Questions tagged [thermal]

Relating to temperature rise, the flow of heat, or cooling of components

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SMD IC mounted upside-down inside a drill hole for extreme low-profile requirements

I don't know if the title is descriptive enough, but I came across this PCB and could stop to wonder about its brilliant design. It is an aftermarket trigger controller for an airsoft gun that works ...
63 views

Connector current/thermal rating

This question started as a design specific question but is (now) more of a general question going forward onto other PCB product designs... For now, I am designing an I/O PCB and want to mix supply ...
225 views

Thermal Management for Arcol HS50/HS100 50/100W Wirewound resistors

I'm designing a 100W dummy load for a guitar amplifier using Arcol HS50 and HS100 resistors. Here's a link to the datasheet: http://www.arcolresistors.com/wp-content/uploads/2014/03/HS-Datasheet.pdf ...
50 views

Non-uniform temperatue distribution

Please assume a semiconductor chip like IGBT or MOSFET heated by a specific power loss. It is found that the more the power loss is, the more severe the chip's temperature distribution non-uniformity ...
232 views

How Can I Find “temperature coefficient” of a Battery?

I am studying mathematical modeling of a battery in simulink and for this it is necessary to determine some parameters. I'm stuck in the part where I need to determine an alpha parameter, which would ...
56 views

Thermo Electric Cooler(TEC) for ICs

I am designing a 9u rack server with optical ports. I want to implement Thermo Electric Cooler(TEC) for cooling the ICs(switches, FPGAs) on board, so that I can reduce the fan speeds. Is this a good ...
182 views

MOSFET mechanism of failure: was it the heat?

I am debugging a failed MOSFET (IRF6662), and in the process of doing so, am having difficulty understanding fully the thermal behaviour of the FETs. Two FETs used for DC switching both failed short ...
57 views

Uneven chip temperature

When injecting a uniform power dissipation in a chip of IGBT power electronics modules by finite element method (FEM) in COMSOL (a good software for thermal analysis), a non-uniform temperature ...
3k views

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

Take as an example a CPU that is capable of changing its clock speed, like a modern computer CPU (Intel, AMD, whatever). When it does a certain calculation at a particular clock speed, does it ...
574 views

Thermal Fuse Crimp material

I speculate this is just barely an EE question, but I'll risk it anyway: I'm replacing a set of 175C 10A thermal fuses (with 172C 10A actually). At this temperature / current range, do we need ...
1k views

What is the difference between a resistor and a heating element?

As far as I know, a resistor and a heating element are the same thing. But one, the resistor, seems to limit the current in the circuit while the other, the heating element, draws more current and ...
2k views

How closely should I space my thermal vias?

How closely do you pack your thermal vias? I know that more vias divides the amount of heat each via can move and that smaller vias allows more vias to be packed together. Knowing this, it seems ...
497 views

Thermal voltage

In Shockley diode equation Vt is the thermal voltage and equals KT/q. In wiki article 'T' is defined as the absolute temperature of the p-n junction.As far as I Know the junction temperature is ...
598 views

Thermal impedance too high for proper use

I'm not sure to correctly understand the datasheet of Traco THN24 family. I read this: Thermal impedance – Natural convection 17.6°C/W but the DCDC is rated for 20W without de-rating (100% output ...
89 views

Can I expect a probe thermometer to still work if I cut it short?

I have a kitchen probe thermometer, a bit like this one It's overly long for my purposes, and takes an annoyingly long time to record a stable value. I assume this is because it takes a while for the ...
208 views

Hot-plug protection: series resistor thermal considerations

I have a circuit in place for the Linear Technology LT3502A switching regulator (datasheet here). To prevent blowing up the whole thing during hot-plugging, I have chosen to add a small parallel ...
95 views

Why do high current wires have fabric/nyon sheathes?

I saw two wires going into a halogen light bulb whose outer sheathes were not a plastic (like PVC, or polyurethane), but rather a woven fabric (like a nylon shoelace). Why is woven fabric better for ...
2k views

Thermal Paste on Cold Side of Peltier Freezing and not transferring “Heat”, what gives?

I am running a peltier element, and on the cold side an aluminum heat sink to effectively spread out the cool surface to the maximum possible surface area. I just bought this new thermal paste: ...
1k views

Liquid Metal Thermal “Thermal Grease” on a Peltier Element?

I was wondering if Liquid Metal Thermal Grease could be placed on a peltier's hot side to better conduct heat from the hot side to the heat sink. I know that aluminum is "Eaten" away by the thermal ...
5k views

Nichrome wire gauge calculation

I know what battery I wish to use (3.7 V 140 mAh which I can swap for larger mAh battery) I know what length of wire (3.5 inches or 7 inches depending on which ever would work better) I know what ...
1k views

TO-92 not getting hot enough

I am controlling a DC fan by an AVR MCU and I am curious about the thermal characteristics of a 2N3904 NPN transistor over which the fan is connected. Reading the transistor's datasheet, I find the ...
252 views

How to increase thermal shock resistance of the electronics components?

How to increase thermal shock resistance of the electronics components assembled on the PCB? Is there any material (or method) for increasing the thermal shock resistance of components? Best Regards, ...
470 views

Will stacked Peltiers produce a greater dT? [duplicate]

I am using this peltier device to ramp an aluminum plate down to -10C in a vacuum environment. I chose this particular device because it had the largest 'Qout' of any single-stage peltier I could find ...
292 views

Help in Thermal PAD and glue calculation (equivalence) in shared heatsink

Hello if I have 15 chips to dissipate 1W each (thus 15W in total), by math calculation, which of the next three possibilities is better: 1) using a unique shared heatsink @1.7K/W with 0.5mm thermal ...
10k views

Why aren't CPUs cooled from below as well as above?

