Tantalums in place of electrolytics in vehicle ECUs

[japlytic]

Inside a VL Holden Commodore ECU (made by Bosch), it had only two electrolytic capacitors. One is a 100uF 63V CE-HF series unit for the injector voltage reference; the other is a 330uF 25V GM series unit for a logic rail. Both of them were Matsushita 105C units, and are still good. All of the other polarized capacitors were tantalum units.

Should manufacturers avoid using electrolytic capacitors (and use tantalum units instead) as much as possible in their vehicle ECUs?

Also, is it safe to replace leaking electrolytic capacitors in vehicle ECUs with tantalum units?

[gg1978]

Re: Tantalums in place of electrolytics in vehicle ECUs

Well, i'd say it would depend on the ESR of the cap you're replacing. Usually the higher voltage series of caps are not "low ESR" type. We're talking about caps with > 25WVDC here. You'll want to make damn sure you get the polarity on tantalum right, as they share the exploding type of characteristic as electrolytics when put in backwards, but they usually do it immediately. When i think of tantalums being in a circuit, they're used more for filtering out noise than for bulk DC storage. Hence why on some circuit boards you'll see a .1uf, a .01uF and a .001uF tantalum all on a DC rail, being used to bypass noise to ground.

[gonzo0815]

Re: Tantalums in place of electrolytics in vehicle ECUs

Tantalum isn`t the solution. Tantalum capacitors are prone to break after several years (the usualy consumer crade ons at least). And if used as inputcapazitors in switching supplies and vrm circuits they explode due to the high ripple current. Only as outputfilter they could used. E.g. under the cpu socket as an fast reacting transient capzitor they are ok.

[PeteS in CA]

Re: Tantalums in place of electrolytics in vehicle ECUs

Sun Microsystems stopped using tantalum caps and forbade their use by their vendors in the mid-late 90s because of such problems. When tantalum caps fail they can catch fire.

[Rubycon]

Re: Tantalums in place of electrolytics in vehicle ECUs

Sun Microsystems stopped using tantalum caps and forbade their use by their vendors in the mid-late 90s because of such problems. When tantalum caps fail they can catch fire.

Indeed. I witnessed this firsthand with some weather instruments that were damaged from a direct lightning strike to our radar tower. When the CB's were reset, really bright white flashes reminscent of burning magnesium(!) were seen through the seems of the power supply chassis. It was those tantalum caps. They were secured with Torr Seal too! Amazing fire they put out.

[kc8adu]

Re: Tantalums in place of electrolytics in vehicle ECUs

when we have a bsu party we often take junk boards and hook up 12v 20a battery charger in reverse to the +5 on one with a ton of tants.
impressive flashes,pops,and purple fireballs flying.
bsu= blow shit up.
i will post video soon.
job gets finished by dr.glock and the 2 brothers.

[Rubycon]

Re: Tantalums in place of electrolytics in vehicle ECUs

Even plain electrolytics blow nice when reversed. You can also take small ones and put them in a x-mas tree top. Remove the bulb, pull the leads of the cap through the plastic base and plug it back in. When they turn on the tree it's like a 21 shot salute.

It smells pretty bad though.

Another trick is to dike off the tips of the lamps (careful not to shatter the bulb envelope and the filament MUST stay intact) and fill it with pyrodex. Nice firecracker effect. Imagine a squibbed tree.

[PeteS in CA]

Re: Tantalums in place of electrolytics in vehicle ECUs

IIRC, Sun had a couple of MBs (not cheap stuff!) ruined by burning tantalums and a couple of data center shut downs when tantalums failed due to customer concerns about fire.

[willawake]

Re: Tantalums in place of electrolytics in vehicle ECUs

i saw a sun doc advising about a bad lytic in their product. they seemed to be on the ball and proactive about it.