LuxeonZ, the making of a copper board, and testing

Flashlight Modding and DIY Parts
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(pictures taken after tests, some flux and solder remains can be seen)

Part of a recent (for my budget) epic bare leds order at Mouser were two LuxeonZ emitters, although I knew I did not have a proper board to mount them. It is a led without dome with the same die-size as the LuxeonQ and XP-E2. Apart from being dome-less, a difference is that the complete led is not much bigger than the die, and the thermal resistance should be a tad better than the LuxeonQ:

I wanted to test them, so first thing was to make a board. I started with a piece of 1mm copper sheet:

Two square 16x16mm pieces were cut and sanded flat:

one piece was sawn in half, one of the halves was soldered on the other square (using a small butane torch), using solder paste, the other piece was sawn in on one side to ease the soldering of a wire (but I did not use that in the end, did not work):

after soldering:

The other piece was now glued in place with Arctic Alumina Thermal Adhesive, and the top was sanded flat afterwards. I looked up what temperature this adhesive could handle and it said more than 150degC , so I hoped that it would withstand reflow temperature.

Resistance test: the two sides were nicely insulated from each other. I should mention now that if I would make such a board again, before glueing, I would have already sanded the board round and make the necessary cut-outs, so that the sanding of the side of the board was completely done. More about that later.

Now the board was sanded round and two cut-out were made. here my relative inexperience with pure copper showed (should have been warned by the lathe folks here at BLF): copper behaves like a paste when sanded, so it smeared across the insulating adhesive layer, causing the + and - to short at numerous places. It took me two hours of carefully scraping the side of the board with a scalpel to remove all the shorts (scraping, resitance testing, scraping, resistance testing, etc. until finally: victory!).

Some solder paste was applied and the led placed, taking care that the led-minus was connected to the core of the board (no electrically neutral thermal pads here!). then the led was soldered on my (rebuild solder iron) hotplate. It was nice to see that at the soldered side the solder melted a bit earlier than at the glued side (direct confirmation that -with these ticknesses- solder conducts heat better than Arctic Adhesive :-) ).

Another mistake: I should have soldered the led wires with the same reflow, there is no way I could get the wires soldered without heating up the entire board again. So I placed the board on a piece of aluminium, taped the wires in place with some Kapton tape (magic stuff for a thousand things!), blobs of solder paste applied, and back on the hotplate:

And voila, the led even lights up with the led-tester at 1mA :-) , and at 50mA . Some glamour shots in stereo:

It is time for some tests....

The first disappointment: when viewed next to a dedomed XP-E2 the light emitting area is clearly bigger than that of the XP-E2. If the die size is indeed the same (1x1mm), apparently the phosfors are less tightly applied over the die. This spoils directly quite some throw potential :-( , the led must perform quite a bit better than the XP-E2 to compensate for this. (and throw is what a flashaholic wants from such a small led, otherwise you take an XM-L and have way better output and efficiency).

Time for the test-set-up (for details of the set-up, see my other led-tests, in short: ledboard on block of alu, led directly to power supply, reflector on top and ceiling bounce lux was recorded and calculated into OTF of reflector lumens, by comparison with reference flashlights. Everything not too accurate, but probably the values are not way off from reality.)

So this is what I got, in the graph the LuxeonZ can be compared to the LuxeonQ and the XP-E2 that I tested recently exactly the same way (well, actually nicely mounted on Sinkpads instead of on this makeshift board):

I am not satisfied with the LuxeonZ. it does outperform the XP-E2 by quite a bit (mind that the XP-E2 from the test was not dedomed, if dedomed the output would be, say, 20% or so less), but surely not enough to compensate for the bigger light emitting area (which is somewhere in between XPE andXPG). Actually, in die-size and output this LuxeonZ behaves quite like the sliced down LuxeonQ that I tested earlier (I measured the OTF output of the cut-down LuxeonQ in a C8 flashlight, see in my LuxeonQ-thread).

The only really nice thing about the LuxeonZ is the low voltage, on average more than 0.2V lower than the XP-E2 at a given current. so the efficiency is a bit better than it looks like in the graph, and good for a led without dome.

One other thing, for what it is worth, these Luxeon dies are less sensitive to the high currents that go above the maxumum output than the Cree leds of the same die-size (=XP-E), the die looses less output when current goes up and can survive higher currents.

I am not sure how much influence the use of this DIY copper board has on the results, compared to a Sinkpad. So to make my life easy, I just assume that the heatsinking properties are just the same .

I should have done a 'real life' test in a C8 or Uniquefire UF-T20, but at this point I was quite sure that it would perform as mediocre as the (sliced down) LuxeonQ, so I called this test a day.

I did have one LuxeonZ leftover however, so the board went back on the hotplate and it got new wires and a new led:

I could not resist it when ordering at Mouser: a luxeonZ-cyan (490-505nm). I love that colour! . On to a quick alu-block test:

Joehoe! this is nice for showing off in a small EDC light:

It actually was a pain to get the led-board in the light, there are no centering rings for a LuxeonZ, and the reflector is pressed onto the board in this type of light when the pill is screwed in, too much pressure and my not too reliable DIY board shorted through the (bit too thin and roughly sanded at the side) Arctic Adhesive layer. Next time I make a board like this, the side sanding is done before the glueing, and the layer of AA-adhesive will be just a bit thicker, so the board will be much more reliable. But I got it done, put an old 105C-driver in it that had 5x7135's left on it, but because the led-minus is directly connected to the body, the driver does not do much and it has no modes (I guess the led is just direct drive), I measured 2.45A on a freshly charged Nitecore 16340 battery and 183 OTF lumens (for what lux-readings are worth with close to monochromatic 500nm light) and was delighted with the result:

The picture does not do justice to the wonderful light this flashlight produces, and because of the small die it is quite throwy. I have even carried this light as my EDC for a week now, made me smile with every switch-on, and discovered how still usefull a light is with zero CRI .

