Cutting premade PCB board led

Hölpötti

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Is it possible to cut these premade lights a bit smaller. The footprint of these are too big.
I am installing this in the middle surrounded by single led-stars (~50pcs) and luxeon Rebel 16's (4pcs). Hoping to get enough Light for 24inch x 24inch x 24inch. With cutting I can install other leds a bit closer to center and make the total size smaller.
You can see where the circut is and by cutting outside of that circut should not harm it.
Is there something else I should consider?
IMG_20190321_195145__01__01.jpg


IMG_20190321_195145__01__01.jpg IMG_20190321_195145__01__01.jpg
 

Reefkeeper14

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I would advise against it. You need to consider the thermal dissipation of the heat generated by the LEDs. The aluminum PCB which you are proposing to cut likely was designed to be large enough to prevent the LEDs from reaching a certain temperature. By cutting the PCB you could increase the maximum temperature that the LEDs run at. In doing so you could shorten the lives/output of the LEDs. This is especially true if you plan to place more LEDs around the board which would lead to even more heat being generated. If you still decide to go along with your plan, you might be able to offset some of this extra heat using a high quality heatsink and a powerful fan.
 

oreo54

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The density and heat is already high probably. Depends on drive current though..

"IF" and that's sort of a big if.. there was much thought in the board heat dissipation other than "eh good enough"..it would be at low drive currents i.e 500mA or less anyways.

see no problem (except a currently existing one i.e small mass_) whittling away.

YMMV..
 

oldchoppy

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I am in agreement with the other posts recommending against the modifications. My primary concern is overheating. It should be relatively easy to check if the board was designed for heat dissipation. However, even if the board was not designed for heat dissipation you will be adding more heat load by placing other LED's closer.

If the board is providing a way to reduce heat you should see a grounding plate around the traces. It would look like there was a small cutout or groove around the traces. Sometimes the grounding plate is exposed so you can see the pads (which are not present in the pictures). Difficult to see from the pictures but it appears you only have copper traces with no grounding plate on this side of the board. The fiberglass used to make the board (I am assuming it is fiberglass) acts as an insulator (holding heat). So based on the picture it would not appear removing the material will reduce heat loss.

Double sided circuit boards are common, so it is possible you have a grounding plate on the back side of the board. If there is a grounding plate on the back of the board you will reduce the ability to cool by removing it.

You could buy CPU heatsinks rated for the wattage of each LED board and attach to the back of each board with thermal paste to help with the heat. I still recommend against placing a bunch of high power LEDs in a confined space because it will be easy for something to go wrong. Testing and validation of temperatures before and after modifications will be important if you move forward.
 
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oreo54

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I am in agreement with the other posts recommending against the modifications. My primary concern is overheating. It should be relatively easy to check if the board was designed for heat dissipation. However, even if the board was not designed for heat dissipation you will be adding more heat load by placing other LED's closer.

If the board is providing a way to reduce heat you should see a grounding plate around the traces. It would look like there was a small cutout or groove around the traces. Sometimes the grounding plate is exposed so you can see the pads (which are not present in the pictures). Difficult to see from the pictures but it appears you only have copper traces with no grounding plate on this side of the board. The fiberglass used to make the board acts as an insulator (holding heat). So based on the picture it would not appear removing the material will reduce heat loss.

Double sided circuit boards are common, so it is possible you have a grounding plate on the back side of the board. If there is a grounding plate on the back of the board you will reduce the ability to cool by removing it.

You could buy CPU heatsinks rated for the wattage of each LED board and attach to the back of each board with thermal paste to help with the heat. I still recommend against placing a bunch of high power LEDs in a confined space because it will be easy for something to go wrong.

none of these boards are made as stand alone heat sinks...
All need to be attached to a proper heat sink..
If you are relying on that small bit of Al cut off as the make/break point ..you have bigger issues AFAICT.. ;)

most common board sans lenses.. + - all on top as would be needed for diodes..
Chance of a back plane ground is slim.... BUT possible..
In which case you would need to seal the edges.
kw-21led122-p1_1__1.jpg
 

mike550

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I’m not sure heat dissipation was a design item as much as getting an nice standardized form factor and layout. @oreo5457 points out once you take of lenses there’s a lot of room. I’d go for it and cut it. It doesn’t look like you’re taking off a ton of material.

Then again I void warranties for sport.
 

oreo54

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oldchoppy

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Okay, if it is one of those boards then it looks like no circuit going to the back panel.

Main concern was heat but if O/P already has an idea for managing heat, then should be a fun project!
 
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