The transistory bits of an integrated circuit are approximately in the centre of the (plastic or ceramic) package. They sometimes get hot, and we cool them by affixing a heat sink to one side. ...
404 views

MOSfet thermal design: die-to-package always DRAIN?

All the MOSfet chips seem to have substrate = DRAIN, which means that the heat-dissipation path goes that way. It is assumed that the package DRAIN pin would conduct away most heat from the package to ...
189 views

Temporary thermal adhesive for PCB measurement

I am making an examination on the effects of adding cooling to some existing electronics (making an comparison between having no cooling of the electronics and adding a heatsink or heatpipe + heatsink)...
123 views

PID for thermal protection

I have a LED controller that has several temperature sensors in different places of the system. I want to implement an overtemperature protection for the system. Now this would be theoretically a ...
993 views

Big heatsink vs. small one with a fan

There's quite a bit of math to be done when you need to calculate a size for your heatsink. As there are many options to choose from if you don't know the size yet, is it just better to pick the ...
1k views

Thermal EMF (seebeck effect) on PCBs

Can poor PCB fabrication process / assembly, and the type of solder used cause thermal EMF (seebeck on PCB) problem? Is it affected by the type of the material used? For example, quality of plating, ...
344 views

Thermal Modeling of 0805 Thick Film Chip Resistor

I recently got confronted with the question what peak/pulse power a standard 0805 thick film resistor can withstand. Background: We are designing a 2kW bidirectional DCDC converter. The Primary side ...
333 views

CD4521 frequency divider warms up while RESET is HIGH

I have a peculiar problem involving the CD4521 frequency divider of which I use two in a redundant configuration as shown in my schematic snippet below: I noticed that while the devices are held ...
8k views

Does the paint colour matter on a heat sink?

Heat leaves a heat sink via conduction, convection and radiation. I was taught that black surfaces are best at radiating heat and correspondingly a lot of heat sinks are black. But they also have ...
134 views

Heat sinking ideas for an HZIP package

I'm building a design involving Toshiba's TB6600 chip which has an unusal HZIP25-P-1.00F package. I've seen implementations where folks have bent the pins manually and soldered them horizontally such ...
641 views

Exponential amplifier thermal stabilisation

I am currently trying to build a DIY analog synthesizer. I've looked at a lot of different designs and I am quite stuck on understanding how some exponential amplifier designs work. In analog ...
115 views

Is it okay to use a device whose junction temperature is more than operating temperature?

I am searching for a voltage regulator which gives output voltage of 3.5V, 2A with input of 7.5V min. I have seen L6932 HIGH PERFORMANCE 2A ULDO LINEAR REGULATOR. In the datasheet there is calculation ...
1k views

If I want to use as little current as possible, then what resistance wire should I use to get the hottest temperature?

I am trying to build a circuit that is able to melt wax (130˚F) and use as few amps as possible since it will need to be powered using a battery. Do I need to be looking for wire that has a high ...
1k views

Enclosure best air flow profile

I'm in final step of a project an I need some advice about what heat evacuation profile should I use to place three fans for cooling, I have four alternatives as shown in the diagram but I don't know ...
754 views

Why did my solder joint fracture?

I've been in the habit of making vias on homemade pcb's by putting the leg of 1N4148 diode into a 0.5 mm hole, cutting it off to length and soldering both sides. However, now my led controller broke ...
69 views

LFP Cells - Case to internal thermal resistance

Semiconductors often specify thermal resistance from case to the junction, but LFP battery cells do not seem to specify this. Instead, they refer only to a generic 'maximum operating temperature'. ...
502 views

SMD resistor with same resistance but with different power will reduce the temperature of my PCB?

I need to reduce the amount of heat generate by some resistors on my PCB. My question is if I use a 10ohms - 2 watts - 2512 SMD resistor instead of a 10ohms - 1 watt - 2512 SMD resistor, the amount ...
1k views

Determine whether chassis is a suitable heatsink?

I picked up a sweet little aluminium box for a small USB powered DAC project... ...and while putting it together I noticed the side panels of the box were very cool to the touch, and made of thick ...
2k views

Hot air soldering without destroying ICs

I have designed a circuit board that has about 20 parts on it, including a surface mount LMV431 Adjustable Zener Shunt Regulator and MMBT2907 PNP transistor. It appears that every time I solder up a ...
239 views

Thermal runaway protection

I'm having an oven that is heating a specific element. I have cascaded P/PI loops. I have two thermo elements as sensors. I would like to know how would I implement a thermal runaway protection. ...
102 views

Evaluating junction temperature from thermal imaging data

I have a SOD-123F diode through which a current of ~1A flows, creating a forward voltage drop of around 300mV. The datasheet does not specify Rjc but gives Rja = 200 C/W and Rjl = 70 C/W for a 10cm x ...
537 views

Can you continuously flash a high power LED bulb or will it break?

I want a bright flashing display light. Imagine the sort of thing on a one armed bandit machine, that flashes a couple of times a second. And it would run for days on end. So either one of these ...
83 views

Thermal design for an IGBT

I am working on a project that involes an inverter made with IGBTs. The device I selected for builing the H bridge is this: STGW60H65DFB. One of my roles in this project is also to select a suitable ...
138 views

Solving for Amps in a selfmade furnace/heating resistance

I made a heating resistance out of a graphite bar I found. I will adapt this bar to a furnace in order be able to sinter Si3N4 (1850°C). After measuring dimensions, max. load of Si3N4 in the furnace ...