I’m thinking of having some solder paste stencils laser cut out of 3.5 mil Kapton sheet (much nicer than mylar, much cheaper than stainless steel). They would be around 1 x 4 inches and have patterns for the MTG, XRE, XML, and XPG. You would use them to neatly (hopefully) apply solder paste to stars for reflowing (align the cutout over the star, squeegee the paste through the cutout using something like an old credit card). Price would probably be around $3
Ignore the white marking in the image, the pattern is the red part. Also, ignore what looks like uneven gaps in the patterns… that’s due to image pixel limitations.
I’d be up for one. Could I talk you into adding an XML-Color? The stencils have been shrunk down how much from the actual footprint? and wouldn’t you leave off the overflow on the anode and cathode?
The patterns for the XML and XPG are what CREE recommends. I believe that paste on the nubs helps wet them and enhances their ability to wick out excess solder. These stencils are 0.0035 inches thick… you will be getting a MUCH thiner and more consistent layer of solder than any manual technique.
The XRE and MTG are a bit different. Mine have the full area under the the thermal pad pasted. CREE’s have a smaller area pasted on the XRE and four blobs under the MTG. They also have the overflow nubs. That should work better for the way we tend to use them… heavily overdriven and manually pasted and reflowed.
Probably won’t do the color XML and MCE any time soon… I might do a “weirdo LED” one later for other models.
Plus, you can’t get a nice, even, controlled amount of paste using eyeball techniques. Even worse is trying to tin the pads with solder. Most people don’t realize just how little solder it takes to do it right… 3.5 mils is about the thickness of a sheet of paper. Hopefully the Sinkpad/Noctigon stars are planar enough to be able to handle it.
I almost always get too much paste on there, and have to press down on the emitter with tweezers o squeeze it out. I’m in for two. Can you get a price on Stainless ones?
OK, I’ll stick with the $3 option and get a backup one.
Oh, any way to add duplicate XM-L and XP-G stencils on the same sheet without driving up the cost much? Those are the ones to get used the most, and therefore get worn out first. Just a thought. I’d still order two.
Based upon the size of the stencil sheet, it works out best with the four patterns on it. They are cheap, just buy more. With a little care, they should last longer than you…
