Electronics > Projects, Designs, and Technical Stuff
Aluminum Electrolytic Capacitor Short circuit failure and Infant mortality
(1/6) > >>
Ashraf Almubarak:
I have produced 1000 units of our new developed energy meter. Almost 20 aluminum electrolytic capacitors (2%) have failed short when we test them during the production processes. The Capacitor is a 470uF 35V (UPW1V471MPD) made by Nichicon.
The failure itself varies between total short circuit to small variable resistance. One of the caps spit out its electrolyte.
I have 3 other different aluminum electrolytic caps from the same manufacturer that didn’t fail. A year ago, I have produced 300 units (same design and part no.) and they running perfectly and didn’t find any failed capacitors.
My question has 3 parts:
1-   How this occurred?
Is it normal to have an infant mortality of 2% with short circuit failure for aluminum electrolytic caps?
Or, may be the cap is counterfeited and the con manufacturer didn’t do enough quality testing. (I bought them through a PCB and components supplier in Shenzhen). If they are counterfeit, how to verify that?
2-   What should I do with the rest of the batch?
If I release the batch, would I guarantee that there will be no more short circuit failure? If it didn’t die during the manufacturing, it will not die in the near future! (U shape/bathtub graph).
Or it is better to run my meters for a period of time (24 hours) if didn’t fail it will not fail in the future.
Or I should go the hard way and change them all?
3-   How to avoid this in the future, because I will be going for large quantities > 100K.
I didn’t find very useful notes about electronics parts quality and reliability other than MIL-HDBK-978B. But it is out dated and didn’t have the electrolytic caps.
MagicSmoker:
Nichicon makes very good quality caps and, aside from the capacitor plague issues in the early 2000's, I have never seen one fail. So, are you sure you got genuine Nichicon parts here? Can you post the link to the actual website you purchased them from?

Ashraf Almubarak:
I didn't buy them from internet.
I have a supplier bought them and my other parts from Shenzhen. He did the PCB and PCBA
The chance to buy a counterfeit one from Shenzhen is high?
Ashraf Almubarak:
These photos of the same capacitor (presumably)
One we purchased 2 years ago and the other one month ago. can you notice any notable difference?
OwO:
No, parts should be the very last thing you blame when troubleshooting failures. Please first give us the important details, like what voltage the cap sees, what inrush and ripple current it sees, what process and temperature they were soldered at, and how the failures were diagnosed (did you remove the caps from the circuit to test? how were they removed?)
Navigation
Message Index
Next page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod