Soldering millimeter components (Cree LEDs)
Soldering millimeter components (Cree LEDs)
(OP)
Hi Guys,
I recently bought myself some Cree LEDs ( XL-M 3 RGB + White ). I am planning on using a micro-controller to generate a light(colour) profile.
These lights are normally used with the four LEDs connected in series (with pre-fitting PCBs), however I require each of these to be individually set.
I have a relatively narrow soldering iron tip (& station). I have already spent hours frustrating away trying to solder leads, along with solid connectors.
I have managed to solder onto some of the legs, but it really isn't pretty. There is a largish copper heatsink inside the centre of the LEDs which needs to be flat (Adhesive heatsink).
Is there a better way to approach this situation ? I only have about 5 millimetres to solder 4 pins. Should I be trying different hookup wire ? Using a hot air gun ?
Thanks in advance (Soldering these devices is not recommended by the manufacturer - However I don't have any other method available)
Martin
I recently bought myself some Cree LEDs ( XL-M 3 RGB + White ). I am planning on using a micro-controller to generate a light(colour) profile.
These lights are normally used with the four LEDs connected in series (with pre-fitting PCBs), however I require each of these to be individually set.
I have a relatively narrow soldering iron tip (& station). I have already spent hours frustrating away trying to solder leads, along with solid connectors.
I have managed to solder onto some of the legs, but it really isn't pretty. There is a largish copper heatsink inside the centre of the LEDs which needs to be flat (Adhesive heatsink).
Is there a better way to approach this situation ? I only have about 5 millimetres to solder 4 pins. Should I be trying different hookup wire ? Using a hot air gun ?
Thanks in advance (Soldering these devices is not recommended by the manufacturer - However I don't have any other method available)
Martin





RE: Soldering millimeter components (Cree LEDs)
Ideally you want to get some preheat into the PCB using a hotplate, or even a chunk of metal heated in an oven, if you possibly can. You need the pre-heat to reduce thermal shock and take the mechanical stress out of the joint, and most of the fluxes work better with some preheat to help activate them, but for prototyping I guess you could forego long term reliability for ease.
RE: Soldering millimeter components (Cree LEDs)
Dan - Owner
http://www.Hi-TecDesigns.com
RE: Soldering millimeter components (Cree LEDs)
That's tiny and beyond anything I've ever done by hand. A binocular microscope or head-mounted magnifiers would be mandatory. You'd need a pick to hold down the components, otherwise the surface tension of the molten solder will have them sticking to the iron. Obviously steady hands and skill.
I doubt the hand soldering technique would work at this scale. It's too small by about 2:1 ratio.
RE: Soldering millimeter components (Cree LEDs)
Nah, I do that scale every day (and smaller). The eyesight started really going south once I hit 40, but I can still do 1mm pitch components by naked eye... but I routinely do 0.5mm pitch and smaller using a microscope and a fine-tip iron. For one-off and repair work it's done every day in shops all over the world, but production-level work would obviously never stand a chance.
Dan - Owner
http://www.Hi-TecDesigns.com
RE: Soldering millimeter components (Cree LEDs)
I gather you're attaching flying leads to the pads on the underside of the LED, and gluing the heatsink on? If so, remember to tin the pads and your wires first - put a dab of solder on the wire and each of the pads before trying to bring them together. If the solder ends up bridging some of the pads, cut the intersection away with the knife. Then bring the wire to the pad while you heat the pad. Most importantly: as soon as the solder runs together, take the iron away and hold the wire in place - don't try to overdo the iron work. Get in, get it soft, then get out. You can always trim up any messy bits with the knife afterwards.
RE: Soldering millimeter components (Cree LEDs)
Second problem is that those LEDs dump boo-koo heat and if you don't have the large pad correctly soldered to heat-sinking the LED will self-immolate promptly anyway. You cannot get that package thermally connected with wires soldered under it. No sticky tape heat pad will not work against the LED's base.
You need a star board that accepts that LED. Have you looked for one?
Your 'tape' thermal tape will work under a star board.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Soldering millimeter components (Cree LEDs)
Next step up is to use a toaster oven on a custom pcb. Get your pcb cheap (if it is small) thru OSHPark. About $10 total (including shipping) for a batch of 3 if they are about 1" square. Watch how to do the toaster oven soldering on YouTube. You can manually place the solder paste using the stereo microscope.
As a side benefit, if you ever get a splinter or glass shard deep in your hand or finger, you can use the stereo microscope to find and pull that puppy right out in no time flat.
RE: Soldering millimeter components (Cree LEDs)
44AWG enamel coated wire:
http://www.ebay.com/itm/like/261086012879?lpid=82
Some inspiration:
https://www.youtube.com/watch?v=tNlad2Dl1A4
RE: Soldering millimeter components (Cree LEDs)
Then its simply a oven reflow or hot air gun process to attach the LEDs to the PCB's.. Then you can solder wire to those or TE has quite a few "solderless" LED holders/mounts to choose from.
There is no need to use a hand soldering iron and you really won't be successful with them.
Heck you can even reflow in a frying pan.