At the end of this session you should be able to:-
(i)create a printed circuit board.
(ii)do placement of the component, manually or automatically routing the board
INTRODUCTION
OrCAD Layout
OrCAD Layout is a powerful circuit board layout tool that has all the automated functions you need to quickly complete you board. The chart in the figure below illustrated Layout’s design flow.
Figure 2.1: PCB Design flow-chart
From figure above, by using OrCAD Capture, we can create a Layout-compatible netlist. This netlist contains much of the design information that Layout uses to produce the board. Next step is placing components by using OrCAD Layout, we can either manually route or autoroute the board. As an output, OrCAD Layout will produces hardcopy on printers and plotters, and also Gerber files for Gerber photoplotter, and a wide variety of report files. We can preview or even edit a Gerber files with Layout’s external Gerber editor known as GerbTool.
PCB Consideration
All PCB are divided into layers. OrCAD Layout supports up to 30 routing layers, it displays the PCB from a top view. Layers can be a copper layers or documentation layers. Base on this consideration, we need to clarify this particular information such as numbers of layers, size and shape of the PCB, PCB fabrication plant specifications that include minimum trace and space width, plating reduction and available drills.
CREATING A PRINTED CIRCUIT BOARD
1. Run OrCAD Layout program, select options File>New as shown in figure below.
Figure 2.1: Initial window of OrCAD Layout
2. Layout window will appear with Load Template File dialog box as shown in Figure
2.2 below, choose DEFAULT template to use in this design. Template can be
found in folder OrCAD>Layout>DATA.
Figure 2.2: Loading template file
3. Next, Load Netlist Source dialog box appear. You need to load your netlist file
that you have created in the previous session, which is PCB1_YOURNAME.MNL as
shown in figure below.
Figure 2.3: Load a netlist file
4. You will be asking to save your board file, save your board a PCB1_YOURNAME in
your own folder as described below.
Figure 2.4: Saving file
5. If there were no error during AutoECO process, your design will appear to be as
in figure below. However if there are error, Layout might abort the process and
you will need to identify and fix the problem accordingly.
Figure 2.5: View of layout design window
6. OrCAD design window settings are controlled by system settings and user
settings. To change system settings, select options Option>System
Settings.Dialog box as in figure below display.
Figure 2.6: System Settings dialog window
7. To change user settings, select options Option>User Preferences. Dialog box
such in figure below will appear. Modify the settings according to your
preferences and then click OK.
Figure 2.7: User Preferences dialog window
8. Now, you can start to place the component manually by clicking button.Sample of
complete placement of the component is shown the figure below.
Figure 2.8: Sample of placed component
9. Choose Obstacles tool usingbutton, right click in the window and choose New.
Draw the obstacle as shown in figure below
Figure 2.9: Draw obstacle
10. Left click and then right click on the obstacles, choose Properties. Edit
Obstacles dialog box display as shown in figure below. Select Obstacles Type
to Board Outline.
Figure 2.10: Edit Obstacles dialog window
button to view the spreadsheet and select Layers. A dialog11. Now, click on the box such in figure 2.11 appear.
2.11: Layers dialog box
12. Click on the layer type column of layer name TOP, right click and choose
properties. Select Layer Type to Unused Routing as shown in figure below. Do
the same modification to INNER1 and INNER2 layers. As routing will be on the
bottom layer only, the PCB is a single layer board (single-sided PCB). Click
OK and close Layers dialog box.
Figure 2.12: Edit Layer dialog box
13. In order to begin routing, you need to set net properties, choose the
spreadsheet toolbar again and select Nets. The Nets spreadsheet displays as
shown in figure below.
Figure 2.13: Nets spreadsheet
14. Double click on net you to edit, the Edit Net dialog box displays as shown in
figure below. Modify the settings that you want and click OK.
Figure 2.14: Edit Net dialog box
15. To route the board automatically, choose Auto>Autoroute>Board. The board will
be route automatically as shown in the sample below. The default color for
bottom layer route is red.
Figure 2.13: Sample of a routing board
16. Next, after the routing is done, choose Auto>Cleanup to smoothes the route on
the board.
17. If there any modification that need to be done to route, you can click on the
button and click on the particular net and do manual routing.
18. Save and close your work.
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