Another problem with the silicone cases is that they are dirt magnets. Silicone provides a great grip it sticks to the hands. And hands have a lot of grease and dirt which are swiftly transferred to the cover. Silicone is also prone to cuts and abrasions, further decreasing its longevity and reliability.
Perhaps the only reason people use it is that it is cheap and does not add bulk to the phone. It acts like a soft cloth for the phone. So there are many problems with silicone material for phone covers (and not cases). This is where TPU or thermoplastic polyurethane comes in. It took the best things from both PC and silicone and combined them into one.
TPU material to make the casing
TPU takes the best of both worlds. It is made of both hard parts and soft parts, giving it both qualities. Cases made of TPU are resistant to scratches, shock, and abrasion. They also don’t add to the bulk (not as light and thin as silicone but also not as bulky as plastic).
Most of the cases that come with the phones (like OnePlus, Samsung, Xiaomi, etc) are made of TPU. They are thick, transparent (and can be colored easily), and very flexible.
TPU is also very long-lasting. Unlike silicone which turns gooey due to friction, the hardness of TPU makes it resistant to friction. So no matter how many times you pick up your phone, rub the case while putting it inside your pockets, TPU will last for years. But this does not mean that TPU is devoid of any flaws.
Phone with a TPU case on it
The cons of TPU as phone cases
Perhaps the biggest flaw in TPU cases is that clear TPU cases turn yellow after a year or so and this is, sadly, inevitable. And I have seen articles claiming soaps and bleach will help get rid of the yellow stains. That’s not gonna work. Here’s why.