Capacitor leakage current

Hi,

I'm having troubles with capacitors that leak current. For example in the range of 10uF to 1000uF. I soldered good quality 470uF in a circuit at 5V and the leakage current is 0.1mA, that is too much.

The old capacitors could recover themself. When not being used for 20 years, they recover a little when a voltage is applied. It seems that newer ones don't do that.

For a 1uF capacitor I used ten 100nF ceramic types, and sprayed pcb fixer over it, so dust can't cause a leak. Result : no leakage current at all.

When I measure the leakage current, I end up using old capacitors. But I don't know if they will last another 10 years.

What is reliable for 10 years with minimal leakage current ?

Generally, solid tantalums.

Looks relevant and useful (the linked articles)... http://www.baldengineer.com/appearances/introduction-to-polymer-capacitors http://www.baldengineer.com/appearances/capacitor-innovations-address-emerging-opportunities-on-psd

Thanks. I don't like tantalum capacitors, they failed on me too easily in the past. However, I ordered a few to replace those capacitors with large leakage current.

Are many of the smd capacitors tantalum ?

A 470uF cap leaking 100uA is not good quality! Should be more like 5uA in my experience.

Is something special about these caps? What's their voltage rating? At what temperature did you measure the leakage? Did you buy them from eBay (ie are they of unknown provenance?)

At normal room temperature, but I plan to them also outside.
I checked the brand, it is Capxon. Searching the internet it turned out they can be bad. They are all over the www.eevblog.com for causing troubles.

Another capacitor leakage current is in wireless alarm detectors. With a 9V lithium battery, they should last for 5 year. When a detector stops after a few months, I have to replace the capacitors … again.
I can’t read the brand of those, I have added a photo.

badcap.jpg

Nichicon, Panasonic, Rubycon - those are trustable brands for high performance low ESR caps.

Capxon? Never seen that before, but a quick search shows them turning up like a rash on badcaps.net...

Google "capacitor plague"

Thanks. I know that story. I had a few routers that lasted less than a year, because of capacitors with the stolen formula.

Dell had a problem with cheap capacitors in the past. Would swell and start leaking badly. Needed to replaced the motherboard.

If electronics are critical, then there is no substitute for quality (more expensive) components. Look at the specs for leakage currents. If you cannot get the specs, then don't purchase them.

Hi, from what I have experienced, the minute you use an electrolytic capacitor to function in a switch mode power supply, you will shorten its life considerably, especially if running the voltage close to its rated voltage.
Low value, high voltage espeially 1uF 63V, 2.2uF 50V are classics, and are the caps that I usually check first.

Any application that uses 50Hz or 60Hz does not seem to be a problem unless high ripple currents, and or heat.

If using in SMPS, make sure you get LOW ESR capacitors, they cost more but it depends on your priority.

Tom… :slight_smile:
And the picture attached needs no explanation as to why the supply was only working at half load.