Sanding heat sinks

[Airwalker16]

Yes however if you look at the link that I posted it shows not just MM pads and paper but also disks to use on a sander to make it a little easier than by hand.
Im a stoner if i can use a machine to make the process easier then i will use it

I have an OLD SCHOOL hand sander I'll try...

 

[qballizhere]

that is what I use most of the time an orbital

 

[Budzbuddha]

If you want them truly flat, you would have to start out with 80-120 grit and 90% of the work is done at those grits, definitely wet sanding. It is quite a lot of work to get the large waves out. The waves run in the same direction as the fins so you can do most of the flattening in the opposite direction.

The really good news is, in my testing it made no difference whatsoever when I flattened and polished them. Even with a mirror finish I could detect no difference in temp droop. Hilarious to myself that I painstakingly sanded so many huge heatsinks before testing to see if it was worth the time
View attachment 3599703

Yeah but you got a sweet reflector out of it

 

[giantsfan24]

Considering most don't drive the COB's at max, I know I won't, the amount of heat generated won't be much and as such, I think based on what I'm reading, that thermal pads may be all that's required at this level??

 

[Airwalker16]

I'm using egraph pads I bought directly from their website.

 

[SupraSPL]

I have never tested thermal pads but CREE did provide some data on that. Because the pads are relatively thick, if you use a high conductivity thermal pad (relatively expensive?) it will perform well but if it is low conductivity it will perform relatively poorly.

Then again they recommend smoothing heatsinks to 1000 grit US so apparently they dont have our application in mind.

 

[SupraSPL]

Yes I did try an orbital sander but surprisingly it did not reduce the work much if at all in my case. Then I got a belt sander but I checked the temp droop results before using the belt sander.

 

[Abiqua]

I'm using egraph pads I bought directly from their website.

been using E-Graf myself [1210A] for about 6 months on Vero's....now for CXB's.... did you order the pre- cuts? or just samples?

 

[Airwalker16]

been using E-Graf myself [1210A] for about 6 months on Vero's....now for CXB's.... did you order the pre- cuts? or just samples?

I ordered pre cuts from egraph

 

[Jp.the.pope]

I ordered pre cuts from egraph

Same thing I'm using. Will keep you posted.

 

[Airwalker16]

Ya I hope they hold up for years to come. Anyone who's used the egraf tim pads, I understand there is a sticker type side you peel the paper from. Which does it go on? CHIP or HeatSink? Id have to think the sticky side would be better utilized with the sticky side stuck to the bottom of the chip ceramic?
Otherwise you're sticking it to the HeatSink but the chip lok holder oughtta do that fine. I juse feel it'd have a possibility to move around being just on top of it, not held in place.

Anyone know the proper way to install with e graf?

 

[Airwalker16]

been using E-Graf myself [1210A] for about 6 months on Vero's....now for CXB's.... did you order the pre- cuts? or just samples?

How are you using them?

 

[Isawthelight]

How are you using them?

Clean finger prints, oils, & oxidations off the ceramic bottom of the cob and the heat sink with rubbing alcohol & let dry before using the e-graf for best results. Sticky side to the cob bottom. Clean bottom side of e graf and bolt down the cob.

 

[Airwalker16]

Clean finger prints, oils, & oxidations off the ceramic bottom of the cob and the heat sink with rubbing alcohol & let dry before using the e-graf for best results. Sticky side to the cob bottom. Clean bottom side of e graf and bolt down the cob.

Ya that's what I thought. Thanks for remindING me to use isopropyl 90%

 

[Jp.the.pope]

Clean finger prints, oils, & oxidations off the ceramic bottom of the cob and the heat sink with rubbing alcohol & let dry before using the e-graf for best results. Sticky side to the cob bottom. Clean bottom side of e graf and bolt down the cob.

This is exactly what I did.

 

[kony brado]

What abute the corrosive reaction betwen grafit and alominum ?
SDS mentioned this feu times before.
Maybe better with graft on cob side,and sticker on the sink?
What do u think guys? idd like to use them myself....

 

[Airwalker16]

What abute the corrosive reaction betwen grafit and alominum ?
SDS mentioned this feu times before.
Maybe better with graft on cob side,and sticker on the sink?
What do u think guys? idd like to use them myself....

I emailed egraf and they sent me application instructions. It ACTUALLY says sticky side to HEATSINK.

 

[Airwalker16]

I don't know about you guys, but I'm gonna listen to what egraf recommends and stick the material to my hs. Definitely going to make it more difficult to apply not having it stuck to the chip though, that's for sure.....

 

[Isawthelight]

I don't know about you guys, but I'm gonna listen to what egraf recommends and stick the material to my hs. Definitely going to make it more difficult to apply not having it stuck to the chip though, that's for sure.....

from HITHERM
Adhesive Orientation from Airwalker16's pdf attachment...
The preferred orientation of the part is adhesive facing the heat sink. Testing has demonstrated negligible advantage to orienting the adhesive side of the part towards the heat sink compared to the LED substrate. However if there is a manufacturing advantage to bonding the adhesive to the LED, it is recommended the thermal designer evaluate both orientations to compare the manufacturing / performance tradeoff.

HITHERM says the heat will flow equally well no matter which way the TIM sits. Maybe Adhesive down is preferred because it is easier to clean cooked glue off your heat sink than your cob?

 

[kony brado]

I emailed egraf and they sent me application instructions. It ACTUALLY says sticky side to HEATSINK.

thanks for this man^^^^^^
i wold listen to them to,and for shure easier to clean the sink than the cob as @Isawthelight mentioned