Why hole in middle of radial heatsink

robincnn

robincnn

Well-Known Member
I am trying to make a Cree COB light with CXB 3070 or 3590 and power it to 50-70 watts. I got this old Chinese COB light that is not working and I am thinking of using it's active cooling.

I do not understand why does it have a hole right in the middle.
Here is another example of heatsink with hole
http://www.digikey.com/product-detail/en/RA002-002999DN/259-1613-ND/3466833
The hole is about 19mm, Cree 3070 is23mm emitter and 27mmx27mm module. Would the hole interfere with the cooling?


29mm by 80mm is the heatsink size and the fan is 12v 0.25A.
 
robincnn

robincnn

Well-Known Member
Thanks for your replies.
I tried to look for a similar size heatsink that does not have a hole in the center but so far have not found any on mouser.com or digikey.com
Would it work fine if i fill up the hole with thermal grease.
 
vostok

vostok

Well-Known Member
Airs gotta be sucked in someplace...in this case its the center, then out the sides via the fan ...good luck with the rest ..!
 
C

churchhaze

Well-Known Member
There's a hole in it because you got ripped off by shady aluminum bandit con artists.

It's unusable.

Probably has something to do with why it broke!

This is a classic case of "fake chinese capacitors" where there's literally nothing under the aluminum shell.
 
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tightpockt

tightpockt

Well-Known Member
robincnn said:
Thanks for your replies.
I tried to look for a similar size heatsink that does not have a hole in the center but so far have not found any on mouser.com or digikey.com
Would it work fine if i fill up the hole with thermal grease.
Click to expand...
yeah..definitely do that
 
Mechmike

Mechmike

Well-Known Member
There are some cobs made in the shape of a doughnut, hole and all. I've seen them on Alibaba. Maybe that sink is designed for one of them? It doesn't appear to be much use for the type of cob typically used in grow lighting.
 
Rahz

Rahz

Well-Known Member
You can find radial heat sinks without holes on ebay. Do a search for 50 watt led heat sink. They also come in 100 watt versions. Although there are no mounting holes the watt rating would require fans. They're good for about half that without fans... which to my mind would be generally be the use of a radial heat sink.
 
robincnn

robincnn

Well-Known Member
Rahz said:
You can find radial heat sinks without holes on ebay. Do a search for 50 watt led heat sink.
Click to expand...
the 50watt one is too big. This one with lens seems nice..
http://www.ebay.com/itm/20w-50w-100W-LED-Aluminium-Heat-Sink-Cooling-Fan-44mm-Lens-Reflector-Bracket-/261742999634?pt=LH_DefaultDomain_0&hash=item3cf1193852

tightpockt said:
yeah..definitely do that
Click to expand...
I will fill it up with artic silver and try.

Read this for thermal management.
http://www.cree.com/~/media/Files/Cree/LED Components and Modules/XLamp/XLamp Application Notes/XLampThermalManagement.pdf
I don't have a thermocouple or IR camera
Would a simple Non contact IR Thermometer from ebay work fine ?
 
tightpockt

tightpockt

Well-Known Member
robincnn said:
the 50watt one is too big. This one with lens seems nice..
http://www.ebay.com/itm/20w-50w-100W-LED-Aluminium-Heat-Sink-Cooling-Fan-44mm-Lens-Reflector-Bracket-/261742999634?pt=LH_DefaultDomain_0&hash=item3cf1193852


I will fill it up with artic silver and try.

Read this for thermal management.
http://www.cree.com/~/media/Files/Cree/LED Components and Modules/XLamp/XLamp Application Notes/XLampThermalManagement.pdf
I don't have a thermocouple or IR camera
Would a simple Non contact IR Thermometer from ebay work fine ?
Click to expand...
I was totally kidding...don't do that
 
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