PCB Placement & Editing Techniques 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.

 

A variety of objects are available for use in designing a PCB. Most objects placed in a PCB document will define copper areas or voids. This applies to both electrical objects, such as tracks and pads, and non-electrical objects, such as text and dimensioning. It is therefore important to keep in mind the width of the lines used to define each object and the layer on which the object is placed.

There are two types of objects in the PCB editor – primitive objects and group objects. Primitive objects are the most basic elements and include: tracks, pads, vias, fills, arcs, and strings. Anything that is made up of primitives and identified as a design object is a group object. Examples of group objects include: components, dimensions, coordinates, and polygon pours.

Object Placement and Editing Commonality

In Altium NEXUS, the process of placing an object is roughly the same regardless of the object being placed. At its simplest level, the process is as follows:

  1. Select the object to be placed from one of the toolbars or the Place menu.
  2. Use the mouse to define the location of the placed object in the PCB editor design space and its size (where applicable).
  3. Right-click (or press Esc) to terminate the command and exit placement mode.

Editing Prior to Placement

The default properties for an object can be changed at any time on the PCB Editor – Defaults page of the Preferences dialog. These properties will be applied when placing subsequent objects..

Use the Primitives column to access properties for objects and edit default values as required.
Use the Primitives column to access properties for objects and edit default values as required.

Default values for the objects are saved, by default, in the file ADVPCB.dft. Optionally, values can be saved in a .dft file with a different name. Controls are available to save and load .dft files, enabling you to create favorite default object value 'sets'. All settings saved in and loaded from .dft files are user-defined defaults. Should it be necessary, original default values can be brought back at any time using the Set To Defaults or Reset All options. The original default values are hard-coded.

Editing During Placement

A number of attributes are available for editing at the time an object is first placed. To access these attributes, press the Tab key while in placement mode to open the associated Properties panel. Pressing the Tab key pauses placement in order for you to make any required edits for the object.

Example properties dialog for a Pad object. 
Example properties dialog for a Pad object.

After edits have been made, click the design space pause button overlay ( ) to resume placement.

Attributes that are set in this manner will become the default settings for further object placement unless the Permanent option on the PCB Editor – Defaults page of the Preferences dialog is enabled. When this option is enabled, changes made will affect only the object being placed and subsequent objects placed during the same placement session.

Editing After Placement

Once an object has been placed, there are a number of ways in which it can be edited. These are described below.

The Associated Properties Panel or Dialog

This method of editing uses the associated Properties panel mode and dialog to modify the properties of a placed object.

After placement, the associated dialog can be accessed by:

  • Double-clicking on the placed object.
  • Placing the cursor over the object, right-clicking then choosing Properties from the context menu.

After placement, the associated mode of the Properties panel can be accessed in one of the following ways:

  • If the Properties panel is already active, select the object.
  • After selecting the object, select the Properties panel from the Panels button at the bottom right of the design space or select View » Panels » Properties from the main menus.
If the Double Click Runs Interactive Properties option is disabled (default) on the PCB Editor – General page of the Preferences dialog, when the primitive is double-clicked or you right-click on a selected primitive then choose Properties, the dialog will open. When the Double Click Runs Interactive Properties option is enabled, the Properties panel will open.
While the options are the same in the dialog and the panel, the order and placement of the options may differ slightly.
Press Ctrl+Q to toggle the units of measurement currently used in the panel/dialog between metric (mm) and imperial (mil). This only affects the display of measurements in the panel/dialog; it does not change the measurement unit specified for the board, which is configured in the Units setting in the Properties panel when there are no objects selected in the design space.

Graphical Editing

This method of editing allows you to select a placed object directly in the design space and change its size, shape, or location graphically. Modification of shape and/or size (where applicable) is performed through the use of editing 'handles' that appear once the object is selected.


Example editing handles for a selected Fill object.

Click anywhere on an object away from editing handles (where they exist) to drag the object to reposition it. Depending on the type of object, it may be rotated and/or flipped while dragging.

  • Press Spacebar to rotate the object counterclockwise or Shift+Spacebar for clockwise rotation. Rotation is in accordance with the value for the Rotation Step defined on the PCB Editor – General page of the Preferences dialog.
  • Press the  X or Y keys to flip the object along the X-axis or Y-axis where applicable.
The number of primitives displayed when dragging multiple selected objects is controlled by the PCB.Rendering.MultiselectionDrag option in the Advanced Settings dialog. The Advanced Settings dialog is accessed by clicking the Advanced button on the System - General page of the Preferences dialog. If any changes are made in the Advanced Settings dialog, the software must be restarted in order for the changes to take effect.

Alignment Commands

Objects can also be moved by changing their alignment. To align objects with other objects, right-click on a selected object, then select Align. The alignment sub-menu contains a number of options for distributing selected objects.

For more information on the individual alignment options, see the AlignComponents command page.

