Yea Scott, the price of your boards can’t be touched. Now that’s designing for a budget.
I don’t have anything to add to the project. But I know I would be a customer for a bunch of them. I have about 100 or so 502B’s not that I want them all to end up quads but I would take at least 25 of them.
I certainly don’t need that many myself but it seems doable for both Hoops’ version and a budget model.
I've already got an Oshpark board that I threw together last week, but as usual it needs to be tested before it's ready for "showtime".
Great! I have a feeling from what Pilotptk did with Scaru’s board and the 35mm driver on board that it needs to be thinner than Oshpark can make them but if you have a fab for .4-.6 mm count me in. I also have a few extra Khatod optics if you’d like to see for yourself.
Nice project. I can’t wait to see what you all produce. $12 a board for thick copper in a quad, that might not be so bad. Especially with all that heat as I’d have to use XPLs.
The Oshpark boards are so pretty, I really like them a lot. But they aren’t direct thermal path.
Hoop’s design looks nice. I wonder if that could fit into a convoy M1 with a copper spacer and a tight Katod optic array.
It certainly could. The M1 and 502B both are 24mm ID down inside but the M1 flares out to a larger diameter at the bezel to accommodate a bigger reflector. It would be a good candidate for the 35mm PL 251106.
The Oshpark board and any production run of thinner fr4 boards would be DTP just not solid copper thermal pads but instead solder filled vias. At this point silver filled is also a possibility but my uneducated guess is that it would not be a budget option.
I think that if done properly the solder filled bias work pretty well, but are more work than most would like. You really need to fill them fully, which always spills out onto the backside, which then needs to be made flat again. The ideal thing would be to have a 4 oz copper board made because you really lose out on the heat spreading capability on the backside, but at that price and volume point you might as well go all the way to an MCPCB. I don't expect that these will perform as well as a DTP copper MCPCB in a direct drive scenario, but at 2A-3A per LED I think they might be a viable solution.
hmm. If the board is set onto a piece of stainless steel plate or ALU when it’s soldered it might not require much backside cleanup, as long as the vias can fully fill this way.
Just a thought, would it make more sense to give the thermal pads 2 or 3 larger vias sized for 14 solid instead of several small vias filled with solder? With maybe 2 or 3 more to either side as in my sketch. Might have to adjust the wire size and via number to ensure the via doughnut is entirely on the pad.
As long as you don’t mind the work to add the wire pieces the copper should be better. The extra work might be more than some people want to do.
1mm-1.1mm dia vias would fit. 17, 18awg wire. 3 x 1mm vias fit under the led, then I would suggest just small solder filled vias on either side. I don’t think you would get as much return for your effort in adding copper wires into the side vias.
3 x 1mm vias vs tiny vias.
I could make up board and upload to oshpark if you would like to try.
That looks great Helios. I like the way Hoop made the jumper pads work for 4S, 4P, and 2S2P. Two mm holes at 8.5mm and 11mm radius don’t overlap so we won’t need slots for that. I’ve been in communication with him about the possibility if combining a fabbed board with a milled plate so I think he should be involved in the design of the Oshpark boards but I like this and believe it could work with his ideas. I’ll let him fill you in.
The PL115106 or PL115125 datasheet shows the pins are at 10.27mm. That overlaps with the 2mm holes at 8.5mm.
I would in interested in 5 or 10 depending on final design/price. I would prefer non-wire filled vias because it would be nice to be able to drill out some of the boards' thermal pads for a heftier DTP copper solution. Just for high current applications. Seems like wires would screw with drilling clean holes.
Adding wires would be a DIY option. Hoop might do base plates with milled with risers to fit reamed pcb’s but needs to mill the slots in the pcb to match. Having boards designed with wire vias allows for a simple DIY option of just adding wires, a more complex option you describe of reaming out the center pad for a larger fill, or going all in with a matching milled base plate and pcb by hoop.
You’re right of course Helios, I was looking at the wrong thing. The pegs do overlap which might be an issue if we stick with Oshpark unless we opt for your idea of one pair of holes at each radius and have to sand off the adjacent peg pins at the step. There’s also the issue of the pegs shearing if there are only two instead if 4 indexed to the board. If you just cut the other set of pegs off the optic will rock since it doesn’t sit directly on the LEDs. I’d rather not have to do that but we should keep that in mind. Another possibility is just having different pcb’s done for the different optics including maybe a larger 31mm version for X6’s.
I should add that while I think collaborative efforts represent some of the best of BLF I’m not assuming it can be done this way, I just hope it can.
Design the board as though I never interjected I would say but know that I can modify existing boards.
Here’s the example with a 1oz trace board; my first attempt at this process so forgive the imperfections. The thin sheeting needs to be held down better for perfect flatness and I need smaller end mills than I currently have lying around. The copper dtp portion is milled into the end of a 1” bar of stock which is to imply that I can do this process directly onto a copper or brass pill or a copper light head, etc. pic1. pic2. Please do not repost those as full images in the thread.
Pretty cool! The center pad looks wide. Is it for an XML? What is the range in thickness for the bar stock base(24mm dia x (?))?
If milled as a 22.5 or 24mm pill with a driver recess and the correct DTP pad height how would that affect cost? I don’t know the total stack height of a p60 drop in vs Khatod optic/pcb/pill but I’m guessing in the 15-18 mm range for a pill/DTP sink.