112
votes
Accepted
Fan and heatsink - suck or blow?
This is such a wide subject it really isn't one you can answer with a simple one is better than the other answer.
Standing alone, the blow side of a fan does produce a more concentrated, faster ...
43
votes
Would this component require a heat sink?
No, this would not require a heatsink.
To answer your problem, you first need to know the power dissipated by the component. To do this, it is a simple calculation of P = IV. Thus, your power ...
39
votes
Copper or Aluminum Heatsink?
Copper has got better thermal conductivity.
Aluminium - \$ \mathrm{ 200 \frac {W} {m\cdot K} } \$
Copper - \$ \mathrm{ 400 \frac {W} {m\cdot K} } \$
(from here, also here)
But thermal conductivity ...
37
votes
Why aren't CPUs cooled from below as well as above?
They aren't cooled from below because they have pins on the bottom, and FR4 below that.
Due to having a much lower thermal conductivity,
$$
\begin{array}{rrl}
\text{Copper:} & 385\phantom{.25} &...
35
votes
Accepted
Optimize heat sink design - connect cooling pad on PCB backside by vias
Ok, first I am going to try to give a nice little primer on thermal engineering, since you say you want to get a better handle on it. It sounds like you're at that point where you understand the ...
33
votes
Using CPU heat to generate electricity
The issue with thermoelectric generators is they are horrendously inefficient.
For a CPU you HAVE to get rid of the heat they produce or they melt down.
You could hook up a peltier module and ...
32
votes
Accepted
Does the paint colour matter on a heat sink?
Yes black has the highest emissivity (it also absorbs radiation best- reciprocity - or Kirchoff's law of thermal radiation). Note that it has to be "black" at the relevant wavelengths, which do not ...
25
votes
Accepted
Is it a good idea to use a single heatsink for two IC's?
Using a single heatsink is very common - sometimes it can even increase performance (thermal matching of discrete transistors for helping against thermal runaway or better matching).
However, there ...
25
votes
Accepted
Why are these SMD heatsinks designed to not touch the IC?
Thermal Pad
The bottom of the IC's TO-263 package has a thermal pad that directly solders to a copper pad on the PCB. Your heatsink then solders to that same copper pad on the PCB. Heat produced via ...
23
votes
How tight can I mount a TO-220 to a bus bar?
The part you are trying to get the heat out of is roughly in the centre of the black plastic part and mounted against the lead frame. Distorting the lead frame (the metal part) by overtightening will ...
22
votes
Why aren't CPUs cooled from below as well as above?
Cooling isn't important, it's crucial. A modern CPU can easily put out something between 15 W and 200 W, from a die that's a few cm². If you're not transporting that heat away, that chip has to stop ...
21
votes
Optimize heat sink design - connect cooling pad on PCB backside by vias
Using a linear regulator where such a lot of power is dissipated is ill-advised. Your PCB is going to be like a heater. This means that from 5.52 watts of power only 1.15 will be useful power which ...
21
votes
Accepted
Is a thermally conductive pad always useful between TO220 and heat-sink?
The thermal conductivity of a dry vs. thermal grease is shown here for TO-264 package (from ON Semi application note AN-4166)
Looks like roughly 0.7 to 1.1 °C/W depending on the torque for dry mount. ...
21
votes
Why are electrically insulating heatsinks so rare? Is it just cost?
One thing that other answers don't seem to have covered is that you only need a very thin layer of electrical insulator (at modest voltages) while the heat spreader part of a heat sink works best if ...
19
votes
Optimize heat sink design - connect cooling pad on PCB backside by vias
Do you see any further things I could optimize?
Without giving it too much thought, about 10 11 12 13 came to mind.
Thermal Pad Area
Junction to Case Thermal Resistance
Thin PCB
Copper or Silver ...
19
votes
Using CPU heat to generate electricity
For generating electricity, you want the hot side (processor) to be as hot as possible for maximum efficiency. The thermal generator slows down the movement of heat as it extracts energy from it.
For ...
19
votes
Using CPU heat to generate electricity
Surprised that nobody else has mentioned this:
Generating electricty from the waste heat from some process that burns fuel can make sense. Generating electricity from the waste heat from a system ...
19
votes
Accepted
Why are DIMMs not equipped with a heat sink like a CPU?
You're assuming that the power dissipation is directly related to the clock rate. That's true but there's more.
Suppose I have this chip A where only 10% of the chip area (die size) runs at the ...
19
votes
Why are electrically insulating heatsinks so rare? Is it just cost?
This is hardly a new problem; those of us of a certain age remember the heatsinks with mica insulators for the TO-220 and TO-3 packages.
The issue (at the time) was both material cost and ...
18
votes
Copper or Aluminum Heatsink?
It's a complex question, with many factors. Let's look at some physical properties:
thermal conductivity (\$\mathrm{W \over m\cdot K}\$)
copper: 400
aluminium: 235
volumetric heat capacity (\$\...
17
votes
Accepted
Using CPU heat to generate electricity
tl;dr
Yes, you can extract a small amount of power from a CPU's waste heat, but your heat sink must be the bigger the more power you want to extract.
explanation
There is no machine which converts ...
14
votes
Does the paint colour matter on a heat sink?
I used to sell high performance coatings including coatings for thermal management, and this is by no means a simple question. For example one vendor made two coatings that were both a matte black ...
14
votes
Why are electrically insulating heatsinks so rare? Is it just cost?
Polymer heatsinks deserve a mention. Polymer heatsinks aren't that uncommon. I come across polymer heat sinks industrial, automotive, prosumer goods once in a while. They are often hard to ...
14
votes
Effect of length on a thermocouple's accuracy
Wire cable resistance is insignificant when compared to the input impedance of the amplifier which is so high that the wire doesn't affect the measurement.
For example, the LT1052 (which would be ...
13
votes
Accepted
Determine whether chassis is a suitable heatsink?
Using the casing as a heat-sink is a common method however a few things must be understood.
As Laptop2d mentions it is hard to model the thermal characteristics of the case, and an experimental ...
13
votes
Why are DIMMs not equipped with a heat sink like a CPU?
DIMMs don't dissipate the same power a CPU does, so they don't need the same cooling. In addition, the power the memory and control chips do dissipate is much more spread out physically.
Power ...
13
votes
Heat Dissipation Calculation for MOSFET
What they told me about MOSFETs when I was at college
MOSFETs don't suffer from thermal runaway unlike BJTs
The lie they told me about MOSFETs when I was at ...
12
votes
How tight can I mount a TO-220 to a bus bar?
Am I correct to assume that all the electronics are within the black plastic part,
yes,
and that I can therefore tighten it as hard as I would like?
No, since that would deform the metal part ...
Only top scored, non community-wiki answers of a minimum length are eligible
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