Make your own giant mosfet - Page 1
Forum section: electronics / general

author: ratatax
author_rank: Regular Contributor
timestamp: July 26, 2020, 09:20:38 am
content: That video totally cracked me upBy the way don't do it..

author: bd139
author_rank: Super Contributor
timestamp: July 26, 2020, 09:30:07 am
content: Yeah that’s going to melt

author: Gyro
author_rank: Super Contributor
timestamp: July 26, 2020, 01:16:03 pm
content: I'd love to see its SOA graph!I can't help thinking he could have got a lot more mosfets in there too (and sorted out the PCB tracks that are going to blow at 600A!)

author: TERRA Operative
author_rank: Super Contributor
timestamp: July 26, 2020, 03:59:19 pm
content: Besides the PCB fuse traces, I see no gate resistors.That thing's gonna have a chain-reaction explosive style style melt-down if it's asked to pass any real current....Also, how do you heatsink it properly anyway???

author: SiliconWizard
author_rank: Super Contributor
timestamp: July 26, 2020, 04:05:52 pm
content: Quote from: bd139 on July 26, 2020, 09:30:07 amYou bet.Too bad the video is just about the making. Absolutely no test whatsoever to be seen. Yeah buddy, get 600 A through that and see what happens. We WANT to watch this. Wear safety glasses and don't get too close.

author: Mr Evil
author_rank: Regular Contributor
timestamp: July 26, 2020, 04:13:11 pm
content: 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.

author: Bud
author_rank: Super Contributor
timestamp: July 26, 2020, 04:56:57 pm
content: Instead of some glue logic Digikey once sent me a bag of power FETs in error . I still have them so maybe one day i will try it (after another 500 projects on tne list)I wonder what resin the guy is using, so it does not trap air bubbles.

author: tooki
author_rank: Super Contributor
timestamp: July 26, 2020, 05:20:35 pm
content: Whatever it is, he had to leave it to cure for ayear. So somehow it can’t be that good...

author: PartialDischarge
author_rank: Super Contributor
timestamp: July 26, 2020, 05:29:37 pm
content: This guy has not heard about IGBTs...

author: tooki
author_rank: Super Contributor
timestamp: July 26, 2020, 05:59:48 pm
content: Quote from: MasterTech on July 26, 2020, 05:29:37 pmAmong other things, like soldering tip cleaner!

author: Gyro
author_rank: Super Contributor
timestamp: July 26, 2020, 06:13:24 pm
content: Quote from: Mr Evil on July 26, 2020, 04:13:11 pmEveryone's cheaping out these days! You expect a package with a decent thickness copper tab get some thin....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.

author: SiliconWizard
author_rank: Super Contributor
timestamp: July 26, 2020, 06:21:42 pm
content: Quote from: MasterTech on July 26, 2020, 05:29:37 pmThe "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.

author: PartialDischarge
author_rank: Super Contributor
timestamp: July 26, 2020, 06:32:58 pm
content: Quote from: SiliconWizard on July 26, 2020, 06:21:42 pmWhat?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

author: SiliconWizard
author_rank: Super Contributor
timestamp: July 26, 2020, 07:19:44 pm
content: Quote from: MasterTech on July 26, 2020, 06:32:58 pmThis 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.

author: Gyro
author_rank: Super Contributor
timestamp: July 26, 2020, 07:37:24 pm
content: Quote from: SiliconWizard on July 26, 2020, 07:19:44 pmYou 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!

author: SiliconWizard
author_rank: Super Contributor
timestamp: July 26, 2020, 07:49:33 pm
content: Quote from: Gyro on July 26, 2020, 07:37:24 pmOh, that's completely right.But still, those beefy IGBTs are fricking expensive.

author: daqq
author_rank: Super Contributor
timestamp: July 26, 2020, 09:09:03 pm
content: MOSFET modules where you get a lot in series/parallel are a thing, but for a bit of a different target application. See:http://www.behlke.com/separations/separation_c1.htmFor instance:http://www.behlke.com/pdf/331-06.pdfNote the rise time.edit:Quote from: SiliconWizard on July 26, 2020, 07:49:33 pmDefine beefy and expensive - this fella:https://ie.farnell.com/infineon/fz600r12ke3hosa1/transistor-igbt-module-1-2kv-900a/dp/2726202switches over 1MW and costs around 120 EUR @ single piece. The bang per buck is insane in my opinion.

