Is it bad that I still don’t use flux to reflow LEDs after all that years of modding ?
I don’t use flux for anything I do X3, I mean, I use flux core solder from Kester and good Kester solder paste, but never put additional flux on anything.
I found that flux is must especially for nice and shiny solder joints. Also used without flux several years ago… I use dense honey like flux for driver to pill soldering and classic not so dense for wire soldering. Premium quality flux from Topnik, and I also use premium stuff Stanoll Sn60Pb39CU1 recently used with some Osram leds and it works perfect, and it looks solid and shiny. But of course I will never use flux with solder paste 
When solder paste drys it goes straight to the junk… Btw I use that mechanic solder paste cause I can’t get any better than that. I use needle injecting package.
I tried the Mechanics a long time ago and it was just too thick, too dry. The Kester solder paste in a syringe flows so smooth and easy, love it!
I don’t care about a shiny solder joint, it’s going to be inside the light anyway! 
I have plenty of other things to be OCD about. lol At least I never have to wash a board, or otherwise clean it. Well, once in a great while if a light is giving trouble and it has to be soldered several times in the overall process it can get kind of messy and then I’ll clean the board up. Building drivers, and I’ve built hundreds, I just don’t usually find a need to clean em up. I use solder paste masks and it leaves a nice neat finished driver.
I would like to try that Koester solder paste but on ebay cheapest solution is 43$ S&H to Europe(plus potential 20% of customs tax on that ), and yes mechanic solder paste is thick and it drys fast if left exposed. It does not look like premium stuff at all… That needle mechanic package is a bit better than box one which will dry a lot faster because of packing itself…
Yes sometimes after fluxing something washout is necessary(like driver to pill). But it is easy. Just few drops of isoproprly alcohol and compressed air resolves that in a second with one good blow.
But flux applicator(like flux pen for example) is also important. If it can put thin layer of flux than no cleaning will be necessary. For wires soldering for example. I like thicker layer of flux for driver to pill soldering, and for that I use thin brush applicator.
Yes… I need premium solder paste in arsenal so I could compare it to mechanic sp and see the difference.
Ok… but I also find that I don’t need solder paste for reflow.
I just use soldering wire :nerd_face:
Which solder wire?
Generic chinese one from a long time ago…
It says “xinfa gao ji han xi zhi pin” :partying_face:
Ok… I’ll try to believe you 
It can be done with a lot more heat than with solder paste and with low melting point solder wire. My personal opinion that solder paste will be less stressful for emitter.
Anyone tried Sekisui 5760 under a non-isolated thermal pad MCPCB? It's pretty thin and it is said to work well.
Cheers ^:)
Djozz has had an underperforming blackie. After lengthy analysis he concluded that the reason for low performance was that led4power’s non-dtp mcpcb was the thermal limit.
This is a different setting, the area under MCPCB is way larger than the thermal PAD. So maybe the tape will work well. But I think there’s a large chance that it won’t.
Anyone ever used Black Flat in a C8?
I tried one today, mounted on dtp board and i find that it is almost impossible to perfectly focus the led in this host. The reflector lip just rests on the flashlight head so the reflector does not protrude down enough. I only got 124kcd with tail draw of about 4.7A.
Before you all ask, i went driver-less in order to be able to use dtp board for the led.
I haven’t done any black flat mods, but I’m happy to see more of them recently.
A copper shim under the MCPCB to lift up the LED is probably the easiest way to get your setup to work.
Focussing these small-die leds is almost an art!
Speaking of which, a few weeks ago I swapped the XM-L2 emitter in the following torch:
GearBest: https://www.gearbest.com/led-flashlights/pp_604347.html
Uses a smooth reflector into which the ∅16mm MCPCB is underside countersunk, using a beefy centering ring which sort of covers the emitter :!!!: dome. It is two plastic rings stacked, the above one of slightly lesser diameter. After swapping the emitter with an LH351C I had to deal with the centering ring, which I sanded down a bit from above where lesser diameter (this to let more light out) and from below to allow the emitter to sit more inside the reflector (had to glue the centering ring, of course).
It was all done quick with my friends at home and we having a :BEER: refreshing drink, and the result was a bit weird: the die of the led could be seen more or less squarely defined and enclosed by four flat isosceles triangles up, down, left and right at a very tiny distance leaving light gaps. My friend was a bit uneasy at first, though I said him a bit of a refocusing would fix the stuff. The beam is unusually consistent in hotspot to corona colour temperature, something very pleasing imho.
What could be the fixup in this case? Sanding down the centering ring even more from below to let the emitter seat even deeper inside the reflector maybe?
Thanks.
Cheers ^:)
This is a good idea, i might try it. I also i found out that even with the reflector all the way down the beam looks horrible, at this point the focus is decent but far from perfect, this led likes to seat very deep into the reflector.
I agree, especially when there is not much room to play with, like in the C8.
Did some tweaking on the C8, it is not perfect but still better than the 160kcd i had with the dedomed xp-g2 plus much better tint than the greenish one from the xp-g2.
So i was able to hit 196.000cd with what i think is fairly good looking beam, the hotspot is actually perfect circle but the corona around it’s a bit weird, probably the led is not centered perfectly.
Worst part about this was the fact that i had to sand down the head of the light in order to fit the reflector deeper into the head, after i did this sanding was required on the bezel also because the reflector sat a bit further and the bezel was not pushing enough to make a good seal with the o-ring.
So is this the best result? Probably not, but as i said it is better than what i had so i call this success given the fact that this is my first time playing with this led.
Sounds like a thorough Job, Bob! :+1:
I wonder…has anyone actually tried SSL80 in aspheric flashlight?
Yes, they are fun. The light extraction is higher than a wide-angle led of course (but not the throw), but most fun is that if the lens focal point is a bit above the led (in the cilindrical part of the dome), the flashlight has a very nice round fairly evenly illuminated hotspot.
The efficiency of SSL-80 leds is not great because it uses a very small die, I think it is 1mm2.