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Concept & How to Pages
Altium hosts a huge array of ready-made PCB Components both in the Vault as well as in several integrated and discrete libraries available through AltiumLive. However, even with this rich set of resources, it is likely that at some point in the designer's career they will need to create a custom PCB Component. PCB Component Footprints are created in the PCB Library editor using the same set of primitive objects available in the PCB editor. In addition to footprints, company logos, fabrication definitions and other objects required during board design can also be saved as PCB Components.
The real-world component that gets mounted on the board is represented as a schematic symbol during design capture, and as a PCB footprint for board design. Altium Designer components can be:
The typical sequence for manually creating a component footprint is:
Metricor vice versa.
.Commentspecial strings on a mechanical layer.
The IPC Compliant Footprint Wizard creates IPC-compliant component footprints. Rather than working directly from footprint dimensions (as the Component Wizard does), the IPC Compliant Footprint Wizard uses dimensional information from the component itself, and then calculates suitable pad and other footprint properties in accordance with the algorithms released by the IPC.
Some of the IPC Compliant Footprint Wizard features include:
The IPC Footprint Batch Generator can be used to generate multiple footprints at multiple density levels. The generator reads the dimensional data of electronic components from an Excel spreadsheet or comma delimited file and then applies the IPC equations to build IPC compliant footprints. Support for the IPC Footprints Batch Generator includes:
\Templatesfolder in the Altium Designer installation.
The PCB Library Editor includes a Component Wizard. This Wizard allows you to select from various package types, fill in appropriate information and it will then build the component footprint for you. Note that in the Component Wizard the designer enters the sizes required for the pads and component overlay.
To launch the Component Wizard, right-click on the Components section of the PCB Library panel and select Component Wizard, or select the Tools » Component Wizard command.
A 3D representation of the component can be included in the footprint. The shape can be created by placing a number of Altium designer 3D Body objects to build up the shape, by placing one 3D Body object and importing a STEP model into it, or a combination of both.
Some footprints require pads that have an irregular shape. This can be done using any of the design objects available in the PCB Library Editor, but when doing this, there is an important factor that must be kept in mind.
Altium Designer automatically adds solder and paste masks to pad objects based on their shape. Default expansion values are defined by design rules by default, although they can also be specified by the Pad Primitive type settings contained on the PCB Editor » Defaults page of the Preferences dialog. These settings can be overridden during placement or after placement through the Pad dialog.
If only pad objects have been used to build up an irregular shape, then the matching irregular mask shape will be generated correctly. But if the irregular shape was built up using other objects such as lines (tracks), fills, regions, pads, vias, or arcs, the solder and paste masks will need to be handled manually.
Manually applying solder and paste mask expansions can be achieved by placing lines (tracks), fills, regions, or arc primitives on the corresponding solder or paste mask layer. Designers can then make use of the Solder and Paste Mask Expansion settings within the primitives used to create the irregular pad shape.
The Track dialog is shown above. Highlighted are the Solder and Paste Mask Expansion settings. The options available in their drop down list are:
Note that if the mask opening requirements are not a simple expansion or contraction of the copper shape, it will not be possible to use a calculated mask. In this case suitable design objects will need to be placed on the required Mask layer.
To check that solder and/or paste masks have been correctly defined in the PCB Library Editor, open the View Configurations dialog (Tools » Layers & Colors or L hotkey) and enable the Show option for each mask layer.
The image under the Footprints with Multiple Pads Connected to the Same Pin section below shows a PCB footprint with a purple (color of the Top Solder Mask layer) border that appears around the edge of each pad. This represents the edge of the solder mask shape protruding by the expansion amount from under the pad.
To quickly walk through layers, use the Single Layer Mode (Shift+S) in combination with Ctrl+Shift+Wheelroll.
When a design is transferred, the footprint specified in each component is extracted from the available libraries and placed on the board. Then each pad in the footprint has its net property set to the name of the net connected to that component pin in the schematic. If the footprint includes copper primitives touching the pads, these primitives will not be assigned the net name automatically and will create a design rule violation. In this case, the designer will need to perform an update process to assign the net name.
The PCB Editor includes a comprehensive net management tool. To launch it select Design » Net list » Configure Physical Nets from the menus. Click the Menu button for a menu of options, and click the New Net Name region to select the net to assign to the unassigned primitives.
The footprint shown below, a SOT223 transistor, has multiple pads that are connected to the same logical schematic component pin - Pin 2. To make this connection, two pads have been added with the same designator - '2.' When the Design » Update PCB command is used in the Schematic Editor to transfer design information to the PCB, the resulting synchronization will show the connection lines going to both pads in the PCB Editor.
The footprint shown below is the contact set for a push button switch implemented directly in the copper on the surface layer of the PCB.
A rubber switchpad overlay is placed on top of the PCB, with a small captive carbon button that contacts both sets of fingers in the footprint when the button is pressed to create the electrical connectivity. For this to happen, both sets of fingers must not be covered by the solder mask. The circular solder mask opening has been achieved by placing an arc whose width is equal to or greater than the arc radius, resulting in the solid circle shown behind the two sets of fingers. Each set of copper fingers has been defined by an arc, horizontal lines, and a pad. The pads are required to define the points of connectivity. Manually placed solder mask definitions will be automatically transferred to the bottom side solder mask layer when the component is placed on the bottom of the board.
