creating a pcb design with orcad pcb editor - nordcad.dk · creating a pcb design orcad / allegro...

Creating a PCB Design OrCAD / Allegro PCB Editor

Nordcad Systems A/S / Nordcad AS 2018 - R2

[email protected] / [email protected] +45 96 31 56 99 / +47 21 55 28 28

of 31

Creating a PCB Design with OrCAD PCB Editor This guide is focused on learning how to create a PCB (Printed Circuit board) design. The guide

will make use of the ‘PCB Flow’ menu that is part of this workshop material.

The Lowpass Filter schematic made with OrCAD Capture CIS is used for the PCB Design.

Table of Contents Creating a PCB Design with OrCAD PCB Editor ............................................................................. 1

Importing the schematic design into the board template .............................................................. 2

Creating a board outline .............................................................................................................. 3

Constraint Manager basics .......................................................................................................... 4

Setting constraints ....................................................................................................................... 5

Placing components .................................................................................................................... 6

Creating copper shapes .............................................................................................................. 9

Routing your design .................................................................................................................. 12

Adding Teardrops ...................................................................................................................... 15

Checking status before creating output ..................................................................................... 16

Creating production data (Post processing) ............................................................................... 17

Creating PDF documentation .................................................................................................... 21

Working with 3D ........................................................................................................................ 22

What did you learn? .................................................................................................................. 25

There is much more to learn in OrCAD PCB Editor ................................................................... 25

Keyboard shortcuts ................................................................................................................... 26

Appendix A: Creating a template board file ................................................................................... 27

Use the PCB flow menu to create the board template ............................................................... 27

Setup units and size of working area (canvas) .......................................................................... 28

Setting up Cross section of the PCB .......................................................................................... 29

Setting colors ............................................................................................................................ 30

Setting up grid settings .............................................................................................................. 31

mailto:[email protected]





of 31

Importing the schematic design into the board template The guide will use a template that’s already been designed, if you’re interested then appendix A

will walk you through the creation of this template.

1. Start OrCAD Capture CIS and open the ‘Lowpass filter’ project created earlier with the

guide ‘1_Creating_a_circuit_using_CaptureCIS’ and

‘3_Component_Management_using_CaptureCIS’

2. Go to the Project Manager and select Tools → Create Netlist

3. The board template is used as a starting point for the new PCB design. This saves time

setting up units, colors and other settings. All the settings can be made once and used for

each new board. Make the adjustments shown where the input board is set to the template

file at C:\Cadence\Company\pcb\template\template.brd

4. In the netlist setup make sure the marked box is set to 255 chars.

5. Press OK after the value have been changed and press OK again to create the board.






of 31

6. Click Yes to create the allegro board directory

7. If presented with a license selection choice, then pick either one of OrCAD PCB Designer

Standard, OrCAD PCB Designer Professional or Allegro PCB Designer and Click OK

Creating a board outline 8. Use PCB Flow → 3. Outlines → Draw/Edit board outline

9. This design is small with only a few components and therefore the outline is also small.

NOTE: Outlines should fit the project you’re working with, if you are making a motor-shield for an

Arduino, the outline will have to fit the Arduino sizes.

10. Start setting the parameters, then click the command line at the bottom and type ‘x 0 0’

and press Enter to place the lower left corner of the outline at 0,0

11. Click Ok to close the Design Outline dialog






of 31

Constraint Manager basics Constraint Manager let you define, view and validate constraints while working. When you

understand the concept behind the constraint manager it is very easy to use. This short

introduction to constraint manager can be skipped if you want to set the constraints now.

Constraints are split into sections

- Physical where cline (trace/route) width and via types are defined

- Spacing where distances (airgap) between objects

on different nets are defined

- Same Net Spacing where distances between objects on the same net are defined

- Manufacturing where fabrication oriented rules are defined (e.g., silkscreen to pad)

- Electrical where differential pairs, impedance, length and matched lengths are defined

For Physical and Spacing there is a Constraint Set folder which contain a constraint set named

“Default”. This is the place where any default constraints can be set and if nothing else is

changed in Constraint Manager these settings (constraints) are used.

Below are shown the key physical constraints, if a column is yellow it shows that online DRC is

disabled for that constraint. Right click the column and select ‘Analysis Mode’ to enable online

DRC for that constraint.

Similar settings can be found for Spacing constraints.

In the Net section all the nets are listed including a reference to a Constraint Set that is defined in

the Constraint Set folder. All nets use the Default Constraint Set until changed.

All boards will require default settings for spacing, trace width and via types. These can set

in the template made in Appendix A






of 31

Setting constraints The following constraints will be set in the constraint manager.

