Electronics Production
Group Assignment:
Do your lab's safety training
Test runout, alignment, fixturing, speeds, feeds, materials,and toolpaths for your machine
Individual Assignment:
Make and test a microcontroller development board that you designed
Extra credit: make it with another process
Have you answered these questions?
Linked to the group assignment page ✅
Documented how you made the toolpath ✅
Documented how you made (milled, stuffed, soldered) the board ✅
Documented that your board is functional ✅
Explained any problems and how you fixed them ✅
Uploaded your source code ✅
Included a ‘hero shot’ of your board ✅
Group assignment
Do your lab's safety training
Test runout, alignment, fixturing, speeds, feeds, materials,and toolpaths for your machine
The group project was done at the Fab Lab iFurniture. For this, the machine that mills Bakelite was out of order, so, with the help of my instructor Cristian, we replaced the end mills with finer ones, 2 mm, 0.5 mm and 0.1 mm, to use the CNC Router and carry out the tests. We used a PNG image that I downloaded from the academy as the basis for the design.
Here is the link to learn more about the group project.
In the Fab Lab iFurniture, our Bakelite milling machine is broken, so I purchased some end mills to use in our CNC Router. To perform the material recessing, I bought a 0.5mm 30° Lance Tip End Mill. Here’s the link where you can find it: Mecatronica Saisac
And to cut the material, I purchased a 2mm Carbide PCB End Mill, which will allow me to cut the Bakelite. Here’s the link so you can find it: Mecatronica Saisac
Reflections
The process of making the board as an exercise was a bit frustrating, as technically it didn’t turn out as expected. Since it was small, around 35 mm, when the end mill started cutting, almost all the copper was removed. I wouldn’t recommend doing the process with the CNC Router; it's better to use a specialized machine for better results.
When I went through the process of having a bakelite made via PCBWay, it was super easy and user-friendly, even though the site is of Chinese origin. The format I had to download from KiCad for this process was Gerber, so they could provide a quote.
Individual assignment
Make and test a microcontroller development board that you designed
Extra credit: make it with another process
1. Working with Electronic Components
| Item |
Components |
Amount |
| 1 |
SEEED STUDIO XIAO RP2040 |
1 |
| 2 |
Header 01x05 P2.54 mm Horizontal SMD |
4 |
| 3 |
RES 1K OHM 1% 1/4W 1206 |
3 |
| 4 |
LED BLUE 1206 SMD |
2 |
| 5 |
Micro Push Button 2 Pins 3x6x2.5mm SMD |
1 |
For this individual assignment, I will be designing a board that I created during week 06. For this, I have a list of the components I will be using.
These are the components I purchased.
2. Importing DXF Files into Rhino
I open the PCB editor in KiCad from week 06, go to File and click on Plot.
In the window that opens after clicking Plot, I verify that the size is up to date, select to export in millimeters, and click Plot. It will immediately be saved in the output directory.
Once in the directory, I open the DXF files marked in a green box, using the Rhinoceros program.
Once in the Rhinoceros program, I verify that both the model units and the layout units are also set to millimeters and click OK.
I open the DXF files individually (Cuts, Cu, Mask, Paste, Silkscreen) and paste them layer by layer into the Rhino file.
3. Cutting Tests on CNC Router
For this activity, my instructor Cristian provided a lot of support. We were doing tests to see the possible results.
Everything seemed to go well, so we decided to try making my design.
FIRST TEST
I imported the DXF file into ArtCam.
Cristian helped me configure the end mill in the program, we entered the technical specifications, and selected the end mill that will allow us to complete the assignment.
We configured the finish depth.
While the end mill was cutting the material, we noticed that it was damaging the traces of the conductor paths on the Bakelite.
The Route Tracks I used, as recommended by my instructor Ronal, were 1 mm or 39.37 mils, since I was going to use the CNC Router, which would make routing easier. I followed his recommendation because he did it this way in his assignment and it worked out well for him, so I wanted to give it a try. However, it didn’t turn out as we expected.
