Thermal paste between LED Array and heatsink

[stephj03]

I have a few Orphek fixtures that I am about to rebuild for the second time.

I didn't use thermal paste between the heatsink and the back of the array board the first go round which led to a few LEDs burning out according to Orphek.

I didn't observe any factory installed thermal paste during the initial rebuild so I am wondering how to properly apply it this time.

Do I smear it all across the heat sink like buttering bread? Or do I dab it on to the back of the LED Array directly behind each LED???

 

[Kazumi]

I would only apply it to the parts that will come in contact with the heatsink. I have never done a LED array, but on CPU's be sure to not apply it too thick otherwise they say it can become an insulator instead.

 

[TheHarold]

My Orphek bars absolutely had thermal paste applied behind each LED.

 

[stephj03]

My Orphek bars absolutely had thermal paste applied behind each LED.

Can you tell me approximately how big of an area the thermal paste behind each LED was on your bars? Quarter size maybe?

 

[PhilSD211]

I just had to do this for my Orphek compact. Like yours, my original V4 Compact did not have ANY paste between the board the the heat sink. Think that caused all the blue/uv led's to burn out.

After purchasing a replacement board, I was not even told to use thermal paste. Found that info in other threads here. :mad:

But what I did was to mark the positions of the LED on the back of the board and dispensed a big dab of paste at each location. Once you put the board down onto the heat sink, it'll spread out so don't think you can over do it.

Hope now the new LED diodes will last a bit longer than 2 years. What a joke of a company.

 

[GabeM]

That's a bit odd I don't remember mine NOT having thermal paste when I cleaned it last. It is about that time again I will check and report my finding.

Definitely use thermal paste wherever there are metal contacts.

 

[GabeM]

Looks like they don't have them - https://orphek.com/upgrade-to-atlantik-v4-from-older-version/

Pretty concerning honestly.

 

[BZOFIQ]

Can you tell me approximately how big of an area the thermal paste behind each LED was on your bars? Quarter size maybe?

You only need to cover exactly what comes into contact with the heatsink. LIttle goes a long way.

 

[PhilSD211]

Yep.. that's the exact PCB replacement instructions I followed. I would have thought most of the fixtures they sold had thermo paste and mine was just a fluke where they forgot to apply paste.

and due to the size of the board, it's not really feasible to apply a layer of paste to the entire board. which is why I just applied a big dab behind each of the diodes and called it good.

 

[Kazumi]

Be careful. Some thermal pastes are electrically conductive. So if you just glob it on, it can cause shorts.

 

[Crustaceon]

You typically want to put a very small amount of thermal compound on the backside of the led and press it against the board. You’ll probably have some compound squish out and that’s ok. Just be sure to clean it up. As noted, a thin layer will conduct heat. A thick layer will insulate.

 

[stephj03]

Yep.. that's the exact PCB replacement instructions I followed. I would have thought most of the fixtures they sold had thermo paste and mine was just a fluke where they forgot to apply paste.

and due to the size of the board, it's not really feasible to apply a layer of paste to the entire board. which is why I just applied a big dab behind each of the diodes and called it good.

Thank you, this is exactly what I was trying to figure out.

Thanks for the input everyone. For those not familiar with Orphek, these are like COB panels where all LEDs are mounted to a PCB board that has the full footprint of the heatsink. The heatsink only touches the back of the board and I am doing a board swap vs swapping individual LEDs.