what do you think about this?
is it good for reflow emitters?
https://www.ebay.co.uk/itm/T962-Infrared-Solder-Led-Free-Reflow-Oven-Windowed-Drawer-IC-Heater-180x235mm/253416094785?epid=2271205256&hash=item3b00c6bc41:g:~WgAAOSwi49bHzgK
Or for a small fraction of the cost… 
Cost only as better flashlight.
That would ok if you are using a solder stencil to ensure that you get the exact amount of solder needed on the LED pads. Personally I think the electric skillet is perfect because if something goes wrong like one of the LEDs sliding out of place I can make adjustments while it is still hot.
What’s the trick with smaller emitters like nichias? Those who have reflowed nichias likely knows what I’m talking about.
trailhunter you mean 3.5 × 3.5mm “3535” emitters, doesn't it? Samsung 351 series, Nichia 219 series, Cree XP series, etc.
These are just smaller emitters. Treat 'em skillfully, with a little more care. Keep good track of reflow temperature. I personally use a pan on an induction stove to reflow. I monitor temperature with an IR thermometer. It's quite easy for me to make MCPCBs hover at ≈200°C or just a lil above that, so no worry of excessive reflow temp. I also keep my hands quite close to the emitter and MCPCB, maneuvering with tweezers, toothpicks and cotton swabs, allows me to sense the temperature in my hands. I use cotton swabs to gently press down the emitter and remove any excess solder from the sides with toothpicks, after first sliding the emitter to check for proper solder soaking on the underside (I use very little to start with). Next I center the thing, then remove power from the stove. Upon cooling, with the MCPCB still hot but well below solder melting temperature, I usually lay a drop or two of alcohol rosin flux over the MCPCB to remove any signs of oxidation. After cooling down minutes later, a quick alcohol bath and done.
:-)
Mmmhmmm, I’m much too under the influence to give a cognitive response, however, I have plucked a few words to make reasonable mea ing to your answer. In Simplistic terms, yes? For example 219bs where rosin lifts the emitters due to their size and weight, for exampme.
But I think you answered the question quiet beautifully and honest in nature. I will use Q tips for lack of a better term, as well as compressed air to free the small bodies of solder that lingers behind as a method to keep such small emitters as level as possible to the mcpcb
Pop/Tap/Smack them on top of the dome to force out excessive solder, (most) mcpcb’s have overflow gates on the solder pads just for this purpose. I use the flat fat end of my tweezers
For you or the LED? :laughing:
For the MCPCB, led and maybe for my hands if 
dirty. Alcohol works best outside of my body, at all times. The associated spirits have no business in my subtle fields.
Bath as in you literally dunk the entire MCPCB+LED in an alcohol solution? Is it also necessary to use 99% isopropyl alcohol? Will there be downsides to using a less percentage alcohol?
A 219B is quite easy to reflow with minimal experience and equipments but fragile E21A always get me nervous which doesn’t help during reflow particularly on a Clemence’s quad VR16SP4, I tend to reflow the quickest as possible to not overheat emitters but I would better stop to be anal with quad LEDs alignment for better serenity. :person_facepalming:
mitsuki08 I always use denatured 96° ethyl alcohol, I can buy it cheap in supermarkets or chinese stores. Never seen 99% isopropyl alcohol around here, at most 70% with who knows what crap else at only a bit less money than denatured 96° ethyl. No electronics or related specialized shops around here.
91% IPA is about the max. Forms an azeotrope…
Just checked and can get 99% Isopropyl Alcohol from Walmart
Yeah.
99% isopropyl alcohol uses a neutral dehydrating agent to create almost pure alcohol.
Just read concerning the azeotrope thing, now I understand why the denatured alcohol I buy is 96°/96%, its actual ethanol ratio is very close to that figure. Its denaturing agent is a 0.064% of benzalkonium chloride, helps making it more efficient in skin disinfecting duties, and I guess it also makes the mixture nasty enough for ingestion purposes.
:-)
I’ve only done one so far, using this video as a guide - an LH351D. I was surprised how smoothly it went despite the small 3535 size.
I was especially concerned about getting too sloppy with the solder paste on such a small solder mask, but after wiping away a little bit of the excess between pads with a toothpick, once it melted, surface tension pulled it all magically together over each pad with no bridging. I was a bit too gentle on the first tap, and ended up with some solder beads adhering to the side of the emitter base, but was able to wipe them away with a toothpick or tweezers.
I didn’t have an IR thermometer. I put a drop of canola oil on the pan as an indicator to turn the temperature down if needed (Canola oil smokes at 400 degrees F). Then I slowly heated the pan on medium until the solder melted, and turned it to medium-low while I played around with the curious springiness of the LED.
Never tap or even touch the LED top during reflow whenever possible. Use proper dosing of solder paste (stencil is the best). Excess solder is better sucked not squeezed. It’s not a good practice. The silicone binder in the phosphor layer and the dome soften during reflow. Use any means of temperature monitoring. Faster is better, use the lowest temperature required to get the job done. For 63/37, I never want to exceed 210C. And no more than 240C for SAC305. 260C is the standard for automated machine reflow oven. With manual reflow soldering, usually you’ll spend more time.
[Clemence]
Hi Clemence, Thanks for sharing your experience. 
Using stencils is great if you have, and know well how to use them. With small XP size emitters I much prefer to do that, or definitely if doing a large batch of any size LED. For single LEDs I think the dome tap is just easier for people. Large foot print emitters like XHP70 have a tendency to get an imperfectly smeared paste when using stencils. If it’s not the perfect consistency and temperature you can get thin spots. Pushing out the excess solder in my opinion can actually create a better thermal path than even using a stencil because it puts the LED down as close to the base metal as possible vs floating it on a thin layer of solder. Not a good plan for mass production for sure, but for a modder wanting to swap mcpcbs it’s great.