SECOND TEST
We reconfigured the finish depth to test it again.
THIRD TEST
We leveled the bed of the CNC Router and tried again, but we kept failing.
I decided to call Ronal to ask which finish depth to use, and he recommended 0.025 mm. We changed the configuration again in ArtCam, but it still didn’t work out.
FOURTH TEST
Now Cristian suggested we try doing it with 2D Area Clearance to see what would happen.
It's Monday, and the iFurniture Fab Lab is open. Today, I focused on continuing to test and develop my PCB. My instructor, Cristian, has been very supportive with this project; he was really a great help. I learned new things about the Router.
In summary, last Friday I created this chart of my failures and can comment the following:
- Cut with a 0.5 mm end mill, 30° angle, and a finishing depth of 2 mm (profiling).
- Cut with a 0.5 mm end mill, 30° angle, and a finishing depth of 1 mm (profiling).
- Cut with a 0.5 mm end mill, 30° angle, and a finishing depth of 0.25 mm (profiling).
- Cut with a 0.5 mm end mill, 30° angle, finishing depth, but this time using "2D area clearance."
The result was not satisfactory for two reasons: the size of the end mill and angle, and also because the bakelite was warped.
FIFTH TEST
In the end mill configuration in ArtCam, we set the spindle speed to 15,000 RPM with a finishing depth in profiling of 0.2 mm. The result was good. The end mill we used for this occasion was 0.1 mm with a 15° angle, and I achieved that result.
SIXTH TEST
Following the recommendation of my colleague Jhonatan, he mentioned that applying oil to the bakelite helps prevent the end mill from producing too much dust. For this, we used a spindle speed of 15,000 RPM with a finishing depth of 0.15 mm.
The results were good that day. We were just testing the machine and getting to know it a bit more. The change of end mill made a big difference and greatly contributed to improving the process.
SEVENTH TEST
A couple of calls were made to expert friends in the field, Jhony and Ronal, who gave us the following recommendations: manually increase the router speed from 0.2 to 0.4, raise the spindle speed from 15,000 to 20,000, and set the finish depth to 0.1.
I configured the other end mill that will be used to cut the bakelite.
With everything ready, I moved to the machine, configured the XYZ axes, and started cutting the piece that I will be soldering.
Once the roughing was done, I tested for conduction with my multimeter. Since the bakelite was uneven, I had to recut some parts, and the roughing became deeper. I was really worried about the outcome. But thank the divine electronic heavens, there was conduction. Right where the button would be, there were difficulties, but I could still develop and make the program work with the LEDs. 😟
I have now changed the end mill to make the cut in the bakelite.
The "costilla de adán" sheet is ready to add the electronic components.
Here’s a brief summary of this process, which was shorter since using a smaller end mill helped a lot:
- Spindle speed 15,000 (end mill configuration) and profiling finish depth of 0.2 mm, machine speed 0.2.
- Oil, spindle speed 15,000 (end mill configuration) and profiling finish depth of 0.15 mm, machine speed 0.2.
- Spindle speed 15,000 (end mill configuration) and profiling finish depth of 0.15 mm, but we manually lowered the end mill a bit more. Machine speed 0.2.
- Following the recommendation of another instructor, Ronal, we changed the spindle speed to 20,000, with a finish depth of 0.1 mm, and increased the machine speed to 0.4.
In the fourth version, the result was much better. However, there is a significant difference between using a mill designed for bakelite, which provides more detail, compared to using a CNC router, which is on a larger scale.
Now it was time to place the components on the PCB. For this bakelite, I lost the LEDs because they were very small, so I had to improvise at that moment.
I tried it, and it wasn't working; it seemed like there was a short. I checked the board, and I didn't find any solder bridging between traces that could cause interference. 😢
Reflections
Since our bakelite milling machine was broken, we opted to use the CNC router as a solution. It was a bit stressful because I thought I was wasting my time, but then I realized that it's a learning process. We had several failures on the first day because we used a 0.5 mm end mill, and it was our first time using the router for this process. I learned a lot that day, especially about how the router works, the speeds it handles, and the setup we did, which was also different.
