Playing around without a heatsink and it got too hot, it has partially slipped off the contact areas.
How is it best to resolder/align, do I need more solder paste and remove it and resolder or can it just be heated and recentered?
yes
ideally you would put the mcpcb on a hotplate set to 230C
I would also put a bit of Flux on the exposed solder pads
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Thanks, I bought some flux, only cheap Chinese stuff, but I will give it a go.
I don’t have a hotplate, so will have to improvise.
whatever heat source you use, under the mcpcb
candle:
electric fry pan:
the flux will be helpful in monitoring temperature… first it will liquefy, and as the temperature reaches the target, the flux will start to vaporize (smoke)
clean up flux (and candle soot) with alcohol
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I used a lighter and it worked great, thanks.
First time I soldered the wires on, I covered the led with a small piece of brass sheet to stop any splashes onto the led, I got carried away and forgot this time, so have a small mark on it, hopefully I will remember next time.
Thanks for the advice, this has given me some confidence to buy just led chips now and solder them to boards myself, always thought it was somehow much more difficult.
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What I’ve done in the past is to add a bit more fluxless solder (eg, melt it on the tip of the iron) and a drop of liquid organic flux (blue stuff, looks like washer fluid or Windex), then let it sizzle away so the LED “floats” on the pads to self-center, then give it a little tap on the dome to shoot out any excess so that the LED is now firmly on the pads.
After it cools, if there are any “beads” of solder around the periphery (should be almost perfectly spherical, like little blobs of mercury), they should flick off easily.
You need to make sure the LED sits firmly on the pads for good thermal transfer. If it “floats”, there won’t be that good contact.
After, soak it then rinse it in alcohol to get rid of any excess rosin flux. Probably not a necessity, but I do it anyway.
While you’re at it, put some fine-grit sandpaper on glass, then swoosh the star around on it to flatten/smooth the bottom for best thermal contact.
Like, you got it out and it’s right there, so why not do it all up, all at once?
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Yay!
congratulations 
the spot on the LED might clean off with alcohol on a qtip, if it is just flux…
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