- Spacing of 0.25mm

- Route width of 0.25mm

- Use via named ‘Via40’ when changing layer during routing

All nets refer to the Constraint Set named ‘Default’ and hence will changing the settings here ripple

down on all nets.

12. Select PCB Flow → 4. Constraint Setup with netlist → 1. Spacing

or use

13. On SCS (Spacing Constraint Set) ‘Default’ set values as shown

14. Constraint Manager is an integrated part of OrCAD / Allegro PCB Editor and has no

individual save button. Saving the board file will also save the constraints.

15. Go to Physical → Physical Constraint Set → All Layers or use PCB Flow → 4. Constraint

Setup with netlist → 3. Physical and set as shown below

a. Change Line Width Min to 0.25

b. Click the Via cell and remove ‘Via’ and add ‘Via40’

c. Enable Via DRC by right clicking the column and selecting ‘Analysis Mode’






of 31

16. Result of changes are shown below

17. Close Constraint Manager using File → Close or Ctrl + F4

18. Save the board using File → Save or Ctrl + s

Note: The settings above could have been done in the template since nothing was depending on

specific net names. If more granularity is needed more constraint sets can be created by Right

clicking on the constraint set name and choosing Create → Spacing/Physical Constraint Set.

Placing components Although the netlist is loaded into the board there are no component placed. PCB Editor does not

require all footprints to be designed before starting the PCB Design process. When a component is

selected for placement the footprint is needed and a warning is given in case it does not exist.

19. Press ‘Home’ or Click the toolbar icon to fit the outline in the working area

20. To place components select PCB Flow → 5. Placement → 1. Component Placement or

use shortcut ‘p’

or use

21. Often connectors are placed close to the board outline, instead of selecting the connector in

the list ‘cross-placement’ from OrCAD Capture will be used to select the P1 on the

schematic. Do the following and see picture on next page

a. With the Placement dialog open swap back to the schematic and use left mouse

button to select ‘P1’

i. Alternatively split the screen between OrCAD Capture and PCB Editor

b. As a result ‘P1’ will be selected in the Placement dialog and attached to the cursor






of 31

c. Use the Middle Mouse button to pan on the PCB working area and press ‘r’ to

rotate P1

d. Place the component approximately as shown on the picture

22. Now select all the components on the list. Do not click Close!

a. Alternatively continue to select components on the schematic page

23. As soon as Components by refdes is checked the first component C1 is attached to the

mouse. Click to place it inside the board.






of 31

24. Continue placing all parts until the list is empty.

25. Finish by clicking Close on the Placement dialog

26. To move components either open the Placement Dialog again or go into Placement mode

where clicking a component will initiate a component move mode. The current mode can

always be seen at the status bar at the bottom of PCB Editor.

27. Now click and move components.

a. You can still use r to rotate and m to mirror






of 31

When all components are placed there are thin connection lines called “Ratsnests”. These

connections need to be routed.

Creating copper shapes Often when doing PCB Design the power nets are flooded with copper. This part of the guide will

create these copper areas for the nets VCC, VEE and 0

28. Just like for Placement there is a mode for working with Shapes. At the Status bar left click

and select Shape Edit

29. Now PCB Editor knows that we’re working with copper areas (shapes) and the Options

panel to the right has relevant options for this.

30. Right click in the work area → Add Rectangle to add a rectangular copper shape and

then Right click → Assign Net

31. Now click ‘VEE’ pin on P1 to assign the copper to VEE and then draw a rectangle around

the complete board






of 31

32. This will complete the shape which will connect to all pins that are part of the net ‘VEE’

33. Right click → Done to finish this copper shape.

34. We will add a new smaller copper shape for the net ‘0’ in the lower left part of the PCB

Design. This shape will also be on the top layer, so leave the settings in the Options panel.

35. Right click → Add Rectangle

36. Right click → Assign Net

37. Left click the bottom most pin on P1 (connected to ‘0’)

a. Make sure that 'Assign net name = 0’ in the Options panel before continuing.

38. Draw a small rectangle that contain the 2 pins connected to ‘0






of 31

39. Again, finish this shape by Right click → Done

40. This shape takes precedence over the large shape and create a small copper shape

connected to 0

41. The next copper shape for ‘VCC’ is on the Bottom layer.

42. In the Options panel change the Subclass to Bottom as shown

→

43. Right click → Add Rectangle

44. Right click → Assign Net

45. Left click the second pin from the top on P1 (connected to ‘VCC’)

a. Make sure that 'Assign net name = VCC’ in the Options panel.

46. Draw rectangle that covers the complete board

47. Again, finish this shape by Right click → Done






of 31

Now the 3 nets ‘VCC’, ‘VEE’ and ‘0’ is fully connected using copper shapes.

