Introduction: Light-Up PCB Necklace V2
If you like making jewelry and have some experience using the Bantam Tools Desktop PCB Milling Machine, this is a great project for you! It offers a wonderful way to get creative and artistic with double-sided machining.
The necklace has four LEDs on the back of the pendant that provide a beautiful glow around the outline of the pendant and highlight the pattern on the front of the necklace by illuminating the etched traces. This tutorial gives you two design options: a blank, solid copper front or a bird feather pattern on the front.
We also made a bat version of this necklace! Everything is the same, except the shape of the board, so the instructions here apply to the bat as well as the hummingbird. Both files are downloadable in the next step.
Feel free to use this technique to design your own pendants by mixing and matching your favorite shapes with your favorite colored LEDs. If you do design your own unique necklace, please post pictures of your creation in the comments. All of us here at Bantam Tools would love to see them!
Note: This is the V2 of our PCB Hummingbird Necklace.
Step 1: Tools, Materials, and Files
- Bantam Tools Desktop PCB Milling Machine
- Computer with Bantam Tools Desktop Milling Machine Software installed
- Flat end mill, 1/64" and 1/32"
- Hotplate, heat gun, or convection oven or very steady hands with fine-tipped soldering iron
- Jewelry tweezers or other precision tweezers
- Needlenose pliers (2)
- Wire cutters unless your needlenose pliers can cut
- Multimeter in case troubleshooting is needed
- FR-1 PCB blank, single and/or double sided
- LEDs, surface-mount (4)
- Jewelry-making supplies:
- Jump rings (4)
- Chain cut to desired length with wire cutters
- Hummingbird Necklace.brd
- OR Bat Necklace.brd
Step 2: Attach the Bracket and Board to the Mill
In order for the design on the front and back of the board to line up, we need to use the alignment bracket. It's included with the Bantam Tools Desktop PCB Milling Machine, as are three mounting screws and an Allen wrench.
Attach the alignment bracket to the bed using the screws and Allen wrench.
In the milling machine software, set up the bracket:
- Click the Setup Fixturing button.
- Click the Locate Bracket button.
- Follow the prompts.
Attach your board to the bed with three or four long strips of double-sided tape, making sure the bottom left corner aligns with the corner of the bracket.Use enough tape so that most of the back of the board is covered, without overlapping (that would increase the height of the surface).
In the milling machine software, set up your material:
- Click the Setup Material button.
- Select double-sided FR-1 as your material type.
- Set the custom size to 2" x 3" x 0.062".
- Click Done to proceed to the next page.
- Make sure all the boxes on the next page are 0 and then click Done.
Now that you've set up your material, right-click it and select Align To > Bracket from the popup menu. This will align your virtual material and bracket, which will match up with the actual physical bracket and material.
Step 3: Import the Design and Choose Tools and Settings
Now it's time to import your design into the milling machine software and configure the settings.
- If you haven't already, download the design from the bottom of this step.
- Drag the design into the software, or click on the Import Files button and locate the design file.
- In the panel for your design, choose a 1/32" and 1/64" flat end mill.
Decide if you want the bird feather design on the front of the pendant or if you'd prefer the solid copper front. They're both pretty awesome, but the feather design requires milling both sides of the board.
- If you want solid copper, select Traces, Holes, and Outline.
- If you want the feather pattern, only select Traces and Holes. You'll cut the outline later.
Step 4: Cut Out Your Pendant
Now that you've attached your material, it's time to cut the design into the board and then cut the board out of the larger piece of FR-1. Since we're using two tools, the milling machine software will cut the finest details with the smallest 1/64" tool, then the larger details with the larger 1/32" tool.
Click the Start Cutting button. The machine will begin milling the design. If there isn't already a 1/64" tool loaded, it will take you through the process of inserting one before it starts milling.
Once it finishes the cuts with the 1/64", you'll be prompted to remove the 1/64" and insert the 1/32". Do so, and the machine will mill the rest of the design. If you wanted just the solid copper front, the machine will also cut the hummingbird shape out of the larger piece of FR-1.
Once the machine finishes, remove the FR-1 from the bed and remove the tape. If you chose the solid copper option, separate the pieces and skip to the next step. If you chose the feather pattern option, the board will still be a single piece. Do the following to mill the front side if you chose the feather pattern option:
- Click the Bottom button to flip the board over in the software.
