HackSpace_-_October_2019

FORGE

you should find that, if you select ‘Extensions’,
svg2shenzen will appear in the drop-down menu.
Hovering over svg2shenzhen in the drop-down
menu should reveal the extension has three
options: ‘Help’, ‘Prepare document’, and ‘Export to
KiCad’. Click the ‘Prepare document’ option. You
should see a dialog box in which you can set the
size of the document. It’s not critical, apart from
it needs to be big enough to contain your desired
design; input a size and then click ‘Apply’. Close
the dialog box.
If you now open the layers window, either by
clicking Layer > Layers or with the CTRL+SHIFT+L
keyboard shortcut, you can see that the Inkscape
document has now been set up with numerous
layers that match some of the physical layers of a
PCB, named as they are
labelled in KiCad.
Let’s begin by drawing
on the ‘Edge Cuts’ layer

• this is the layer into
  which we draw the edges
  of the PCB. Within KiCad
  we are limited to arcs/
  circles and straight lines,
  whereas in svg2shenzhen we have no limitations to
  the geometries we can draw. To draw the outline of
  the rocket PCB (Figure 1), we used the Bézier tool
  and some common path tools in Inkscape, including
  Union and Divide. A rule for edge cuts created with
  svg2shenzhen is that they must be a single path that
  is completely connected. It’s easy when drawing
  perhaps with multiple tools in Inkscape to create
  an outline that has a couple of unconnected nodes,
  making it incomplete.
  Once you have made an outline shape of your
  PCB, you might next want to add some details,
  shapes, and lines that will appear as exposed copper
  when the board is manufactured. For the rocket
  PCBs, we wanted to also add some components

Figure 2

Using the Inkscape preferences menu

to locate where to install extensions

and traces to the front copper layer in the standard

KiCad workflow, so we decided to add the more

decorative items to the back copper layer of the

board. Before we add some decoration, let’s looks

at how the mask layers work. Currently, the mask

layers are set to ‘disabled’. To enable them, simply

select the layer and rename the layer by removing

the ‘-disabled’ text. For example, the back mask

layer would change from ‘B.Mask-disabled’ to

‘B.Mask’. This actually (due to the nature of PCB

fabrication) sets the mask layer to not appear where

you draw a black item. In this configuration, you

have to manually draw where you want mask to not

appear. Changing the mask layer name to ‘B.Mask-

invert’ sets this layer so that what you draw is where

you get mask on the PCB, but for the rocket project,

we found the simplest

solution was to change

the mask layer to

B.Mask-auto. In auto

mode, when you

add an object to the

corresponding copper

layer (B.Cu in this

case), it automatically

removes the mask in that area, allowing the object

you have drawn to be seen through the removed

mask as copper.

LET’S GET MASKED!

Having set the B.Mask layer to auto-select the B.Cu

(Back Copper Layer) and draw our items onto this

layer, we add the copper rounded triangular sections

seen on the rocket (Figure 1), and it automatically

adds these shapes onto the mask layer to allow

them to be revealed through the solder mask. This

means that if you want to disable the visibility of

the B.Cu layer in Inkscape (we will do so later when

we want to place an object on the other side of the

PCB), you will need to close both the B.Mask-auto

SEND DIRECT

In this tutorial, we are going to export the design from Inkscape using svg2shenzhen,

and then further manipulate the design using the KiCad regular workflow. However,

svg2shenzhen is also designed to be able to create complete art PCBs in KiCad that

could be sent directly to manufacture. The authors of svg2shenzhen use PCBWay and

even have an option in the export dialog box to open the PCBWay website after export.

PCBWay needs you to upload separate Gerber files from KiCad for manufacture. Later

in this tutorial, we will use OSH Park to order PCBs, as the site directly takes the KiCad

‘PCBnew’ file and doesn’t require Gerber files to be generated. It also has the benefit of

providing in-browser renders of the layers of the board, which is useful for double-

checking your design.

YOU’LL NEED

A laptop

with KiCad

and Inkscape

installed

Some familiarity

with basic use

of Inkscape

Whilst on the

svg2shenzhen

GitHub repository,

check out the

images of amazing

designs made in

svg2shenzhen

for inspiration.

QUICK TIP

Once you have made an

outline shape of your PCB, you

might next want to add some

details, shapes, and lines

”

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