MOSFETS?

[Bluejay0]

Why is it importiant to keep MOSFETS cool?

[Godlygamer23]

They generate heat as they work.

[Samdb]

MOSFETS often need a heatsink to prevent overheating, transistors don't require cooling but are not as compact as MOSFETS, causing them to be used less often.

[Andi]

Why is it importiant to keep MOSFETS cool?

"Circuits operate more slowly at high temperatures, and have reduced reliability and shorter lifetimes. Heat sinks and other cooling devices and methods are now required for many integrated circuits including microprocessors.

Power MOSFETs are at risk of thermal runaway As their on-state resistance rises with temperature, if the load is approximately a constant-current load then the power loss rises correspondingly, generating further heat. When the heatsink is not able to keep the temperature low enough, the junction temperature may rise quickly and uncontrollably, resulting in destruction of the device."

[fishymamba]

Mosfets can get very hot during use, without a heatsink they can get up to 100C+ if they have a large load on them. 

Most are rated for a max temperature around 105C, they can blow up or melt if they get that hot. 

 

I was using a couple transistors to lower the voltage for a DC=>DC power supply I made and I did not put any cooling on them. it exploded ~10 minutes after I put a load on it. 

[Bluejay0]

MOSFETS often need a heatsink to prevent overheating, transistors don't require cooling but are not as compact as MOSFETS, causing them to be used less often.

 

WHen would they Heat up?

[Samdb]

WHen would they Heat up?

Whenever in use really, they can be quite sensitive to heat.

[Wats]

What board are you using? If you can find out what you have under the heat sinks and find data sheets you can see what they're rated for.