When a footprint is placed on a board it is given a designator and comment based on information extracted from the Schematic view of the design. Placeholders for the designator and comment strings do not need to manually defined since they are added automatically when the footprint is placed on a board. The locations of these strings is determined by the designator and comment string Autoposition options in the component's Properties dialog. The default position and size of Designator and Comment strings is controlled by settings contained in the Component primitive in the PCB Editor - Defaults page of the Preferences dialog.
There may be situations where additional copies of the designator or comment strings are required - for example the assembly house might want a detailed assembly drawing with the designator shown within each component outline, while in house company requirements stipulate the designator to be located just above the component on the component overlay on the final PCB. This requirement for an additional designator can be achieved by including the .Designator special string in the footprint. A
.Comment special string is also available for stipulating the location of the comment string on alternate layers or locations.
To cater for the assembly house's requirements, the
.Designator string would be placed on a mechanical layer in the library editor and printouts that included this layer could then be generated as part of the design assembly instructions.
There are a number of special requirements a PCB component can have, such as needing a glue dot, or a peelable solder mask definition. Many of these special requirements will be tied to the side of the board that the component is mounted on, and must flip to the other side of the board when the component is flipped.
Rather than including a large number of special purpose layers that may rarely be used, Altium Designer's PCB editor supports this requirement through a feature called layer pairs . A layer pair is simply two mechanical layers that have been defined as a pair. Whenever a component is flipped from one side of the board to the other, any objects on a paired mechanical layer are flipped to the other mechanical layer in that pair.
Using this approach, an arbitrary mechanical layer would be defined as the glue dot layer (or other special requirement) and any shapes necessary for defining the position and size of component glue dots would we specified on this layer in the PCB Library Editor.
Layer pairing cannot be defined within the PCB Library Editor itself; only within the PCB Editor. So once the component is placed on the PCB, the layer pairing for that design must be defined from the Layer Pairs button in the View Configurations dialog (Design » Board Layers & Colors).
At the simplest level of 3D representation, height information can be added to a PCB Component. To do this, double-click on the footprint in the Components list in the PCB Library panel to display the PCB Library Components dialog. Enter the recommended height for the component in the Height field.
Height design rules can be defined during board design (select Design » Rules in the PCB Editor), typically testing for maximum component height in a class of components, or within a room definition.
A far better option for defining Height information would be to attach 3D Bodies and/or a STEP model to the PCB Component. Details of this will be discussed in another module.
PCB Components can be copied from other PCB Libraries and then renamed and modified within the destination library to match the specifications required. There are a number of ways to execute this copy:
There are a series of reports that designers can run to check that footprints have been created correctly as well as identifying which components are in the current PCB library.
The Component Rule Check report (Reports » Component Rule Check) is useful for validating all components in the current PCB library by testing for duplicate primitives, missing pad designators, floating copper and inappropriate component references.
Including PCB Libraries as part of a Integrated Library Package provides an additional layer of validation because it allows the Design Compiler to examine the Schematic and PCB models together. This, of course, requires that a Schematic Library that matches the PCB Library exists however assuming this is the case, a range of additional checks are possible.
Updating a PCB Footprint can be done in either of two ways: either by "Pushing" the PCB from the PCB Library or by "Pulling: from the PCB Editor. Pushing a PCB Footprint update takes a selected footprint(s) from the PCB Library and uses it to update all open PCB documents containing that footprint. This first method is the best option when a complete replacement is desired. The second option, pulling, allows designers to review all the differences between the existing footprint and the footprint in the library before the update is performed. As well, designers can select which objects are to be updated from the library. This second method is the best option when you need to figure out exactly what has changed between the footprint on the board and the footprint in the library.
From the PCBLIB Editor, use the Tools » Update PCB with Current Footprint or Tools » Update PCB With All Footprints command. From the PCB Library panel, right-click in the Components region of the PCB Library panel and select Update PCB with [Component] or Update PCB with All. Running these commands opens the Component(s) Update Options dialog, from which you can select the primitives/attributes to be updated.
From the PCB editor, use the Tools » Update From PCB Libraries command, which in turn opens the Update from PCB Libraries - Options and the Update from PCB Libraries dialogs.
Full article: Release a PCB 2D-3D Model to an Altium Vault
After completing the creation of a PCB Footprint, the footprint and any additional 3D model/body info (all of which come together to create the component model) can be released to and stored in an Altium Vault. A vault-based component gathers together all information needed to represent that component across all design domains, within a single entity. It could therefore be thought of as a container in this respect. A 'bucket' into which all domain models and parametric information is stored.
In terms of its representation in the various domains, a vault-based component doesn't contain the domain models themselves, but rather links to these models. These links are specified on the design-side, as part of the source component definition – from which the released Component Item is generated. As such, before you can delve into the process of defining and releasing vault-based components, you must first ensure that all the domain models themselves have been created and released.
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