I probably didn’t give them near as much info as needed for the inquiry: I basically asked for approximate figures for producing 100 or so copper core 32mm or 16mm boards designed for a single XM or XP LED footprint with the core material being 2mm (for the 32mm boards) or 1.5mm (16mm boards) thick copper.
I think this is only worth doing / paying for the efficiency gains if the center pad of the LED is directly bonded to the copper core otherwise I fear we will be left with something not much better then a normal aluminum star. Surely this is as simple as placing something over the right spot on the PCB during application of the dielectric and other masks?
If its not too much of a bother PilotPTK would you mind doing whatever you have to do to the gerber file to ensure this is what is happening? Then I will send them another inquiry with the file, correct terminology, volume and material specifications.
I like the idea with using multiple footprints on the single board but with some reflectors that push against the board this might cause shorting.
As for the dimensions of the screw holes: on the 32mm boards I have in front of me they are 2.5mm in diameter and the center is 2mm from the edge. Whats peoples opinion on where these should go?
Googled Sinkpad and this is what came up:
SinkPAD™ technology has magnitudes higher thermal efficiency than even the very best MCPCB in the market. SinkPADTM MCPCB is available with Aluminum base metal or Coper base metal. Aluminum based SinkPADTM MCPCB can transfer heat at the rate up to 135 W/m.K compared to the conventional MCPCB of 1-4 W/m.k. The rate of transfer for heat can be increased up to 385 W/m.k. by using copper base SinkPADTM MCPCB.
I wonder if this is just the same as the LEDtech copper MCPCB?
Hmmmm I’m going to try request a sample from these guys and send it to Match for testing.
EDIT: After a bit more digging it appears this is exactly what PilotPTK was talking about: simply a lack of any dielectric material between the main LED base and the metal core.
@Manual Man
It looks like the first quote was for aluminum MCPCB’s, seems a little on the high side.
I had an aluminum MCPCB quote for some 34mm stars from circuitgraphics.com and it came out to about $5 a board at quantity 80 pcs. (includes a $150 NRE setup fee). Fairly reasonable all things considered. You are going to have to up the quantity substantially. Don’t know if they do copper boards or not, but you can email them and see.
A regular thin FR4 PCB with proper thermal via’s is about equal to a standard MCPCB. Neither of those will be anywhere near as good as direct to copper.
But those from DX and various other sellers do. If all it takes to raise heat conduction from 1-4W·K−1 to 50W·K−1 (thermal conductivity of solder as I think this will be the limiting factor) is a quick touch up with a Dremel I am all for it.
I actually havent found any real copper PCB so far. I dont know about those from DX right now, but I remember I asked someone over at CPF about them and he said they werent copper.
If there are some from DX and "various other sellers", please share. :)
I stand corrected then. Regardless I think provided you can solder the LED directly onto it it should provide a substantial cut back in thermal resistance due to the removal of the dielectric bottleneck.
The “various other stores” were Intl-outdoor (no longer sold) but it turns out this would not work with them anyway… Intl-Outdoor's "Copper" XM-L MCPCB, I’ll get back to you once I find the “other” stores I was talking about.
Another double post but SinkPad just emailed me with the following:
1.6mm thick copper core 20mm XML and XPG boards with direct copper-LED bonding!!!
The have also offered to give me a quote for the above 32mm boards so will inquire about those but I think the above could work out very cheap as they have them in stock… :bigsmile: :bigsmile: :bigsmile:
They have XPG to but I cant be bothered putting the picture up: it looks the same with the XPG footprint instead of the XML. I will ask for pricing of 100 of each.