Another observation I can make is that, since the machine we used is larger, it lacks a bit more precision in the details. However, it was helpful, as long as the correct end mill is used. The end mill that made this possible was the 0.5 mm with a cutting tip and a 15° angle.
One more point I will add, which I think is important, is that if I had made the traces thinner, my PCB definitely wouldn’t have worked. The traces I used were 1 mm, and being thicker helped the milling machine avoid eating the material. This point, especially, seems very important if this assignment is going to be done with a large router. It's an important consideration to prevent the board from getting destroyed.
"In the end, during the assembly process, when I started placing the electronic components, I realized that I had lost the LEDs. It's important to maintain an organized workflow so this doesn’t happen again, as the components are very small and require careful handling.
4. PCB Manufacturing Process with Screen Printing (I requested this documentation from Carlos at Bora company, who provided the service of manufacturing this additional board.)
Because I was worried about my PCB, I had another one made at Bora. A technician Carlos helped me assemble an additional board and assisted with the documentation. So, as an additional contribution, I’m sharing a bit of this experience of assembling a PCB using a screen printing process.
his documentation is thanks to Carlos, who helped me with this process, and also to ChatGPT, which explained the PCB manufacturing process in more detail
The first part of this process is digitizing the file in DXF and printing it on paper. I also took the opportunity to make "traces+exterior" in bakelite as a reference, since in my group assignment it didn’t turn out as expected.
The development in the screen printing process is done with a negative image, which allows the design to be transferred onto the board accurately. This process is crucial for creating the areas that won’t be etched and protecting the desired zones on the PCB.
For the development process, a homemade oven with fluorescent lamps was used. This type of oven helps expose the board evenly, allowing the negative image to be correctly transferred onto the surface of the board. The fluorescent lamps provide the right UV light for this process, speeding up the development of the board.
The revealed image is transferred onto the fiberglass material. This process ensures that the PCB design is accurately printed onto the surface of the material, protecting the areas where no etching should occur. Fiberglass is a commonly used material for PCB manufacturing due to its strength and durability.
The process of printing the image with epoxy paint involves applying a layer of epoxy paint onto the printed circuit board (PCB) and then transferring the design image onto the surface. This process is used to create the circuit tracks and connection areas on the PCB. Epoxy paint is used due to its ability to adhere well to the board material and provide long-lasting protection.
The procedure includes several steps: first, the PCB is cleaned and prepared. Then, a uniform layer of epoxy paint is applied. Next, the design image is placed over the board and exposed to ultraviolet light to cure the paint in the desired areas. Finally, the development process removes the unexposed areas, leaving the circuit image intact on the PCB surface.
The ferric acid etching process to define the tracks is a crucial step in PCB manufacturing. Once the circuit image has been transferred onto the board, the etching is done using ferric acid. This process removes the unwanted copper from the board, leaving only the circuit tracks that have been protected by the epoxy paint or photosensitive material.
Once the material has been etched (burned) in ferric acid and washed, the process is nearly complete. The acid has removed the unwanted copper, leaving only the protected circuit tracks. After removing it from the acid bath, the board is carefully rinsed with water to remove any acid residue, and then dried thoroughly.
The next step is to shape the PCB using a routing bit. This process involves using a larger or specialized bit to cut the edges of the board and give it the final required shape. The routing bit helps remove any excess material around the circuit tracks and define the edges with precision.
Ready with the leaf shape.
Now it's my turn.
With this done, it's my turn to place the electronic components.
I tested the board and it worked! I'm not that happy because I would have liked the PCB I made in the lab to work, but I'm really glad I was able to understand a bit more of these processes and learning experiences that are new to me.
Reflections
The takeaway from this activity are the different processes involved in creating a PCB. This additional documentation seemed like an art to me due to the manual processes carried out, and it has also taught me, in a general way, the procedure for making a board in this manner.