Adding and Editing PCB Layers | Altium Designer 17 Essentials | Module 16

Adding and Editing PCB Layers | Altium Designer 17 Essentials | Module 16


[Chris Jennings] Welcome to
Altium Designer PCB Layers. In this module we will learn how to configure the
layers on the PC board. Starting with a blank PCB, we can set up the layer definitions using the layer stack manager. The layer stack manager entry is found on the design pulldown menu. Here we see the default
two signal layer stackup for the PC board. Setting the units for the stackup is done using the measurement unit manual. While schematics are
typically in imperial units, there is a growing trend
towards metric for the PCB. There are a number of
predefined layer stackups. To load one, click on
the preset pulldown menu, and select from one of the options. These options can be
modified after being loaded. To add a layer, either
signal or power plane, use the add layer pulldown menu. To do so, let’s first select where you want to add the new layer. Click on the add layer, and
select the desired type to add. If needed, a new layer’s
location in the stack can be changed by selecting it and clicking on the
move up or down buttons. Assuming we want a PCB
with four signal layers, and no power planes,
we would want to remove the two power plane layers, it’s as simple as selecting each layer and then hitting the delete button. Now we have a four signal layer PC board. Viewing the layer stackup
with a 3D perspective is easy, just click on the 3D check box. An image of the layer stackup
can be copied and pasted using the copy image to clipboard icon. Let’s paste the image into a Word doc now. Like so. Assuming we have a final layer stackup that we want to reuse, we can save it using the save button. Let’s call it my company PCB stack. Later on, we can use it
to define a new PC board with this particular layer stackup by using the load button. One issue that bears some consideration is the tradeoff between power
type planes and signal layers. With the polygon pour feature in Altium, any signal layer can effectively
become a power plane. The advantage of using
polygons is that if needed, signal routing can be added to that layer. In the case of a defined power plane this is not an option. Power planes do allow for the tool to calculate trace impedance using the impedance calculator as shown. One recommended approach for your PC board without power planes would be to use an external impedance calculator to drive the trace widths and
the layer stackup dimensions. The approach of using polygons can in some cases avoid
needing to add extra layers to the PC board. Some companies may have
strict requirements for the layer stackup,
so if that is the case, I would recommend creating and using the company standard stackup, saving it, and then loading it in when
needing to start a new PC board. Let’s load up the four signal
layer PCB we saved earlier, using the load button. Within the layer stack manager window, a number of fields can be edited, including the layer thickness,
and the layer materials. Clicking on the thickness
entry allows for edits. Likewise, clicking on the materials entry provides the typical options menu. Altium Designer has direct support for flex rigid PCB design. To create the multiple
stack layers needed, click on the advance button at the bottom of the layer stack manager window. Here we see an example
flex rigid PC board, with the connected cube project included with all tool installations. Opening up the layer stack manager, we can see that there are
two layer stack definitions. Notice the layer named
rigid defines all the layers for the PC board, and flex uses a subset of those layers. This is an important concept
for flex rigid PCB designs. The layers must be contiguous
through all sections. The layer stack named Flex also
has the flex check box set, indicating that this
is a non-rigid section of the PC board. It is also possible to have multiple flex
and rigid PCB stackups for a single PC board design. One useful feature in 3D mode is the ability to interactively
fold the PC board. This is done using the PCB panel, and selecting the layer
stack regions mode. The bend align placement,
angle, and radius are configurable in the
board planning mode. We will explore the board
planning mode in another module. Altium provides for exporting
the PCB as a STEP model. This is especially useful
when the components have 3D models built into them. To export a PCB as a STEP model,
click on file, then export. Note that there are a
number of options here, which we will explore later. For now let’s select a
3D STEP model option. This opens up a new window, prompting us for a location and name for the STEP file. Particularly useful is
the ability to export the flex rigid PC board with
the fold state specified. This allows for mechanical CAD checking with the case or housing interfaces. Clicking okay generates the model.


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