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Electronic Production

Toolpath Generation

The toolpath generation is a multistep process that takes the exported png. file from KiCAD first to a raster image through Inkscape, then to a the tool path generation through MODS.

KiCAD/svg - Inkscape (opensources)/Raster Image - MODS/ Toolpath/

1. KiCAD

First we need to generate an SVG file that includes all the layers. To do this go to file/ plot and follow the following instructions: Instead of choosing all the layers on the include layer tab. Choose the main layers and all the additional layers on the adjacent plot in all layers tab. In our case, I chose the copper layer in one tab and the edge layer in the other. This ensures to have a single file with both layers perfectly aligned! Make sure to press the negative plot

2. Inkscape

After plotting the SVG file from KiCAD we will edit it on Inkscape to produce a png file. Organize the layers into: Traces Outline
Background

Make sure to fill the between the paths with white.

Export PNG

Choose the file time/ PNG Edit/ resize to selection to resize the png to the scale of the drawing Increase DPI / 1000

Make sure that the file are the same size.

3. MODS

MODS will generate the toolpaths. Choose the SRM-20 mill Mill 2D PCB Program!

Change the following settings Set PCD setting 1/64 flat Still Raster 2D make sure the offset is 4 (the rest of the settings can be seen in the image) Set speed to 2 and origin to 0,0,0 (see image) Turn on the edit info collaps Then Calculate

After all the settings are set we can calculate the toolpath and produce a G-code.

Milling

Steps to use the Roland SRM-20. 1. Place the Board FR4 firmly on the bed by double sided tap. 2. Put in the correct cutting bit - in my case since I was only engraving the traces and the outer edge. I only using the 1/64 bit. 3. Zero the coordincates starting with x-y by moving the head and bed to the left corner - press zero for xy when close 3.Zero the z coordinate. Move the bit to a more central location of the bed to avoid less error. keep the bit a few mm over the board. drop the bit naturally on the board and resecure it.Then set the Zero for the Z.

Now with all cordinates set we are ready to mill. You wan to look out for dust in this case and make sure you board is cutting beyond the copper layer.

The board cut really well. Not its time to solder the components and make the circuit.

Make a components list

Base on my KiCad design I went to collect all the components I need to make the board. You can see them in this image:

soldering

Now its time to put things in place. I followed the following method when soldering.

  1. First I place a drop of solder at the footprint of each componet. Ie. for the ATtiny I just place a drop at the top corner rather than all of it.
  2. Now a secure all the components in place using this drop of solder. I first place the component in the right position. I then heat the base so that it melts and at the same time I adjust the postion of the component holding down in place using the tweewzers.
  3. After all components are held in place. I then further secure all the rest of the their connections with the copper foot print. We have to make sure here to use the right amout of solder. To have it be smooth and shiny and to make sure its making the connection.

Here is the final result: