Taiwanese Capacitors Leaking, Exploding

ackthpt writes "A few astute slashdot readers were on to something back when this article was published. After a tip (at e-insight.net) on failing caps over at amdmb I did a little looking around and found this article by Dennis Zogbi on TTI Inc.'s site, which goes into more detail. In a nutshell, many motherboards are now failing due to electolytic capacitors made with an inferior water-based electolyte. Within days or a few months these capacitors build up hydrogen gas and blow the rubber bung out the end of the capacitor, leaking electolyte and causing havoc. The problem may be widespread, as many consumer electronics made with these capacitors may also fail prematurely. Gary Headlee specializes in Abit motherboards, but as his FAQ states, he will work on other makes and the FAQ has more info on capacitor problems."

Comments

Cheap capacitors

[HotNeedleOfInquiry]

Nothing new about the annoucement. Cheap electrolytic capacitors have been around and been a problem for years. There are other failure modes. i've fixed several old Mac's where the cap has pissed it's electrolyte all over the motherboard. Usually removing the cap, scrubbing the board and installing a new cap fixes the problem. Even worse is when the electrolyte is lost gradually. The product that it's in gets flakey over time and the problem is very hard to find. These problems are all made worse by exposing your gear to high temperatures. Never leave your electronics in the passenger compartment of your car in the summer.

Tanatlum shortage

[huie]

Do a Google search on "tanatlum shortage" and you'll see that there was a flury of articles about a year and a half ago. This prompted development of other electrolytic capacitors, one of which is the aluminum electrolyte that seems to be having problems.

I assume that it's only taken this long to find the problem due to the development time and time to qualify (ha!) and integrate these new caps onto boards. Needless to say, I guess they needed to develop the caps better, but they may have rushed to market since there was little else available (at a decent price).

Re:Recalls?

[sigwinch]

I think that's overly harsh on electrolytics. Like everything else, what you get depends on what you buy. You can buy from respected companies that have been making good caps for 20 years, or you can buy from whatever random Chinese company was cheapest this week. You can settle for any specs you can get, or you can insist on caps that are rated for 5000 hours of operation at 105 degrees Celcius (hotter than boiling water!).

There are also system design issues. You can push the caps to the very limit of their rated ripple current, or you can use more caps and share the current around.

Good god...how many of these things could be lurking about in automotive airbags, ABS systems, or in any sort of medical device?

For the most part, none.

Medical stuff routinely uses electrolytics. It doesn't have to be perfect, it just has to fail a lot less often than doctors and nurses.

Electrolytic capacitors have a fixed lifetime and are by nature unreliable.

They do not. The lifetime depends on the grade selected by the engineer, and how hard the design pushes the cap. A good cap used properly can last for many years of continuous service. That's good enough for many applications, even in safety-critical systems.

Where reliability is critical, Tantalum capacitors are used, but they're physically larger and more expensive.

You can't be serious! Tantalums are notoriusly flaky. Not only that, the usual failure mode is that the cap vanishes in a spectacular flash of purple fire. Every capacitor failure I've ever seen in computing equipment has been a tantalum. An engineer who used to work at Motorola told me that tantalums were banned from pager designs. At the time, Motorola would rather pay the premium for ceramic caps than risk tantalums.

Any -critical- system manufacturer(automotive safety systems, medical equipment, etc) that uses electrolytic capacitors should be shot.

It depends entirely on the service life that is needed, and the degree of redundancy you can afford. Satellites and airbags have to remain in service for decades without repair, so electrolytics are probably unacceptable. Medical equipment generally doesn't need such high reliability, and frequently uses electrolytics. (Seriously. Med equipment is regularly replaced, there's no point in making it more than a couple of orders of magnitude more reliable than physicians, and the critical stuff has spares sitting on shelves.) Telecom equipment can afford redundancy in almost everything, and so it's full of electrolytics.