Anyways, I think we should rather be talking about the best ways to isolate the board, if we don’t go the way of having cathode across the entire housing of our lights. Aluminum nitride can be bought cheaper at some chinese suppliers at alibaba for example, but the thing is, you’d have to have two additional layers of thermal compound. With some pad or thermal foil (both insulating type of course), you wouldn’t have to use any thermal compound in between and such a foil usually comes in much thinner as a disc or sheet of ALN.
That's what I was talking about earlier. An MCPCB manufacturer could assemble emitter boards with a foily layer of Aluminium Nitride as dielectric. That's it.
Yeah, or diamond PVD coating. But with this board, as it is, what would be the best, affordable way to put it to a good use? What’s the best foil for this application?
Guys, please remember that AIN coated MCPCB can’t conform to irregular rough surface as good as soft thermal pad. This fact offset its benefit. Unless, you always have to lap your heatsink/pill to near perfect FLAT mirror like finish.
Thermal pad/adhesives is the way to go for our application and my current budget.
clemence, I only said slots, not holes. Two holes, and 2 slots at each hole's sides. This allows routing two thinner wires per slot, resulting in a flatter profile, handy when you have a retaining ring screwing down over the board (I think Noctigons suck because of only 2 slots). :-)
For the 20mm:
Do you need the screws to be completely flush with the board surface (countersunk).
OR…
Is it OK to just let the head protruded (normal M3 x 0,5 screw head)?
In many flashlights they are just pressed down by the reflector, or adhesive is used under the board, this is especially common for 16mm boards. 20mm boards are sometimes screwed down. The holes in the board may best be somewhat wider than the used screw, to have some wiggle room to center it under the reflector. Thinking of that, it may be a good idea to not make countersink holes.
I thought so too. With countersunk holes, the free play is limited. It’s also easier to isolate the screws from the board (CDTP limitation).
You know what Djozz? “CDTP” is popularized by you! You were the first to use that term, AFAIK
- The (three) designs are 90% ready for upload, only holes/slots placement left. I also design another aluminum square DTP 30mm x 25mm linear 3535 single/triple config exclusively for use with LEDIL STRADA and SHELLY
- ASAP in early February. But please, please, don’t take it tightly. I’ve been trying my best to be a faster designer/provider, yet still not fast enough for BLF.
Will TRY to bring them here at approximately USD 3 - 4/pcs
No, plain washer still expose the screw thread to possibly contact to the MCPCB body
You have to at least use waisted/flanged washer to insulate both the screw head and the thread body, otherwise you’ll screw it. But flanged washer will need bigger holes. Normal clearance fit for M3 x 0,5 is 3,2mm. With flanged washer you have to open up to 3,8-4mm minimum hole diameter.
With plastic screw you can save the precious surface area and simplify installation. Plastic screw comes in wide variety of materials and designs.