This PPT Gives information about: 1. New component creation 2. Creating many parts in multiple packages 3. Creating Netlist 4. Design Rule Check 5. Generating Netlist from the schematics 6. Generating Bill Of Materials (BOM).

2. Introduction toIntroduction to
PCB DesignPCB Design
Library CreationLibrary Creation

3. Drawing the schematicDrawing the schematic
• We have a new version of cadence in the lab now.
You will find it listed under ALL PROGRAMS as
cadence 16.1 (I am not sure if 16.1 but 16
something)
• We will use design entry CIS to make the schematic
• If given an option you will choose PCB design
allegro in the beginning
• Start a new project as we used to do in the older
version

4. Drawing the schematicDrawing the schematic
Click this icon to
bring up the place
part window
Click this icon
to add libraries

5. LibrariesLibraries
You can pick up your components from the
following libraries
Diode from Pspice-diodes
TIP 31A and TIP32A from Pspice-pwrbjt
Voltage regulator and LM741 form Pspice-Opamp
Resistors and capacitors from Pspice-analog
Note: You will not find your diode number in the diode
library. You can use any other diode because we
only need to select the right foot print. More on this
later in the slide show.

6. PCB designPCB design
• The PCB board that we will build is the simplest type
with insulating layer in between two conducting
layers of Cu on top and bottom
• Since our aim is to export the design to layout plus
and create a layout for our PCB board, we are not
concerned with the values of the components. You
can leave them as default values.
• Do not connect a AC source as an input to the
voltage rectifier.

7. • In place of the AC source we want two vias where
we should be able to provide transformer
connections.
• A via is a through hole in the PCB
• We could connect a resistor across the two points
where the AC power supply to the rectifier is
connected
• This will generate 2 vias where we will be able to
connect power supply from the transformer

8. Matching the pinsMatching the pins
• Once you have connected all the components,
recheck your circuit because once the PCB is made
you cannot change your connections.
• Match the pin numbers on the schematic with the
pin numbers of the parts in your kit.
• For example, TIP BJTs have pins 1,2 and 3 as the
base, collector and emitter for the component in
your kit. The numbers should correspond to the
same in the schematic.

9. • Can you find any component for which the pin
numbers don’t match?
• LM7805 has pins 1 input, 2 gnd and 3 output on the
part in your kit but in the schematic it has 1 input, 2
output and 3 gnd
• This will swap pins 2 and 3 for us when we put the
component on the board
• So we will create our own symbol for LM 7805 and
give it the pin numbering that we want

10. Creating a libraryCreating a library

11. You will see a new
library appear in the
library folder

12. New libraryNew library
You can save
your library
with a new
name if you
like

13. Creating a partCreating a part
Select library name
and right click to
get the menu and
then click New Part

14. Creating a partCreating a part
You can
name your
part
LM7805C
and PCB
Footprint
as TO220.
Click OK

15. Creating a partCreating a part
Use “draw
line” from
the tool bar
on the right
to draw a
box along
the dotted
line.
Next use pin icon from the toolbar to draw
pins. Name them IN, GND and OUT and
number them 1,2 and 3 respectively. Type
will be input, power and output respectively.

16. Creating a partCreating a part
• Having created the part, you can remove the LM7805 symbol
that you had used from opamp library and replace it by the
symbol that you just created.
• Now you are ready to create a Netlist for your design.
• Before that you will have to modify the footprint name for
some of the components as this software will not accept /
and . in the footprint name. This is just a software compatibility
problem.
• We will modify the footprint name for the resistors, capacitor
and LM 741

17. Modifying footprint nameModifying footprint name
• Select a resistor
• Right click and choose edit properties
• Scroll to the right to find part footprint
• Note the value of the footprint as you will need it
later
• Now modify the footprint name to remove any . or /
in the name
• Do this for all the resistors, capacitors and LM741

18. Creating the netlistCreating the netlist
Click on schematic,
then go to Tools and
click on create netlist.
Create netlist window
pops up, hit OK.
This should create a
.MNL file in your
project folder.
Sometimes it doesn’t
show the .MNL file
immediately in which
case try creating the
netlist again.

19. Starting Layout PlusStarting Layout Plus
Now we will start the layout plus software again from
cadence 16
Go to file->New
For input Layout TCH
browse the file default.tch
(not _default.tch)
For input MNL file read
your netlist file from your
project folder
Hit apply ECO.

20. Select footprintSelect footprint
• You will now need to link your components to the
footprints.
• The software will automatically read some footprints
but not all so you will
have to enter the ones
that it does not take
on its own.
• We will use 1st
option
of linking existing footprint to component

21. FootprintsFootprints
Footprints basically contain the information about
physical dimensions and distances between pins of the
device so that vias for placing the component on the
PCB can be made accordingly.
For your design look for the footprints
LM 741 will be in DIP100
LM7805 will be in TO, look for TO 220 showing pins 1,2 and 3
Capacitor, Resistor and Diode footprints are in the libraries
TM_CAP_P, TM_AXIAL and TM_DIODE respectively. Use
the footprint names that you earlier made a note of. For
diode use DO35

22. • After choosing all the footprints you will get a view
of all your components
•Place the footprint within the rectangular outline.
•Place the design components so that they are evenly spread
out. This will make routing and tracking easier later on.

23. SettingsSettings
• Select View Spreadsheet in the toolbar (A grid like
icon). A pop-up menu will appear.
• Select Nets. The Nets spreadsheet will appear.
• Select the "Width" cell. All the cells in that column
should be highlighted.
• Right click the mouse and select Properties from the
pop-up menu. The Edit Net dialog box will appear.
• Change Min Width to track width 30 (mils). Change
Conn Width to 50 (mils). Change Max Width to 65
(mils). Click O.K.

24. • Next ensure the pad widths are 80mils.
• Select View Spreadsheet in the toolbar. A pop-up
menu will appear.
• Select Padstacks. The Padstacks spreadsheet will
appear.
• Select the Pad Width and Pad Height cells. Right-
click and select Properties.
• Enter 80 (mils) for both Pad Width and Pad Height.
Click O.K.

25. • Next disable all layers for routing except the
BOTTOM. Select View Spreadsheet in the toolbar.
Select Layers.
• In the Layers spreadsheet, click on the Layer Type
cell to highlight the entire column. Press the Ctrl (on
the keyboard) and click the BOTTOM.
• Right-click and select Properties. In the Edit Layer
dialog box, select the Unused Routing option.
• Now all tracks will be routed on the bottom layer.
This will simplify component soldering once the
board is fabricated.

26. Drawing the boardDrawing the board
outlineoutline
• Click on the Obstacle Tool in the toolbar.
• Place the crosshair of cursor on the black field of the design
window and double click.
• The Edit Obstacle window should appear.
• Select Board Outline for the Obstacle Type.
• Change the Width to 62 mils.
• Select Global Layer for the Obstacle Layer. Click OK.
• Begin drawing enclosed border of the design.

27. Select Auto-> Autoroute -> Board. The software will
route the board.
When it is done, a pop-up window will announce
that the task has been completed. Click O.K.
Any thin yellow connections still present in the layout
show that those tracks have not been routed.
Select Auto->Unroute->Board. Move the
components around and try routing it again.
Its more of a hit and trial thing but if you are not
able to route it, you can enable both top and
bottom layer for routing.

28. Creating Gerber filesCreating Gerber files
• Once done with routing proceed to creating
Gerber files
• Step by step instructions are on the lab website

29. ThankThank You !!!You !!!
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