Tutorial - Creating and Configuring the PCB Document in Altium NEXUS

This documentation page references Altium NEXUS/NEXUS Client (part of the deployed NEXUS solution), which has been discontinued. All your PCB design, data management and collaboration needs can now be delivered by Altium Designer and a connected Altium 365 Workspace. Check out the FAQs page for more information.

 

Parent page: Tutorial - A Complete Design Walkthrough with Altium NEXUS

Creating a New PCB

Before you transfer the design from the schematic editor to the PCB editor, you need to create the blank PCB, then name and save it as part of the project.

The blank PCB has been added to the project and saved, and the project has been saved locally.
The blank PCB has been added to the project and saved, and the project has been saved locally.


Configuring the Board Shape and Location

There are a number of attributes of this blank board that need to be changed before transferring the design from the schematic editor, including:

Task Process
Set the origin The PCB editor has two origins: the Absolute Origin, which is the lower left of the design space, and the user-definable Relative Origin, which is used to determine the current design space location – the coordinates shown on the Status Bar are relative to this origin. A common approach is to set the Relative Origin to the lower-left corner of the board shape. Select the Edit » Origin » Set command to set the Relative Origin; use the Edit » Origin » Reset command to reset it back to the Absolute Origin.
Set the units to Imperial or Metric The current design space X / Y location and Grid are displayed on the Status Bar, which is displayed along the bottom of the editor. For this tutorial, metric units will be used. To change the units, either press Q on the keyboard to toggle back and forth between Imperial and Metric units, or select the View » Toggle Units command from the menus.
Select a suitable snap grid You may have noticed that the current snap grid is 5mil (or 0.127mm, which is the default imperial snap grid converted to metric). To change the snap grid at any time, press G to display the Snap Grid menu, from where you can select an imperial or metric value. Note the shortcuts shown in the menu; use Ctrl+Shift+G to open the Snap Grid dialog, which is handy when you want to type in a specific value. The other useful shortcut is Ctrl+G, which opens the Cartesian Grid Editor dialog, in which you can change the grid from dots to lines, and change the grid color. Grids are discussed in more detail later in the tutorial.
Re-define the board shape The board shape is shown by the black region with a grid in it. The default size for a new board is 6x4 inches; the tutorial board is 30mm x 30mm. Details for the process of defining a new shape for the board are available below.
Configure the layers As well as the copper, or electrical layers on which you route, there are also general-purpose mechanical layers and special-purpose layers, such as the component overlays (silkscreens), solder mask, paste mask, and so on. The electrical and other layers will be configured shortly.
  • Press Ctrl+PgDn at any time to zoom to show the entire board.
  • Zoom in/out using:
    • PgUp / PgDn
    • Ctrl+Mouse Wheel
    • Ctrl+Right-click, Hold&Drag

The board size has been defined, and the units, origin and grid have been set. The required layers will be configured shortly.
The board size has been defined, and the units, origin and grid have been set. The required layers will be configured shortly.

A good approach to defining the shape of a non-rectangular board is to place a series of tracks (and arcs for curved boards) on the keepout layer. As well as being useful as placement and routing keep-away barrier, these tracks and arcs can be selected (Edit » Select » All on Layer) and used to create the board shape using the Design » Board Shape » Define Board Shape from Selected Objects command.

Learn more about Defining the Board Shape

Configuring the Defaults

When you place an object in the PCB editor design space, the software will define the shape and properties of the object based on:

  1. An applicable design rule – if there is a rule defined that applies to that object, the properties object are defined from the rule. For example, during a layer change when you are interactively routing, a via is automatically added with its size and hole size properties taken from the applicable Routing Via Style design rule.
  2. Default settings – if an applicable design rule does not exist or does not apply, the properties of the object are defined from the default settings configured in the PCB Editor – Defaults page of the Preferences dialog. For example, if you run the Place » Via command, the software does not know if that via will be part of a net, so it will present a via at the size defined in the defaults.

