Match's Mods: Emitter to Copper Reflow in a 1C mag mod (How To)

Sidenote: As far as I can tell, this is the only post out there detailing exactly how to mount an emitter directly to copper and not simply reflow onto another star.


This was going to start off as just another stubby mag mod (Yea Match, we've seen it....), but seeing as how that's been covered many times I decided this one needed a new twist:

What we have here is a Cree T6 xm-l directly mounted to a rather large chunk of copper pressed into a custom aluminum pill. Let's take a closer look.

No flimsy star here, but rather a thick piece of pure copper (machining it - grrrr....) freshly cut from barstock. The 7mm diameter riser has been polished smooth in anticipation of the xm-l emitter reflow. The size of this base worked against me later when I tried to solder the leads to the mounted emitter - i.e. it worked too well and prevented me from attaching the +/-. More on that later...

First thing to do was prep the emitter. I unsoldered a spare xm-l from its 20mm star and commenced to filing away the outer two electrical contact points. This is better explained with a picture, so here you go:

I used the two solder points on top of the emitter for electrical connection, again best displayed by a fuzzy photo:

As indicated above, there is a clear insulating coating applied that needs to be removed (LEDSeal I believe). Here's a pro tip - Tin these connections before reflowing the emitter onto the heatsink. I didn't the first time around, and for the life of me I couldn't get the leads to stick due to the amazing heat transfer going to the copper base (this is actually a good thing!). So, what does it look like mounted?

You'll notice that in the first pic there are two holes drilled, which was to be for the + and - wires respectively. After a brief debate, I decided to only use the + and make this direct drive via 1x18650. My reasoning was that if it can't take the juice, then I don't want it in my light and it's back to the drawing board. So, Let the Big Dog Eat! (or something to that effect...)

The actual mounted process involved 2 eyes, 3 hands, and 1 propane I wasn't able to snap a pic of the actual process. Thankfully it was pretty straighforward:

  • Apply flux to the mounting surface on the copper base
  • Hold the copper base with pliars and heat up from the bottom side to tin
  • As soon as the solder flows, set the emitter in place using tweezers
  • While holding the emitter in place, gently set the copper base/emitter on a slightly damp sponge.
  • Marvel at the directly bonded xm-l to copper masterpiece :)

I am fully aware of the temperature reflow calculations as provided by Cree, and they are important. But since most of us, including yours truly, don't have a reflow oven handy I used what I had on hand. Looking at the charts, the main concern is to avoid getting the copper base too hot while having a controlled cooldown to avoid brittle fracture stress failure. I used the visual indication of the solder changing states to aid in this. Due to the size of the copper base, the damp sponge didn't cause any shock cooling but mearly helped lower the peak temperature quickly and allow the solder to set.

So, now that the pill is complete, a host is needed. Coincidently enough I had an old beat up 2C Maglite given to me by a friendly co-worker. Using a similar method to my 1D mod, I shortened it to the minimum length required in order to hold 1x18650 resting inside the tailcap, then added a few racing stripes :)

Also a Rebel reflector and a used UCL glass lens that I had lying around were implemented. Here's a few shots of the results (keep in mind it was a well used light, and I tried to repair the scratches/dings best I could):

In the photo of the emitter inside the flashlight above, you may notice the xm-l yellow reflection is slightly off center. This was due to me holding the flashlight with one hand and my cellphone in the other to take the picture. The emitter is perfectly centered.


Here's where things get interesting. The results of all this are borderline unbelievable. Being direct drive, emitter current is based soley off of the cell quality. I have roughly 60 18650 batteries, all of which are reclaimed from old laptop batteries. Selecting the best ones of the bunch for testing I was able to get 4.2 amps at the tail. I'd like to retest with a quality cell someday. Regardless these are my results:

I.S. measurement: 1145 Lumens out the front and 71.5kcd ! Just playing with it for a brief time easily convinced me this is the brightest single cell light I've ever used. Talk about throw? Wow....

These results lead me to the following conclusion:

  • Stock stars are really holding these emitters back
  • Match's batteries are terrible
  • I really need to mount another one to my test rig and redo my XM-L test to see how it reacts.
  • The whole body of this light gets warm really quick! ( The battery is centered in the body via pvc spacer, so no worries there).

I'll leave y'all with the only beamshot I currently have, which was taken just after lunch on a sunny South Carolina day on the side of my house:

Yep...Take that, Sun....

I'll update again with nighttime beamshots as soon as time allows. As always, thanks again for your time reading this.


reserved for future updates / process improvements.

Great job Match. The question comes up now and again and now we know how to do it. Thanks for the effort.

Awesome job Match!

really awesome, thanks for posting!

That's the simplest (complete) reflow explanation I've seen, and now I have the confidence to try it (and destroy a few emitters lol).

I'll have you know, I sort of wish you'd not mentioned this and just surprised us, as now I'll be laying awake nights, contemplating the possibilities...

Thanks for the compliments, folks.

As I stated in the opener, I think mine is the ONLY expanation out there. Unless someone's google-fu is better than mine, I couldn't find any how-to's to go off of. Despite all the excellent modders over at candlepowerforums, I've seen nary a hint on how to perform this. Might be because it's harder to charge $200+ for a custom light with this feature if the secret is out Wink

Great write up!
I’m also just staring at those pictures of sunshine :slight_smile: Sunshine is the drug of choice in cloudy Seattle!
Just think of the lux measurements you would get with an aspheric in that light!

OOOH! Me like!

Nicely done Match. I personally have not seen any LED reflow tutorials out anywhere.

A 2C? You should stick a 26650 in there, either the MNKE or King Kong. :P

(but I'm afraid a MNKE could give you 20 amps without sweat, I doubt XM-L would handle that even if cooled by stream of liquid helium.. :D)

My hero! 8)

Match, very nice job and tutorial! I did a mod with a small copper pedestal for an SST-90. The raised pedestal was rectangular to fit the center of the emitter base and I wired to the underside for +/- . I Soldered the emitter to the copper and AA'd that assembly to an aluminum heatsink, but the AA kept from letting enough heat transfer go into the Aluminum, for an SST-90. I never pursued it any further and I never did any photos, since I wasn't satisfied with the result. Copper heatsinks really transfer heat fast, but of course, sooner or later it all gets too hot. How about doing an active cooling flashlight or spotlight Match? With your talent...........Wink

Oh, Match? Be careful - If you turn that beam on the sun itself, it will probably end up causing another solar flare!

I like the way you did this one. CoolLaughing Thanks for taking the time to post this thread, for people to learn from.

And great tutorial.

Always wondered what those little pads on top were for ;-)

Daytime beamshot?? Amazing. No further comments.

As usual .

THanks guys.

O-L, last year I also tried just using epoxy for a bare emitter, with similar results as you. As for a spotlight, I think this is as close as I'll come for awhile. I have a few of those plastic handheld halogen spotlights that I bought years ago, but haven't bothered to try and mod one yet. I think the bulkiness of them turns me off, not sure...

Oh, but you would love the output of a nice, crisp HID light! Car replacement kits are fairly cheap on ebay ;)

Plus: everyone here would love to see you do it (well, at least I would).

While it may not be the best explanation of it, it is out there.

Love you mods BTW, I so want to make that copper light.


Am I missing something here? Those videos are showing reflowing onto a star, very different from what this thread is about.

This is beyond incredible. It's that bright in broad daylight on a wall? Unbelievable.

Might a better beam pattern be possible if the reflector were a little tighter around the emitter? I know you're working what what you have but . . .

A 26650 is a bit tight in a Mag C, by the way.