Review / Test: Intl-Outdoor Noctigon XM16 Direct-Bonded 16mm Copper Star

Intl-Outdoor Noctigon XM16 Direct-Bonded 16mm Copper Star

Reviewer's Overall Rating: ★★★★★


Diameter 16mm
Thickness 1.5mm
Material Copper with upper dielectric, lower nickel/gold plating
LED Type: None supplied (XM-L2 U2 1C used for tests)
From: Intl-Outdoor
Date Ordered: Review samples provided by Intl-Outdoor


  • Excellent thermal transfer properties
  • Easy to reflow, good solder spillways for conductor and thermal pads
  • Thick traces to wire pads
  • Nickel/Gold plating on pads and base protects from oxidization
  • Perfectly flat bottom (appears to be lapped)


  • Thermal pad is very slightly depressed, although does not appear to affect performance

Features / Value: ★★★★★

Design / Build Quality: ★★★★★


The Noctigon Direct Copper Bond (DCB) XM16 emitter stars from Intl-Outdoor offer improved thermal transfer characteristics over traditional aluminum stars with a dielectric layer. When attempting to push an emitter to extreme power levels, heat begins to negate any potential gains. By bonding the emitter thermal pad directly to the star base material, heat is transferred to the star and on to the heatsink at a much faster rate. The result is a cooler emitter die at the same current, therefore more photons out the front.


First, a little bit on the setup. The emitter is mounted to a 900g aluminum heatsink with large fins on the back. A fan is blowing on the back to maintain as close to an ideal heatsink as possible. This setup is close enough, but not perfect.

In addition to Luminous Flux (lumens), measurements of Emitter Current (IF), Emitter Voltage (Vf), Emitter Temperature, and Heatsink Temperature were taken. Measurements were taken at 0.2A increments from 0.2A to 6.2A.

In this first image, you can see where Vf and Emitter Temperature were measured.

I used duplicate wires to feed back to the voltmeter; no wire drop was measured. The goal was to measure the voltage drop across the star being tested.

I used a standard thermocouple glued to the edge of the emitter, as per recommendations found in a Cree app note (a reference link will be provided).

This second shot shows the three meters used to capture Emitter Temperature (Vichy VC99), If (Metex M-3800), and Vf (Metex M-3800).

The Heatsink Temperature was measured right under the emitter placement, between the heatsink fins. This measurement was taken with an IR temperature probe (the heatsink is anodized). In other words, as close as I can get to the base of the star without needing to move the setup between measurements.

Here is the complete setup (power supply is out of frame to the left)

Closeup of heatsink in position.

And finally, the light meter:

Performance Tests

The first test is with the emitter/star in stock form, as shipped.

Test Results Data:

I-O Noctigon XM 16mm Star with XM-L2 U2 1C Emitter (Stock)
If Vf Pled Lumens
0.2 2.77 0.55 95
0.4 2.85 1.14 186
0.6 2.92 1.75 273
0.8 2.97 2.38 356
1.0 3.02 3.02 434
1.2 3.07 3.68 513
1.4 3.12 4.37 589
1.6 3.15 5.04 657
1.8 3.19 5.74 728
2.0 3.23 6.46 793
2.2 3.26 7.17 857
2.4 3.30 7.92 917
2.6 3.33 8.66 981
2.8 3.36 9.41 1038
3.0 3.39 10.17 1096
3.2 3.42 10.94 1150
3.4 3.45 11.73 1204
3.6 3.48 12.53 1254
3.8 3.50 13.30 1304
4.0 3.53 14.12 1350
4.2 3.56 14.95 1396
4.4 3.58 15.75 1441
4.6 3.61 16.61 1482
4.8 3.63 17.42 1552
5.0 3.66 18.30 1590
5.2 3.68 19.14 1627
5.4 3.71 20.03 1664
5.6 3.73 20.89 1694
5.8 3.75 21.75 1731
6.0 3.78 22.68 1769
6.2 3.80 23.56 1799

These results look very good. The star appears to be doing its job at getting the heat away from the emitter and keeping it as cool as possible.

Once the test was complete and things cooled down to room temperature again, I retested the emitter at 0.4A to look for signs of fatigue or wear. The results were identical to the first pass. I will note that the emitter was not run at 6.2A for more than a minute.

