How to reflow solder an LED emitter on a PCB or MCPCB.

Thanks, very helpful.

Whew! And I was just thingking in assembling a mixture of emitters like a “XP-L HI”/“219B” and “219B/XP-L HI” plaid fashion … DERP!

Cheers :partying_face:

Better get this one to the top again in time for the made from scratch contest :slight_smile:

A lot off effort from vestureofblood. Very nice and educational video. :+1:

I still use Old Lumens bench vise - soldering iron method and I found that as a best method for me (btw it is also very safe and regulated through regulated soldering station)

Worth to mention that there are emitters which will not automatically suck into MCPB and they require steady hand, eagle eyes and firmly pressed MCPCB to properly set up emitter on tray :slight_smile:

So if you have emitter on MCPCB that refuses to suck it Old Lumens method is only one that will do and especially if you want to tap and hold emitter until it cures to push excess solder and to make as thin layer of solder between it and trays.

This! XPE2 simmilar ones do that often, they are just too light to push the extra solder aside

Something else that is important and worth mentioning: sometimes the emitter + pad and the core pad could solder toghether yet the emitter will work( xml, xpl, xpg est).

It will work even if you connect the proper driver for testing outside the flashlight, but then inserted in the host the MCPCB will contact the host body and ofc this will cause a short connection.

Thats valid for DTP MCPCBs, non dtp in this case wont suffer that issue yet the emitter core isnt electricaly neutral: sometimes it could affect driver memory mode and/or correct driver modes

Ya, doing small emitters is the hardest. For me either setting a piece of glass on them to weight them down (like when doing a triple) or a very quick “tap”, hard and fast enough to eject the extra solder like a projectile is about the best way.

Hi!

My first reflow guys, done with helping hands, standard solder wire and a cigarette lighter. Toasty! LOL!

Cheers ^:)

Great video, thanks! You make it look very easy, and explain it very well.

Ah, but does it work? :+1:

Nice you asked, because I had not tested it.

Just hooked it up to a 5V PSU (output: 5'16V). I dimmed the room a bit at first because nothing seemed to happen and, anyway, at 2'58V per die I thought it would be barely visible under my 5000 lumen kitchen lamp. Then I realized I was trying to drive it inversely… Aaah! WHOOOSH! }P

@#$%! That stuff is shining bright for such a low Vf! Is that normal? Maybe I should take some current measurements tomorrow…

Cheers ^:)

Well, my multimeter shows 0'02 onscreen using the 10A (unfused) scale so, current is ≈20mA. And I remembered I had popped off the ammeter fuse long ago. :FACEPALM:

Cheers ^:)

Thanks for the video! I was wondering about that. Despite my age I still have childlike curiosity and a need to know.

Way to go man, I’m so glad you decided to try it. Getting a lot of light even at low power it normal. When I check to see if my reflowed XHPs are working I apply 4.6V with my bench power supply. This will allow me to look directly at the dies to see if they all light up. Going up to only 4.8V and doing this would result in a sharp piercing of the eyes.

Keep up the modding…

Great video. Thanks for doing this. Turned out to be a fun thread too………

Looks like that sinkpad got way to hot, its gone brown!

I reflow on my stove top using an aluminum pie pan and sometimes my sinkpads turn color but they seem to work just fine.

It's gone plaid!

Yep, the thing got tanned. That's what happens when you're a n00b in these matters and try to dissolve/spread some solder onto the base “the way of the tiger” (i.e. no rosin/flux). :FACEPALM:

I'll have my packet of rosin at hand next time.

Cheers ^:)

Good video! You got your hand/fingers in the way a few times when it gets interesting but hey… no problem :wink:

There is one thing I was always very curious about: the LED and pad have 3 connection points, two for + and - connections and one large pad that is resposible only for heat transfer from the LED to the sinkpad, right? Now you took A LOT of that solder paste on that first pad. now what happens if you take so much that the solder under the LED creates a electric connection between + and headpad, or - and heatpad, or even between all 3 of them? When connecting this to power it should create a short and destroy the LED, right?

How do you make sure this does not happen? You seem to be very tolerant and even move the LED around on the pad when the hot solder is fluid, I don´t get why it works anyway.

EDIT: those DTP boards like the sinkpad also have some kind of “cavity” or pit where the solder can “flow in”, while cheap aluminium stars like this don´t. Does this affect the process?

K.

I’m betting everything on that sinkpad that isn’t copper actually “repels” the solder. It has to, otherwise yes, it would short out.

Of course, whatever is in between the contact pads and the thermal one “repels” the solder.

When converting a non-DTP copper board to DTP via milling the thermal/central pad even to the very edge of the contact ones, the same behaviour can be observed: it's the dielectric layer, of course.

Take a look at these base plates:

These look like… unbranded Sinkpads!

I bet you my kingdom they come from the same OEM, but the Sinkpads undergo custom tailoring.

By the way, just had some more reflowing practice:

This time it went really shiny. That small heatsink (which once cooled the northbridge of an 8KHA+) is my new reflowing pan, thanks to it I've been able to carefully monitor the reflowing temp.

Cheers ^:)