4. Electronics production¶

Group assignment:¶

Characterize the design rules for your in-house PCB production process: document feeds, speeds, plunge rate, depth of cut (traces and outline) and tooling.
extra credit: send a PCB out to a board house
Document your work to the group work page and reflect on your individual page what you learned

To see our group assignment click here

Individual assignment:¶

Make and test the development board that you designed to interact and communicate with an embedded microcontroller
extra credit: make it with another process

monoFab¶

For this week, we need to create a print circuit. To do this, we’re going to use the monFab SRM-20. It’s a machine that makes printed circuits. Monofab is a brand of additive manufacturing machines, also known as 3D printing. These machines are designed to create objects by adding successive layers of material, such as plastic, metal or ceramic. Monofab offers a variety of models to suit different needs, whether for professional or personal use. These machines can be used to produce prototypes, custom parts, models and much more. They offer great precision and design freedom. In short, the Monofab is an innovative solution for the manufacture of three-dimensional objects.

For the choice of circuit to print, I decided to take inspiration from that of a previous fab academy student. KONE Zie

To build our circuit, we began by retrieving the .PNG files of our circuit’s traces and contours, as shown below. Click here to download PNG files.

Before we start building our circuit, we first need to generate the toolpaths for the traces and contours of our circuit.

FIST STEP : GENERATION OF THE TOOL PATH¶

For the generation of toolpaths we have several solutions at our disposal: the use of Vcarve, FlatCAM, mods CE … For the choice of our solution we chose mods CE because it is an open-source solution and was designed taking into account the tools we have in our Fab Lab.

Uses of mods CE¶

Mods CE is an online tool developed by Niel’s Center for Bits and Atoms used to convert image files to milling files.

For more information on mods click here.

Access to mods by clicking on the link mods CE.
Once on the CE mods page make a right click on your mouse in the white part as shown below. select “programs>open program>SRM-20 mill>mill 2D PCB” you should have the display below.

Go to the “read png” module and click on “select png file” select the png file of the circuit traces as shown below and click on “Open”.

Now that we have imported the image of the traces of our circuit we will proceed to the parameterization of Mods for the generation of the G-code for the Roland SMR-20 milling machine.

To do this we first go to the module “set PCB defaults” where we click on “mill traces (1/64)” to choose the cutting parameters of the tools we have selected. Then we go to the module “Roland SRM-20 Absolute coordinates” where we enter the value 0 for the fields x,y and z so that the tool starts machining at the coordinates (0,0,0) that we have set on the machine and the value 12 for jog height.

Once these settings are complete, go to the “on/off” module and link to the “save file” module as shown below. Switch the module to “on” so that we can download the cutting file once its generation is complete. To generate the G-code file go to the “mill raster 2D” module and click on “calculate” a “.rml” file should download automatically as shown below.

Now that we’ve finished with the circuit traces, let’s move on to the circuit contours.

To do this, go to the “red png” module, click on “select png file” and choose the contour image as shown below. note that the mods algorithm for generating toolpaths considers the black areas of the image as the areas to be machined. so that the mods can correctly generate the toolpath for the contours of our circuit, we click on “invert” in the “read png” module as shown below.

We move to the setting of the tool, go to the module “set PCB defaults” click on “mill outline (1/32)” to choose the cutting parameters of the tool for cutting the outline of our circuit.

To generate the G-code for the Roland SRM-20 milling machine follow the same procedure as for the circuit traces.

Now that we have finished generating the G-codes for the toolpaths we can move on to the machining of our electronic circuit.

SECOND STEP : Machining of our electronic circuit¶

For the machining of our electronic circuit we followed the tutorial of the Fab Academy. For a better understanding of the machining procedure of the circuit we have broken it down into several steps namely :

I.Preparation of the machine¶

Turn on the Roland SRM-20 milling machine, connect it to your computer, and open the VPanel software for SRM-20. A good tip is to warm up the spindle for 10 minutes at half speed before using it. To do this, move the gauge in the “Spindle Spend” module to the middle as shown below, click on “ON” in “Spindle” and wait 10 minutes.

After 10 minutes, click on “OFF” and we’ll move on to installing the copper plate on our circuit board, as shown below.

The PCB layout tool is then mounted

Remember that we have two types of tool for this task - one for engraving the circuit and another for cutting the contour. Be careful that the tool doesn’t fall off or it will break and that will be a shame 😔😔😔😔.

Since we’ll start by machining the traces of our circuit, we’ll mount the milling cutter at the 1/64 inch.

Once the tool is mounted, we move on to the definition of the X, Y and Z axis zero.

II.Definition of the X, Y and Z axis zero.¶

First we start with the X and Y axes. We use the buttons Y+; Y-; X+ and X- to move the X and Y axes to the original position we want. Note that the (0,0) of the file we created with mods is in the lower left corner.

As our copper plate is half-used, we won’t define the coordinates (0;0) for our layout, but directly position our copper plate according to where we want to cut our circuit and directly retrieve the coordinates of this point and define it as the origin.

III.Cutting out PCB traces¶

To machine the circuit board traces, click on “cut” in Vpanel and select the trace file generated by mods as shown below and launch the machining by clicking on output.

We obtained the following results after 30 minutes of machining.

Once the PCB traces are complete, we move on to machining the PCB contour. To do this, we change tools and use a 1/32” end mill. Once mounted, we take the Z-axis origin before starting machining.

After 6 minutes of machining we obtained the following results.

I’m proud of the result.

Once we have finished manufacturing our printed circuit board 👏👏👏👏

Soldering components to the printed circuit board¶

We move on to soldering the various components onto the printed circuit board.

For soldering we need the following components :

N°	Components	Quantity
1	ESP32-WROOM-32D	1
2	REGLINEAR 3.3V 1A	1
3	RESISTOR 100 ohm	1
4	LED	1
5	CAPCER 10000 mF	1
6	CAPCER 0.1 µF	1
7	SLIDE SWITCH	1
8	TACTILE SWITCH	1
9	SOLDERING IRON TS100	1
10	TIN	-
11	CIRCUIT BOARD	1

I spoiled my first circuit because I’d never welded such small parts before.

So I had to print another circuit and I finally got my soldering right.

Test of our ciruit board¶

To test our circuit board we programmed it with IDE Arduino to display characters on an LCD screen. For the program we used the example program “HelloWorld” from the library “LiquidCrystal_I2C.h”

For uploading the program to our circuit we used a TTL-232R-5V cable which allows to convert USB to UART. To connect it to our board we followed the description of the pins below from the data sheet.

To be able to upload a program on our circuit, it is necessary that the ESP32 microcontroller is in Boot mode. To do this, we have to activate the switch on the circuit as shown below, in fact the switch allows to connect the IO0 input of the ESP32 to GND.

RESULTAT ¶

Here is the final result we can confirm that our electronic circuit board works. !!!YOUPI 😊

THANK YOU FOR FOLLOWING THIS TUTORIAL 🤝🏾🤝🏾🤝🏾🤝🏾🤝🏾

FILES ¶

Last update: July 9, 2024