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The unfortunate shrinkage of capacitors

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Nauris:
These oil filled Shizuki caps are good I have not yet seen one fail

But the usual dry polypropylene are all bad, even the good brand ones don't last long

mazurov:

--- Quote from: coppercone2 on January 12, 2022, 03:20:48 am ---I think the key to this might be the improvement of QC practices for film materials.

--- End quote ---

I'd say that improvement of QC practices (process control rather) is the cause of modern caps being less robust.  Devices that in the past required 30% margin to have a desired yield now are produced with 2%. Consequently, when a manufacturer says the device will maintain its specs for 5 years, 95% of the devices will fail between 5.1- 5.5 and the rest in 6.

This is not specific to electronics. In a bag of screws all 100 will have their diameter 0.1% above minimum, milk will go bad 2 days after exp.date, even when unopened, etc. The meaning of the word "rating" has changed.

SilverSolder:

--- Quote from: mazurov on January 12, 2022, 10:08:43 pm ---
--- Quote from: coppercone2 on January 12, 2022, 03:20:48 am ---I think the key to this might be the improvement of QC practices for film materials.

--- End quote ---

I'd say that improvement of QC practices (process control rather) is the cause of modern caps being less robust.  Devices that in the past required 30% margin to have a desired yield now are produced with 2%. Consequently, when a manufacturer says the device will maintain its specs for 5 years, 95% of the devices will fail between 5.1- 5.5 and the rest in 6.

This is not specific to electronics. In a bag of screws all 100 will have their diameter 0.1% above minimum, milk will go bad 2 days after exp.date, even when unopened, etc. The meaning of the word "rating" has changed.

--- End quote ---

That definitely rings true.  So if you want 30% margin, you now have to spec that up front when you select the component?

coppercone2:

--- Quote from: mazurov on January 12, 2022, 10:08:43 pm ---
--- Quote from: coppercone2 on January 12, 2022, 03:20:48 am ---I think the key to this might be the improvement of QC practices for film materials.

--- End quote ---

I'd say that improvement of QC practices (process control rather) is the cause of modern caps being less robust.  Devices that in the past required 30% margin to have a desired yield now are produced with 2%. Consequently, when a manufacturer says the device will maintain its specs for 5 years, 95% of the devices will fail between 5.1- 5.5 and the rest in 6.

This is not specific to electronics. In a bag of screws all 100 will have their diameter 0.1% above minimum, milk will go bad 2 days after exp.date, even when unopened, etc. The meaning of the word "rating" has changed.

--- End quote ---

that is true, people want to get rich off the 'margin' at equipment owner expense. Add 30% cost increase for repairs and duds for every purchase you make. The illusion of cheapness to most, only really short term users benefit.

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