Kaidomain copper mounted led's

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pinkpanda3310
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Kaidomain copper mounted led's

I don’t know if this has been brought up before or if it’s common knowledge but it’s somewhat of a community announcement.

I recently bought a few led’s from kaidomain and most of them arrived on copper stars. I took off an sst-50 to mount on something else and thought since the star is not in use why not check it out. Just as I suspected the copper is just a direct replacement for aluminium and is not a sinkpad, there is an MCPCB layer over the whole star. Whilst it might transfer the heat a little better than alu it cannot be compared to a sinkpad so don’t be fooled. Kaidomain is actually one of my preferred chinese vendors and they don’t claim these to be sinkpads but it is easy to make the wrong assumption.

If these pics show up properly you’ll see the copper solder pad ring around where I scratched it. In the second shot I circled where I scratched through to the copper star.

Happy illuminating Wink

  

comfychair
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You can do the same test with an ohmmeter, checking between the center pad and the backing. Smile

pinkpanda3310
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I get a reading on the little bit I scratched right through and open circuit reading on the solder pad.

  

comfychair
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Yes, if it's a board with a dielectric layer under the center pad it will measure open circuit. On a direct copper one it'll read 0 ohms.

Tom E
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FastTech sells these too and some lights ship with them. Awhile ago, I bought a couple just to see. You can grind/sand off the layer and get a cheap SinkPAD style, but then you have to fill that hole back in with solder. I've had troubles reflowing this setup -- can't get the LED to sit down even. Either too much solder or too little - dunno, I found it very hard to get right - don't think I ever did. I never compared head-to-head against alum and SinkPAD's, but the most common opinion is it's somewhere in the middle.

SinkPAD (SinkPAD.com) rates their aluminum direct path XML star for thermal conductivity of 135.0 W/m.K, while the copper direct path XML is rated at 385.0 W/m.K. Not sure what this means in "real world" use for us...

Old-Lumens
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I figured they were fake, but I think these might be direct to copper.

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comfychair
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A dielectric layer on top of copper or a dielectric layer on top of aluminum, I think it's probably a waste of good copper. You could put a LED and a dielectric layer on pure diamond and it still wouldn't help.

pinkpanda3310
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Old-Lumens wrote:

I figured they were fake, but I think these might be direct to copper.

I’ll tell you tomorrow as I bought 1 or 2 of those as well. Wasn’t planning to use them just yet but I’ll check out the boards in the meantime.

  

leaftye
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These types of stars are why I hate when people suggest that manufacturers put their LED's on copper stars.  That's worthless unless it's a direct bonded copper star, and that really needs to be said when these suggestions are made.  Direct bonded copper or don't bother. 

The low mode should be lower.

comfychair
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Has anyone dissected an aluminum Sinkpad? Is there a copper trace just without the dielectric?

Tom E
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SinkPAD's site (http://www.sinkpad.com/what-is-sinkpad.php) says the average star is 1-4 W/m.K, and the aluminum SinkPAD is 135 W/m.K, then copper SinkPAD is 385 W/m.K, so the major improvement is removal of the dielectric layer.

In their presentation (http://www.sinkpad.com/sinkpad-presentation.php) interesting in that they identify a "thermally conductive" dielectric. They call it MCPCB Type 2. So it appears there is difference in the stock aluminum stars out there, and even if they have a dielectric layer, it could be a "good" one or "bad" one.

Everything I see on their site is saying the aluminum SinkPAD is the same exact design as the copper one, just different base metal used.

leaftye
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Since comfy frequently brings up how copper pills don't work any better than aluminum pills, I wonder if the same would be true with direct bonded mcpcb's.  I'm betting testing would come up with the same results for both aluminum and copper direct bonded mcpcb's, but I'm rooting for copper.

