Thursday 28 February 2019

reliability - What happened to electrolytic capacitors in the 21st century?


We can sometimes see decades-old capacitors (such as ones made in the USSR) still working. They are bigger and heavier, but durable and not desiccating. Modern aluminium capacitors serve for about 11 years, if you are lucky, then become dry and quietly fail. I remember early 2000s devices where capacitors failed after 3–4 years of service, and not necessarily low-end devices (one example is E-TECH ICE-200 cable modem worth ∼ 240 USD in 2000). A repair due to failed electrolytic capacitors became a commonplace, something uncharacteristic for 1980s.


Was this 1990s degradation caused by cheap mass production? Or by poorly-tested technologies related to miniaturization? Or many manufacturers just didn’t care?


It appears that the trend is by now reversed, and recent capacitors are a bit better than the ones from 1994–2002. Can experts confirm it?



Answer



Principal reasons were:



  • The capacitor plague of 1999–2002 – an attempt to reproduce a stolen Rubycon Inc.’s formula for electrolyte, which went bad.


  • Otherwise changing composition of electrolyte; more H2O (useful to obtain lower ESR) makes it more corrosive.

  • Cost optimization due to increasingly mass production of electronics.

  • Errors in design, process, or low-quality materials; bad quality control.


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