How to solder emitter on PCB

[rayman]

I often unsoldered emitters from PCBs but I never did it the other way. So whats a best way to solder an emitter to a PCB espacially a XR-E on a small 16mm PCB.

My idea was to really heat the PCB up with a heatgun but I don't know if this will work. So whats the best way?

rayman

 

[tonysworld]

Looks like good info here

http://www.gamesx.com/misctech/solder1.htm

 

[datiLED]

I use a mug warmer to heat the LED for about 10, or 15 minutes to cook out any moisture, and get the LED hot enough to avoid thermal shock. I hold the PCB with my "3rd hand", and use a soldering iron from the bottom to heat the MCPCB. When it is getting hot, I put a small dab of flux on the board, and hit it with a thin coat of solder. When the solder flows smoothly, I grab the LED (using tweezers, or pliers) and set it into place. I seat the LED to get good board contact, remove the heat and let it cool. I check the LED for continuity between the board and the anode and cathode. If all is OK, then it is good to go.

It is not very high tech, but I get excellent results.

 

[mudman cj]

I use a hotplate set to the peak soldering temperature, then place a steel socket from my tool set on one corner and a steel plate on top of that. By selecting the right socket size you can transfer the right amount of heat to the upper plate to make it the right temperature for preheating. It's like a dual-zone hotplate. Temperatures are monitored with a thermocouple.

With this setup, I apply solder paste to the MCPCB, place the LED right where I want it, and then heat the assembly, following the manufacturer's recommendations in the data sheets. I get excellent results with this method.

 

[HarryN]

Hi Mudman CJ,

What kind of hotplate do you have? Is this a commercial type soldering hot plate, or more of a cooking type hotplate?

Thanks

HarryN

 

[Linger]

Mudman, what is the reason not to set the hot-plate to a lower temp and just set the pcb on the plate?

 

[romteb]

I just successfully changed 3 xr-e on 3 stars today, my process was very simple, i just put a 1mm aluminum sheet i had over the smallest fire of my gas cooker, and drop the star on it, just waited something like 20 seconds till the solder melted and i could remove the emiter from the star with pliers, pushed the star on a cooler part of the alu sheet, positionned the new emiter on the star and pushed back the star to the hot area of the alu sheet, waited till the solder melted and the emiter seated, removed the star from the sheet.

3 tries, 3 successes, no damage to the emiters who work like charms.

Although it worked just fine for me , i wouldn't recommend it and do not take any responsabilty if any damage occurs if someone tries this process.

 

[Paul Baldwin]

Hi,
I've had some success using a jet 2000-C lighter. I've used it for straightening and swapping emitters and havent any yet!

It takes roughly 4 or 5 seconds with the flame set to low to melt the solder. I then quickly damp the bottom of the star with a sponge when I'm done. Very simple and cheap!

Paul.

 

[kramer5150]

I tried it with my stove top. I have seen others use an electric iron with better results.

 

[mudman cj]

Hi Mudman CJ,

What kind of hotplate do you have? Is this a commercial type soldering hot plate, or more of a cooking type hotplate?

Thanks

HarryN

It's an old hotplate from a lab. It is a 750 Watt Thermolyne model. There is a dial for selecting the temperature, which is indicated around the dial. The socket I use is a 19mm socket.

 

[mudman cj]

Mudman, what is the reason not to set the hot-plate to a lower temp and just set the pcb on the plate?

The plate is set to the highest temperature needed in the soldering profile - to actually melt the solder.

The second, cooler zone provided for by the socket is used to preheat the MCPCB and LED. This helps to reduce the time needed at the solder melting temperature, which of course minimizes thermal damage to the LED. It also helps reduce thermal shock arising from high rates of thermal ramping (ie. sudden temperature changes).

 

[parnell]

I tried it with my stove top. I have seen others use an electric iron with better results.

I found that my wifes clothes iron worked perfect for removing an emitter. I assume it will work just as well the other way around.

 

[mudman cj]

A clothes iron - now there is a readily available adjustable hotplate that won't break the bank! :thumbsup: