I’ve not used the WS2812 before but when I have what I think is a delicate part, I will solder two leads on opposite corners then move to another part, only coming back to the first part when it cools down.
This may be looked as over kill, however it takes no additional effort.
If a part is that stinkin’ delicate, then it may be that a cold solder joint is okay for the first pin; to hold the part in place such that the remaining pins are properly located over the PCB Footprint Pads.
The first lead/pin to reflow it such that it is no longer a cold solder joint.
My point was heat the joint, solder and GET OUT!
He has tiny pads and small leads. This won’t require much heat, but he can not “sit and think about it” once the iron is on the device/pad. This is a challenging task for an intermediate skill level.
…and it is virtually impossible to explain “good technique” in a brief text field.
Folks post questions and we can only infer their knowledge and skill level from the text. All I can do is try to give some general advice and wish them luck. Rarely does minutia have much value in most of these cases.
I’m not sure I explained myself correctly. My suggestion was that, after the leads on the opposite corners were soldered successfully, leave the remaining two leads for later after the part cools back to Room temp.
Yep, that’s why I mentioned Youtube. Also, about half a year I’ve bought an Amscope (clone?) from Ali and it is my best soldering tool yet. I of course already knew it would be a usefull addition to my toolbox, but the clarity of being able to exactly see what is going on has a much larger impact than I expected. You can see when tin on a SMD pad starts to melt, you can see the flux burning off (as big steamy clounds). You can see imediately if a component is properly wetted, etc. You can also see if the temperature of your iron is right. If it’s too cold it takes to long to melt the solder, and wetting aint to great, if it’s too hot, the flux burns off too fast. Louis Rossman has hunderds of hours of soldering and repair video’s on youtube. Watch a few of his vid’s and you’ll understand what I mean.
First solder the right side of all components, then turn the board around, and solder all left sides of the components again. 
Perhaps I didn’t reference the original goal.
We were told the WS2812B is extremely sensitive to heat.
The goal of my recommendation was to build up as little heat on the component body as possible.
But as I said in my original post… there is more than one way to skin a cat**…
** I believe this refers to catfish not the 4 legged kind.
JR
The particular problem with these LEDs is that the plastic is Extremely soft and low melting point. With any amount of heat it turns to a marshmallow. I killed quite a few of these before finally getting it right, that’s using a Metcal with a tiny tip, you still have to be fast.
My guess is that “hilmi28” will have a very low success rate initially, but hopefully he’ll learn.
Just thinking out loud, but I wonder if a conductive adhesive of some sort might work?
I’ve read some articles about conductive ink and glueing PCB’s together, but it seems to be a very niche buiziness, with expesinsive materials and reliability issues.
Low meltin poit solder (usually with bismuth) seems to be a much more common way to handle difficult or heat sensitive components. It also seems to be used a lot in the repair buziness (phones, laptops) where components can be very small and closely packed, and with a low melt point solder, you can place new components in between others whihout melting the solder on those.
I’ve also had troubles with hand soldering SMT PPTC’s. They seem to turn into chewing gum during soldering. Usually I prefer SMD components:
1), Not getting constantly confused by mirror images for soldering on the bottom.
2). Not having to turn the board around and fiddling with components to prevent them from dropping out of the board.
3). No bending and clipping of leads.
4). Not having to put those leads through holes.
But for PPTC’s i’m considering going back to THT, because those seem to be much more robust.
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