Preferences dialog, configuring the default settings for Designator and Comment


Transferring the Design

Main page: Managing Design Changes between the Schematic & the PCB

The design is transferred directly between the schematic editor and the PCB editor; there is no intermediate netlist file created. From the schematic editor, select Design » Update PCB Document Multivibrator.PcbDoc, or from the PCB editor, select Design » Import Changes from Multivibrator.PrjPcb.

When you run either of these commands, a set of Engineering Change Orders is created, which:

  • List all components used in the design and the footprint required for each. When the ECOs are executed, the software will attempt to locate each footprint and place each into the PCB design space. If the footprint is not available, an error will occur. For this tutorial, all of the components have been acquired to the connected Workspace from the Manufacturer Part Search panel, so the software can reference back to the Workspace and retrieve each footprint.
  • A list of all nets (connected component pins) is created. When the ECOs are executed, the software will add each net to the PCB then attempt to add the pins that belong to each net. If a pin cannot be added, an error will occur; this most often happens when the footprint was not found or the pads on the footprint do not map to the pins on the symbol.
  • Additional design data is then transferred, such as net and component classes.

    Once the ECOs have been executed, the components are placed outside the board shape and the nets are created. Note that the default Designator (and Comment) fonts have been changed.
    Once the ECOs have been executed, the components are placed outside the board shape and the nets are created. Note that the default Designator (and Comment) fonts have been changed.

Before transferring the schematic information to the new blank PCB, it is essential that all the related libraries for both schematic symbols and PCB footprints are available. Since all components have been acquired from the Manufacturer Part Search panel with their footprints and placed from the connected Workspace, the footprints required for the tutorial are already available.

Configuring the Display of Layers

Once all of the ECOs have been executed, the components and nets will appear in the PCB design space to the right of the board outline, as shown in the image above. Before you start positioning the components on the board, you need to configure certain PCB design space and board settings, such as the layers, the grid, and the design rules.

Your view of your board is a bird's-eye view – looking down the Z-axis into the board from above. The PCB editor is a layered design environment; the objects you place on signal layers become copper when the board is fabricated, the strings you place on the Overlay layers are silkscreened onto the board surface, and the notes you place onto mechanical layers become instructions on the assembly drawing that you print.

You design the board looking down into this stack of layers, placing components on the top and bottom sides of the board (Top Layer / Bottom Layer), and other design objects on the copper, overlay, mask, and mechanical layers as you build up the design.

You design the board looking down into a stack of layers; hover the cursor over the image to show the same board in 3D, stretched in the Z-axis.
You design the board looking down into a stack of layers; hover the cursor over the image to show the same board in 3D, stretched in the Z-axis.

As well as the layers used to fabricate the board, which include: signal, power plane, mask, and silkscreen layers, the PCB Editor also supports numerous other non-electrical layers. The layers are often grouped in the following way:

  • Electrical Layers – includes the 32 signal layers and 16 internal power plane layers.
  • Component Layers – layers used in the design of the components including Overlay (silkscreen), Solder, and Paste layers. If an object is placed in a component footprint on one of these layers in the library editor, when the component is flipped from the top side to the bottom side of the board, all objects detected on a Component layer are flipped to their partner Component layer. This includes objects on user-defined Component Layer Pairs (paired mechanical layers).
  • Mechanical Layers – the software supports unlimited general-purpose mechanical layers, which are used for design tasks such as dimensions, fabrication details, assembly instructions, and so on. These layers can be selectively included in print and Gerber output generation if required. Mechanical layers can also be paired; when they are paired, they behave as Component Layers. Paired Component Layers are used for tasks such as 3D body placement, glue dots, and selective gold plating on edge connectors.
  • Other Layers – these include the Keep-Out layer (used to define keepouts that apply on all copper layers), the multi-layer (used for objects present on all signal layers, such as pads and vias), the Drill Drawing layer (used to place drilling information, such as a drill table), and the Drill Guide layer (used to display markers that indicate drill locations and sizes).

The copper layers are added and removed from the design in the Layer Stack, which is discussed shortly. All other layers are enabled and configured in the View Configuration panel.