Via the PCB List Panel

Panel Page: PCB List

The PCB List panel allows you to display design objects in tabular format, enabling quickly inspection and modification of object attributes. When used in conjunction with the PCB Filter panel, it enables you to display just those objects falling under the scope of the active filter – allowing the targeting and editing of multiple design objects with greater accuracy and efficiency.

Locking Design Objects

Design objects can be locked from being moved or being edited on the PCB document by enabling their Locked attributes. For instance, if the position or size of specific objects is critical, lock them. Locking can be done in the Properties panel by clicking on the padlock icon ( ) for the desired object(s) as shown in the following examples. 

Examples of the Lock icon in the Properties panel in Component mode and Pad mode. 
Examples of the Lock icon in the Properties panel in Component mode and Pad mode.

If you attempt to move or rotate a design object that has its Locked property enabled, a dialog appears asking for confirmation to proceed with the edit.

If the Protect Locked Objects option is enabled in the PCB Editor – General page of the Preferences dialog and the design object is locked, the object cannot be selected or graphically edited. Use the Lock icon on the Properties panel to unlock the object or disable the Protect Locked Objects option to graphically edit this object.

If you attempt to select locked objects along with other objects, only those objects that are unlocked can be selected and moved as a group when the Protect Locked Objects option is enabled.

Component Primitive Locking

If a PCB component has its primitives locked (the Primitives option in the Component mode of the Properties panel is in its  state), all or the most properties of these primitives cannot be modified using graphical (e.g., using drag-and-drop) and non-graphical (e.g., using the Properties or List panel) editing methods. This will help to prevent occasional changes of component primitives that can result in incorrect assembly and fabrication outputs.

To enable/disable the preventing modification of PCB component primitives functionality, use the Protect Locked Primitives In Component option on the PCB Editor – General page of the Preferences dialog.

By way of an example, the Pad mode of the Properties panel is shown in the image below for a pad that is a constituent part of a PCB component that has its primitives locked. Note that all properties of the pad (except for Net and Testpoint properties) are dimmed and not available for editing. Note also that the  icon is shown at the far right of the pad's Component field, which denotes that the parent component has its primitives locked, and pad properties cannot be modified.

The Pad mode of the Properties panel (on the left) for a pad of a PCB component that has its primitives locked (on the right).
The Pad mode of the Properties panel (on the left) for a pad of a PCB component that has its primitives locked (on the right).

Re-Entrant Editing

The PCB Editor includes a powerful feature called re-entrant editing. This allows a second operation to be executed using keyboard shortcuts without the current operation being terminated. Re-entrant editing allows you to work more flexibly and intuitively. For example, consider starting to place a track and then realizing that another track segment must be deleted. There is no need to drop out of Interactive Routing mode. Press the E, D shortcut keys, delete the required track segment then press the Esc key to return to interactively routing the design.

Setting the PCB Cursor Appearance

By default, the PCB cursor is set as a small green 90 degree cross. This can be configured using the Cursor Type and Cursor Color settings, on the PCB Editor – General page of the Preferences dialog. For example, a large 90 degree cross that extends to the edges of the design window (Large 90 option) can be useful when placing and aligning design objects. Alternatively, a cross at 45 degrees (Small 45 option) might be useful if the 90 degree options are hard to see against grid lines.

Priorities When Pasting Objects

When an object is being pasted on a copper layer, and it overlaps a set of objects of different types when pasted, a net of the highest priority object will be assigned to the pasted object. The priorities are as follows (1 is the highest priority):

  1. Pad
  2. Fill
  3. Region
  4. Track
  5. Arc
  6. Via
  7. Polygon Pour

A net of the highest priority object is assigned to a pasted object. Here is shown an object (track) pasted over a set of objects of different types with different nets assigned. Since the pad is the object of highest priority in this set, its net (Pad_Net) will be assigned to the pasted object. Hover the cursor over the image to see the result.
A net of the highest priority object is assigned to a pasted object. Here is shown an object (track) pasted over a set of objects of different types with different nets assigned. Since the pad is the object of highest priority in this set, its net (Pad_Net) will be assigned to the pasted object. Hover the cursor over the image to see the result.

When an object is being pasted on a copper layer, and it overlaps a set of objects of the same type when pasted, a net of the object that is under the cursor when clicking to paste the object will be assigned.

A net of the object under the cursor is assigned to a pasted object. Here is shown an object (track) pasted over a set of objects of the same type (pads). Since pad 2 is the object that is under the cursor when clicking to paste the object, the net of this pad (Pad2_Net) will be assigned to the pasted object. Hover the cursor over the image to see the result.
A net of the object under the cursor is assigned to a pasted object. Here is shown an object (track) pasted over a set of objects of the same type (pads). Since pad 2 is the object that is under the cursor when clicking to paste the object, the net of this pad (Pad2_Net) will be assigned to the pasted object. Hover the cursor over the image to see the result.

When a set of physically connected objects is being pasted on a copper layer, and objects of different types in this set overlap existing objects with different nets, a net of the highest priority object in this set will be assigned to all pasted objects. The above priorities are applied in this case.