Thanks for reading!

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It outperforms XP-E2 or is outperformed by XP-E2? Because what I see in your graph is that it needs more current to achieve the same brightness and it needs 1A mote to produce 10 more lumens.

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He posits that the domeless LuxZ should outperform a dedomed XP-E2 (a dome enhances photon extraction).

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I should have been more clear probably: by performance I mean maximum output (at any current), of couse this is a narrow-minded flashaholic point of view .

And this LuxeonZ led without dome should be compared to a dedomed XP-E2, while the XP-E2 led from the graph still had its dome, I have no output-measurements of a dedomed XP-E2, but that would be lower than the domed XP-E2 results in the graph. With some guessing I think that up to 2A the output of the LuxeonZ would be about the same as a dedomed XP-E2 (but with a bit lower Vf), and (at higher current) it has a higher maximum output.

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awesome board build and gotta love the range of luxeon colours =) cyan is def one at the top of my list to get, whether cree 7090 or luxeon :wink:

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I often wonder how you guys think up these tests and then actually carry your testing out to completion. If your on drugs please PM me the right ones. Orsm work as usual djozz. I love the green mixing bowl.

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Sometimes I am surprised as well when something that I make up in my mind actually works. It is usually a struggle though.. As for how I think up these things: my entire workspace for the hobby is 1 meter square, so what I do is limited to small stuff that is not too messy, so that is where the thinking goes. If I had the space that I wanted for the hobby, I'd probably be making big impressive flashlights entirely from scratch ;-)

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Hmm, think it was not fair to the led not to test the led in a c8. I am going to make a new copper board one of these days and do the c8 test :-)

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I’m really going to be needing some advice soon. I ordered a bunch of Luxeon Z emitters and some boards.

Unfortunately, after I ordered I realized I had ordered a bunch of Luxeon Z ES emitters and they don’t have the same footprint as the Z. I had to make another order for Z emitters, and there seems to be no boards available for that footprint. Actually, the place I ordered from had Z ES single stars pre mounted so I bought five that had the least expensive emitters on them. I can reflow a couple to test. Too bad I couldn’t get the multi boards.
Anyway, I got way more Luxeon Z than I really planned on, so will have to come up with mods. Got a bunch of colours too. I was limited in my choices of emitters since most of them were only available in lots of 2000. I took what were available singly.

I wonder why there aren’t any boards available for the Z ES. As opposed to the Z, the Z ES have a thermal path.

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Can you ever have to much of something? You are a certainly a high achiever Of. All the best for your future projects.

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This is a duplicate of a post from the modding thread. I just wanted to file it with djozz’s Luxeon Z thread to keep the info integral with the thread.

Today’s mod is not so much of a mod as part of a series of experiments with the Luxeon Z ES emitter. Djozz has already done some trials with the Luxeon Z, which has no thermal pad, whereas the Luxeon Z ES has a thermal pad. The Z ES is rated at 1A and the Z is rated at .5A.

It’s impossible to find boards for the ES except for this 20mm star it came mounted on.
4000k @ 80 CRI

Here it is beside an XP-E2. Note the thermal pad area of the Z ES below the actual emitter. The Z ES doesn’t have a dome.


I couldn’t find a suitable host to accommodate the 20mm star, so I had to adapt the pill from a four year old 1st gen convoy M2. Since the pill threads up and down I can compensate for the extra hight.


1.4A 17mm nanjg that needed to be soldered to a 20mm contact board to fit the pill.



Lets turn it on and see what it can do.
And the answer is…FAIL

A black spot right at the edge of the hotspot. I think it may be reflected from the thermal pad area, although Luxeon rebels have the same pad setup, but with no black artifact. Mind you, the rebels are domed while the Z ES is not.
To be fair, I’ve never liked the M2 reflector and the shiny SS bezel which I think are responsible for the uneven rings in the beam profile. I’d like to see it in a smooth C8 reflector, although I don’t think there’s anything to be done about the black spot in the center.

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I like that spirit!

Btw,there is an aluminium Sinkpad for the Z ES, but I have no idea how to get hold of them (politely ask the Sinkpad company?)

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I saw them, but they only come in 21mm. A big pain. Anyway, for the amount of current I’m running, these boards are pretty nice. Although not DTP, they’re constructed of a layer of copper on top, then dielectric, then aluminum.

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I got the emitter centered better and the black spot is gone. The M2 reflector and bezel suck though. Only good for a big fat floody emitter I think.

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Luxeon Z quad board. 5700k @ 70 CRI

C8 @ 2.8A in parallel

Initially after building I wasn’t sure what I thought. To much staring at a wall profile. There is a ghost in center of the hot spot which I expected. All the multi emitter dies I’ve used produce this ghost, or donut. Not large, but you know it’s there.

Indoor wall shots were kinda…meh, but when I tried it outside tonight when it was dark (as if it is ever dark in the city) I realized that wishy washy wall shots mean nothing. This thing can throw. I’d have to go down to a ravine to test it against an XPG C8, but it has potential.

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Welcome to the I hate white walls club. I nearly said something earlier but let it go. Its good to hear that it has come alive where it really belongs, in the great outdoors, city bound as it may be. :stuck_out_tongue: