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Week 8: PCB Design & Milling

Circuit Design & Customization ✈️⚡

I already had my schematic in place from the circuit design week, but a few minor tweaks were needed. Since I wanted to use a custom circuit design, I took inspiration from the Northrop stealth jet and designed a PCB outline based on it.

Designing the PCB 🖥️

  • Imported the custom outline into EasyEDA.

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  • Laid out components to fit within the stealth-inspired shape. image Image 2nd itteration of the design for board outline

  • Used the autoroute function to handle basic routing.

  • Set design rules to ensure proper clearances and trace widths.

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Troubleshooting & Learning 🔧

My friends Sohan & Devanshi tried milling their PCBs first, only to discover that our original design rules weren’t compatible with the milling process. This was a valuable learning moment! We had to: - Update our design rules based on their experience.

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  • Adjust trace widths, clearance settings, and pad sizes.
  • Move a few components around for better routing.
  • Manually route some connections where autoroute wasn’t optimal.

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After some tinkering, adjustments, and manual routing, my board was finally ready! 🎉

Personal Touches 🎨

Since this board is mine, I wanted to make it unique. So, I added: - My favorite emojis 😎🔥

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  • My custom logo 🛠️

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PCB Milling Process 🏗️

Exporting & Setup 🖨️

I exported the Gerber file of my PCB from EasyEDA and imported it onto the FabLab laptop, which had Control Panel Software and CopperCAM preloaded onto it. First, with the help of Akhilesh Sir, I installed a 0.2 mm engraver bit into the PCB milling machine.

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We stuck the copper-clad onto the machine bed.

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I set the XY origin first and then, with some complex maneuvers, adjusted the Z-axis. Once this was done, I moved on to CopperCAM.

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CopperCAM Workflow ⚙️

  • Imported the top layer file (engraving) into CopperCAM.

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  • Added the drill file, but the drill holes were misaligned.

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  • Set one pad as a reference and aligned the drill holes accordingly.

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  • Traced the track contours and set the board outline as the card contour.

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  • Set the origin to (0,0) so it aligned with the machine's origin.

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  • Hit OK, and my very own PCB started materializing! 🚀

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Milling & Drilling 🛠️

Once the engraving was done, I changed the bit to a 0.8 mm end mill. Then: - Queued the drill file to create the necessary holes in the board. Image - Queued the cutout file to cut the board out from the stock. - After each cutting cycle, I opened the lid and used a vacuum to remove the dust. Image

Soldering & Final Adjustments 🔩

Now came the soldering part.

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Initially, I had designed the USB-C port to face the bottom edge, but I soon realized there wasn’t enough clearance for the cable to move in and out properly. On top of that, the LED bulb was also in the way. ❌

If I soldered it the way I had planned, it wouldn’t work. Instead of forcing a bad design, I remilled the circuit board with a new XIAO RP2040, which had drill holes in it. This allowed me to use headers and mount it from the back side.

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Image Trying solder paste

Image Heating the paste

I know this is just a workaround, and I will have to make a new board for future explorations. But for now, I have the new board milled, and I will complete the soldering part ASAP.

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Wrapping Up 🎯

That was Week 8—so many learnings from mistakes made along the way, a super fun process, and a newfound love for soldering! 🔥⚡