two years ago i promised to tell the Capacitor Plague story. that time has come! 🧵 https://t.co/zAqLq0BTBM

(original thread)
https://twitter.com/TubeTimeUS/status/1277412681897525253

what is capacitor plague? in the early to mid 2000s, a whole lot of poorly-designed capacitors hit the market and failed spectacularly after only a few months of operation. https://t.co/Jr70eP5oQ8

these capacitors failed by popping open and venting hydrogen gas that built up inside.

the root cause of the failure is the electrolyte, a conductive liquid crucial to the operation of the component.

(read more about that in this thread, where i use Gatorade as a capacitor electrolyte)
https://twitter.com/TubeTimeUS/status/1542917879133114369

in 2002, an article in Passive Component Magazine reported that a scientist quit his job at Rubycon in Japan and went to China to work at a competitor, Luminous Town Electric. at the new company, he developed a clone of Rubycon's P-50 water-based electrolyte. https://t.co/npGvO6yvT1

some of the scientist's other staff members decided to leave Luminous Town Electric, but they took the formula for the P-50 clone with them! https://t.co/glzV1yjump

however, the staff members made an incomplete copy of the formula, leaving out critical stabilizing ingredients, which allowed the electrolyte to build up excessive amounts of hydrogen gas. https://t.co/oUZN9Gf5ui

electrolyte made using this renegade copy-of-a-copy formula started getting used by many capacitor manufacturers throughout Taiwan. and soon after, the failures began to pile up. https://t.co/QoVnFMrtfe

electronics equipment manufacturers began to scramble to track down the source of the issue, many of them switching to capacitor manufacturers who used only Japanese-sourced electrolyte.

great story, right? it has all the juicy elements of intrigue, a little racism, and espionage--thieves stealing the secret formula from a thief, and all that. https://t.co/PYgTrNS4Zk

but something about it doesn't ring true.

why would capacitor manufacturers continue to make products based on a "faulty" formula for *ten years* after they knew it was a problem? these formulas aren't really all that secret--they're often disclosed in patent filings in great detail. https://t.co/3haTORW8oe

and i've found plenty of failed capacitors made by name-brand Japanese companies, presumably using the "better" formula. so what gives?

the article in Passive Component Magazine has a long publisher's note shrouding their sources in anonymity. https://t.co/thEfOq1k7R

but there is also a tantalizing comment from a Taiwanese capacitor company, Teapo, who believed that the story was an attempt by the Japanese capacitor manufacturers to regain market share lost to cheaper competitors. https://t.co/a2qYYyNTbs

and also, failures like this are not always the fault of the electrolyte. if a designer put a capacitor next to a hot component like a switching transistor, or if a capacitor is subjected to high ripple current, it will fail pretty quickly in essentially the same way. https://t.co/xdOUwMkBaa

how about this--companies tried to save money by buying ultra-low-cost electrolytic capacitors whose manufacturers used cheap, bad electrolyte. when they got caught, they blamed industrial espionage. why'd it go on for years? companies kept buying the cheap, crappy capacitors!

i'll leave you with this fake commercial i made for a cheap, crappy capacitor that failed in a power adapter.
https://twitter.com/TubeTimeUS/status/1093344618769305604

sources. #1 the article in Passive Component Magazine (https://web.archive.org/web/20160303234525/http://old.passivecomponentmagazine.com/files/archives/2002/PCI_02_05Sept-Oct.pdf)

#2 Gurevich, Vladimir. Power Supply Devices and Systems of Relay Protection, pp 67-77.