On Wed, Nov 27, 2024 at 8:57?PM Brian via <brianclarke01=[email protected]> wrote:
Hello Gary,
Tantalum capacitors¡¯ working Voltage rating is for marketing purposes only. The Arrhenius equation regarding time to failure applies. As you approach the rated Voltage, the time to failure gets shorter and shorter. When I replace tantalum capacitors, I use ones rated (marketed) with double my expected operating Voltage.
When tantalum capacitors first became available, printed wiring board designers took advantage of the smaller size of tantalum capacitors and crammed them onto the board.? When I repair a board, if there¡¯s enough room, I generally replace tantalum capacitors with good-quality low-ESR electrolytic capacitors.
I'm sure we've all repaired some equipment where a tantalum capacitor has shorted.?
?
I lived for 30 years in San Jose, and collected lots of parts, including a lifelong supply of teardrop tantalum capacitors of various values and voltages. I have used these in projects over the years with no trouble. But over the past few years they seem to fail immediately. Today I had to replace a tantalum capacitor in an HP 5328A counter, and the replacement immediately failed. I placed another one on a power supply and ran the voltage up to 15 volts for a 20 volt capacitor. The supply briefly went in to current? limiting multiple times before the capacitor failed completely.
?
Do tantalum capacitors degrade with time with no voltage supplied? Or do I just have a bunch of poor quality parts?
?
Any information would be appreciated - although regardless, I think it may be time to toss my collection of tantalum capacitors.
