I've been looking through multiple cellphone chargers and I have noticed that they all use solid state capacitor for the output capacitor of the switching power supply (flyback converter). Is there any specific reason for that?
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\$\begingroup\$ Phone chargers probably have a very loose ripple voltage spec, compared to some general purpose AC/DC converter. If the switching frequency is high enough, you can get away with such small capacitance value, where it becomes easier and cheaper to use MLCC over Al electrolytics as explained in @Justme 's answer. The more capacitance and the higher voltage rating you need in a design, the more the advantages of the Al electrolytics may take over. \$\endgroup\$– tobaltCommented Jan 22 at 13:58
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They last longer, have lower ESR, and are smaller and cheaper than comparable electrolytic capacitors.
But it's not just one aspect, it makes the whole product smaller, lighter, more efficient, which again means you can pack more chargers in the same shipping container etc. They heat up less and need less effort in cooling them. Which again allows for a simpler case design.
If it would be economically cheaper as a whole for a manufacturer to make worse and larger products, they likely would, as long as they are legal and safe enough to sell.
