siliconchip.com.au Australia’s electronics magazine April 2019 73
Fig.9: using the Multi-Board Assembly feature, we have
placed the PCB for the Opto-Isolated Relay into a UB3
jiffy box. If we then added 3D footprints for the relay and
capacitor, a relatively simple job, we could then check that
the assembled PCB fits in the enclosure before even having
the boards manufactured.
copper in unwanted areas which were pre-laminated onto
the substrate.
Multiple circuit layers can be added by placing insu-
lating or dielectric material between the conducting lay-
ers. As such, the PCB layout process is much the same in
principle, except that the shapes for the intervening die-
lectric layers need to be generated, not just those for the
conducting tracks.
Altium Designer 19 can work with such designs and
generate the dielectric shapes.
This is controlled through the Layer Stack Manager,
where the Features option is set to “Printed Electronics”.
The layer stack itself should be modified to suit the de-
sign; typically, there is no bottom silkscreen as there is no
easy way to print it onto the bottom layer due to the or-
der of printing.
With printed electronics, the conducting layers are gen-
erally not made of copper; normally a conducting polymer
is used, with significantly more resistance. Its properties
can be set in the Layer Stack Manager too. An AD add-on
is required to generate the shapes on the insulating layers,
and this can be installed by finding the “Dielectric Shapes
Generator” in the Extensions and Updates tab.
Once the tracks have been laid, the Dielectric Shapes
Generator is run from the Tools → Printed Electronics →
Dielectric Shapes Generator menu. The dialog box which
appears is shown in Fig.7. This will give you an idea of how
the various layers pile up, and how the dielectric shapes
create the necessary separation.
Some emerging PCB prototyping technologies will use
printed electronics techniques. There are even some peo-
ple modifying 3D printers to extrude conductive filament
or modifying ink-jet printers to lay down conductive ink
at the moment.
The output of the Printed Electronics mode is standard
Gerber files as per a regular PCB design, and these files
could even be a handy option for anyone who develops a
method of printing in conductive inks at home.
Multi-board assemblies
We noted in our review of Altium Designer 18 that it
introduced better integration of multi-board designs, and
it made the creation of flexible designs easier too. In fact,
practically any rigid design could be made into flexible ver-
sion by substituting a flexible dielectric layer for the rigid
fibreglass layer (and many PCB manufacturers can do this
for you, for a price!)
But this becomes more difficult when you need to com-
bine both types of board in a design. Not only do you need
to visualise how the boards themselves come together but
you must also determine how they fit together with other
parts such as enclosures.
To test this out these multi-board assemblies, we created
an assembly of a few of our Stackable LED Christmas Tree
boards, mentioned earlier, along with the compatible USB
Digital Interface board that was published in the same is-
sue (siliconchip.com.au/Article/11299).
The resulting assembly can be in Fig.8. This would have
come in handy while we were designing that project, as
we had to resort to printing the PCB pattern and making
paper cutouts to check that the boards would stack and
fan out neatly.
The steps required to implement muti-board assemblies
involve creating the various PCBs and, if you wish to in-
clude enclosures, 3D STEP file representations of them. A
“Multi-Board Assembly” is created, and the various parts
added and moved into place in a 3D view, not unlike the
3D view accessible from the PCB layout tab.
As we noted, it is possible to incorporate enclosures into
a multi-board design to be able to see how the entire prod-
uct fits together. We think that this is actually the most use-
ful aspect (for us, anyway) of the Multi-board feature; to
see how complete assemblies fit in enclosures.
That would be true whether we are trying to fit one board
or several into an enclosure; we do the latter from time to
time, with more complex designs. As an example, Fig.9
shows a mock-up of the 230V Opto-Isolated Relay board
(October 2018; siliconchip.com.au/Article/11267) fitting
inside a UB3 jiffy box.
When you bring the various parts of the project togeth-
er, you will then be able to see whether there are any con-
flicts, for example, components that would foul parts of
the case, such as the lid.
If you find such a problem and need to modify one of the
PCBs (or even the case) to fix it, once the source files are
changed, the complete assembly can be refreshed with the
modified parts to confirm that the changes fix the problem.
When using off-the-shelf enclosures, it is easy to do a
real-world test fit, but there would be many companies
(and even individuals with 3D printers) who are design-
ing their own enclosures, making this a bit more difficult.
This feature gives the option of being able to test fit many
parts without waiting weeks for samples to be manufac-
tured for test fitting.
Another potential use for the multi-board assemblies fea-
ture is using the 3D renderings and visualisation to dem-
onstrate to potential customers or others what a product
under development will look like when complete.3D Export
Completed multi-board assemblies (and even plain PCBs)
can now be exported as 3D STEP files too, allowing 3D repre-
sentations of the assembly to be used in other applications.
You could, for example, use a 3D printer to print dum-
my versions of the PCB for mechanical testing, or import
the 3D object into another application that is not able to
accept Altium’s normal file format.