How to Solder SMT with a toster oven (Luxeon Rebel)

[Brlux]

The approach is rather striate forward, you put down solder paste lay your components on top and bake it in a toaster oven until all the solder has melted. You then tap/drop the oven while the solder is still melted to get everything to set properly. I here you can also do it with a hot plate/gridel. Just remember you probable don't want to eat from the oven/hotplate after you do this.

I thought I would take some pictures from my recent playing with the new Luxeon Rebels but it didn't go as planed. My solder paste is very old and dried out, It is supposed to be refrigerated while in storage and only has a shelf life of a couple of months. I have been scooping some out and mixing it with 99% rubbing alcohol to weten it up. This has worked rather well for me until this attempt. This time I tried re wetting the leftovers from the day before and it seems I must have washed the flux out of the mix. Some of the solder never flowed causing me to leave the board in the oven so long that the board turned nearly black. All of my connections were made and the LED's still work, I definitely did not follow the recommended soldering recipe. I had to use a hand soldering iron and some flux cored solder to clean the project up. This leads me to think one could possibly make due without having solder paste. If you pre tined the PCB pads and the contacts of the Rebel you could probably then bake it and all would come together. The problem with hand soldering these is you have to have all 3 pads melted at the same time for the part to set flat.

When pulling it out of the oven I check all the LED connections using a Multi Meter on the continuity check setting. Mine provides enough power to cause the LED to glow if all is good. If not nothing happens or I get the buzz. If I have a problem I place it back in the oven and use a pair of gloves and some tweezers to slightly adjust the parts once the solder has melted.




My board has several small vias under the LED heat pad that help conduct heat the the trace on the bottom of the board. I pree tinned these vias because I didn't want them sucking up all of the solder paste and not allowing any for the heat pad. The potom of the board is stuck to a heatsink with screws and thermal grease. I am quite pleaded with the results.

I also hand soldered one to a Copper sheet for first my first time playing with one. I pre tined the LED heat pad and the copper sheet. then used the soldering iron to heat the copper sheet a little above where I wanted the LED and placed it with tweezers once the solder had melted. I then soldered small wires the the + - Contacts that were hanging off the sheet.

 

[sysadmn]

Wow! Thanks for posting.

 

[chris_m]

How do you get your PCBs made? Would really like to be able to make something like that, but my homemade method doesn't allow me to do proper vias (which are essential for heat transfer).

Am actually planning on mounting Crees using a method similar to your bottom one, soldering the slug to a small piece of copper in order to raise it enough above the main heatsink to solder to the bottom connections. Should hopefully make for better thermal transfer than glueing straight to the heatsink, given the area of copper is much greater than that of the slug. Will post details if I have success!

 

[Brlux]

I really like using ExpressPCB. They give you a free cad program which is quite good and very easy to learn. They also offer an inexpensive prototyping service. For $59 shipped you get 3 boards which have to be 3.8"x2.5" they are double sided with plated through holes. They don't offer solder masking or silk screening on the prototyping service. You get the boards prity fast, at best about 3 biusnes days. They ship UPS 2nd day, if I get my order in early Monday morning I can sometimes get it delivered on Thuresday.

As far as soldering the Crees to the copper strip, it sounds like a good idea and like it would be a good candidate for the oven/hot plate soldering method.

 

[Blinding]

Read a really interesting article about making a tool for doing surface mount soldering. They used a desoldering iron from Radio Shack. In place of the rubber suction bulb they added an aquarium pump so it would blow a tiny jet of hot air. Supposed to work quite well. Planning to make one some day.

 

[TORCH_BOY]

I use a heat gun to mount SMD components

 

[Brlux]

I have read that article and it seemed interesting. They have high end soldering irons that work similar to that using a very fine stream of super heated air to solder.

I have also used a heat gun but found it tended to burn components that were being soldered to large ground/heatsinking contacts when I applied the heat from the top. It worked better for me when heating from the bottom of the board.

 

[OddOne]

I feel compelled to insert a shameless plug for my how-to article on building a controller for reflow soldering, as it adapts well to ovens and griddles and hotplates oh my...

oO