Next test is with the star lapped flat. This did not take long at all, the star is basically already flat. This (blurry) image was after lapping for a short session with 2000 grit sandpaper. The Gold layer quickly sanded off and we are left with the nickel plating underneath. There was no sign of unevenness. Hank from I-O has stated that Noctigon stars are lapped before being plated. Based on my experiences, I believe it.

I continued with 2000 grit to remove the nickel layer.

Test Results Data:

I-O Noctigon XM 16mm Star with XM-L2 U2 1C Emitter (Lapped)
If Vf Pled Lumens
0.2 2.77 0.55 96
0.4 2.85 1.14 184
0.6 2.92 1.75 274
0.8 2.98 2.38 357
1.0 3.03 3.03 436
1.2 3.07 3.68 510
1.4 3.11 4.35 585
1.6 3.15 5.04 657
1.8 3.19 5.74 725
2.0 3.23 6.46 793
2.2 3.27 7.19 857
2.4 3.30 7.92 918
2.6 3.33 8.66 981
2.8 3.36 9.41 1037
3.0 3.39 10.17 1093
3.2 3.42 10.94 1147
3.4 3.45 11.73 1202
3.6 3.48 12.53 1252
3.8 3.51 13.34 1301
4.0 3.53 14.12 1349
4.2 3.56 14.95 1395
4.4 3.58 15.75 1440
4.6 3.61 16.61 1484
4.8 3.64 17.47 1552
5.0 3.66 18.30 1590
5.2 3.69 19.19 1627
5.4 3.71 20.03 1664
5.6 3.74 20.94 1701
5.8 3.76 21.81 1731
6.0 3.79 22.74 1769
6.2 3.81 23.62 1799

Virtually identical results. In fact, only the emitter temperature changed by any amount. The probe fell off during lapping, and I was forced to reattach it. I expected different results as the thermal bond is likely to change depending on how it's attached. Therefore, I would say that the emitter temperature from these tests is unreliable due to inconsistent probe placement.

At this point I desolder the emitter to move it to a different star for comparative testing, and to confirm that the reflow bond was good. (no image, but it was confirmed, 100% of the thermal pad bonded to the star)

Comparison to Other Emitter Stars

I have also tested Illumination Supply, SinkPAD, and aluminum 16mm stars with the same emitter. The results are very comparable, when comparing apples to apples (properly mounted emitters on lapped stars). Since I do not have pre-mounted emitter products available for all competitor stars, I am comparing the lapped reflowed data (what I consider apples to apples).

Note: This particular aluminum star did not perform well. I have another that I want to try at some point.

Closeup of 5.0A to 6.2A for the three leaders:

These results (3.7% variance) are probably well within my measurement tolerance. I would give a very slight edge to the SinkPAD followed closely by Noctigon, but it's so minor that it is probably unnoticeable in all but calibrated equipment. In practical use, these three DCB stars seem to give comparable results.


  • Thickness: 1.58mm
  • Diameter: 15.88mm
  • Widest diameter: 16.06mm


The Noctigon XM16 star definitely does perform much better than an aluminum star. An emitter mounted on this is definitely capable of serious light output.

Highly Relic Recommended!

Thanks for reading! searchID8934


Orsm work again relic38. Thanks.

Thanks, relic, most of us do not have the expertise or equipment to do testing as do you. We are deeply appreciative for your time and efforts, :beer: :beer: :bigsmile:

Thanks, relic. I reckon your temperature measurements are fine if you are interested in delta T.

I’m not sure about that. I have to think about it, but I don’t believe it is useable for delta T either. It’s too late for any serious thinking… :weary:

Thanks a lot for the review! Frontpage’d and Sticky’d.

Thanks for Noctigon review…

Really appreciate the effort you spent on this, very interesting to see even slight differences between the Big 3 and how badly they all whip the old standard.

Well done!

Thanks a lot again for some tedious but very useful work, great stuff!

Thanks for such a detailed analysis and comparison. I’ll be ordering these for now on.

Fantastic testing!


Well done! relic. Thanks for testing it out.

Just found this review, very nicely done! :slight_smile:


I somehow missed this fantastic thread.

Relic38 - think I saw this, but failed to comment. This is excellent work and a great setup you have there!!

I'm just getting into some of the things you got there - need to order a bench power supply, and I put together a 2-56 tap setup, so plan on screwing down the stars, if possible in various lights. Still have to work out a preferred setup for tapping, screw sizes, head types, etc. Not sure what the best is, or best sources for the hardware.

Another thank you for the time and effort you spent Relic. :beer: