Carbon Fiber Phone Cases: “Just Say No”

carbon fiber iPhone case 2

Have five minutes? Good.

Because that may be all it takes to save your iPhone.

Well, if you were to do a search on, you will find a staggering number of “carbon fiber iPhone cases”, 108,043 to be precise (and if you search for “carbon fiber phone cases”, even more at 166,581). Look further and you can find plenty more on other online shopping sites, all of them look great, sleek and stylish.

Carbon fiber phone case block cell phone signal reception
Carbon fiber phone case block cell phone signal reception 2

So what does that mean?

That means you get big chances of buying a carbon fiber cases, which are not wise buys. Yet read on and reasons show in the blog. You won't have 5 minutes to lose.

1. Carbon Fiber Cases Block your Phones Signal Dramatically!

The reason why I advise you not to get a carbon fiber case is quite simple, it blocks your signal and I mean dramatically.

But why do they do this?

Whilst it is an outstanding and impressive composite material, carbon fiber features in high stiffness, high tensile strength, high chemical resistance, high temperature tolerance, low weight and low thermal expansion. This makes it perfect for plenty of applications in the aerospace industry, civil engineering, military, sports equipment, formula 1 etc. as well as making it as good as a Protective Durable Phone Cases but this is where it all goes wrong.

Why? Because carbon fiber is conductive.

Amongst some of the most common materials used for phone cases, aluminum and carbon fiber have been proven to dramatically reduce your phones cellular signal reception via Radio Frequency Interference (RFI). Carbon fiber phone cases have been shown to reduce the average cellular signal by as much as 40%- 60% and Aluminum and other similar metal phone cases don’t do much better and can often affect your signal strength in a similar way.

This means that both materials are the often the fundamental reason why your phone’s signal is lower than if you took the case off. Ironically however, metal phone cases and carbon fiber phone cases are two of the most wanted and searched for materials for buyers and manufacturers, mainly because of its stylish sleek appearance, durability and strong properties. But, in truth, this turns out to be the wrong decision when it comes to signal reception.

A video shows how carbon fiber effect the signal strength of your iPhone

As I pointed out earlier, the conductive carbon fiber makes it a terrible material for phone cases.

I know that this simple explanation is not enough, so here goes.

Carbon fiber is comprised of at least 95% carbon. The atomic structure of carbon fiber is very similar to graphite, with sheets of carbon atoms arranged in a regular hexagonal pattern. The reason why it conducts electricity so well is because of the mobility of the electrons in the outer valence shells. It’s displaying the properties of both a metal and a nonmetal.

Since carbon fiber is a conductor of electricity and magnetism, this also means that it absorbs electricity very well. Therefore, as radio waves are electromagnetic, it means that carbon fiber absorbs these very well too.

Oh, and the larger the conductive capacity of carbon fibers, the more the incoming radio signal is attenuated (reduced). Simply put, the more genuine a carbon fiber case is, the worse it is for your phones cellular radio reception.

Alternatively, I can explain this by referring to Faraday or a Faraday cage (Electrostatic Shielding). This should clear things up a little more:

" A Faraday cage or Faraday shield is an enclosure used to block electric fields. It is formed by a conductive material or by a mesh of similar materials. It's named after its inventor, the English scientist Michael Faraday".

Electricity is the lifeblood of so many aspects of our world (thanks to Faraday); it’s what drives technology and fuels innovation. Likewise, it can kill modern electronics and machines (the electromagnetic effect). So quite often, people will use a Faraday cage to develop ways to control electricity and make it safer.

Faraday cages come in all shapes and sizes, but with one fundamental attribute, they all use some form of a screen that conducts electricity, which subsequently creates a shielding effect.

So a Faraday cage shields its contents from static electricity fields, which is a force field surrounding a charged particle, such as an electron or proton. With the invention of the Faraday Cage, these undesirable and downright disruptive radiation fields can be controlled.

Faraday cage often look like

carbon fiber application involve military, aircraft, automobile

So, When a phone is wrapped with a carbon fiber phone case or a metal phone case, your signal will decrease dramatically because the carbon fiber absorbs the radio waves instead of your phones internal antenna.

A phone wrapped with it’s own Mini Faraday cage:

faraday phone case

2. So, what’s the Best Material for a Phone Case?

When great materials like carbon fiber or aluminum are not suitable for making phone cases, finding an alternative can be really tricky, especially if they don’t look very good.

Checking the phone case market, it is mostly comprised of plastic cases, polyurethane (PUR) and polycarbonate (PC) phone cases, silicone rubber phone cases, leather phone cases and of course the above mentioned carbon fiber and metal phone cases. If these last two, do not work very well for your phone, what about the others?

Polyurethane (PUR) phone cases are made from a material predominately used in foam form in things such as furniture and shoes. It’s not as strong as another commonly used plastic, e.g. Polycarbonate, but it can still provide your phone with a certain degree of protection. Depending on the formulation of PUR, it can either be strong or be soft.


  • - Usually a low price
  • - Readily available
  • - Easy to customize or decorate


  • - It’s appearance can often look cheap
  • - Smells strange
  • - Not durable
  • - Needs cushioning materials to make it more protective
  • - Rigidity makes it easy to crack or break when hits on hard surfaces

Polycarbonate (PC) phone cases are usually a bit bulky although strong. PC is widely used in the manufacturing of toys, storage containers, eyeglasses and even bulletproof glasses.


  • - Offers good enough protection
  • - Can be customized
  • - Lightweight


  • - It’s appearance can often look cheap
  • - Not durable
  • - Can change color after long exposure to sunlight
  • - Can be quite bulky
  • - Gets dirty really easily

Silicone rubber phone cases often have a good tactile feeling and can be pleasant to touch. Becoming more and more common at the consumer level, silicone rubber products can be found in every room of a typical home. It is extensively used in automotive applications, cooking and baking, sportswear and footwear.


  • - Soft but uneasy to break
  • - Durable
  • - Easy to grip or hold


  • - Bulky and maybe uneasy to slip in or out the pocket
  • - Cheap to look at
  • - Gets dirty really easily
  • - Single color available

As for real leather phone cases, they are the classic choice to convey ones style and elegance, but they are not that good at protection. Oh and it may go against a greener lifestyle.


  • - Stylish and elegant
  • - Long-lasting life
  • - Water-proof


  • - Not Environmentally friendly
  • - High in price
  • - Not enough protective against strong impacts

Our full list of commonly found materials for phone cases is almost done, as shown above.

Personal Recommendation Rating

Score (Total Score: Five- Star)
polyurethane (PUR) phone case ★★
polycarbonate (PC) phone case ★★
silicone rubber phone case ★★★
genuine leather phone case ★★★

3. The Aramid Phone Case - The One that can meet All Your Requirements

So, you want to find a phone case that does not interfere with your phones cellular signal reception, has to be slim, lightweight, protective and strong.

And you are thinking that none of the above can match your needs..

But hold on, can you recall our aramid fibers (Kevlar fibers) discussion that we had several weeks ago?

Remember that, it’s a material as strong and as durable as carbon fiber. It has high stiffness, high tensile strength, high chemical resistance, high temperature tolerance, low thermal expansion and it has an even lower density.

When being made into a phone case, it has slim profile, its lightweight and it’s long-lasting just like a carbon fiber case.

Material Strength-to-weight
Ultimate Tensile Strength
Kevlar (Aramid) 2514 2757 1.44
Carbon Fiber 2457 4137 1.75

And, more importantly, it’s a great nonconductor, which quite simply put, means it does not interfere in any way with your phones cellular signal.

All in all, an aramid (Kevlar) phone case meets all the requirements and turns out to be the perfect phone case.

The only downside is that it could be relatively high in price due to the expensive raw materials, Aramid fibers (Kevlar fibers). But really, that shouldn’t be considered a downside when you realize that you CAN enjoy your iPhone and satisfy all of those important case requirements.

So, what’s the bottom line:

Okay, well, the five-minutes reading is over.

Hopefully, you have learned something in this blog.

  1. It’s best to avoid choosing a carbon fiber phone case the next time you need to buy a new case, “Just say No”.
  2. You can now clearly explain to your friends why their iPhone with its carbon fiber case has the worst signal strength ever.
  3. Oh, and last but not least, I told you the secret as to how to pick the best phone case.

About the Author

Love of tea, movies, video games, and writing. I've been writing hundreds of online articles over the past few years, mainly about technology. If I'm not writing, you can probably find me reading or playing video games.

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  • James on
    "Wow! Thank you so much. I love smart people!"
  • Amy on
    "I found your article when googling carbon fiber cases. Thanks for your clear explanations and for the compare/contrast of other phone case materials :)"

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