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Make your own giant mosfet

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Gyro:

--- Quote from: Mr Evil on July 26, 2020, 04:13:11 pm ---That's actually quite cool, in a novelty giant pencil sort of way. It would have been better if the FETs were soldered directly to the aluminium tab though.

--- End quote ---

Everyone's cheaping out these days! You expect a package with a decent thickness copper tab get some thin....  :D


Maybe he could have re-flowed them onto a copper sheet and used decent thickness wires between the drains (TO220 packages would probably better) and possibly local resistors on each gate.

SiliconWizard:

--- Quote from: MasterTech on July 26, 2020, 05:29:37 pm ---This guy has not heard about IGBTs...

--- End quote ---

The "beefiest" MOSFET I've found so far is an IXYS one, spec'ed at 650V/170A max. Big package.

Yes, there are more options with IGBTs. Vishay has 600V/400A max devices, for instance. 600V/600A is really pushing it even with IGBTs. There probably are some but those are VERY expensive. Think about > $100 for ONE.

PartialDischarge:

--- Quote from: SiliconWizard on July 26, 2020, 06:21:42 pm --- 600V/600A is really pushing it even with IGBTs.

--- End quote ---

What?  :palm:

https://www.infineon.com/cms/en/product/power/igbt/igbt-modules/fz3600r17hp4_b2/

And there are IGBTs up to 6500V for use in multilevel topologies, like CHB or NPC

SiliconWizard:

--- Quote from: MasterTech on July 26, 2020, 06:32:58 pm ---
--- Quote from: SiliconWizard on July 26, 2020, 06:21:42 pm --- 600V/600A is really pushing it even with IGBTs.

--- End quote ---

What?  :palm:

https://www.infineon.com/cms/en/product/power/igbt/igbt-modules/fz3600r17hp4_b2/

--- End quote ---

This thing is actually a module made of several IGBT transistors. We were kind of talking about single transistors - at least I was - since that was compared to some DIY module made of several MOSFETs. So, that's just a module too. And that's why I mentioned one of the beefiest, yet single discrete MOSFET transistors I could find. Finding off-the-shelf, single IGBTs with those specs is harder.

And I didn't say those didn't exist. I said they were few and VERY expensive. The module you referred to is about 1500 euros. Holy crap. Even a 600V/400A single IGBT is around 100 euros or over.

So point is related to the original video, the idea of making a custom module to cut cost is not necessarily stupid. Just happened that they didn't design it properly, but paralleling several MOSFETs instead of using a huge one is relatively common, and suggesting an IGBT instead here, unless you have a very good technical reason for doing so, is debatable.

Gyro:

--- Quote from: SiliconWizard on July 26, 2020, 07:19:44 pm ---This thing is actually a module made of several IGBT transistors. We were kind of talking about single transistors - at least I was - since that was compared to some DIY module made of several MOSFETs. So, that's just a module too. And that's why I mentioned one of the beefiest, yet single discrete MOSFET transistors I could find. Finding off-the-shelf, single IGBTs with those specs is harder.

--- End quote ---

You rapidly reach the point where it's cheaper and much higher yield for manufacturers to put multiple dies down in a package rather than a single very large die. You run into major problems with bond wires when they get too big too. Just look at an electric car inverter teardown.

The only really big die devices I know are large disk ('hockey puck') SCRs and the like, where the internal contacts to the die are made by physical device clamping pressure (they often read open circuit if not clamped into a heatsink module).

Edit: Then you start to get figures like 5000A @ 1600V!

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