Do I need a better/secndary heatsink? 40x1w on a PCB

I've got 40x1w leds (red/blue) on a PCB this one: http://www.ebay.com/itm/wdm-2x-HeatSink-Aluminum-Base-plate-for-40pcs-HP-leds-size-225-175mm-/171070057015?pt=LH_DefaultDomain_0&hash=item27d491ea37

It will be inside a makeshift box (a tupperware container somewhere near 12inch(Long)x8inch(Wide)x5inch(deep)) with a computer fan blow air out the top (sucking air from around/next to the PCB). Do I need to add a secndary heat sink ontop of the PCB?

If I do need would something like this work? http://www.ebay.com/itm/150977250300?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

two of them so one of row 2 and 4.

You definitely need a heat sink to keep those LEDs cool. Those pcbs are not a heat sink no matter how they are advertised. Those heat sinks are pretty small. Not much surface area. Check this one http://www.heatsinkusa.com/7-280/ It is the right width and cut to 9" length would cost a little under $22 + shipping. It's less cost and has much more surface area and you wouldn't have to figure out a way to attach 11 lengths of 20mm wide heat sinks to the backs of each pcb.

http://www.webstaurantstore.com/chicago-metallic-41800-eighth-size-aluminum-sheet-pan-6-1-2-x-9-1-2/32641800.html?utm_source=Shopzilla&utm_medium=cse&utm_campaign=Shopzilla+Campaign

Is that big enough? You could hang it by the pan, and if you really wanted you could attach a few heat sinks on the back (they're pretty cheap on eBay).

36 x 1W LED's, 1/4 size baking pan (the one I linked is 1/8 size baking pan, but should still be big enough), and a few small Aluminum heat sinks JB Welded onto the back. Got me through an entire harvest and are still kicking strong. No fans, all passive, heat sinks barely get warm. The drivers should probably have a small heat sink on them, though, they give off a bit of heat. You might want to keep the drivers outside of the tent, tbh.


-Edit-
The pan is for durability and to help spread the heat away from the LED and to the the heat sinks. The MCPCB's from Merry can be bent by hand. I'd rather glue them to the baking pan with thermal adhesive and forget they're even fragile.

I already orders the PCB with led's attached on it. *and box with fan is already made

Couldn't I just use thermal adhesive for the two smaller heatsinks and put it on the back of the PCB?

It'll cost me maybe $7


Also anyone know what temperature range the led/heatsink should be at?

I shouldn't need durability the box will be protecting it and 4 bolt's holding it in place.

That heatsink I was eyeballing (the ebay one's) will take awhile to get here (15~days) if I order them could I run the PCB with just the fan for a while?


/edit new plan: Found a AMD cpu heatsink (the stock one) I think if I scrap off the old paste and put adhesive it'll work (cpu fan/heatsink+ compuer case fan) or is that to small of surface area were they connect? -_- nvm thats dumb I'll just go for heatsinks.

If you blow enough air on it you can use something like a baking pan. I don't know the exact temperature at which LEDs would overheat as measured at the heat sink but most LEDs develop problems such as lower output and early death at temps above 85c and most are rated at 25c. My rule of thumb is that if the heat sink feels hot at all it's too hot. Warm, like 40c is OK. Unlike other light sources LEDs have to transfer all of the excess heat produced through the back of the LED to something that will get rid of that heat. With heat sinks more surface area = better cooling because there's more area to radiate heat. Enough air moving across a flat surface can accomplish the same thing to a point. For instance, the baking pan will probably work fine with 1w LEDs but might be inadequate for cooling 3w LEDs. I like passive cooling because it's silent and has one less possible point of failure.

Those are pretty much exactly the same heat sinks as the ones I put on my baking pans.

You might want to attach the PCB to the tupperware container at a couple more than 4 locations.

It is the heatsink Baseplate. Kind of like single XP-G's that had the star behind the actual diode. Most times manufacturers are already adding the baseplates. Which is how you attach a heatsink to an led diode.

Not just diode - heatsink, but diode -baseplate - heatsink.

As far as calculating your heat sink [Tj] needs, this video has been one of the better one's I have found. [He even has another one too...gotta look for it]

EEVBLOG#50 Solid State Cree LED Lighting and How Thermal Design Sucks
http://www.youtube.com/watch?v=GkVRX3h_A30

EEVblog #105 Electronics Thermal Heatsink Design Tutorial
http://www.youtube.com/watch?v=8ruFVmxf0zs

Mechmike said:

Check this one http://www.heatsinkusa.com/7-280/ It is the right width and cut to 9" length would cost a little under $22 + shipping. It's less cost and has much more surface area and you wouldn't have to figure out a way to attach 11 lengths of 20mm wide heat sinks to the backs of each pcb.

Click to expand...

The only place I go for heatsinks. These guys are the shit for typical heatsinks, sans funky designs.

Thanks for the help.