The net assigned to the highest priority object is assigned to the set of the physically connected objects. Here is shown a set of connected objects (from left to right: Fill, Region, Track, Arc, Via, Polygon Pour) pasted over objects (vias) with different nets assigned. Since the fill is the object of highest priority in this pasted set, the net assigned to it (Via1_Net) will be assigned to each object in this set. Hover the cursor over the image to see the result.
The net assigned to the highest priority object is assigned to the set of the physically connected objects. Here is shown a set of connected objects (from left to right: Fill, Region, Track, Arc, Via, Polygon Pour) pasted over objects (vias) with different nets assigned. Since the fill is the object of highest priority in this pasted set, the net assigned to it (Via1_Net) will be assigned to each object in this set. Hover the cursor over the image to see the result.

True Type Font Support

The PCB Editor offers the ability to use Stroke-based or TrueType fonts for text-related objects in a design (string, coordinate, and dimension text). Choice of font is made from within the associated Properties panel. Three Stroke-based font options are available - Stroke, Sans Serif, and Serif. The Default style is a simple vector font that supports pen plotting and vector photoplotting. The Sans Serif and Serif fonts are more complex and will slow down vector output generation, such as Gerber. The Stroke-based fonts are built into the software and cannot be changed. All three fonts have the full IBM extended ASCII character set that supports English and other European languages. When using TrueType fonts, TrueType and OpenType (a superset of TrueType) fonts fount in the \Windows\Fonts folder is available for use. The feature also offers full Unicode support.

Note that only detected (and uniquely named) root fonts will be available for use. For example, Arial and Arial Black will be available but Arial Bold, Arial Bold Italic, will not.

The PCB Editor – TrueType Fonts page of the Preferences dialog provides options for embedding TrueType fonts when saving a design and for applying font substitution when loading a design.

Embedding fonts is useful when text is required to be displayed in a font that may or may not be available on a target computer upon which the design is loaded. Font substitution enables specification of a TrueType font to be used as a replacement when loading a design where fonts have not been embedded and where fonts may not be available on the computer upon which the design is currently loaded.

Net Information

For copper objects on a PCB (track, via, polygon, etc.), the following information is presented in the Net Information region of the Properties panel when the object is selected:

  • the parent Net, Diff Pair and/or xSignal and associated class in each case. Note that the Diff Pair and xSignal entries are shown only if the object is a part of a differential pair or xSignal, respectively.
  • Delay – the delay of the selected object(s) and the delay of the routed segments of the entire net. Include the Propagation Delay values of pads and vias, if they have been defined for the pads and vias.
  • Length – the total length sum of the selected object(s) and the total Signal Length. The Signal Length is the accurate calculation of the total node-to-node distance. Placed objects are analyzed to: resolve stacked or overlapping objects and wandering paths within pads; and via lengths are included. The Pin Package Length is also included if it has been defined for the pad(s). If the net is not completely routed, the Manhattan (X + Y) length of the connection line is also included. For more information regarding Signal Length and its applications, see the information about the PCB - Nets panel.

    The total length includes an estimate for the unrouted part of the net (the Manhattan (X + Y) length of the connection line), but for the total delay, it does not.
  • For a selected Track, Arc or Via object, the calculated Max Current and Resistance values are also provided.

The Net Information region of the Properties panel. Shown here is an example for a selected track.
The Net Information region of the Properties panel. Shown here is an example for a selected track.

Click a link in the Net Information region to open the associated net/differential pair/xSignal in the PCB panel.

Primitive Objects

Primitive objects in the PCB Editor are fundamental elements of design. They are called 'primitive' due to their raw or most basic nature. Certain primitive objects are used as building blocks to create more advanced design objects, such as arcs, fills, and tracks, to create PCB 2D component models.

Primitive objects are available for placement in the PCB Editor, with many object types also supported for placement in the PCB Library Editor. Commands for placement can be found in the main Place menu, as well as the Active bar, the Utilities toolbar, and various drop-downs of the Wiring toolbar. Depending on the object, placement may require several mouse clicks to define the object's appearance.

PCB primitive objects can be placed from the Active, Utilities, and Wiring toolbars.PCB primitive objects can be placed from the ActiveUtilities, and Wiring toolbars.

Objects are placed on the current layer. Ensure the correct layer has been made the current layer before effecting placement. The layer on which an object resides can be changed after placement.
 
 
 
 
 

Group Objects

A group object is any set of primitives that has been defined to behave as an object. These may be user-defined, such as components and polygon pours, or system-defined, such as coordinates and dimensions. A group object can be manipulated as a single object within the design space. For example, it can be placed, selected, copied, changed, moved, and deleted.

Group objects are available for placement in the PCB Editor with the coordinate object also supported for placement in the PCB Library Editor. Commands for placement can be found in the main Place menu, as well as the Wiring toolbar, and various drop-downs of the Utilities toolbar. Depending on the object, placement may require several mouse clicks to define the object's appearance.

Objects are placed on the current layer. Ensure the correct layer has been made the current layer before effecting placement. An object can be changed with respect to the layer on which it resides after placement.

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