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Once schematics are complete, board layout allows the designer to decide the physical locations of components and route connections between them. All annotations on the schematics will be incorporated into the layout tools Altium provides, enforcing that your physical implementation does not breach requirements set in the schematics!

CONTENTS

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Workflow

This flow chart isn't color coded as all stages can be completed by anyone; it really just comes down to if you feel ready to participate in these tasks

Read more below:

 Click here to expand...

Import Changes

Once schematics are complete, the first import will populate the layout file with all the components and connections necessary to design the actual board.

Changes may still be imported again if there are last minute changes to schematics. This will impact how the layout needs to be completed, which is why it is best to be confident in the schematic before starting layout.

Setup Design Rules

Before starting placement and routing, it is best to go through the design rules and ensure they meet the project requirements. By default, the NER template will include a set design rules based on manufacturing requirements. This will not however account for clearances that need to be enforced for other reasons, such as high voltage, water resistance, or anything else.

Complete Component Placement

Using the “rats nest” view, it is possible to see how all the pads on a PCB should be connected, without actually placing copper. Component placement is arranging the components loosely such that pins should be able to connect when we start routing, but without putting in the actual effort of routing every pin. This allows the opportunity to think about overall layout of the board and potential major collisions that need to be discussed.

Preliminary Placement Review & Feedback

It’s recommended before routing to complete a preliminary design review. This will allow for others to provide feedback before you need to go through the efforts of complete routing. In this stage a design review should be hosted and feedback should be recorded and addressed.

Complete Routing

Once confident in component placements, the actual routing can begin. This consists of running traces, polygons, vias, and more to actually establish the connections dictated in schematic.

Complete Silks

Completing silks includes formatting and arranging designators, adding caution labels, adding team logos and attributions, and anything else we want printed on the board. Typically this is done last in the processes, as they are low priority and need to avoid any collisions if we want them visible.

Final Design Review

As you’d expect, we need a final design review to collect team feedback and address issues that are discovered.

Execute OutJobs

Once the board is 100% ready for production, we need to initiate an OutJob. These automatically create a release in the version control system and generates fabrication outputs to upload to a fabrication house.

Order PCBs

The lead can now order the boards and components! The OutJob should automatically have created the needed Gerber files and BOM.

Importing Changes

As mentioned in the workflow above, importing changes instructs Altium to determine changes to the schematics and implement them in the layout. Altium has this rigid barrier between the two to allow the designer to preview and confirm the impact to the board before changes are made via an ECO (engineering change order).

In the normal day to day, you should always import changes to the layout such that you minimize major changes that accumulate in schematics.

 CLICK HERE FOR MORE

{explain how to do it}

{explain the minor variations (import to schematic and such)}

Basics of Layout

Before going deep into a layout, make sure design rules are all setup!

For navigation basics, check out https://nerdocs.atlassian.net/wiki/spaces/NER/pages/153026566/Intro+to+Altium#Layout-View

This section will provide a cursory look at how to create a PCB layout. Covered in this will be all you need to make and manage connections. The following section, design rules, is also quite important for forming a successful layout!

As always, check out the Vault Guidelines for requirements in NER projects and Altium Reference, Tips, Troubleshooting for quick tips.

Altium is a massive piece of software and even more is covered in the Advanced Layout page.

Selecting Grid Size & Snapping

These options apply to how all objects in layout behave, including components and traces.

Grid Size & Units

Particularly important in layout is selecting how precisely you’d like to move your components. While in 2D layout, hitting G will open the grid size menu, where you can select what grid you’d like to snap to.

{image}

Additionally, Q will swap which units are displayed (mils for imperial, mm for metric).

MechEs hate the fact that mils is imperial since they sometimes think millimeters are mils. In Altium, 1 mil = 0.001 inches (a.k.a. 1 thou (as in one thousandth))!

Snapping Options

Beyond snapping to a grid, objects can also snap relative to other objects within the board. This is controlled via the snapping settings in the layout toolbar.

{image of button}

Play around with what you think is most useful. The list is quite comprehensive in terms of what you can snap to, so you often will be toggling them on and off depending on situation.

I don’t recommend turning everything on. Once a board gets dense, you’ll have snapping points in so many places that you won’t be able to move anything anymore!

Arranging Components

After an import, components will be automatically populated in the layout based on the schematic. Components can be moved by clicking and dragging. Additionally while dragging a component:

  • Rotation: Spacebar

  • Layer Flip: L

Never ever ever use X and Y when in layout. You will get a warning from Altium for good reason: your component will (most likely) no longer solder onto the board!

Alignment Tools

When placing components, it is often difficult to get things to “look pretty” by just clicking and dragging. The most useful tool for this is the alignment menu. First select which components you’d like to align, then the menu can be accessed via the right click menu or the toolbars:

{images of how to access}

From here, the names and icons imply what will occur. Below are some examples:

{example 1}

Ex2

ex3

Some alignment tools will require a secondary click to indicate what to align in reference to. In this case you would select a group, right-click, select alignment option, then left-click which to align to.

Adding Traces

Routing traces is initiated by hitting Ctrl + R, opening the interactive routing tool. This is just a tool that is initiated by clicking on any pad needing a connection, and then moving the mouse along the path you would like the trace to take (you do not need to drag, just click and then move the mouse). The trace will terminate when you click a destination pad to route to.

While moving the mouse there are a few options:

  • Click → You can click anywhere on the PCB and if it is not a pad it will effectively just add an in-between point to route through

  • Spacebar → Toggles between routing x-then-y vs y-then-x

  • Tab → Pauses routing and opens properties. This allows for selecting settings of the trace being routed while in progress of routing (such as selecting width!)

  • Shift + Space → Toggle corner modes. This will change your corners between radii, 45°, and 90° angles. We typically just stick with 45° angles

If your design rules and settings are setup properly (they should be if the project was created properly), your trace will have design rules automatically enforced while dragging around!

Once a trace is routed, you can reselect the entire segment by left clicking one segment, and then pressing Tab. You can then open properties to retroactively change trace width if needed.

Using Polygons

Polygons are how we place large regions of copper. These may be used for high current connections, frequently used nets (such as Chassis), or for shielding of sensitive signals.

The polygon tool can be found in the layout toolbar or right click menu:

{images}

It will start creating a poly on whichever layer you have active when you select the tool

Once selected, the polygon tool allows the user to place points outlining a region. Once done, right click to finish the sketch. The points can then be refined by clicking and dragging. While dragging you can hit Delete to remote a point or Spacebar to change the corner type (90, 45, or radius). You can hold Ctrl while selecting a side to create an additional node.

After your geometry is set, open the properties panel to edit a few important parameters. Primarily, the net and your pour over options should be set.

Polygons will then need to be repoured to appear as copper in the layer. This can be achieved by selected the “Repour” button in the top of the properties panel. Another method is to repour all properties via the toolbar:

{show how to repour polys}

If the polygon does not behave as desired you may need to edit other properties or manually change the pour order via the buttons at the top of the properties panel (shown above).

Polygons depend heavily on priority to resolve overlap. If you have multiple polygons you will need to play a lot with their pour order. For some you may want: https://nerdocs.atlassian.net/wiki/spaces/NER/pages/156205136/Advanced+Layout#Polygon-Manager

Look to the official documentation for more: https://www.altium.com/documentation/altium-designer/pcb-signal-layer-polygons

Design Rules

Design rules and DRC are one of the key features of PCB layout software. It allows the designer to program rules based on engineering requirements and allow the software to complete checks for compliance across the thousands of interactions that may occur within the board. Some examples include:

  • Clearance and creepage distances needed to maintain isolation

  • Copper width needed for current/power

  • Transmission impedance for high speed signals

  • And so much more!

 CLICK HERE FOR MORE

Defining Rules

By default, the NER project template should include design rules that meet the requirements of our most common PCB fabricators (JLCPCB and PCBWay). If not, the most recent version can be downloaded from the Vault Guidelines {need to add section for it}

There are many many rules that

{give a quick list of critical/frequently used rules. Perhaps we treat this list as “template will set it but you should confirm it matches your needs”}

Design Rule Check (DRC)

{explain difference between rules being live checked (“Online”) and only via reports (“Batch”)}

{show how to change which are which, and strategies for when it’s best to enable or disable certain checks}

Export for Fabrication (OutJobs)

Typically when ordering plain boards or simple assembly fabrication houses will require fabrication files in Gerber format. To simplify this process we have created “OutJobs” which are a feature of Altium allowing automatic generation of Gerbers, BOMs, STEP files, and other useful exports. Additionally, releasing via out jobs creates a “release” in the version control system.

Some nicer (more expensive) “turn-key” PCBA companies will take direct Altium files and do all the processing for you.

 CLICK HERE FOR MORE

Out Job Configuration

{include reference to template files. Maybe we’ll add to the guidelines page}

{brief overview of what it should look like and how to tweak things}

Creating a Release

{explain out job release process}

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