Going order http://www.ebay.com/itm/5pcs-lots-x-150-20-6mm-Aluminum-Heat-Sink-for-LED-Power-IC-Transistor-Module-PBC-/350836644394?pt=LH_DefaultDomain_0&hash=item51af7e5a2a and http://www.ebay.com/itm/2Pcs-Thermal-Conductive-Heatsink-Plaster-Viscous-Compound-Glue-for-PC-GPU-v-h9-/221297936516?pt=LH_DefaultDomain_0&hash=item3386628884 tomorrow.

I realize some of the led's won't be right next to the heatsink but they should have the most air flow (outside layer). Also gong modify the box so there's more air flow inside the fins.

Also what you could do is contact Merry and ask her what heatsinks she has to suit. You could get it all posted at the same time if she hasnt sent it yet. She offered them to me not long ago but i didnt need it.

She sent it a few days ago.

I'm probably going need another one I'll keep that in mind for next time.

whose good at the math?

If I get 5x150x20, 1x150x75, and 1x28x28 that covers everything right? (with 3x3 extra)

http://www.ebay.com/itm/5pcs-lots-x-150-20-6mm-Aluminum-Heat-Sink-for-LED-Power-IC-Transistor-Module-PBC-/350836644394?pt=LH_DefaultDomain_0&hash=item51af7e5a2a
http://www.ebay.com/itm/150x75x7mm-Aluminum-Heatsink-for-Electronics-Computer-Electric-equipment-H143-/171015159281?pt=LH_DefaultDomain_0&hash=item27d14c3df1
http://www.ebay.com/itm/1-pc-Black-Square-Aluminum-Heatsink-for-1w-High-Power-LED-/170909387068?pt=LH_DefaultDomain_0&hash=item27cafe493c
total: $16.45

Best/cheapest I could come up with.

Sorry it won't let me edit my post. My math is wrong on the last post and it would cover up the wire's/screw wholes.

Could I just do a bunch of small (say 20x20) ones just on the other side of the leds? leaving alot of it bear.
http://www.ebay.com/itm/Wholesale-50PCS-20-20-6mm-Silver-Aluminum-Heat-Sink-Chip-IC-LED-Power-Transistor-/370885495714?pt=LH_DefaultDomain_0&hash=item565a7f8ba2

I like the second link. 20x20 could also work, imo. The 1W'ers really don't need too much attention, imo. I saw picks of Ganja running a 24 x 1W mcpcb with no form of cooling whatsoever and he said it was perfectly fine. If you're not worried about the durability of the mcpcb then any type of cooling you attempt is icing on the efficiency cake.

I will say, however, that a few of those 1W heat sinks could be really good somewhere on your LED driver. I've got three 36W Merry panels and I know exactly where I'd place a heat sink on all of those drivers.

Bumping Spheda said:

I like the second link. 20x20 could also work, imo. The 1W'ers really don't need too much attention, imo. I saw picks of Ganja running a 24 x 1W mcpcb with no form of cooling whatsoever and he said it was perfectly fine. If you're not worried about the durability of the mcpcb then any type of cooling you attempt is icing on the efficiency cake.

I will say, however, that a few of those 1W heat sinks could be really good somewhere on your LED driver. I've got three 36W Merry panels and I know exactly where I'd place a heat sink on all of those drivers.

Click to expand...

You must spread some Reputation around before giving it to Bumping Spheda again.

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Rep+ that you brought that up, that it might not even need cooling.

I was going to suggest just picking up a little 80mm 12v fan and mount little teflon spacers around each mount tab for 3mm or so of of gap between metal and fan and just blow on it @6v's.

It'sTure said:

I already orders the PCB with led's attached on it. *and box with fan is already made

Couldn't I just use thermal adhesive for the two smaller heatsinks and put it on the back of the PCB?

It'll cost me maybe $7


Also anyone know what temperature range the led/heatsink should be at?

Click to expand...

Thanks for bringing these up, I usually only have seen these as part of some kit and didn't realize they were sold like this.

I poked around and some really cool configurations [1x6 strips]
These could make some badazz supplementary side lighting too.....

Abiqua said:

These could make some badazz supplementary side lighting too.....

Click to expand...

Wouldn't it be cool if Merry carried those high CRI Warm White LED's from Yuji? I think we should pressure her into buying a batch as soon as Yuji starts selling them, I know I'd buy a couple more panels from her if she did.

Btw, if anyone's interested, the 36 x 1W mcpcb by Merry is the biggest square panel that she carries that's entirely in series. After 36W the pcb's begin to have lines of LED's in parallel. AFAIK, if an LED fails it could be really bad for the rest. One entire row of lights will go out and your driver could burn the other rows out with too much voltage. With the 36W panel one LED burns out, they all go out, you get the multimeter out, you find out which LED went bad and then just replace it. No harm no foul. I'd like to think by the time an LED would fail I'd have already purchased new lights, but you never know.

If anyone was wondering the PCB/led's hit 105 fahrenheit with no fan/heatsink in 5 mins.

With the fan/box it stayed around 92 at 15 mins.

I'll do a with heatsink/longer time test once they get here.


/edit 88~ inside grow box with growbox and led fan's set on mid setting.