I use a butane torch to heat the MCPCB from below but I don’t apply the flame directly. I hold the torch 10-15cm away to heat it more gently and it typically takes 60-90 seconds before the solder melts and the LED centers itself. I usually tin the pads for the leads so I can see when the solder melts and immediately remove the heat. After it melts, a quick, gentle tap on top of the LED (s) with a swab squeezes any excess solder out and its done.
I’ve had great success with this method on everything from E21a to SBT90.2. I’ve even reflowed the same emitter multiple times without any measurable (ceiling bounce) reduction in performance, which is acceptable to me. I’ve thought about trying the frying pan method or getting a hot plate, but since the $10 torch has served me well I continue to use it.
I use a household hot plate. It’s rudimentary, but it’s step up from the skillet I started with.
Temperature control is just a number dial so I use an IR temp gun to make sure it’s in the right arena. Really quick to heat up, cheap, and widely available.
I might have to give that a shot. I think I have some spare MCPCBs I can practice on. Are there any preferred US retailers or overseas dealers that sell bare emitters besides Mtn? Looking to get some emitters in 2-3 weeks.
Specifically looking for anything I could swap into an XP-L2 MCPCB for my Wuben E05. The MCPCB is ~1mm thick and I believe the LED4Power/Mtn boards are 1.5mm.
If you’re looking to get them in 2-3 weeks, domestic is your best bet. Arrow, Digikey, and Mouser are large electronics suppliers so it might take some searching around to find what you’re looking for (verifying datasheets for flux bins, etc). I know I’ve purchased Luxeon V2 of various CCTs, LH351D 90-CRI (the “DA0GF4RTS”), lots of different Cree LEDs. The nice thing about ordering from MtnE (or a BLF member) is that you have an idea of what tint you’re getting (and it supports a fellow BLF’er). Let me/us know if you’re looking for something in particular.
I’ve reflowed new LEDs into those Wuben E05s. They’re a good candidate (get rid of that stinking Cree rainbow!).
There are two main package sizes: 3535 and 5050. There are also some 3030 emitters out there (notably Osram White Flat) and 4040 (Luxeon V and a different line of Osram white flats). Current modern emitters I can think of:
Note for nick779: the 3535 name means “3.5mm x 3.5mm”, 5050 means “5.0mm x 5.0mm” and so on. Generally, most LEDs with the same footprint dimensions (eg, 3535) are swappable. However, there are some LEDs out there that only have 2 pads instead of 3 (they’re “missing” the central thermal pad). These are not common in our high-output LEDs though, are are generally found in low output ones. An example that we deal with would be the Nichia E17A (a 1.7mm x 1.7mm LED). And a couple (though again, rare) have a central thermal pad that is not electrically neutral. The only one that comes to mind is the Osram Black Flat.
I’m more confident in my soldering skills than my metalworking, so instead of a brass bar, I decided I would solder 5 small pogo pins together as a signaling contact. Cheap and effective, bought 100x pogo pins for $11-ish.
Made a S2+ shorty with a Nichia 219B 3000K LED (from azhu) and a Convoy V.2 driver. Added a 470 ohm bleeder resistor for the aqua (mix of green and blue 0805 SMD LEDs) lighted tailcap. The tailcap takes just 0.15 milliamps so lasts almost a year on the 18350 Keeppower 1200mAh battery.