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I wanted to do a project using these ws2812b leds, and I find them nearly impossible to hand-solder them because of the tiny contact points. Can someone teach me how to solder these by hand? They are surface mount components as you can see in the images. enter image description here enter image description here

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  • \$\begingroup\$ It'll take some practice, but what I would do is put down a little bit of solder on the PCB at pin 2 or 4 (assuming potential for ground or power pours requiring more heat). Then, place the component on top and heat up the bit of solder and the pin simultaneously for about 10s, while lightly pressing on the LED. once the first pin is secured go around and do the rest. Alternatively, use a bit of kapton tape and tape it down then go around pin by pin. The key is heating both the pad and the pin so that solder wicks up onto the pin to make the connection \$\endgroup\$
    – ks0ze
    Feb 22, 2020 at 15:09
  • \$\begingroup\$ I do it the same way with these and other smt parts, put solder on one pad. When I bring the part in warm it with the iron and center the part. With these parts they were easy to damage with too much heat or too long, burned up a few of them before I figured that out. Now you have the fun of trying to remove one (even more fun that putting them down in the first place). If you see a wave of heat pass across the window and change the color of the logic/planes inside, you might have damaged it completely or perhaps just one of the colors. \$\endgroup\$
    – old_timer
    Jan 5, 2021 at 7:32
  • \$\begingroup\$ I use the tape solution as well sometimes for more than two pad components. \$\endgroup\$
    – old_timer
    Jan 5, 2021 at 7:33
  • \$\begingroup\$ @ks0ze 10s is far too long. \$\endgroup\$
    – SiHa
    Jan 8, 2021 at 10:32

2 Answers 2

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I assume you don't have an SMT rework station :)

Put some solder paste on each pad. Place the part on the board. Use a toothpick or something similar to hold it in place, and use your iron to melt the soldering paste on each pad individually. I would guess about two cubic millimeters. If you are not happy with the result, you can touch up each pad individually. Use plenty of flux for the touch-up.

Practice on a scratch board with a dead part first, as it's easy to mess it up if you haven't done it before (but then again, how would I know :) )

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  • \$\begingroup\$ Sounds like a good idea, thank you! \$\endgroup\$
    – Jc S
    Feb 23, 2020 at 1:35
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Assuming you have clean PCB and diode, and you don't have any special equipment other than soldering station and small chisel tip. If you don't have soldering station, buy one, even a cheapo from AliExpress.

These diodes aren't hard to solder at all. They have huge pads which extend outside the package. With a tiny bit of technique this can easily be done.

  1. If you design the PCB, ensure that pads are larger than the diode so that you can touch the PCB pad with your soldering iron and not just LED pad.
  2. Add flux onto PCB pads
  3. With your soldering iron, add a tiny bit of solder to each of the pads so that each has noticeably convex amount of solder. There should be just enough solder to coat LED pad and not more than that.
  4. Add more fresh flux (you can never have too much flux)
  5. Place diode and delicately press it (so that it doesn't move anywhere) while you
  6. Delicately touch either just the PCB pad or both PCB pad and LED pad with your soldering iron, at the same time. Wait just enough for the solder to melt and visibly coat the LED pad. With well set temperature this should take half a second to a second.
  7. Clean the flux off the diode and the PCB

Some notes:

  1. If you don't have good technique, you will be safer using leaded solder. Leaded solder melts in lower temperature which means you have more margin for error before you destroy the LED. I use leaded solder exclusively because it makes my life easier.
  2. Set correct temperature on your soldering station. You want it just enough to melt the solder comfortably and that's it. Each station reacts differently and will require different setting, and frequently also different setting depending on what you are soldering. You need to experiment with it.
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    \$\begingroup\$ The only thing making these kind of LEDs harder to solder is that they don't like heat much at all, so you pretty much only get one chance to get it right. Re-heating it multiple times might damage the component. Apart from that, these are indeed not hard to solder at all. \$\endgroup\$
    – Lundin
    Jan 8, 2021 at 10:05
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    \$\begingroup\$ I'd agree apart from the "tin all pads" bit. You should apply solder to one pad only, first, just to hold it in place. That way the device will be flat to the board when you then solder the others. Otherwise it will be hard to get it to sit flat without repeated re-heating (and possible melting). \$\endgroup\$
    – SiHa
    Jan 8, 2021 at 10:29
  • \$\begingroup\$ The reason to "tin all pads" is that you only have two hands and that it is much easier to judge and handle good amount of solder when it is on the pad vs when it is on the iron. When you have right amount of solder on all pads, you put flux on them, place the part, keep the part pressed with your one hand and use the soldering iron with the other hand to reflow the solder that already is on the pads. You don't have to bring any new soldier from wire (which would require third hand which most of us don't have) and it does not require you to bring solder on the soldering iron (which is finicky) \$\endgroup\$ Jan 24, 2021 at 12:16

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