I work in the R&D Department and we don't have a reflow machine here, so we get the LED Reflow done at our factory which is 25km away from the R&D, takes almost half day.
I and my colleagues came up with a plan to reflow the LEDs using clothes iron. And guess what it works perfect and saves a lot of time and fuel.
MCPCB is a Metal Core Printed Circuit Board, which has a Aluminum base, and the tracks are of 35um or 70um Copper and there is a thermal epoxy between the two metals. MCPCB are used in Medium and High power LEDs as it dissipates heat.
Step 1: Things Required
1. 1000W clothes iron with temperature control (without steam)
2. Philips Luxeon Rebel LEDs
3. MCPCB (Metal Core Printed Circuit Board)
4. IR Thermometer to check the temperature during reflow solder (optional)
5. Soldering lead
6. No clean liquid flux
7. Regulated Power Supply with current adjustment (to check the LEDs after reflow)
8. Tweezers - one to hold the MCPCB and the other to place the LEDs
9. IPA (Isopropyl alcohol)
Step 2: Start the Reflow...!
Important thing is to keep the Clothes Iron straight, for that we used the inside packing box of Hakko-880D soldering iron.
Wait for 3-5 min and place the MCPCB on the clothes iron. Then wait again for 2 minutes and just touch the Thermal, Anode and Cathode pads with the soldering lead, just to fill the pads. Repeat the same all the LED pads.
Now, place the LEDs using tweezer and put some little pressure on the LED such that the excess solder comes out and there is a good contact with all the pads on the MCPCB and the pads on the LED.
Pour 1 to 2 drops of "No clean liquid flux" on all the LEDs.
Remove the MCPCB from the clothes iron and keep it on some wooden board to cool.
After the MCPCB cools, clean with IPA to remove traces of flux on the MCPCB.
See the video.
Well, its so easy...!
Step 3: Testing...!
Set the RPS Voltage to zero and the current to minimum.
Now, slowly increase the voltage. In our case we used 10 numbers LED of 2.8V each and the final voltage is 28V max. The current should not exceed 1A (for Philips Luxeon Rebel).
In case, some LEDs does not glow, try to fix that led by repeating the same process. You can easily remove the LED, remove the MCPCB, clean the MCPCB using IPA and place the MCPCB on the clothes iron and solder it.
Finally, i should thank my colleague Mr. Preetham who did all the Reflow Soldering and Testing.
See the video for testing.