Reflow fail, too much heat

Flashlight Modding and DIY Parts
1

Hi

I watched the video about the skillet method, I think the guy said about 400 degrees. So I tried to use a soldering iron clamped in a vice, pointed up, with the PCB sitting on top of the soldering tip to transfer the heat.

It was going well at first, I nearly had the LEDs in place, but then I realised there was way too much heat as the PCB contact layer separated.

So will try again with lower heat on a new PCB, but what setting should I use? clearly 400 is way too much.

Thanks

2

It is indeed too much (maybe he meant °F)

My ”hotplate” is not too different, it’s a small copper sheet in a vice heated by my soldering iron, for SnPb I put it at 250°C, and if I need more time to adjust things I reduce the heat to 220°C once the solder has melted.

3

Maybe this helps:

:+1:

4

Trying clamping the star instead of the soldering iron.

  • Place the star in a wooden clothespin that is clamped into your vise.
  • Hold tweezers in your right hand and use that hand to manipulate the LED.
  • Hold the soldering iron in your left hand and touch the tip to the bottom of the star. When you see the solder melt and the LED jump into position, only continue holding the iron to the star for a few more seconds.
  • The key is not to leave the heat on it longer than necessary.
  • You will need to lap the bottom of the star afterwards to flatten any solder that transferred from your iron to the bottom of the star. A few swipes with a handfile should do. You can skip this step if you use a hot air reflow station’s heatgun instead of a soldering iron to apply the heat.
5

success!

6

Congrats!!! :sunglasses:

Welcome to the wonderful world of reflowing LEDs.

Pretty soon you won’t care what LEDs come with your lights. You’ll have plans in advance to swap in your favorite LED even before you buy the light. :person_with_crown:

7

I have only had a few reflows that needed higher than 200°C. And those were around 225°C iirc (unleaded solder)

8

link?

9

I’ve done several leds with the 12 inch electric skillet Matt shows in his video Here
With no problems. Never overheated once, never tried an iron. I tested everything using a temperature test gun and temperature probe prior to the first reflow to verify melting point and the best position ( center ) on the skillet. Its max temp is 400 deg.
.
The thing I do different than Matt is, as soon as reflow is acomplished, turn off skillet and as soon as a test piece of solder hardens, remove the mcpcb with needle nose pliers and set it on wood to cool. I never leave it in the skillet to cool.
.
Cooking will most likely ruin your led. :wink:

10

Then after that you buy lights — hotplate—every which kind of LED and drivers — have grand plans and then they just sit — I have shit piled up with all sorts of plans