author: Syntax Error
author_rank: Frequent Contributor
timestamp: July 26, 2020, 09:24:04 pm
content: I've thought that a thunder cloud (CuNb) works just like a giant Mosfet; with accumulation and depletion zones, and a 'gate' mechanism that allows 10,000+ amps to flow. Any semiconductor experts care to vehemently disagree in a green comic sans font?

author: jpanhalt
author_rank: Super Contributor
timestamp: July 26, 2020, 09:28:11 pm
content: Just another hideous YT "DIY" fake. The music is even worse. Mosfets have been paralleled since they were fist invented. Potting them in plastic is just plain...

author: tooki
author_rank: Super Contributor
timestamp: July 26, 2020, 10:20:34 pm
content: Quote from: jpanhalt on July 26, 2020, 09:28:11 pmAnd he uses that same looped music in every single one of his videos. Oh, and the guy is Vietnamese, not American, making the channel name perplexing, too.

author: amyk
author_rank: Super Contributor
timestamp: July 27, 2020, 01:21:19 am
content: Quote from: tooki on July 26, 2020, 10:20:34 pmVietnam. The same place those fake "restoration" videos come from...

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: July 27, 2020, 02:38:23 am
content: No no no no. This is how you handle large currenthttps://library.e.abb.com/public/871a18f5be50461b83cfceae9f021978/67-71%204m6009_EN_72dpi.pdf

author: SiliconWizard
author_rank: Super Contributor
timestamp: July 27, 2020, 02:25:22 pm
content: Quote from: Alex Eisenhut on July 27, 2020, 02:38:23 amInteresting.

author: SiliconWizard
author_rank: Super Contributor
timestamp: July 27, 2020, 02:34:53 pm
content: QuoteWell, I didn't really consider this metric. But yeah, if you have to get the same switching characteristics with a number of cascaded and paralleled MOSFETs, I guess this makes sense.Just comparing some IXYS MOSFET I mentioned (600V/170A) which costs about 30 euros per one. By your metric, that would be about 111 kW. So, by this metric, the ratio "power" over cost is about 2.25 in favor of the IGBT.

author: MadTux
author_rank: Frequent Contributor
timestamp: July 27, 2020, 09:43:45 pm
content: What's the point? I don't get it.Youtube 2020, solder some fricking MOSFETs into a big package, make 17min video about it and collect youtube cash?

author: tooki
author_rank: Super Contributor
timestamp: July 27, 2020, 11:28:27 pm
content: Quote from: MadTux on July 27, 2020, 09:43:45 pmPretty much. The underpants gnomes had it all figured out way ahead of us!Edit: reworded since the forum replaced the hyperlink with an inline video.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: July 28, 2020, 01:09:10 am
content: Eh...https://boingboing.net/2017/07/03/this-guy-built-a-storage-ottom.html

author: bd139
author_rank: Super Contributor
timestamp: July 28, 2020, 07:42:17 am
content: Now that’s actually cool. I’d hate to sit on it by accident if it was upside down though.

author: tooki
author_rank: Super Contributor
timestamp: July 28, 2020, 09:55:56 am
content: Quote from: Alex Eisenhut on July 28, 2020, 01:09:10 amThat is freaking adorable!Maybe I should make one in NE5532.It could go atop a TQFP-304 area rug.

author: tom66
author_rank: Super Contributor
timestamp: July 28, 2020, 10:51:07 am
content: Well if you are talking about MOSFET power ratings, Tesla uses single SiC MOSFETs in their drive inverters rated to well over 600A each. These SiC devices are proprietary to their vehicles (probably a custom Infineon part.) Previously they used multiparallel IGBTs.SiC MOSFETs are the future for high power. Fascinating devices.Also what on earth is a 'PCT' device in that diagram? I have never heard of it and can't find any reference on Google? Some form of GTO thyristor?