Netlist

is

simply

the

pin

connections

of

your

circuit

diagram

(i.e.

how

they

connect).

8) Creating the layout project Load Layout Plus (i.e. not Layout) from the Start menu. Go to File>New. Select

DEFAULT.TCH file from C:\Program Files\Orcad\Layout_Plus\Data and open. Now select

the netlist file saved in step 7. Thesreafter select the lacation where you want to save

your PCB layout. The PCB layout will be saved as a .MAX file.

Inactivating (from the button) online DRC would be preferable as we do not bother

about PCB design rules. If DRC is not turned off, placing components and routing will,

perhaps give errors.



Go to Auto>Place>Board in order to place the components inside the board (i.e. This can be done manually as well). Then move the components using the component tool. You

should place the components in such a manner that it is possible to route and an

arranged manner.

Then go to Tools>Layer>Select from Spreadsheet. Then click on layer type column

header. The entire column will be selected. Then click on the second cell that is already

highlighted(bottom vs. layer type).Then Press ctrl+e (i.e. right click>properties). Click on

the radio button Unused Routing and click ok . Then close the spreadsheet. What really

should happen is making all the unnecessary planes deactivate because here we only

route on the bottom layer.

Go to Auto>Auto Route> Board. If the space is enough and routing trace width is not

very high, routing should happen properly.

Note: Unrouting – go to Auto>Unroute>Board Note: Increasing the trace/track width – Before routing, go to Tools>Nets>Select from

Spreadsheet . Cancel the message asking to select the criteria. Click on the Width

column and ctrl+e. Type the Min/Connection/Max width and ok. Close the spreadsheet

and try to autoroute.



12) Etching Keep the transparent sheet on a dry and well‐cleaned (clean using an emery paper and

wash well) copper board and heat well (using a domestic iron that is used to iron

clothes) till ink tracks are traced on to the copper board. Keep a typing paper on the

transparent

sheet

for

safety.

It’ll

be

traced

within

5‐

20

minutes.

However

it’s

your

ability

to trace properly from the very first attempt. Draw the untraced places using a

permanent marker.

.

Dissolve Ferric Chloride(FeCl3 (S)) powder in water and put the copper board to etch.

Time will vary from 2 mins – 1 day (typically 15 mins) depending on the concentration of

ferric chloride. To increase the concentration of ferric chloride use slightly hot water

(45oC) and add more powder. But it may harm the traces. After etching is completed

clean the traces using turpentine liquid. Then drill holes using a PCB drill (manual or

electrical).

ferric

chloride

and

a

PCB

drill

could

be

bought

from

shops

where

electronic

components are sold. You are done!

Note: This note is for a beginner of PCB designing. There are many alternatives for most

of the steps. Also ‘ferric chloride method’ kan be considered as the easiest and most

economical method of etching. Safety precautions and disposal of chemicals is also

important. It is all practice to become a good PCB designer! Good Luck!!

Prepared by: (28‐ Dec‐ 09)Ransalu SenanayakeYear 1 Student,{ B.Eng(Hons) Degree in Electronic Engineering – Sheffield Hallam University(UK)},Department of Electronic and Computer Engineering,Sri Lanka Institute of Information Technology, Sri Lanka.

Reference: forum ‐ www.edaboard.com

[Format of the document is NOT in the IEEE standard]

introduction to pcb designing with orcad 9

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