So how hard is it to reflow solder?

I'm trying to upgrade my Fenix E21 to an XPG high CRI, Illumination supply finally got some in on boards, 10mm, not the 20mm I really needed and I thought I could make it work. I can't! The board is thicker and the bezel has to be tight to get both modes to work, no real way to mod it all etc.........
So, I measured and the dies are the same size, and I've read and read on this, but it's still the unkown to me!
So how hard is it really? How much heat? How much heat is too much heat? Meaning I don't want to melt the die's!
My "plan" is to set both of them in a pan, heat them together facing the same way, then remove the one from the original board, immediately take the high CRI die off and set it on the old board and let cool. Good plan or not?
Sorry for the newbie questions, I don't mind having to get another LED, but I don't want to screw up the original board!
Thanks for any and all help/suggestions you can give me on this!

It's not hard, but it can be tedious if you don't have the right stuff, such as soldering paste. Here is an example of someone using a temperature controlled heat gun, but you can use a soldering iron. Just apply solder paste to the LED pads on the board, put on the LED after making sure of polarity, hold the board with hemostats or needle nose pliers over the soldering iron until it melts, allow to cool slowly on a non- heat conducting surface.The most important concerns are not exceeding recommended temps and heating times (Don't heat too quickly or cool too quickly). Also don't use too much soldering paste. Read the data sheet for the LED you will be using for specifics concerning heating and cooling the LED. Make sure your boards are clean (Free from any) contaminants. If you have any fried emitters/old boards you can use those to experiment with to get a feel for reflowing. Good luck!

If you have helping hands and a heat gun you can do it pretty easy. Put the emitter board in the helping hands to where it's level and use the heat gun under the emitter board (I use high) and hold it close for just a few seconds and you will see the solder pads start to turn molten. Use tweezers to remove the old emitter and remove heat. Place the new emitter on the board and repeat the heating process, when the solder goes molten the emitter will settle into place or can be adjust while hot if it doesn't for some reason. The key is not to worry or over-think it. Be sure to remember the emitters orientation before removing it.

Jamie

FWIW: I prefer reflowing over just swapping boards out for the reason you mentioned about the boards having different thickness.

Thanks guys! Guess I need to go see the neighbor and borrow his heat gun, hope I orient them right, and hope the wife leaves soon

Well, much ado about nothing! That was sleazy easy! Took maybe 10 seconds over the heat gun to take the new one off, set it on a cast iron pan to cool, took the old one off, aligned it, heated it about 5 seconds, moved it center and let it cool off!
It's mostly centered in the reflector, about like it was from the factory, and it's the beautiful yellow light I love, no more blue!
That's twice you've helped me on this light Jamie! Thanks a bunch!

your very welcome. I'm glad you found it easy to do, I was just about to post a pic of an emitter with a rough diagram of how to tell pos and neg on the emitter.

It is quick and easy after you get past the thoughts of possibly ending up with a dead light.

I've no idea on the pos and negative on the emitter, so that would be great! I just noted which way the contact pads (the little tabs of solder on the two corners were) and put the new one on the same way. I guess I got lucky there?

For removal of small SMD parts in the future, it might be worth your while to pick up a ChipQuik kit. This kit includes some low temperature solder that blends in with the existing solder and stays molten longer, making it easier to remove it.

Here's what I did.

http://www.candlepowerforums.com/vb...d-Pic-Heavy.&p=3909400&viewfull=1#post3909400

Very slick! I'd have had to use a pan of some sort, induction oven, to make that work, but doable! The heat gun really worked better than I could have dreamt, and the XP-G's look about 1/4 the size of that emitter!
But Think2x really has me curious on how to tell pos and neg on these things! Mine was easy to do, XP-G for XP-G, but if I do more in the future it may not be that easy!
I've got that Lumapower M3 Transformer in the storm shelter that I'm just itching to upgrade to HCRI, even though we hope to never use it!

Didn't have time last night, the wife and I had a Netflix night without the kids. Here's the basics of the XP-G,XP-E and XM-L. FYI: if you do get it reflowed backwards on the board just wire the board up backwards to match(done that one once :shrug The center pad is isolated from both connection pads. I always use a cr123 primary and jumper wires to test an emitter board after reflowing to make sure all is well before putting it in a light.

sawlight said:

I've no idea on the pos and negative on the emitter, so that would be great! I just noted which way the contact pads (the little tabs of solder on the two corners were) and put the new one on the same way. I guess I got lucky there?

Click to expand...

Using the 'power' of search/google on the web...

Search for Cree XPG and within the first few hits will be the datasheet for the XPG. It contains specs etc AND drawings that show how to identify the anode (+ve input).

Or click http://www.cree.com/products/pdf/xlampxp-g.pdf

cheers,
george.

Thank you both, I just thought it might be nice to have it all in one thread, that's easy to search on CPF in case another member where to want to try it also.
Think2x had offered the pics last night, that was the only reason I asked him to post them as I had already gotten my project done. That and information isn't always a bad thing to have!
Again, thanks for all the help with this, I can't express how pleased I am with the outcome! The switch from low to high isn't much, it wasn't much to begin with, but with the lower efficiency of the HCRI the difference is even less discernible! But man do I love the tint!!