Here, I’ll link that Cutter video again. Go to the 9 sec mark.
Draw a thin line of solder paste that goes across all three pads. You don’t have to smear it around. Just set the emitter on top of the paste and gently place it in position. Then add heat. The heat will take care of the rest.
Do all three at the same time.
Don’t over think it.
rojos,
Thanks again, and you’re right. The longer it takes for the parts, etc. to get here, the more I’m thinking about it, and not doing it :)!!
EDIT: Oh, oh. Looks like the emitters and PCBs are going to arrive today from IS (their shipping has always been super fast), but the solder paste is still not going to be here for a few days :(…. So I get to stare at the parts while I wait for the paste…!
I use a hot plate from work. Works great and I have better heat control.
I use a hotplate made from a 12V 30W solder iron on which I mounted a small block of aluminium, connected to a adjustable bench power supply. After some trying out, the heat regulation is very precise (reflowing a led on a board works best at 10.7 Volts). The only disadvantage is that you can not just remove the heat like you can with a small butane torch, you have to remove the led board from the block for it to cool down.
ditto what Rojos said, don’t over think it. Although it’s not as precise as a reflow oven, a stove top is perfectly capable of producing good repeatable results. If you’re worried about the star falling through the ring (blech), use a piece of aluminium plate or a frying pan.
Put paste on star (all three pads). I also put some on one of the + or - pads as a visual aid for when the solder starts melting.
Put LED on star.
Put star on hob.
Set hob to 2 or 3 or whatever corresponds to about 1/3 power.
Sit down and watch
Paste will turn liquid grey (starting to melt) then shiny silver (melted). At that point the LED should suck itself down and squidge the excess out.
Turn off hob. Move star/ plate/ pan to adjacent unheated hob. Don’t touch for a while, they’re really hot.
that’s it. Simple as pie. I’ve done 20 or so like that without a single problem, even an LED on a stinkpad pill.
Darn! I knew that this would happen :(!
I ordered the emitters and PCBs from IS (four XP-E2s and 2 parallel 3up PCBs…. just in case), and the solder paste from Ebay…… and the emitters and PCBs arrived today already, but no solder paste!!
Darn IS ships so fast (as usual)!! If Craig or Calvin happen to read this post - SLOW down!!
JUST kidding :)!!
FYI, I am going to wait for the paste, because I haven’t worked with it before (seen wave soldering many times in factories, though, which is different), so I want to try it (paste).
In the meantime, I’ll keep myself busy ohming out the parallel PCBs so I know how they’re “wired”… been curious about that.
Stupid question: How do you get the emitters out of the carrier strip that they came in?
I peel back the clear part with a pair of tweezers.
Peel it back to expose just one emitter at a time or peel it all the way over a bowl.
That Ebay seller I ordered from is sure taking his/her time. I have a tracking #, but it’s stuck. Not recommended. I emailed him/her tonight, but haven’t heard back yet.
I have a feeling the he/she accumulates some orders before fulfilling the orders :(….
So, I’m back to thinking about just using regular solder again. I’ll wait until this Saturday to see if it gets here, but I’d like to get it done this weekend, if possible.
EDIT: Looks like my message got his attention - he finally put it in the mail, and it’s on it’s way. Hopefully will get here by Saturday so I can try this reflow!
Those XP-E2s are really hard to find when they fall on floor under your bench! Don’t ask how I know that.
same way I do I’d imagine 
I reflow via the soldering iron method as shown in the video below.
I prefer this way as you can somewhat control the heat ramp up stage.
Great info in this thread. I think I have reflowed almost every way except with a reflow oven. For me, a heat gun used under the base while in Helping Hands works best. I just have a cheapo heat gun from Harbor Freight and it works great for all kinds of things.
So, with this, you put the star on a small metal piece, and then some solder on the metal piece (presumably to get heat transfer), and hold the iron until the star heats up enough to cause the reflow?
Do you have to put some thermal compound under the star when you do this (again, for heat transfer)?
Also, how big (watts) is that soldering iron (or the one you use)?
I like this approach, like you said, for controlling heat. I have to find a small metal plate like that :)!
Hmm, I was just going to buy a cheap hotplate, but I might go with this method. I have the same heat gun. How close do you get it to the MCPCB?
The rest makes sense but I don’t understand this statement. Solder has higher heat conductivity than air does, though not as much as copper or aluminum. Do you mean the extra solder will make it float up and make a wider gap?
Yup, use a piece of aluminum so solder doesn’t stick to the plate.
Yup, I use a tiny blob of thermal paste (you don’t need much). I then press down on the star with tweezers so the paste spreads out between the star and plate.
I use a 50 watt iron with a extra tip that is not wide. No need for a fine tip in this application.
For small pcbs (16mm or less) I have actually used a spare/junk 20mm aluminum star as a plate. If you are working on larger stars then you will obviously need a larger aluminum metal plate that is larger than the star (but not too big).
Yes.
lilkevin715,
I wonder if the lid from a can would work, i.e., cut the lid off of a can and use that lid, assuming it has enough flat area so that the star can sit flat on it?
Assuming the lid is made of aluminum and relatively flat enough sure it should work. Only one way to find out 