Smartphone overheating has become a common issue in recent years as phones have gotten more powerful while getting thinner and sleeker in design. Powerful processors crunching data and graphics combined with long periods of use can make a phone’s internal temperature rise quickly. This overheating can lead to poor performance, slow charging, and even permanent damage if left unchecked.
One way to help prevent or reduce overheating is by using a well-designed phone case. The materials used in the case construction play a big role in heat dissipation and insulation. Choosing a case material with effective thermal conductivity properties can help keep your phone cool during intensive use. In this article, we will examine the thermal characteristics of various common phone case materials in order to recommend the best options for preventing phone overheating.
Heat Transfer Basics
Heat transfer is the movement of thermal energy from one object or system to another due to a temperature difference. There are three main mechanisms of heat transfer: conduction, convection, and radiation (Heat Transfer Basics).
Conduction
Conduction is the transfer of heat between two objects in direct physical contact. Heat energy is transferred from higher energy to lower energy molecules through interactions. Metals like copper and aluminum are good conductors of heat.
Convection
Convection is the movement of heat through a fluid like air or water. As the fluid is heated, it expands, becomes less dense, and rises. The cooler, denser fluid then sinks to take its place – creating a convection current. This allows for efficient heat transfer through liquids and gases.
Radiation
Radiation is the emission of electromagnetic waves from an object due to its internal energy. All objects with a temperature above absolute zero emit thermal radiation. Radiation doesn’t require direct contact between objects for heat transfer.
Common Phone Case Materials
Phone cases come in a variety of materials, each with their own properties that impact protection, durability, grip, weight, aesthetics and heat dissipation. Some of the most common materials for phone cases include:
Plastic – Plastic is one of the most popular phone case materials due to its durability, light weight, and affordability. The two main types of plastic used are polycarbonate and thermoplastic polyurethane (TPU). Polycarbonate is more rigid while TPU is flexible and absorbent. Both offer decent protection against drops and shocks.[1]
Silicone – Silicone cases are made from synthetic rubber and known for good shock absorption and grip. They are bendable, protect against minor drops, and resist dust. However, silicone can tear relatively easily.[2]
Leather – Leather cases add a premium, stylish look and feel to phones. Leather is naturally soft and develops a patina over time. However, leather offers minimal protection against drops and the material can wear down over time.[3]
Wood – Wood cases made from bamboo, walnut, and other woods add a unique, natural aesthetic. They are rigid and scratch-resistant. However, wood is less shock absorbent than other materials and can crack if dropped.[1]
Metal – Metal phone cases like aluminum and steel provide a sleek, industrial look. They dissipate heat well and are extremely durable. However, metal cases add significant weight and offer less grip.[2]
Thermal Conductivity
Thermal conductivity refers to a material’s ability to conduct heat. It is measured in watts per meter-kelvin (W/mK). Materials with higher thermal conductivity values tend to transfer heat better than materials with lower values.
According to this source, common phone case materials have the following thermal conductivity values:
- Silicone – 0.2 W/mK
- TPU (thermoplastic polyurethane) – 0.2 W/mK
- Plastic – 0.2 W/mK
- Leather – 0.14 W/mK
- Wood – 0.05 W/mK
- Glass – 1 W/mK
- Aluminum – 205 W/mK
- Copper – 385 W/mK
Materials like copper and aluminum have very high thermal conductivity, allowing them to dissipate heat quickly. Materials like leather, wood, and plastics have lower conductivity meaning they trap heat inside the phone case.
Impact on Phone Temperature
The material a phone case is made from can significantly impact the phone’s operating temperature. Testing by Carved found that plastic phone cases cause phones to run around 5-10°F hotter compared to bare phones or phones with wooden cases. Plastic is an insulator that traps heat generated by the phone’s processor and battery, leading to higher temperatures.
Materials like silicone rubber and thermoplastic polyurethane (TPU) allow for better dissipation of heat compared to plastics like polycarbonate according to testing by Pepper Lady. Silicone cases lowered phone operating temperatures by 2-5°F compared to polycarbonate cases in standardized tests. The soft, flexible properties of silicone and TPU promote airflow and allow heat to dissipate from the phone through the case.
Metallic or aluminum cases can also help dissipate heat away from the phone due to the high thermal conductivity of metals. However, metal cases may get hot themselves when the phone heats up. Overall, silicone, TPU and metallic materials are better choices for allowing phones to maintain lower operating temperatures compared to insulating plastics like polycarbonate.