48. This is a good time to save your work. Press Ctrl + s

Routing your design The rest of the board will be routed using interactive routing functionality.

49. PCB Editor has a special routing mode which is called ‘Etch Edit’, change to this mode in

the status bar like previously done.

Within the Etch Edit mode there is certain functionality depending on single left click or click and

keep the mouse button clicked (drag). For reference a small chart of this functionality is shown

below.

Main functionality to remember is highlighted with green. (cline ~ routed piece of copper)

Tip: The Find panel at the right side lists what objects can be selected. If pins are unselected you

cannot single click a pin and start Add Connect!

50. Now that Etch Edit is selected above the routing can start 😊

51. Make sure that ‘Pins’, ‘Vias’ and ‘Cline Segs’ are enabled in the Find Panel and then go

back to the Options panel and select TOP






of 31

→

52. To start routing left click on U1 pin 6 connected to the net ‘OUT’ to start. The Options

panel will show settings for routing. Change Line Locking to 45 and move the mouse to

U1 pin 2 where ‘OUT’ also is connected and notice how it autosnap to the pin.

53. Left click on U1 pin 2 to finish routing that connection and notice that spacing is

automatically made between the cline and the copper shape






of 31

54. Continue routing by left clicking the pins with a ratsnest (thin line)

a. Double click to insert a via and swap layer

55. Left click a routed segment to slide it

→

56. Now do the rest of the routing using the methods just learned until there are no ratsnest

lines left.

57. Save the board using Ctrl + s






of 31

Adding Teardrops Adding teardrops routed cline into a pad creates a better connection. If it is a drilled pin or via and if

the hole gets misaligned in the copper pad there is a risk of a disconnect and adding a teardrop will

reduce that problem

58. Select Route → Teardrop / Tapered Trace → Add Teardrop and then click on the routed

nets to get teardrops added.

a. You can area select everything to get Teardrops on all connections






of 31

Checking status before creating output Before proceeding to output generation it is very important to check the status of the PCB Design.

59. Select PCB Flow → 8. Status Check or use shortcut ‘,’ (comma)

→

The status dialog will show important information before creating documentation and output.

Examples are

- Are all components placed

- Are all nets fully routed






of 31

- Any copper shapes without a net attached

- Any Design Rule Check (DRC) errors and if so, any that are shorts

60. If there is any issues a list of DRC Erros will be shown when clicking the small color icon

next to the problem. Example below although there are no issues here.

61. If there are any DRC errors, you can also use the DRC Browser to run through them. (Tools

→ DRC Browser)

Creating production data (Post processing) The board is finished and the final parts are to make production data and PDF documentation.

62. Select PCB Flow → 10. Post Processing

63. This will open the Post Processing application that will create all the production data

needed. First go to ‘Gerber Setup’ and click the ‘All ON/OFF’ checkbox to enable creation

of all Gerber film settings. Then go to ‘Output Data’






of 31

64. The output data section has the most often used output enabled.

65. Click Save Settings to save the Post Processing setup.

66. Then click Run to create output data






of 31

67. At some point during the generation of output data the program will ask if you want to view

the log files. Answer Yes to this (always look through any log files for warnings or errors)

68. After the post processing is finished a readme file will be shown with details about the

board and data generated.






of 31

69. Close the Postproc status report and any other log windows.

70. Before closing the Post Processing program click Open Dir at the bottom of the dialog

71. This will open the directory with the generated output data. The zip file contain all the

relevant data for the manufacturer to fabricate the board.

NOTICE: It is always strongly recommended to check production data in a third-party tool before

sending of for manufacturing. Always send the readme file to the manufacturer since it explains

data, file naming and also specify that the gerber data should be compared against the ipc netlist

data.






of 31

Creating PDF documentation It is very simple to create PDF documentation with the PDF Generator.

72. Select PCB Flow → 11. PDF Printing to start PDF Generator

73. If the PDF Font list is empty click Refresh and Save the board when asked

a. In rare occasions it can be necessary to click Refresh twice. If this does not help,

make sure to check that the PS Printer Driver specified in the ‘Printer Setup’ tab

exists.

74. Make the following changes to the PDF Generator under PDF settings

→

After it completes the PDF document is shown. Settings can be changed to produce output with

colors, higher resolution and other details. Experiment with the settings if time allows.

75. Close PDF Generator by clicking Close






of 31

Working with 3D If time permits, this section show a few of the 3D capabilities that are part of OrCAD/Allegro.

76. Click the 3D icon

77. This will show the PCB design in 3D, this is called the “3D Canvas”. However, U1 does not

have a STEP model defined and the first step is to assign a 3D STEP model to U1

78. Close the 3D Canvas

79. Select Setup STEP Package Mapping

80. In the Device/Package STEP mapping dialog do the following

a. Enable Symbols missing STEP model, this leaves ”DIP1008W300L450”.

b. Left click DIP1008W300L450 to select it

c. Select DIP254P762X445-8N.step in the list of Available STEP Models

d. Set Rotation X: 90

e. Set Rotation Z: 90

f. Set Offset X: 3.8

g. Set Offset Y: 3.82

h. Select Save to save the mapping between the footprint and the 3D STEP model

Picture showing this can be found on the next page. There are numerous ways to perform the

mapping between the footprint and the 3D STEP model and this is just one of them.






of 31

81. Select Close to close the dialog

82. Click the 3D icon again to show the 3D Canvas

83. You can navigate around with the mouse the following ways:

a. Hold the middle mouse button pressed for panning






of 31

b. Use the scroll wheel to zoom in and out

c. Use the Shift + middle mouse button to rotate the PCB

84. There are also several controls for working with 3D Canvas

a. Visibility: Layer visibility can be turned on/off

b. Symbols: Individual (or all) components can be turned on/off

c. Collision Detection: Perform spacing check between 3D models

d. Options: Contain options for moving components in 3D or when working with Bend

functionality for flex and flex-rigid PCB Designs

e. File Export contain many different export formats, examples are IGES, STL, 3D

PDF and more

85. Experiment with 3D Canvas and when done, close 3D Canvas

86. Save the board using File → Save or Ctrl +s and close PCB Editor using File → Exit

This concludes the workshop.






of 31

What did you learn? ✓ To create a new board template (appendix A)

✓ Creating a board from a schematic

✓ Setting up constraints using Constraint Manager

✓ Placing components using OrCAD Capture

✓ Adding copper shapes

✓ Routing nets and adding teardrops to improve production quality

✓ Check the board for any errors

✓ Creating production data for PCB fabrication

✓ Creating PDF Documentation

There is much more to learn in OrCAD PCB Editor

Setting and routing differential pairs

Setting up and routing with matched length

Routing with impedance constraints

Extracting nets for Signal Integrity simulation

Working with 3D and collision checking

Working with Flex-Rigid

Autorouting

Setting up fabrication checks

ECAD-MCAD collaboration

Dimensioning

Creating Variant Assembly PDF documentation

Creating your own shortcut keys

Customization using scripts or SKILL API

And much much more






of 31

Keyboard shortcuts This list of shortcuts is based on the setup that is part of downloading this workshop material. It is

also part of the general Nordcad setup.






of 31

Appendix A: Creating a template board file Typically, it is preferred to use the same settings for units, colors etc. each time a PCB Design is

made. This part of the guide will explain how such a template can be made.

1. Start PCB Editor

2. A new board must be created. Follow the steps shown in the picture below.

Use the PCB flow menu to create the board template 3. The PCB Flow menu is already numerically ordered with a task sequence. This part of the

guide is limited task 1 + subitems and task 2






of 31

Setup units and size of working area (canvas) 4. Set as shown for the Display and Design tabs

Here some of the default settings for display is specified. Place the mouse above a setting

and a description will be shown explaining that setting.






of 31

The design pane is where the parameters for the board design is set, such as the working

size. Remember to check the User units is in Millimeter.

In this case the size is set to A4 which means that the PCB cannot fill more than

297x210mm. The Left X setting of -110 and Lower Y of -110 means that the coordinates of

the lower left corner of the A4 is -110,-110 or in other words that 0,0 on the paper is 110mm

from the left and 110 from the bottom.

5. Click OK to accept the changes

Setting up Cross section of the PCB 6. Next step in the PCB flow menu under the board setup is the stack up design, also called

Cross section editor. The Cross Section Editor is a tool to control the board layer thickness,

material of the layers, layer count and conductivity. In this guide we won’t be changing

anything in the Cross section Editor.

or use






of 31

Setting colors 7. The Color Dialog is used to set colors for all layers and objects in the board.

or use

First pick the color at the bottom and then set it either on an object or on the complete layer. In the

example above the bottom layer is assigned the color red.






of 31

8. Continue and set your preferences for colors.

a. Or import a set of color preferences using Import → Color/Board Parameters

Setting up grid settings 9. The grid setup determines the resolution of placement and routing if this is performed with

grids enabled.

10. The template is now finished.

11. Save the file using File → Save or Ctrl + s

A template board file can contain much more information than what this guide explains. Examples

are constraint settings, what via types to use, pre-placed components like connectors and also

board outlines.



creating a pcb design with orcad pcb editor - nordcad.dk · creating a pcb design orcad / allegro...

Documents