How to reflow solder an LED emitter on a PCB or MCPCB.

[Lumencraft-Matt (Formerly: vestureofblood)]

@clemence

Never tap or even touch the LED top during reflow whenever possible. Use proper dosing of solder paste (stencil is the best). Excess solder is better sucked not squeezed. It’s not a good practice. The silicone binder in the phosphor layer and the dome soften during reflow. Use any means of temperature monitoring. Faster is better, use the lowest temperature required to get the job done. For 63/37, I never want to exceed 210C. And no more than 240C for SAC305. 260C is the standard for automated machine reflow oven. With manual reflow soldering, usually you’ll spend more time.

[Clemence]

Hi Clemence, Thanks for sharing your experience. Using stencils is great if you have, and know well how to use them. With small XP size emitters I much prefer to do that, or definitely if doing a large batch of any size LED. For single LEDs I think the dome tap is just easier for people. Large foot print emitters like XHP70 have a tendency to get an imperfectly smeared paste when using stencils. If it’s not the perfect consistency and temperature you can get thin spots. Pushing out the excess solder in my opinion can actually create a better thermal path than even using a stencil because it puts the LED down as close to the base metal as possible vs floating it on a thin layer of solder. Not a good plan for mass production for sure, but for a modder wanting to swap mcpcbs it’s great.