For an upcoming project, I needed to mount 9 high power RGB LEDs (3W each). I was a little concerned about heat buildup, but I didn't want to shell out for any fancy heatsinks. I could have bought some on eBay like these, but I decided to use copper pipe end caps - I always liked copper...
This will be a short little instructable showing you how I mounted my LEDs. Very simple process.
Step 1: Materials
- A high-power RGB LED ($10 for 10 on eBay)
- (I used the 6 pin variety to give me more flexibility in circuit design).
- An aluminum "star" heatsink ($7 for 20 on eBay)
- A 1/2" copper pipe end cap. $0.69 each at my local hardware store
- thermal compound ($1 on eBay)
- electrical tape
- *optional* contact cement or some other adhesive that can bond metal and plastic
- *optional* high power LED lenses ($2.50 on eBay)
Step 2: Mount the LEDs on the Aluminum
The first step is to mount the LEDs onto the aluminum star heatsinks. You could always purchase pre-mounted ones, but I found they were more expensive, and I don't mind a little soldering.
One caveat - be sure to check the connections with your multimeter, and watch out for polarity. My heatsink label for blue actually controls red, and vice versa. Not a problem as long as you're aware of it!
To mount the LEDs, tin the pads on the aluminum heatsinks. Use only a small amount of solder (I like thin gauge solder for this job). Then carefully smear a small amount of thermal compound onto the back of the LED, check polarity, and gently place it onto the aluminum heatsink. Line up the contacts with the pads, and solder one by pressing down with your soldering iron.
Before soldering any more, check the alignment of the contacts. It's easy to move them now by heating one pin, but once you've got a few attached, that sucker isn't going anywhere! Got it? Great! Now do it 59 more times!
Lastly, double check the connections with your multimeter. Identifying any problems now will save you a ton of hassle later on.
Step 3: Mount the Aluminum to the Copper
Now take your copper end caps, and use a whetstone, a file, or sandpaper to make the back surface flat. Place the abrasive on a flat surface, and gently swirl the cap on it. This step may not be necessary, and I didn't take any photos while I was doing it. However, it's a great way to spend the time you'll have to wait for your components to arrive!
Actually, maybe this should be the first step?
Now that you've got your LEDs ready to mount and your copper nice and flat and shiny, you're ready to proceed. Again, smear a little thermal compound on the back of the aluminum heatsink, and place it on the copper cap. Take a short length of electrical tape, and begin to wrap the copper cap, leaving a little overhang to grab the edges of the aluminum star. Stretch the tape as you go around, and it will lean in and grab hold of the aluminum. Leave more sticking up than you might think you'll need, and you won't end up going back to redo this step like I had to.
Voila! You've now got a stack that goes LED - Aluminum - Copper.
Step 4: Clean Up the Tape Edge
Since the tape was stretched out, the edge probably isn't very clean. No problem - we can make it look nice, and get rid of some of the extra that will insulate the heat in the copper (thus foiling our efforts!)
Place the unit LED-side-up, and grab your utility knife. You do have one, right? No? Okay, go out and get a utility knife because it's only one of the most useful tools around!
Now lay your utility knife on something wide and flat. I used the whetstone, but a thin book would also work. You could probably also use a breadboard if you're really stuck. Rotate the copper cap against the blade, and it will cut a clean even line around the tape.
Now pick up the cap, and peel off the excess tape. Looks nice, doesn't it?
If you want more than one light stuck together, now would be a good time to put that adhesive to use. Try to line up the contacts in a reasonable pattern before you stick 'em together. I wired mine in series (never run them in parallel without drivers for each led).
Step 5: Wire Them Up!
Your assembled units are now ready to go! Add wires and lenses (the latter is optional, the first, not so much). Fire them up, but please don't look directly into them. I'm speaking from experience!
I used a terminal block with 4 posts configured with a common anode. If you need common cathode, adjust your wiring appropriately. The 6 pin LEDs give you flexibility in your designs.