FabAcademy - Achraf Ben Jamaa

Procedure of characterizing the design rule of PCB production

To characterize the design rule of PCB production we had to test the precision of the machine used. To do that our fabacademy instructor provided us with a design file to be traced in the Roland and then test the accuracy of traces.

1- First step, we have visited fabmodules website and uploaded the design as (image.png) as shown below

Roland mill (.rml)

4 - Finally, click on calculate and Save.

At this stage the trace file was ready, and we had to prepare the outline file to cut the PCB boarders as shown below.

Next step is to calibrate the machine. We had to use the Z-probe snap it over the special socket as shown.

Also, we had to make sure that the detection pin is loaded to tool slot number 6. We used the hand wheel to select the tool where the bit is attached to the tool holder (tool 6) which is the detection pin is selected. The spindle will move to get the selected tool then it will show on the screen that the selected tool is tool 6.

At this stage the Z axis is ready to be calibrated, We used the hand wheel to move, the x and y to have the spindle directly facing the z-probe metallic piece. After that, clicked on Z0 SENSE from the panel. There will be a message displayed on the screen, to confirm Z0 SENSE click ENTER.

The final step in setting up the machine was to use the automatic tool changer to pick the milling tool 1 (V-tool) and then to pick tracing tool.

Then we had to plug in the USB in the laptop and upload the file in the machine software. As shown below.

We opened VPanel and selected “Cut” icon. This allowed us to upload the RML file for the PCB. Then it automatically added to the list of cut files. Finally, make the file was ready to be cut by selecting the file and clicking “Output”. Once we click on cut the machine will start operating and the result of tracing is shown below.

To sum up, the purpose of this section was to test the machine accuracy by varying the machine tools and parameters. As a result, we have concluded that the Roland machine is able to cut boards of 0.001 mm with high accuracy. There was no variation between the designed part and the actual printed part.

Individual assignment

For the individual Assignment we had to make an in-circuit programmer by milling and stuffing the PCB. In this section I will not cover in details the machine operation process as it was covered in the group assignment section. However I will focus on soldering part and testing of the PCB.

First step we have uploaded the file in the FabModules website and set the cutting parameters as shown below.

Same process was repeated for the outline file, by changing the parameter to 1.8 mm depth of cutting and PCB outline (1/32).

Then files were uploaded to the machine to perform the tracing and cutting as shown below the machine operating.

Result of CNC milling shown below. Now the PCB is ready for the soldering part.

At this stage I had to prepare the list of components needed to be soldered on the PCB. The Fabacademy instructor supported us to select the exact components for the PCB as it was challenging with the small SMT (surface mount technology) pieces. Below is the list if components mounted on the PCB.

As the components were ready, I made the set up for the soldering station. As shown below all tools used during the soldering process.

The soldering process started by making different trials for random components. It was challenging to solder the SMT component, however after few tests I managed to get succeed. Shown below the progress of soldering.

One of the important steps to follow during the soldering process is to conduct the continuity test to check if current flows or not. This was done by using the multimeter, if a short circuit occurred the device will buzz, and this means the issue should be solved by dissoldering and repeating the process carefully.

Finally, I was able to finish soldering the PCB and test it the computer. By having the LED turned on shows that the soldering was a success.

Challenges faced

For my case it was my first-time soldering PCB with SMTs. It was very challenging for me to hold the tiny SMT in the board and solder it. Multiple times I was having a short circuit and had to fix it. In total I had t repeat the process 3 times and the third was success, but it was a fun experience and taught me how to be very passion and very sophisticated. Below shown the unsuccessful trial 1.

Additionally, I have used the soldering flux as it helped on removing any oxidized metal from the surfaces to be soldered, seals out air thus preventing further oxidation, and improves wetting of the liquid solder. Shown below both continuity test and flux usage.

Programming FabISP with Arduino

To program the FabISP I followed instructions provided in Fab Tutorials. It was recommended to use Mac for to program the ISP for easier process, however it can be done on any operating system. So I used my colleague Mac laptop through out the process.

1- First step was to download the FabISP firmware. XCode and Crosspack AVR.Once the required files are downloaded, I unzipped the firmware folder.

AVRDUDE = avrdude -c stk500v1 -b19200 -P /dev/cu.usbmodem14201 -p $(DEVICE)

#AVRDUDE = avrdude -c avrisp2 -P usb -p $(DEVICE) # edit this line for your programmer