(Updated July 16) Review/Test: Illumination Supply Direct-Bonded 16mm Copper Star with Cree XM-L2 U2 1C

Very useful info. A Subscribed!

Thanks relic!

These measurements look very well done, thanks for doing the job! Apart from the performance of the IS copper board, it gives some nice information about the XM-L2 emitter as well. I am looking forward to the pictures of the light measurement set-up, and to the rest of the tests.

I would have thought it would have scaled better……

Thanks!

The lumens are a bit under, 1080lumens at 3A for the XM-L2 U2.

+1 - Nice Job! Who's missing Match? I'm also interested in seeing how you did the lumens measurements.

I noticed that too, and I believe part of it is due to the emitter no longer at 25C when at those drive currents. The rest may be tolerances in my measurement equipment. I’m sure Cree are slightly better set up than I. :slight_smile:

Great job relic! Regardless of any minor inaccuracies in your calibration, your direct comparisons should eek out any differences between test samples. I wonder how an aluminum sinkpad would fare since they are the same in construction as their copper counterparts (direct thermal path).

Do you plan on removing and reflowing the same emitter to each board you test?

Thanks FP. I am planning to reflow the same emitter in each test. I am aware that repeated reflow cycles are not advised my Cree, however I am confident that the stress this introduces will create less variation than trying to do the test with different emitters. I also have full control of max reflow temperature so I do not overheat the emitter any more than I have to.

I do not have an aluminum SinkPAD. Maybe I should fill out that survey…

Thanks very much Relic for the hard work.
I’m still missing Match though, I believe he’s part of members that give some inspiration for many others here. Will be glad if he back, that’s not mean he have to do some testing :bigsmile:

Great info and report. Thank you.

Just don’t plot lumens/watt, that might depress me.

My thoughts exactly about production variations between emitters. You’ll notice a sudden plunge in luminosity should your emitter start to fail after a reflow and turn-on readings should all be close.

The survey is how I got my AL sinkpads. Just a hunch, but I bet they will perform far better than most people would expect.

The Vf and lumens are consistently lower than Match's tests on a SinkPAD - I think he used a U2 1C as well. Now this difference isn't a bad thing at all - just interesting to note. More important is it's in the neighborhood and your lumens curve looks really, really good and match's up with Match's, accept for that hitch at 5.2-5.4A. So could be just the measurements/calibration, emitter differences, or the copper star is that much different from a SinkPAD - no telling yet, still early... Very interesting to watch this data fill out...

FP, I just filled out the survey at SinkPAD, one more product to compare to (eventually).

Tom E, that blip at 5.4A is when the light meter went from the 20,000 lux scale to the 200,000 lux scale. I believe the 2,000 and 20,000 lux scales read slightly low on my meter. Nothing drastic, but noticeable.
I’m avoiding interpreting any data at this point. Once I have more data from more tests and can compare to other direct-bonded stars.

One important note is that in statistics, a sample size of one is mostly useless. There could be some undetected defect in that sample, or it could be a stand-out performer. Either way, the test results from one sample are likely not going to represent the average performance of a mass-produced product. Product characterization requires several samples from several production batches to average out those anomalies.
But alas, we live in the budget world. I would not expect a supplier to sent multiple samples from two production runs, nor would I have the time to test that many. We work with what we have and as long as we are aware that the data is limited, all will be OK.
One thing I would not like to see is someone read through the review, see the positive test results, order a bunch and have them comparatively under-perform and then blame the review for misleading them. This potential issue exists with any product review of one sample. Most reviews out there are just that.
[\rant]

I will make one observation though; these stars perform much better than a standard aluminum star. That I am confident in saying.

I was curious too about the Vf data. Seems good cells (i.e. Sanyo 2600mAh) in single cell lights could sustain regulation at drive currents up to about 2.8A.

-Garry

relic - +1, agree on all points... Scale change explains the 5.4A hitch.

One other note Tom; on Match’s data, it is not clear where Vf was measured at. I measured directly across the star wire pads to eliminate wire drop.
I will be testing the drop across the star traces as well. It is possible that the IS-DCB star traces are thicker than the ones on a SinkPAD (I have not compared them yet). That could also be a contributing difference in Vf.
Actually, I just did a quick comparison of the four XM-L DCB stars I have:

  • SinkPad 20mm star (what Match used) has a ~1mm trace ~5mm long from wire pad to emitter pad, both pos and neg.
  • SinkPAD 16mm star has a ~2mm trace ~2mm long from wire pad to emitter pad, both pos and neg.
  • Noctigon 20mm star has a ~4mm trace ~4mm long from wire pad to emitter pad, both pos and neg.
  • IS-DCB 16mm star has a ~3.75mm ‘trace’ ~2mm long from wire pad to emitter pad, both pos and neg.

Curiosity got the best of me, so I went ahead and tried a quick current test. 6A driven directly from the wire pad to the emitter pad. Multiply by two to get the total voltage drop on the star traces.

  • SinkPAD 20mm star: 43mV (7.1 mOhm)
  • SinkPAD 16mm star: 21mV (3.5 mOhm)
  • Noctigon 20mm star: 22mV (3.7 mOhm)
  • IS-DCB 16mm star: 14mV (2.3 mOhm)

Nothing conclusive, as I need to do this a little less ad-hoc. It does indicate how Match might have gotten a higher Vf reading.

Edit: It has been pointed out that comparing trace resistance of 16mm boards to 20mm boards is not entirely fair. I tend to agree with that, and was not suggesting anyone do that with this data. I recommend limiting comparisons to within the sizes of the stars.

Interesting. So the preliminary results suggest that the traces on the Illumination Supply stars have the least resistance.

You know, this could change some think'n around here, that the bigger the star, the better. The 16 SinkPAD is half the 20, and the IS one even better, hhhmmm.

The difference between the best and the worst board is 0.7V, at lower currents that will be lower. That is important stuff for the fine-tuners, that means I am ok .

Even though it may not be of much relevance to my mods, I love data, the more the better, keep it coming !