Displaying Layers – View Configuration

Panel page: View Configuration

The display attributes of all layers are configured in the View Configuration panel. To open the panel:

  • Click the Panels button button at the bottom right of the application window then select View Configuration from the menu, or
  • Select the View » Panels » View Configuration menu entry, or
  • Press the L shortcut, or
  • Click the current layer color PCB editor design space, Layer Set control icon at the bottom-left of the design space.

The two tabs of the View Configuration panel    View Configuration panel, View Options tab
The two tabs of the View Configuration panel

As well as the layer display state and color settings, the View Configuration panel also gives access to other display settings including:

  • Color and visibility of System Colors, such as the Selection color, or if Connection Lines are visible.
  • How each type of object is displayed (solid or draft), and its transparency (Object Visibility section).
  • Various view options, such as if the Origin Marker, Pad Net names, and Pad Numbers are to be displayed (Additional Options section).
  • The amount the display is faded when objects are dimmed or masked (Mask and Dim Settings section).
  • The creation of Layer Sets, which provide a quick way of switching which layers are currently visible, using the PCB editor design space, Layer Set control control (Layers section).
  • The creation and selection of View Configurations, which are used to pre-configure all of the layer properties, such as color, visibility, object transparency, and so on (General Settings section).

Layer Tips

  • The currently enabled layers are shown as a series of tabs across the bottom of the PCB design space. Right-click on a tab to access frequently-used layer display commands.
  • In a busy design, it can help to only display the layer currently being worked on; this is referred to as Single Layer Mode. To toggle the display in/out of single layer mode, press the Shift+S shortcut. The Available Single Layer Modes are configured in the PCB Editor – Board Insight Display page of the Preferences dialog. Each press of Shift+S will cycle to the next enabled single layer mode.
  • To switch the active layer:
    • Click the layer tab at the bottom of the design space, or
    • Press the + or - numeric keys to cycle through all layers, or
    • Press the * numeric key to cycle through signal layers, or
    • Use the Ctrl+Shift+Mouse Wheel shortcuts.

Physical Layers and the Layer Stack Manager

Main page: Defining the Layer Stack

The definition of the PCB layer stack is a critical element of successful printed circuit board design. No longer just a series of simple copper connections that transfer electrical energy, the routing of many modern PCBs is designed as a series of circuit elements, or transmission lines.

There are also numerous other design considerations that come into play when designing a modern, high-speed PCB, including: layer-pairing, careful via design, possible back drilling requirements, rigid/flex requirements, copper balancing, layer stack symmetry, and material compliance.

These layer stack requirements are configured in the Layer Stack Manager, select Design » Layer Stack Manager to open it.

  • The Layer Stack Manager opens in a document view, in the same way as a schematic sheet, the PCB, and other document types.
  • The Layer Stack Manager (LSM) can be left open while the board is being worked on, allowing you to switch back and forth between the board and the LSM. All of the standard View behaviors, such as splitting the screen or opening on a separate monitor, are supported.
  • A Save must be performed in the Layer Stack Manager before changes are reflected in the PCB.

The Layer Stack Manager is used to:

  • Add, remove and order the signal, plane, and dielectric layers.
  • Select the Material properties from the Materials Library, or configure them manually.
  • Add additional user-defined fields to the Layer Stack.
  • Configure the allowed Via Types, defining which layers each Via Type spans.
  • Configure the Impedance profiles, when controlled impedance routing is being used.
  • Configure advanced features, including rigid-flex design, printed electronics, and back drilling.

This tutorial PCB is a simple design and can be routed as a single-sided board, or a double-sided board with thru-hole vias. In the image below, the Material for each layer has been selected.

The properties of the physical layers are defined in the Layer Stack Manager. To configure the allowed via types, click the Via Types tab at the bottom of the Layer Stack Manager.
The properties of the physical layers are defined in the Layer Stack Manager. To configure the allowed via types, click the Via Types tab at the bottom of the Layer Stack Manager.


