3070's melted.

Airwalker16

Airwalker16

Well-Known Member
So I'm wondering how this happened, but the 2100ma driver was runnine 3 3070's. Apparently the surface of one of them was cracked but all 3 are ruined. Purchased new ones com PCL and also the thermal pads. I'm wondering if that egraph isn't really a great product. Hopefully the thicker ones from PCL do a better job. I'm almost tempted to just use TIM grease.
 
p4id

p4id

Well-Known Member
I lost a cxb to cracking and melting, turns out there was a speck of dirt on the cob that created a hot spot.
 
skorchem

skorchem

Well-Known Member
That is now worrying me as im still building mine slowly around my other works and I have used 8 egraphs, should I order the paste instead ?
 
mc130p

mc130p

Well-Known Member
people used to recommend the thermal compound over the pads, but it doesn't seem to get mentioned much these days. I use Arctic Silver thermal compound- a brand new razor blade to get it very thin. a dab the size of a small grain of rice is more than enough. There are other brands though. I've also used some Noctua thermal compound and it seems to work well too. Noctua heat sinks are really good, so i figure they know what they're doing.
 
brettsog

brettsog

Well-Known Member
mc130p said:
people used to recommend the thermal compound over the pads, but it doesn't seem to get mentioned much these days. I use Arctic Silver thermal compound- a brand new razor blade to get it very thin. a dab the size of a small grain of rice is more than enough. There are other brands though. I've also used some Noctua thermal compound and it seems to work well too. Noctua heat sinks are really good, so i figure they know what they're doing.
Click to expand...
They perform well. Too many people use too much thermal compound so it's easier to recommend thermal pads as you can't really get them wrong lol. They should only be paper thin though.
 
skorchem

skorchem

Well-Known Member
the egraphs are very fragile and leave a graphite residue like powder on your finger tips, not much though.
I got 8 in place and haven't fired them up yet, but I assume whoever made them must know what they are doing so Im putting my faith in them
that they will be ok.
 
superbak3d

superbak3d

Well-Known Member
As someone who builds computers and such as my other hobby,

thermal paste is the best way to transfer heat. You'll get a much better surface to surface connection with paste than a pad.

Not to mention, stuff like AS5 is designed for computer chips, which run far hotter than any cob. You'll get better cooling with AS5 and it will help increase the lifespan of your chips.
 
brettsog

brettsog

Well-Known Member
superbak3d said:
As someone who builds computers and such as my other hobby,

thermal paste is the best way to transfer heat. You'll get a much better surface to surface connection with paste than a pad.

Not to mention, stuff like AS5 is designed for computer chips, which run far hotter than any cob. You'll get better cooling with AS5 and it will help increase the lifespan of your chips.
Click to expand...
I have always had lower temps using artic silver ceramic thermal compound only a degree or 2 difference but it all helps.
 
stardustsailor

stardustsailor

Well-Known Member
Devil's advocate ......:fire:

CXA/CXB COB LEDs have very tightly packed diodes ...
Which are epoxy glued to a ceramic substrate ...
Which in turn is very fragile and prone to crack / brake ...
Holders available for the series ,are not eactly the type of holders that apply enough
pressure to COB towards the heat sink ...
CXA/CXB COB LEDs also have very thin ,sensitive LES ..

All these contribute to a very poor ( at my opinion ) and "unstable " cooling of these COBs...

https://www.rollitup.org/t/thermal-grease-application-method.871322/page-2#post-11617859

https://www.rollitup.org/t/fried-egg.873381/

" Time will show ...."
8)
 
Greengenes707

Greengenes707

Well-Known Member
I have put together literally 1000's of cxb's and hundreds of cxa's(old substrate)...as well as dropped them, tossed them, crammed them in drawers, stepped on them, poked them with screwdrivers, sprayed them with foliar, hot plugged them...just about everything you are not supposed to do to them. Most of them with pads I might add. Never once have I cracked one, "blown up" one, or damaged a bond wire.

"thicker" pads do not mean thick...it means thicker than before.

Pads come right off like a perfect sticker. They are not fragile, and can be reused. I have a bunch on personal projects.

Cree actually said that they prefer user to use plastic holder vs metral ideal...because of the possibility of over torquing(too much pressure) is easy with them. I've never had it happen..and screwed them down pretty tight...but could see it happening.

I had one cxb3070 DOA in a 500 pack one time. Cree took care of me and then some.
 
bicit

bicit

Well-Known Member
I've never tried the thermal pads, thermal paste has always treated me right. Done a few hundred cobs now, not thousands though.

I apply my paste directly too the cob by weight.
1: Put cob in holder
2: Put cob+holder onto scale, then zero the scale.
3: Apply two thin, parallel lines of thermal paste to the back of the heatsink
4: Weight the cob+holder again, I like to get ~.07 grams of thermal paste on the cob.
5: Using a NEW(or at least clean+sharp) razor blade, spread the thermal paste out. Work quickly.
6: Optional, but you can weight your cob one last time to calculate the actual thickness of your tim layer. Some will be left on the blade.

Not as quick or convenient as the thermal pads, but is much cheaper.
 
You must log in or register to reply here.
Top