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38 votes

How to solder a 70 °C (158 °F) thermal / temperature fuse

This was a problem with transistors in the early days and standard advice was to use a pliers as a heat shunt close to the body of the component. Figure 1. Protecting a capacitor from overheating ...
Transistor's user avatar
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38 votes
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How to solder a 70 °C (158 °F) thermal / temperature fuse

I think those thermal fuses are normally connected using crimp terminals, rather than by soldering. Even with the heatsinks the other answers mention, it would be much too easy to damage the device ...
Peter Bennett's user avatar
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} &...
Voltage Spike's user avatar
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33 votes
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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 ...
Spehro 'speff' Pefhany's user avatar
33 votes
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TO-92 not getting hot enough

The 0.83 W is the power going into the fan, not the transistor. The power dissipated by the transistor is essentially the same current value, but multiplied by the voltage from C to E, which is ...
Dave Tweed's user avatar
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33 votes
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Entire Perimeter of FPGA Getting Hot - Why?

The shiny heat spreader/transfer section in the middle of the chip almost certainly has a much lower emissivity than the rest of the body so will show lower temp on the IR camera. If you used ...
colintd's user avatar
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31 votes

How much of the power drawn by a chip turns into heat?

If it drives no loads, all of it. 100 %. If it drives loads, then subtract out the power to the loads. The loads themselves may turn that power directly into heat as well, or into something that will ...
Davide Andrea's user avatar
26 votes

Why do 0 dB attenuators exist?

A 0dB attenuator is an attenuator that is electrically and mechanically just like other attenuators in that product line. You can use them in place of another attenuator when doing tests. It acts ...
JRE's user avatar
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25 votes
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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 ...
Andy aka's user avatar
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22 votes

Can an infrared thermometer (IR gun) be used to measure the ambient room temperature?

In the relevant part of the infrared spectrum for this application\$^1\$, air has a high transmittance: (taken from here licensed under Creative Commons Attribution-Noncommercial-Share Alike 3.0 ...
Arsenal's user avatar
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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 ...
Marcus Müller's user avatar
22 votes
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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 ...
Chris H's user avatar
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What is the most common electronics IC package material?

You bascially always have an epoxy resin as molding compound ("because of their inherent low viscosity, fast cure properties, low shrinkage during cure, good adhesion to the other components in a ...
jusaca's user avatar
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21 votes
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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. ...
Spehro 'speff' Pefhany's user avatar
21 votes

Film/TV question: How to build Foam Cutter from only household items

"Cut the foam! Cut the foam!", she cried as she wriggled and squirmed in the styrofoam dishwasher packaging she got stuck in. "With what?", cried Bob as he scanned the kitchen for something suitable. ...
Transistor's user avatar
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21 votes
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Why is my op-amp getting hot?

Junction-to-ambient (JA), not junction-to-case (JC) because the heat is being sinked to ambient, not the case. Junction-to-case is used when you are connecting a heatsink directly to the case, and ...
DKNguyen's user avatar
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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 ...
Misunderstood's user avatar
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 ...
Peter Smith's user avatar
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18 votes
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If I want to use as little current as possible, then what resistance wire should I use to get the hottest temperature?

If you currently require 28 volts and 2.4 amps, that's a power of: $$ 28\:\mathrm V \cdot 2.4 \:\mathrm A = 67.2\:\mathrm W $$ 67.2 watts. Unless you can somehow use the heat more efficiently, this ...
Phil Frost's user avatar
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18 votes
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What makes the value of the surface to case thermal resistance?

It might seem strange for them to include that in a datasheet, but it is actually fine. The typical range for case-to-heatsink thermal resistance for a TO-220 clipped or screwed to a heatsink and ...
metacollin's user avatar
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17 votes
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What mad solder type is used for BGA?

Thermal inertia is playing against you. Also take into account that lead-free solder needs temperatures in excess of 220°C to melt down (compared to 180°C for tin-lead solder), so the thermal gradient ...
Enric Blanco's user avatar
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17 votes

Thermal relief for a chip without metal plate on the bottom

The effect will be minimal without anything more thermal conductive than air between the chip and that thermal pad. What you can do is to increase the width of the traces, that will work way better.
MiNiMe's user avatar
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15 votes

In a CPU, does the speed of a calculation affect the heat generated?

Besides clock speed, keep in mind that in a real "big" CPU (one that has caches, a MMU, TLBs, pipelined execution, SIMD, etc) another important factor of how much heat is generated would be how well ...
anrieff's user avatar
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15 votes
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OP1678 running hot

The large capacitor on the output of U3B is more than likely causing your amplifier to oscillate, dissipating lots of excess power. Looking at the datasheet, you can see the following graphs: With ...
John D's user avatar
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15 votes

How to solder a 70 °C (158 °F) thermal / temperature fuse

You can use a heat shunt - really just a pair of pliers on the lead, and keep the soldered joint as far away from the body as practical, but ideally use crimp joints, soldering these things is always ...
Phil G's user avatar
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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 ...
hildred's user avatar
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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 ...
Nick Alexeev's user avatar
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14 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 ...
Andy aka's user avatar
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