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

[Mitko]

Indeed, sometimes you wont be having a short connection but just a modes lost( it stucks on high), or like on some of my drivers offtime memory function disabled

[luminarium_iaculator]

@Mitko

Indeed, sometimes you wont be having a short connection but just a modes lost( it stucks on high), or like on some of my drivers offtime memory function disabled

That is so irritating… A lot of effort to assemble everything and than wtf happens!

Mitko what is your method of correcting this issue?

[vestureofblood]

@luminarium iaculator

@Mitko

Indeed, sometimes you wont be having a short connection but just a modes lost( it stucks on high), or like on some of my drivers offtime memory function disabled

That is so irritating… A lot of effort to assemble everything and than wtf happens!

Mitko what is your method of correcting this issue?

I’ve had a similar result when there is power bleeding off to ground to led negative on the driver board. High mode always.

If there is a short of some kind in the MCPCB the best solution would be to just dump the mcpcb and use another one. Trying to prevent a short with thermal epoxy would likely result in having to use a layer so thick it would negatively effect the thermal path.

[luminarium_iaculator]

@vestureofblood

I’ve had a similar result when there is power bleeding off to ground to led negative on the driver board. High mode always.

If there is a short of some kind in the MCPCB the best solution would be to just dump the mcpcb and use another one. Trying to prevent a short with thermal epoxy would likely result in having to use a layer so thick it would negatively effect the thermal path.

No first version is not for sure. Triple checked that.

It is pita to reflow dedomed emitter on new mcbcp since I can’t use tap from above cause I’ll damage perfect emitter.

[Agro]

Great video. I guess on a chemically dedomed LED you don’t tap the emitter. How do you remove the excess solder then?

[Sledgestone]

You reflow them before dedome

[Agro]

OK….
Thanks.

[luminarium_iaculator]

@Sledgestone

You reflow them before dedome

So you would solder mcpcb with domed emitter to flashlight and then you would de solder it, de dome it and then solder again?

Nah… This is not right technique.

I usually reflow around 10-20 emitters and check them on my test rig and then de dome all of them at the same time so there are ready to go.

We are talking about curious cases when everything works on testing rigs and yet it does not work when assembled in flashlight.

Edit:

I just saw you were not replying to me. But it is ok lol

[Sledgestone]

Um, no… Solder the LED to the mcpcb you want and then dedome it.

Where did you get the other part from?..

Edit: Saw your edit

[luminarium_iaculator]

Mitko and myself just want to point on this:

@Mitko

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

[eh4]

Wow that is great, thank you!
I particularly appreciate the intentionally casual technique, and lack of precision shown, to highlight the effect of surface tension with the wetted solder.

Very illuminating video, I had no idea that the leds could tolerate that duration of time at the solder’s melting point, or that thermal shock was the greater issue. I would have hurried it and had poor joints and raised, heat shocked emitters if I’d tried it on my own experimentally.

This is something that I’ve been putting off learning to do, I’m now quite inspired.
Thanks again.

[Lexel]

If you reflow an LED try to stay within the heat up and cool down speed in the reflow diagram, too fast is bad for the LEDs lifetime

[ZoomieFan]

So the vertical side of the T is the - (right) and the horizontal side is the + (left).
How can I know the + and - of the PCB?

[vestureofblood]

@ZoomieFan

So the vertical side of the T is the - (right) and the horizontal side is the + (left).
How can I know the + and - of the PCB?

Hi Zoomie,

Most mcpbs are marked with + and - near the pads.

[MtnDon (Don Miller)]

You can also verify with a multimeter by checking continuity.

[ZoomieFan]

Is an iron hot enough?

[FPV]

@ZoomieFan

Is an iron hot enough?

I have a 60W adjustable iron and it is perfectly fine for reflowing. My smaller 45W also works fine.

[ZoomieFan]

@FPV

@ZoomieFan

Is an iron hot enough?

I have a 60W adjustable iron and it is perfectly fine for reflowing. My smaller 45W also works fine.

That’s great. Never done this before, but it looks easier than with a skillet.
Any advise about the temp setting? Cotton?

[teacher]

@ZoomieFan

@FPV

@ZoomieFan

Is an iron hot enough?

I have a 60W adjustable iron and it is perfectly fine for reflowing. My smaller 45W also works fine.

That’s great. Never done this before, but it looks easier than with a skillet.
Any advise about the temp setting? Cotton?

I think you all are talking about two different type “irons”.

Clothes vs. Solder

[ZoomieFan]

I think you are right. I was wondering 60w was one of those small traveling irons.
Now I think about, LEDs get very hot. Hotter than a clothes iron I guess.

I have a Weller solder station.
I’ll scrape the corn bread out of my skillet and use that

Tnx teach