Week 08

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

* Make and test a microcontroller development board that you designed.

☑ 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.

This week, I am going to use the designed printed circuit board (PCB) on week 06 and fabricate out using STEPCRAFT CNC machine.
A small recap on generating the G-Code for this week production: Create the PCB using AUTODESK EAGLE --> Export into PNG files. --> Send to MODs online program and generate the G-Code.
Attached below are the PNG files of my PCB design:

Using MODs to generate G-Code

Once after i have prepared the 2 PNG files for tracing and milling, I will bring them to MODs online program.

Referring to the diagram above, most of the setting are by default. But the are still some settigs that we need to take note:
1) Choose option 1: Mill traces (1/64) for tracing path or option 2: mill outline (1/32) for vector cut outline.
2) Check both figures for Cut Speed and Spindle speed.
3) Press the "Calculate" button and a G-Code trace path will generate. A G_Code file will also be created and we will use this file to bring to STEPCRAFT CNC Machine to mill my PCB.
Same procedure applies to milling outline for my PCB.

STEPCRAFT CNC Machining

Before send for CNC milling, I need to paste the copper board with double-sided tape to secure on to the machine bed.

On the machine side, I need to:
1) Choose the correct tool bit.
2) Secure the copper board onto the acrylic sacrifition board.
3) Place the Z-height probe sensor onto the copper board to perform a Z-zeroing process. Toggle the Directional Arrow Keys to move X-axis and Y-axis positioning.

4) Load the file by selecting UPLOAD button.

5) Manually turn on the STEPCRAFT CNC Milling Router and press the Cycle Start button.

For more details on setting up, please refer to our group work page.

Same goes to OUTLINE milling process, just that we need to change the drill bit from 30deg engraver become 0.8mm diameter end mill.


it takes almost an hour to trace and mill the outline my PCB.

After all the milling process has completed, we need to vacuum away all the debris from the copper board before we bring my PCB out from the machine bed.

After I took my PCB out from STEPCRAFT CNC machine, the very first thing that I do is to check the continuity of ALL the trace lines to ensure that no broken lines during milling process underwent.
Initial state of the Multimeter before testing:

Result shown on same trace line are being check:

Results shown on different trace line are being check:

Next, I will need to get the following components to prepare the soldering of my newly fabrication circuit board:
* LED x 1 pc
* Resistors x 2 pcs
* Press Button Switch x 1 pc
* Pin Header x 1 bar
* Seeed Xiao RP2040 micro-controller.
We can now start to solder all the components on to the PCB

To be frank it was not easy to solder the components especially the small LED and Resistors. It took me an entire day just to get a hang of it. Each and every time after I solder one point, I will use multimeter to check on the continuity of the respective trace line to ensure that:
1) The solder is intact with the component on each ends.
2) To ensure that the solder would not cause any short circuit to other nearby trace line.
With the guidance of my instructor - Mr. Steven Chew on step-by-step demostration on using proper tools with proper settings, after a few errors and re-soldering, I manage to get my circuit board done and this is how it looks like!

Before I continue solder for the rest of the pins onto my PCB, Mr. Steven Chew spotted a problem on my current PCB. Refer back to my board diagram, there should be one data line drawn from P$10 to the push button Pin03. But during initial stage, it never shown in my board diagram telling me that there isn't any unrounted line missing from my board diagram.

Also, when i tried to put up those pin headers on the right side of the PCB, I found out that there isn't any continuity between my GND trace line.

Initially, I was planning to remake another board, my instructor said that this missing trace line and broken trace line can be solved by adding an external copper wire to link up the 2 points.

It was a tough time for me to perform rework on my tiny PCB. Firstly, my first draft soldering work was not perfect, as there are some extra solder iron left between SEEED XIAO RP2040 and push button. Also, the soldering on left side of my 10kOhm resistor was so bad and I need to make sure that this point is to be neat for me to perform external linking with Pin10 on SEEED XIAO RP2040. So, before I start my rework, I tidy up this area and desolder both the push button and 10kOhm resistor and so clean up the mess. After replacing both components, I make sure that the soldering process is OK by checking their continuity. Then I used 2 cables to join the 2 sections:
1) Pin10 on SEEED XIAO RP2040 must link to push button.
2) GND pin on SEEED XIAO RP2040 to right side of the LED.

Testing on my PCB with a program

The final step will be a test to check if my PCB works. I uploaded a simple Button programme to test the board. I link up the button Pin to D9 pin and LED to D8 Pin of the SEEED XIAO RP2040 board.

After verifying my programme before send to my PCB with correct port, it flashes in RED colour when the button was pressed which is what the program code should do.

WOW!! my PCB are working good. Bless!!

Reflection

It has been a tough week for me to come out this week's assignment. Even though it doesn't really take a long time for me to mill out my PCB. But I have limited time to solder all the components onto my PCB due to work commitment. Moreover, my soldering skills are still under a very beginner stage, whereby I need more time to make my PCB works. Put aside on the quality of my PCB, I am glad that my PCB works with 1st attempt.
Some notes on this week's assignment:
1) Polarity of the components - Ex, the green dot on the LED represent Katod (Negative polarity).
2) Number combination indicated on the resistors - Ex. 1002 on resistor means 100 x 10^2 = 10Kohm.
3) Using hot air gun to rework the soldered components rather than vacuumed suck out the solder and resolder again.