Doubt SMD capacitors

Thread Starter

barretff7

Joined Nov 16, 2022
10
Ceramic, tantalum, polyester SMD capacitors if left unused for a long time will present the same problems as aluminum electrolytic capacitors directly affecting their durability and high current leakage, loss of capacitance, depolarization etc? are they also unstable to long term storage?
 

Ya’akov

Joined Jan 27, 2019
6,856
Welcome to AAC.

The short answer is no. Electrolytics depend on an electrolyte, which is a liquid. As the capacitor heats up over the long term, this dries changing the value, or if it overheats it will cause the capacitor to bulge and then be released from the safety valve.

Solid types, like tantalum, ceramic, and the like may suffer aging, but they do not share the problems of electrolytic, which frankly, if there was any reasonable alternative that could deliver the capacitance in the space and low cost, we wouldn't use because they are basically terrible.
 

MisterBill2

Joined Jan 23, 2018
13,798
The different kinds of capacitors DO have storage temperature limits but those limits are generally quite a bit above normal operation temperatures.They often have soldering temperature limits as well. But if stored at reasonable temperatures they will not suffer. The common failure with time is solderability, since oxidation and corrosion can happen as time passes.
 

rsjsouza

Joined Apr 21, 2014
368
As mentioned before by Ya'akov, the aluminium electrolytic capacitors' degradation is several orders of magnitude higher than other dielectric technologies.

However, other materials and construction techniques can still present problems in the long run.

Specifically for SMD, pay special attention to ferroelectric composite materials such as Class 2 MLCC:
https://www.edn.com/class-2-ceramic-capacitors-can-you-trust-them/
 

Thread Starter

barretff7

Joined Nov 16, 2022
10
the temperature where i live ranges from 33-35C humidity is hard to control on rainy days but on dry days i use a compressor dehumidifier for a few hours every day because if i turn off the dehumidifier the humidity goes to 73%

is polyester capacitor considered solid or not? The main reason ceramic, tantalum, and polyester capacitors don't suffer from long-term storage is because they're all solid?

electrolytic capacitors mounted in electronic circuits need to be energized in a time interval but I don't know what that interval is
 

Ya’akov

Joined Jan 27, 2019
6,856
Get some desiccant punches or reusable aluminum containers with indicator silica gel in them. Store the item is a sealed container like an intact ziplock or box with a gasket and the desiccant. This will go a long way in protecting the components.
 

Thread Starter

barretff7

Joined Nov 16, 2022
10
I used silica gel inside ziplock but moisture always gets in and completely saturates the silica gel, ziplock bag does not seal completely but if moisture gets in and silica saturates then moisture is trapped inside the bag so it would be worse today I store it in boxes cardboard to have a change of humid air for dry air air renewal
 

Thread Starter

barretff7

Joined Nov 16, 2022
10
if ceramic, tantalum, polyester smd capacitors are solid doesn't this solidity make them lose capacitance in storage for years?
 

Ya’akov

Joined Jan 27, 2019
6,856
I used silica gel inside ziplock but moisture always gets in and completely saturates the silica gel, ziplock bag does not seal completely but if moisture gets in and silica saturates then moisture is trapped inside the bag so it would be worse today I store it in boxes cardboard to have a change of humid air for dry air air renewal
If you use aluminized mylar bags (the static protection or even better the long term food storage kind) and a heat sealer, it will be effectively moisture proof. You can heat seal above the ziplock fastener so the bag can be resealed with it after being cut open.

Heat sealing ensures that the only path for moisture is through the plastic itself. The multi-layer mylar bags for long term food storage are specifically designed to resist this. These bags are particularly good, though I know you can’t necessarily source them where you are. The same company makes a heat sealer that is a little more costly than average but is designed to handle 8 mil bags, which is very thick. It’s adjustable so lighter bags can also be sealed.

As far as your coin cell concern, I don’t think you can get a definitive answer, so I would suggest just removing any cells on the boards. Concerning a capacitors, different dielectrics behave differently. For example some ceramics age in a way that loses capacitance, but can be “de-aged” by heating over the Curie point (about 125℃). Some ceramics do not age at all.

Polymer tantalum capacitors don’t exhibit capacitance drift with aging. The graphic below shows the curves for different types.

1668941713391.jpeg
As far as I can tell, polyester capacitors are classed with other film dielectrics and do not have aging problems in storage. Thy do age with use, though, by various mechanisms depending on operating voltage and temperature.

Overall, you don‘t really have a choice. I think removing any cells, then heat sealing in heavy mylar with 0₂ absorbers and small desiccant pouches would be the best you can hope for. You can’t change the degradation of capacitors or any other components that happen with time, that‘s just a given you will have to live with.
 
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