4. Electronics Production

This week is all about electronics; we were asked to build a PCB and solder its components. For this task, we were provided with the etching and cutting template of the PCB. The purpose of this PCB is to create a programmer that we will be using in future electronic practices and for our project. Essentially, this week we will focus solely on the construction, soldering, and functional testing of the PCB, without designing any circuits since the goal is to introduce us to PCB design. And how will we manufacture the PCB? First, I'll explain what a PCB is and how it works. PCB?

what is a PCB?

A PCB (printed circuit board) is an integrated circuit where components and conductors are embedded within a mechanical structure. This structure consists of alternating layers of conductive material, like copper, and laminated insulating material. During manufacturing, copper layers are etched to create traces that connect the circuit's components. Finally, electronic components are added to the outer layers using automated or manual assembly techniques and are soldered onto the board. The board is completed with a solder mask and a silkscreen for component identification.

Now that we know what a PCB is, I will explain the type we will use and the machine we will operate.

CNC MILL

The machine we will use for this practice is the Roland SRM-20. The features of this machine can be found on the GROUP PAGE .

Roland SRM-20

Manufacturer: Roland
Model: SRM-20
Specifications: 203x152x60 mm, 1800 mm/min, 0.001 mm/step, 7,000 RPM
Applications: Precision three-axis machining, including PCBs down to 0.25 mm feature size, and machinable wax to make tooling for molding and casting

CUT TOOLS

To manufacture the plates we use the following cutting and engraving tools:

Engraving bit

milling cutter 1mm

PCB FABRICATION

PCB

We will start by installing the software to operate our CNC mill; the program will not open unless the machine is connected to the computer.

We will cut the sacrifice bed, which will serve to avoid damaging the machine's aluminum base and to place and remove the piece more easily.

We will stick the phenolic board in the center of the sacrifice bed, using double-sided tape across the phenolic board's surface.

Once the photic board is well-adhered, we will place the sacrifice bed in the machine and secure it with the screws that are on the machine.

Using the PNG photos provided for this week's practice, we will create the program that we will upload to our machine.
Cut png
Tra png
Cut rml
Tra png

On the Mod page, we will right-click, select Program, open program, and look for our machine. In this case, the Roland SRM-20 mill and click on mill PCB. On the left side, we will find this window where we will click on select PNG file and upload the trace photo. Below that window, we will click on mill trace (1-64).

On the left side, we will find this window where we will click on select PNG file and upload the trace photo. Below that window, we will click on mill trace (1-64).

On the right side, we will find a window with an off switch. We need to turn it on so it will download the file. There is also this window, where we will have to change the X, Y, and Z origin parameters. We will set them to zero.

In this last window, we will change the offset number to two and hit the calculate button, and a window will open, and our file will be downloaded.

On our machine, we will place the V-cutting tool with the help of an Allen tool.

With the machine program open and using the controls, we will place our tool at the desired coordinates, in this case, touching the board at the bottom left corner.

We will save the coordinate origin with these buttons and load the file we generated earlier.

We will click on the cut button; a window will open. We will click on the add button, load the file we took from mods, and give output. Our machine will start making the trace.

This is the video of the first cut of the plate, it is the engraving of the tracks that is done with the sharpest tool

When the trace of the track is finished, we will change the tool for the cutting mill. We will update the Z origin coordinates, the x and y do not touch.

On the mods page, we will upload the PNG cutting image, go to the invert button, and click on the clear copper (1/32), calculate button.And we will load the generated file into the machine's program to be able to make the cut with the mill.

All that remains is to peel off the PCB from the sacrifice bed, and it will be ready to start soldering the components on it.

SOLDERING

For the soldering process, first, I will need to sand the PCB to make it shiny and smooth.
Using the photos and diagrams provided, I identified where each component goes and in what orientation.
Using the soldering iron at 370 degrees, I placed a solder dot on each site for a component.
With the help of small tweezers, I held the components to be able to solder them at the solder point already made.
In this way, I soldered all the components until obtaining the final board.

TEST RUN

To test that our PCB works, we'll need to upload a code. We will use the Arduino program to upload the code. To install it, we have to visit its website and download it. In the main window of Arduino, we'll enter the File menu, then Preferences.

In the lower part of the Preferences, we will paste the following link () and close the window. A download will start. In the "Select Board" section, we will search for the Seed Xiao RP2040 and download the board extension. Next, we will enter the code provided to us, connect our board, and upload the code.

The code we will upload will intermittently light up the two lower LEDs, and the top one will only light up when we press the top button. Blink code