The low mode should be lower.

comfychair
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The aluminum MTG2 stars from Cutter have a layer of pure evil where the dielectric would usually be. It eats drill bits like you wouldn't believe.

ryansoh3
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leaftye wrote:

Since comfy frequently brings up how copper pills don’t work any better than aluminum pills, I wonder if the same would be true with direct bonded mcpcb’s.  I’m betting testing would come up with the same results for both aluminum and copper direct bonded mcpcb’s, but I’m rooting for copper.

Using copper on a PCB definitely shows output improvement, mostly because the heat density is much higher compared to a pill.

Match’s tests:

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comfychair
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ryansoh3 wrote:
leaftye wrote:

Since comfy frequently brings up how copper pills don't work any better than aluminum pills, I wonder if the same would be true with direct bonded mcpcb's.  I'm betting testing would come up with the same results for both aluminum and copper direct bonded mcpcb's, but I'm rooting for copper.

Using copper on a PCB definitely shows output improvement, mostly because the heat density is much higher compared to a pill. Match's tests: !https://lh4.googleusercontent.com/-SGngl7iqLqs/UTLIHWdw2TI/AAAAAAAABdM/T...

But is that improvement from the copper or from the elimination of the dielectric layer... that the improvement exists isn't the question.

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comfychair wrote:

ryansoh3 wrote:
leaftye wrote:

Since comfy frequently brings up how copper pills don’t work any better than aluminum pills, I wonder if the same would be true with direct bonded mcpcb’s.  I’m betting testing would come up with the same results for both aluminum and copper direct bonded mcpcb’s, but I’m rooting for copper.

Using copper on a PCB definitely shows output improvement, mostly because the heat density is much higher compared to a pill. Match’s tests: !https://lh4.googleusercontent.com/-SGngl7iqLqs/UTLIHWdw2TI/AAAAAAAABdM/T...!

But is that improvement from the copper or from the elimination of the dielectric layer… that the improvement exists isn’t the question.

Whoops, that’s true, sorry about that.

I vaguely remember a discussion that concluded that copper PCB’s with a dielectric layer was similar to an aluminium PCB rather than a SinkPad/Noctigon.

BLF ≠ B-grade Flashlight Forum

 

B25364
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Ok where is the lumen graph for copper sinkpad and alum sinkpad ?

djozz
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B25364 wrote:
Ok where is the lumen graph for copper sinkpad and alum sinkpad ?

No one has done that, aluminium Sinkpads are not widely spread so there is no output graph of it

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I have 10 sinkpads that I got as free samples, some aluminum and some copper. Does anyone want a copper XM-L and an aluminum XM-L bare sinkpad for some testing? Shoot me a PM, and I’ll try and hook you up.

B25364
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djozz wrote:

B25364 wrote:
Ok where is the lumen graph for copper sinkpad and alum sinkpad ?

No one has done that, aluminium Sinkpads are not widely spread so there is no output graph of it

A machinist told me that the alum might be better . We need to find out.

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rollinstone157 wrote:
I have 10 sinkpads that I got as free samples, some aluminum and some copper. Does anyone want a copper XM-L and an aluminum XM-L bare sinkpad for some testing? Shoot me a PM, and I'll try and hook you up.

I see a little project coming up: a kind BLF-er (Slim Pickens) has just this week offered me some aluminium Sinkpads for the Luxeon TX (that I do not posess as yet, by the way). and I would not mind finding out what the aluminium ones do compared to copper, so yes, I would like them, but I do have a spare 20mm copper Sinkpad, so unless it is not going to be used anyway (I will never say no to an extra Sinkpad Smile ) I am already happy with just the aluminium one. PM sent.

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pinkpanda3310 wrote:
Old-Lumens wrote:

I figured they were fake, but I think these might be direct to copper.

I’ll tell you tomorrow as I bought 1 or 2 of those as well. Wasn’t planning to use them just yet but I’ll check out the boards in the meantime.

It seems you are right Old-Lumens. I removed the sst-90, hit the board with a dremel and tested it with the DMM. All results point to direct copper.

