Ceramic Capacitor Failure

eeboy · 2010-03-30T20:50:59+00:00

I've got a situation where boards are being returned all of the sudden.Thisparticular board has been in service well before my time so it seemsas if it isperhaps related to a particular batch. The problem is with an0805 ceramiccapacitor. The same capacitor seems to have failed on each.The result is a 56ohm DC resistance. The capacitor is a simple decouplingcap for a logic IC. Onceremoved, the board behaves nicely again. Is this acommon failure mode forceramic caps? What's the probability that we simplygot a bad reel of thecomponent? What potential causes are there for thisfailure?I can rule out over voltage. The cap is rated at 25V but the maximumvoltage itwould see during operation is 5V. I think I can rule out ESD asthere are manymore sensitive components that would have fried before thiscap. The circuit isa low power logic circuit... no large switchingcurrents.Any thoughts? --------------------------------------- Posted through