Configuring the Grid

The next step is to select a grid that is suitable for placing and routing the components. All the objects placed in the PCB design space are placed on the current snap grid.

Imperial or Metric Grid?

Traditionally, the grid was selected to suit the component pin pitch and the routing technology that you planned to use for the board, i.e. how wide do the tracks need to be, and what clearance is needed between tracks. The basic idea is to have both the tracks and clearances as wide as possible to lower the fabrication costs and improve reliability. Of course, the selection of track/clearance is ultimately driven by what can be achieved on each design, which comes down to how tightly the components and routing must be packed to get the board placed and routed.

Over time, components and their pins have dramatically shrunk in size, as has the spacing of their pins. The component dimensions and the spacing of their pins have moved from being predominantly imperial with thru-hole pins to more-often being metric dimensions with surface mount pins. If you are starting a new board design, unless there is a strong reason, such as designing a replacement board to fit into an existing (imperial) product, you are better off working in metric. Why? Because the older, imperial components have big pins with lots of room between them. On the other hand, the small, surface mount devices are built using metric measurements – they are the ones that need a high level of accuracy to ensure that the fabricated/assembled/functional product works and is reliable. Also, the PCB editor can easily handle routing to off-grid pins, so working with imperial components on a metric board is not onerous.

Suitable Grid Settings

For a design such as this simple tutorial circuit, practical grid and design rule settings should be:

Setting Value Where
Routing width 0.25 mm Routing Width design rule
Clearance 0.25 mm Electrical Clearance design rule
Board definition grid 5 mm Cartesian Grid Editor
Component placement grid 1 mm Cartesian Grid Editor
Routing grid 0.25 mm Cartesian Grid Editor
Via size 1 mm Routing Via Style design rule
Via hole 0.6 mm Routing Via Style design rule

While it might be tempting to select a very fine routing grid so that routing can effectively be placed anywhere, this is not a good approach. Why? Because the point of setting the grid to be equal to or a fraction of the track+clearance is to ensure that the tracks are placed so that they do not waste potential routing space, which can happen if a very fine grid is used.

  • Select View » Toggle Units (or press the Q shortcut key) to toggle the design space units between metric and imperial.
  • When a dialog or panel is active, press Ctrl+Q to toggle the units of all measurements in that dialog or panel.
  • Regardless of the current setting for the units, you can include the units when entering a value in a dialog or panel to force that value to be used.

Support for Multiple Grids

  • Altium NEXUS allows multiple snap grids to be defined. There are two types of grids supported: Cartesian (traditional vertical/horizontal grid) and Polar (circular grid).
  • As well as defining the type of grid, you also define the area where that grid applies. Note that the Default grid always applies to the entire design space even though it is only displayed over the board shape.
  • Since only one grid can be used at a time, grids also have a priority that is used to determine which grid should be applied when they overlap. There are also controls for defining if a grid is for all objects, components only, or non-components only.
  • Grids are created and managed in the Grid Manager section of the Properties panel. Use the buttons in the panel to add, edit or delete a grid.

Only the default grid is used in this tutorial.

Multiple grids can be configured in the Grid Manager; the second image shows these three grids (click to enlarge). PCB editor, example of different grids
Multiple grids can be configured in the Grid Manager; the second image shows these three grids (click to enlarge).

Setting the Snap Grid

Related pages: Grid Manager, Cartesian Grid Editor, Polar Grid Editor

The value of the snap grid you need for this tutorial can be configured by pressing:

  • G to display the Snap Grid menu, where you can select an imperial or metric value (note the shortcuts shown in the menu).
  • Ctrl+Shift+G to open the Snap Grid dialog, where you can type in a new grid value.
  • Ctrl+G to open the Cartesian Grid Editor dialog, where you can enter the grid value, as well as configure how the grid is displayed (shown below).
  • Editing the grid in the Grid Manager section of the Properties panel.

Set the Snap Grid to 1 mm, ready to position the components.
Set the Snap Grid to 1 mm, ready to position the components.

Learn more about Working with the PCB Grids System

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