  

DB Custom
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Test the board as is, the way the emitter will see it. If you have continuity then you should also have a direct thermal path. And that board is not the one they showed in the link.

pinkpanda3310
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Because I’m stupid and I like to do things the hard way :Sp I can find another way to mount the led, it doesn’t really bother me.

I hadn’t picked up on the board being a different colour. The specs are the same in every other way though.

It appears the white boards are sold out.

  

Gj
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comfychair wrote:

A dielectric layer on top of copper or a dielectric layer on top of aluminum, I think it's probably a waste of good copper. You could put a LED and a dielectric layer on pure diamond and it still wouldn't help.

Actually, it would. Diamond, except for blue and doped synthetic, is a non-conductor and would constitute it's own dielectric layer.

B25364
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pinkpanda3310 wrote:
Because I’m stupid and I like to do things the hard way :Sp I can find another way to mount the led, it doesn’t really bother me.

I hadn’t picked up on the board being a different colour. The specs are the same in every other way though.

It appears the white boards are sold out.

i think what he is saying is that when you hit the board with a dremel , you are grinding down to the copper, and now you have no idea if it was direct to copper before you dremeled it.

comfychair
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Gj wrote:

comfychair wrote:

A dielectric layer on top of copper or a dielectric layer on top of aluminum, I think it's probably a waste of good copper. You could put a LED and a dielectric layer on pure diamond and it still wouldn't help.

Actually, it would. Diamond, except for blue and doped synthetic, is a non-conductor and would constitute it's own dielectric layer.

If there is a separate dielectric layer, it is the dielectric that determines the thermal properties, not what it is on top of. A diamond board with no dielectric layer would not have a separate dielectric layer, just like a direct copper board has no dielectric layer... hence why on purpose I included the words 'and a dielectric layer' in there.

pinkpanda3310
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B25364 wrote:
pinkpanda3310 wrote:
Because I’m stupid and I like to do things the hard way :Sp I can find another way to mount the led, it doesn’t really bother me.

I hadn’t picked up on the board being a different colour. The specs are the same in every other way though.

It appears the white boards are sold out.

i think what he is saying is that when you hit the board with a dremel , you are grinding down to the copper, and now you have no idea if it was direct to copper before you dremeled it.


Honestly I was just to lazy to scratch it by hand and my train of thought was a dielectric layer would be easy to see anyway. I did a dremel scratch on the original sst-50 board to double check myself.

Sorry, my photography skills suck.

  

B25364
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I could be wrong about this, so I am asking, should you have scratched it at all. ? If you test to see if the led goes thermally direct to copper, don’t you test from where the led would be, instead of scratching down to the copper ?

pinkpanda3310
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I thought that was the angle of DBCstm’s question.

  

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You guys do understand the physics of it right?

Conventional MCPCB is just a very very thin PCB on top of a metal backing

Noctigon and sinkpad, they remove the center heatsink area (between the + and – solder points) to provide a direct solderable path of heat to the hunk of metal underneath
http://www.pcb007.com/pages/zone.cgi?a=59637

sinkpad actually punched the center portion out then pressed in a plug of copper underneath (or as above diagram shows presses a slug upwards to the base of the emitter), noctigon cuts the pcb BEFORE they machine out the stars…is one better than the other…maybe but they BOTH are heads and shoulders above the heat insulative layer of the PCB

A solution to those crappy MCPCB’s is to figure out a way to cut and remove the center PCB material and then solder directly to the star underneath
Thermodynamics
http://www.engineeringtoolbox.com/conductive-heat-transfer-d_428.html

Thermal conductivity of fiberglass (standard pcb material correct?)…horrendous compared to solder
http://www.engineeringtoolbox.com/thermal-conductivity-d_429.html

Thermal conductivity of solder
http://www.electronics-cooling.com/2006/08/thermal-conductivity-of-solders/

Which do you think would be “better” at moving the heat generated by the LED?

so the above star with the PCB on it made out of copper or diamond or aluminum…until the heat can force it’s way thru the very low thermally conductive PCB…it doesn’t matter what the star is made out of.

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