General causes of SMD Capacitor Faults on PC

[caspian]

Dear Technicians,

What conditions (of voltage, current, humidity, frequency, and so on) do cause a SMD capacitor go weak or bad in a CPU VRM circuit on a computer/laptop mainboard?

I want to know them only for three major types of SMD capacitors which are used in recent mainboards:
- Polymer electrolytic SMD capacitors
- Tantalum SMD capacitors
- Ceramic SMD capacitors

I attached sample photos (taken from the Internet) of these three types of capacitors for better understanding. Interestingly, some of them seem bad. but I do not know the reasons.
I heard polymer electrolytic capacitors rarely go bad. But I am still interested in knowing the possible conditions that make them weak or bad. Specifically, causes of weakness are more important because they can not be detected by observation.

thanks

[Th3_uN1Qu3]

Re: General causes of SMD Capacitor Faults on PC

For tantalum it is usually overvoltage or too much ripple current, while the number 1 killer of ceramic caps is humidity.

[Wester547]

Re: General causes of SMD Capacitor Faults on PC

Hmm... those “solid capacitors” in the picture are anything but solid. They are Sacon FZ, the most unreliable capacitors produced over the past ten years or so. Polymer SMD and radial capacitors can fail for the same reasons - overbias, extreme humidity, inadequate sealing, and subpar manufacturing processes (moisture entrapped inside the cap causes a steady rise in ESR, iron particles in the dielectric increasing leakage current, etc).

[sam_sam_sam]

Re: General causes of SMD Capacitor Faults on PC

Hmm... those “solid capacitors” in the picture are anything but solid. They are Sacon FZ, the most unreliable capacitors produced over the past ten years or so. Polymer SMD and radial capacitors can fail for the same reasons - overbias, extreme humidity, inadequate sealing, and subpar manufacturing processes (moisture entrapped inside the cap causes a steady rise in ESR, iron particles in the dielectric increasing leakage current, etc).

Thanks for the information I did not know that these two types of caps are the ones to replace on site if you see them

What brand name are good quality for these types of caps that are shown in that photo

[Wester547]

Re: General causes of SMD Capacitor Faults on PC

What brand name are good quality for these types of caps that are shown in that photo

I'm not sure brand matters that much when it comes to polymer, ceramic, and tantalum capacitors - there doesn't seem to be an unending "plague" of sorts in that regard. I would (obviously) avoid counterfeits at all costs, and the NEC Tokin OE128 and OE097 proadlizer decoupling polymers are very prone to failure (at least there was a bad batch of them many years ago).