Other Factors
While thermal conductivity is important, there are other factors to consider when choosing a phone case material for heat management:
Color: Darker colors, especially black, absorb more light and heat compared to lighter colors like white or silver. A black case can run several degrees hotter than a lighter-colored case. If trying to prevent overheating, a lighter or reflective case color is better.
Thickness: Thicker cases provide more insulation and prevent heat transfer, which could cause internal heat buildup. Moderate thickness is ideal for heat flow while still protecting the phone.
Venting: Small holes or cutouts allow for airflow, helping dissipate heat. However, openings also allow dust and debris inside the case, and reduce protection for drops. A balance of ventilation and protection is optimal.
Recommendations
Based on the thermal properties of various materials, some clear recommendations emerge for choosing phone case materials that prevent overheating.
The best materials for phone cases to prevent overheating are those with high thermal conductivity like metals, which allow heat to dissipate away from the phone more effectively. Copper and aluminum, for example, are great choices that will keep your phone cool.
The worst materials are plastics and rubbers, which act as insulators and trap heat inside the phone. Phone cases made predominantly of ABS plastic, polycarbonate, silicone rubber or similar materials will contribute to an overheating phone.
Ideally, phone cases designed to prevent overheating would use metallic materials on the part touching the phone, like a copper or aluminum back plate. Openings and ventilation along the sides and front would also help facilitate air flow and heat dissipation. Avoid fully enclosing plastic cases with no ventilation.
In summary, choose phone cases made of highly conductive metals like copper or aluminum, with ventilation, to prevent overheating. Avoid plastic and rubber cases that insulate the phone and trap heat in.
Pros and Cons
When choosing a phone case material, there are tradeoffs to consider. Different materials have advantages and disadvantages when it comes to preventing overheating.
Silicone cases are flexible and shock-absorbent, providing decent drop protection. However, silicone is an insulator that can trap heat inside the phone. According to Case-Mate, silicone “can be prone to trapping heat inside the case.”
Plastic cases like polycarbonate are lightweight yet durable. Polycarbonate disperses more heat than silicone. But it may not offer as much shock absorption. As Carved notes, plastic is “not quite as protective against serious impacts and drops.”
Leather and wood cases look stylish but typically provide less protection than plastic or silicone. Natural materials like leather and wood don’t conduct heat as well and can lead to phone overheating. However, leather cases in particular develop a “patina” over time that some find aesthetically pleasing.
In the end, there are always tradeoffs to consider with phone case materials. Silicone excels at shock absorption but traps heat. Plastics like polycarbonate disperse heat better but are less protective against drops. The choice depends on your priorities – style, protection, heat dispersion, and more.
Case Studies
Studies have been conducted examining the impact of different phone case materials on device temperature. A report published in the Journal of Thermal Science and Engineering Applications looked at several popular case types (link: https://www.carved.com/blogs/life-at-carved/case-overheating). Cases made from plastic, silicone, leather, and wood were tested with an iPhone X. The phone’s surface temperature was measured after 30 minutes of processor-intensive work. The plastic case caused the largest increase in temperature, up to 5.4°F hotter than using no case. The wood case had the least impact, only raising the temperature by 1.8°F.
Another study by Arizona State University engineers specifically examined the cooling abilities of different case materials (link: https://www.fox10phoenix.com/news/wireless-cooling-device-for-phones-created-by-asu-student-tired-of-heat-draining-his-battery). They 3D printed specialized phone cases using plastics with varying thermal conductivity. The case with the highest conductivity plastic kept the test phone nearly 10°F cooler compared to a standard plastic case. The researchers concluded metals like aluminum and copper would allow even better heat dissipation. However, metal cases impact wireless signal strength and are prone to denting.
Conclusion
In summary, the best material for a phone case to help prevent overheating is one that has high thermal conductivity to dissipate heat efficiently. Materials like aluminum and copper are ideal, though metals can impact wireless connectivity and add bulkiness. Composite materials like metal-infused plastics can offer a balance, combining the conductivity of metal with the lightweight nature of plastic. Ultimately the choice comes down to your priorities – whether optimizing for cooling, aesthetics, drop protection or other factors. Carefully consider the pros and cons of each material and look for an optimal blend given how you use your phone. With so many options on the market, there is likely a phone case material out there that will keep your phone cool while meeting your other needs.