Thermal Interface Materials: Do they matter?

pulpoinspace

pulpoinspace

Well-Known Member
Hey Guys

My roommate does inside sales for Henkel-Bergquist
When he saw me working on my lights one day, he offered to get some samples of TIM for me.
He also told me that Spectrum King orders gap pads from them,
and that spectrum king uses https://www.digikey.com/product-detail/en/bergquist/GPHC5.0-0.040-02-0816/BER370-ND/6137084 specifically

the ones he brought home for me are
https://www.digikey.com/product-detail/en/bergquist/GP5000S35-0.040-02-0816/BER328-ND/2185113?utm_adgroup=Fans & Thermal Management

he says its like top of the line stuff. of course it was free. I'm excited to test it and i'll report back but does anyone have an early hypothesis. Going to test on VERO29C@1400ma on 180mm Kingbrite Pin Heatsink. I'm currently using the 99c gap pad from rapid. Runs at about 60C

do you think this will change the running temperature of my lights?
maybe the warm up time?
increase the temp of the sink, while lower the temp of the chip?
maybe nothing?

all replies welcome. I know there are several kinds of TIM and i'm uneducated here.
 
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whytewidow

whytewidow

Well-Known Member
I prefer to use thermal tape. You get a 25m roll for 12 bucks on Amazon. That's just over 75 feet of tape. Or they sell pads you can cut into any size or shape. The tape works great. I'm running it on sammy single rows on thin u channel and a small fan blowing on the back of the light. And you can lay your face on the leds. Why spend 100 bucks on thermal material when the samething for 12 bucks. Kinda like driving 20 extra miles to a gas station bc its 10 cents cheaper. Doesnt make sense.
 
AuBlue

AuBlue

Member
The Amazon tape at 1.5 W/mk would be easier to use and should work fine.
I purchased samples of Kingbali 1500-1700 W/m.K product in 180x220mm sheets.
Product No. was DSN5040. When you get ambient temps of over 45 Degree C it all helps.

This material is designed with a thermally conductive orientation.
Spreading heat along the sheets length, so the full heatsink surface is used.
Worth understanding for high performance applications
 
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pulpoinspace

pulpoinspace

Well-Known Member
sethimus said:
amazing, you found the reason why they are so expensive :lol:
Click to expand...
i know right. when i told him a little bit about "spectrum king" and how they're viewed in our industry he said it makes a lot of sense and that they're one of the companies he doesn't like dealing with. apparently they tried to pay a quarterly invoice in cash haha.
 
wietefras

wietefras

Well-Known Member
Maybe on COBs (especially on high power) it matters, but nowadays people use strips more and more and they have so much contact surface already that it doesn't really matter what TIM you use (if any).
 
AuBlue

AuBlue

Member
wietefras said:
Maybe on COBs (especially on high power) it matters, but nowadays people use strips more and more and they have so much contact surface already that it doesn't really matter what TIM you use (if any).
Click to expand...
Yes, for our interest, the new thermally orientated material is mostly for high power LED's spaced across large boards.
The heat is dispersed more quickly along the Graphite sheet away from LED.
These new materials are not expensive to make, freight is the biggest cost.

Already very common in Computers and especially devices like phones.

I think in the next year we might start seeing this type of product on Amazon etc.
 
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AuBlue

AuBlue

Member
Major Blazer said:
Yes, it can matter for sure. Look at youtube videos of people comparing thermal materials on cpu's.
Click to expand...
I use Infrared thermometer to see the thermal dispersion.
Also cooler LED’s function more efficiently with higher performance, and the Spectrum closer to specification.
 
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pulpoinspace

pulpoinspace

Well-Known Member
I guess I should have been a bit more explicit in what I was asking. I understand what TIM is and what it does. And the question in the post title was rhetorical. Meant to mean, how much do they matter for this specific purpose. I'll reiterate what the specific purpose is:

Going to test on VERO29C@1400ma on 180mm Kingbrite Pin Heatsink.
Currently using Sur-Seal Sur-Cool 1.5 w/m-K gap pad from rapidled
Will compare with Bergqvist top of the line 5 w/m-K gap pad

1)operating temperature at the core of the chip
2)operating temperature at different parts of the heatsink
3)heat up time to operating temperature

i will be testing these specific things and only changing the two gap pads. i'll report back with my findings.
if anyone has any hypothesis about these 3 questions, give it a shot.
not interested in any other products, just doing this for fun really.
 
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AuBlue

AuBlue

Member
With increased thermal conductivity of pad the efficiency is improved.
If the pad conductivity is greater than that of board/heat sink material, the improvements moslly stop.
This is not the case for thermally orientated Synthetic Graphite, up until a point.
Synthetic graphite works very good with Direct Thermal Path boards to transfer heat away.

Thickness is another factor, where the pad could arguably replace the heat sink.
So all factors are relative. I think you will find, what you would expect.

Standard Graphite sheets as used on Sinkpad 1950 are fast becoming obsolete.
 
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pulpoinspace

pulpoinspace

Well-Known Member
AuBlue said:
If the pad conductivity is greater than that of heat sink material, the improvements moslly stop.
Click to expand...
Good point.
Interesting. Because the heat has to travel through the heat sink as well. I looked up thermal conductivity for anodized aluminum and it doesn’t get much above 1.5w/m-k. So I may see little to any difference.
 
pulpoinspace

pulpoinspace

Well-Known Member
My biggest take away from this is spectrum king might be wasting thousands on over spec gap pads. Why do they buy 5w/m-k gap pads? What are their heat sinks made out of?
 
AuBlue

AuBlue

Member
pulpoinspace said:
My biggest take away from this is spectrum king might be wasting thousands on over spec gap pads. Why do they buy 5w/m-k gap pads? What are their heat sinks made out of?
Click to expand...
The real take home should be horses for courses. Thats why I took the time to share some knowledge in the thread.
I think your on track
 
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pulpoinspace

pulpoinspace

Well-Known Member
AuBlue said:
The real take home should be horses for courses. Thats why I took the time to share some knowledge in the thread.
I think your are on track
Click to expand...
I catch your drift. I knew these were for different uses i think my roommate mentioned he mostly sells them to aerospace companies.
I just wonder what spectrum king uses them for
 
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