- Clean any swarf (dust or chips from milling) off the board.
- Apply tape to the side of the board that was just milled, and then flip the board left to right from how it was placed when it was milled.
- Place it on the board, making sure the lower right corner is flush with the lower right corner of the bracket. Press it down firmly.
- Click Start Cutting and follow the prompts.
Step 5: Add Light
Now that you've finished cutting the hummingbird circuitry, it's time to solder the electronics. You have 4 very tiny LEDs, a switch, and a battery clip that need to be soldered.
Be careful when opening the LEDs, as they are so light and tiny that they can easily be lost! It's best to work on a large, dark surface so you can keep track of them.
Soldering components this small is pretty challenging with a soldering iron and conventional solder, so we recommend using solder paste and a hot plate, heat gun, or small convection oven to melt it. You can also melt the paste with a soldering iron if you're nimble. This tutorial uses a hot plate because more people have hot plates than heat guns, but all methods are valid.
OK, here we go:
- Apply small dabs of solder paste to each pad on the circuit side of the board.
- Orient yourself. Using fine tweezers, pick up an LED and look at the bottom. You'll see a green line dividing the chip in half, and then another tiny green line protruding from the middle of the first line. This tiny line is pointing away from the positive side of the LED. The squares to the left and right of the circle on the board are for the positive contact of the battery, so if you follow the traces from there, you'll get to the first little square of each LED pad, which is the positive side. The positive ends of the LED (which the little green line is pointing away from) go to the positive pads. We've highlighted the positive pads on the diagram and also on the picture of the LED.
- You now know where to place the LEDs and which way to orient them. Place them onto the dabs of solder and gently press them down.
- Now for the battery clip. It has a plus (+) sign on the top. Make sure that the plus sign is pointing up, so that it's closer to the top wing of the bird rather than its belly. Place it onto the solder pads and press down gently.
- Lastly, the switch. It has little nubs on the bottom that need to be scraped off. Use your fingernail or a sharp knife. Then line the pins up with the solder pads ("4A" should be on the right) and press it down gently.
- Now that you've placed all the components onto dabs of solder paste, it's time to melt the paste. Use either a hot plate at about 40% or 420°F, a heat gun, or a small convection oven. If you have very steady hands, you can use a soldering iron with a fine tip. The key is to heat until the dabs of solder paste flash bright silver, then quickly remove the heat. They'll slowly get lighter in color once you start heating them, but wait until they turn bright silver. If you're using a soldering iron, they flash silver almost immediately. If you're using a hot plate or oven, it takes a minute or two. A heat gun varies, but it's on the quicker side. Once all the dabs of solder have melted and turned silver, remove the heat and wait for the board to cool.
Put in a battery and flip the switch. Do the LEDs light up? If so, great job! If not, you'll have to do a little troubleshooting:
- Start by using a multimeter to test the battery. Does it show 2.5–3.2 volts?
- If it doesn't, get a new battery.
- If it does, the LEDs are the next likeliest suspect.
- Switch your multimeter to continuity mode.
- Place the probes on both ends of each LED, making sure the positive probe goes to the positive side.
- If the LEDs light up, that's good news. You should check your switch contacts and battery clip to make sure they're soldered properly.
- If you hear beeping and the LEDs don't light up, that means one of the LEDs has a short. You'll need to find out which one and fix it.
- If they don't light up and you don't hear a beep, try switching the probes to opposite ends. If they light up then, it means the LEDs are backwards.
Once your board lights up, you're ready to add the chain and clasp.
Step 6: Add Chain and Clasp
You've done the hard part. Now you need to attach the chain to the pendant and attach a clasp to the chain:
- Grab your jump rings and use your pliers to twist the ends about 1/8" apart. Make sure you're twisting, so the ring still stays round. You don't want to pull the ring into a U.
- Thread a ring through one end of the chain and the other end through the hole in the eye or tail of the hummingbird. Now use your pliers to twist the ring closed. Do the same for the other ring.
- Add a jump ring and the clasp to the other end of one of the chains. Then add the remaining jump ring to the end of the other chain.
Enjoy your awesome necklace! It'll last for about 24 hours of continuous use before you'll need to replace the battery. If you make one, post a picture of it in the comments. And if you have any questions, drop us a line at firstname.lastname@example.org. We're always happy to hear from you!