Thought I’d just give you guys a heads up. I ordered three of the XM-L U2 emitters on 16mm copper MCPCBs (w/ brass cap) from Intl-outdoor (link) in early June, received them a few weeks back. I realized that what I received was different from the pictures on their website, in fact the MCPCBs I got seemed like FR4 boards with thermal vias.
What I thought I was getting:
What I got:
So I sent an email today to Hank asking about it and this was the reply I just received:
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Hi, Moses:
Please be advised that what you received are the latest “U2 1A 16mm Copper MCPCB”,
(in the attached), the heat resistance is close to zero.
The one on our website is the old version which will be updated today.
The old type can get rusty after some time.
Sorry didn’t let you be aware of it in advance.
Regards!
Hank
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I doubt the heat resistance for the new PCB is “close to zero” and I was looking forward to real copper MCPCBs, but I’m going to let this one slide since Hank’s been good so far.
Well the ones I received and I guess the ones that Intl-outdoor’s been shipping since June are not copper. They are definitely not aluminum either, it’s most likely FR-4, which is the same stuff driver PCBs are made from (FR-4 wiki).
I’m no expert on this by any means, but from what I’ve read on FR-4 and thermal vias applications so far, they seem like a more cost-effective route than “full” metal core PCBs - from a materials standpoint that is. Cree provides FR-4 PCB design suggestions in their Optimizing PCB Thermal Performance application notes.
30 ºC/W is for an FR-4 board without thermal vias, it should be way higher than that with thermal vias, but still lower than the thermal conductivity of copper or aluminum.
Rusty boards?sounds like a shady supplier,I, glad to find out about this before I ordered some of these.True copper boards would be great but seems here another fail unfortunately.
I did get the old version board and it did have a bit of oxidation on it, not too bad though. Looks like I will be avoiding these in the future though.
The thin black one is from DX and the fat black is from Led-tech, don’t remember where I got the white star.
I don’t appreciate their customer service as they don’t reply on messages but their shop works flawless.
Watch out for the material thickness as well. Many of the copper sinks I have seen are thinner material than comparably sized Aluminum. Its not that big of a deal, unless your host design requires the LED heatsink to push the reflector up against the bezel or window glass area.
Another member recently modded his HD2010 with (thinner) copper heatsink and his reflector ended up rattling lose inside the light.
So what I make of it: mass helps in transporting the heat -> better heatsinking if it has exposure to ambient air.
The heat of the led at first travels down from the die, just down, not omnidirectional. But from the contactarea of the led to star the heat spreads wider and wider, making it easier to the heatsink to transport the heat away with as less temperature rise as physics allow.
So mass counts (cross area of thermal conductive material), for a star, for the heatsink, for the body, helps cooling the led.
Usually for 8,90€ -> about 11$. If you contact customer service, you can get almost any LED on almost any kind of star. But I think they have copper stars only for XML..
