I ordered some PCBs from JLCPCB and it appears all leds are soldered backwards. I've filed a complaint, but it seems I have at least to try resoldering them myself. This is the board:
Any good advice? I thought of using some kind of a hot plate technique. But placing the whole board on a hot plate will melt all components. They might start drifting. The only hot plate I can come up with is an old small iron saucepan I haven't used for decades. I have an IR temperature gauge to measure the temperature of the saucepan. What should it be?
Just pointing with a soldering iron will only melt the white plastic until I manage to melt both sides of the pins at the same time.
A hot air gun would be a good tool or alternatively remove the LEDs with a soldering iron, remove excess solder from the board and replace them with new ones
Happens a lot, usually they will send a message to confirm how the components should be placed. Which then in turn causes some message back and forth with people that are called 'engineers' but are really factory workers. I have also suggested that they add their placement of each component to their library, but they do not seem inclined to do so. When using KiCad it often does go wrong with WS281x's like you have. Their 'zero' rotation is not the same as the one that KiCad uses, but really read the messages well, and if it doesn't seem to be correct, ask them to remove the order and re-submit a new one with the rotation that you think it should be. (eg. if it was 90 and they should be rotated 180, set the rotation to 270) The intelligence of the people you are actually dealing with can not be overestimated, they are not electronic engineers and have no idea how electronics work.
For the problem at hand i would use a soldering iron with some extra tin on it and heat up all 3 points on one side while using a flat screwdriver to move that side upwards, and go back and forth between side until there is enough space to suck out the excess tin and leave the joints unconnected.
Other option is to use to soldering irons and 3 or 4 hands. Again the extra tin will make it a lot easier to melt all 3 spots.
Who designed the board. You or JCLPCB? The notch on the Leds does appear to correspond with the white dot on the silk screen so these do not appear at first sight to be rotated through 180 degrees, which would be the classic manufacturing error.
Anyway, you may be able to lay a short piece of solderwick across 3 pins on one side to melt the solder on all simultaneously and then prise the component up on that side. Repeat it for the other side.
With this method, there is a great danger of tearing the track off the board. I prefer to use a thermoair soldering station and melt the solder on all 6 pins simultaneously
I designed the board. My design was faulty. They produced very accurate PCBs according to my design, nothing to complain (although I can see that the white plastic is slightly broken and will jeopardize my attempt to unsolder it). But my design fault was due to their faulty advice.
Then use a knife blade and cut the traces on the board and use #30 jumper wire to make the correct connections. That is what everyone does to fix errors in design.
I tested my old iron saucepan and I managed to remove the leds. But I didn't get them back properly. The pads for the pins on one side are too big and touch each other. I have to consider using a cnc router to make the gap between them wider. Six small cuts on 15 boards.
I got the damned leds loose. Only to discover that they are totally wrong! They aren't ordinary rgb arrays. They have an integrated chip. They accept only one voltage in and one ground. Well, the tree pins on one side seem to be internally shorted. Applying power will start a smooth breathing colour rotation. Cool! But not what I ordered. So I have to try to attach other components instead.
I happen to have a lot of ordinary SMD RGB LEDs, detatched from a led strip. I'm going to try the saucepan method in soldering them, hoping that the tin remains are enough.
And btw, the temperature was some 220 - 240 degrees C. Far from an even temperature all over the surface of the saucepan. The resistors might be ok. The leds are, even though they are the wrong component. I hope the photoresistor in the very middle didn't suffer from the heat. This method is very slow and the boards lye on the heat very long.
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