When should I use "Thermal Paste" to mount an Audio Amp to a heat sink?

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Dolmetscher007

Joined Mar 21, 2019
36
I do not have any thermal paste. I've built a PCB kit that has a TDA2030 Audio Amplifier, and it came with a small ~1" x 2" heat sink. I've screwed the chip to the heat sink, but... when is it advisable to use thermal paste between the chip and the heat sink?
 

Papabravo

Joined Feb 24, 2006
19,578
It is not worth buying a whole tube for one project. Monitor the temp of the heatsink as a function of volume and don't be in a hurry to run it at maximum volume until you know what temperature it will get to.
 

WBahn

Joined Mar 31, 2012
27,880
I do not have any thermal paste. I've built a PCB kit that has a TDA2030 Audio Amplifier, and it came with a small ~1" x 2" heat sink. I've screwed the chip to the heat sink, but... when is it advisable to use thermal paste between the chip and the heat sink?
Best practice is to always use thermal paste. If you need a heat sink, then you need to get heat into the heat sink.

But if you are only a ways into needing a heat sink, you might get away without the thermal paste, particularly if you can get a good, solid mount. Clean the surfaces very well, perhaps even lightly sanding them (depending on the surface material and finish).

Try it and see if the components (not the heat sink) are getting too hot. If not, then you are lucky and a no-paste connection is "good enough" for your application.

I don't know if they are still available, but years ago I bought a box of thermal grease packets. Each one was about the size of a salt or pepper packet you get from a fast-food place. On a per-gram basis they were pretty expensive, but on a per-pack basis they weren't bad at all. Was very convenient to have around since I seldom needed heat sink compound but was nice to have something at hand when I did.
 

Audioguru again

Joined Oct 21, 2019
5,416
If the obsolete TDA2030 stereo amplifier is producing a continuous tone in both channels for a few minutes then it will get hot and need the tiny heatsink with thermal grease.
But music usually has various output levels with pauses.
The Output power with the minimum supply voltage of 12V is very low and so it the amount of heating.
 

DickCappels

Joined Aug 21, 2008
9,512
There are second sources for the TDA2030, just as you can find second sources or the old LM386. Just because it is old does not mean that it is no longer useful.

A heatsink of ~1" x 2" will not do much and in that case the thermal resistance to ambienet will be large (many degrees C per watt) so the slight improvement in thermal resistance to ambient that would be obtained by using thermal paste would be pretty small.

Follow @WBahn 's advice in post #3.
 

Audioguru again

Joined Oct 21, 2019
5,416
The website that sells the TDA2030 amplifier kit knows nothing about it since they say it is a 14W amplifier and say to use a power supply that is only 12VDC.
The datasheet for the TDA2030 does not say its low output power at its minimum supply of 12V. It says its output is 14W per channel (12W guaranteed) into 4 ohms when the supply is 28VDC or 28W output power when both channels are bridged into 8 ohms.
 

dl324

Joined Mar 30, 2015
15,453
when is it advisable to use thermal paste between the chip and the heat sink?
Always.

If this is something you might need in the future, you can buy the packets mentioned earlier. I bought a hundred or two years ago (before counterfeiting from China became so bad)...
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The fact that they ship from China gives me pause, but there are other, more expensive, options.
 

DickCappels

Joined Aug 21, 2008
9,512
I guess I didn't make my point: If the heatsink has a thermal resistance to ambient of 15° per watt, the extra degree per watt that is added because there is no heatsink compound won't make much difference. 15° per watt vs 16° per watt. Not worth the trouble.
 

DickCappels

Joined Aug 21, 2008
9,512
What's your basis for the estimate of an "extra degree per watt"?
Residual memories of projects between 1971 and 1983. Yes, there are many variables, the "extra degree per watt" is meant to illustrate with the high thermal resistance of a tiny heatsink the thermal resistance is already high, but I think you already understood that.
 
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