I. Preface

The rapid growth of smartphones has driven the entire industry’s supply chain forward. Phone cases have evolved alongside the development of smartphones, and major manufacturers have produced a wide array of phone case products to meet users’ demands. However, since genuine, original-brand cases tend to be quite expensive, many counterfeit and imitation accessories have emerged in the market. Take the Huawei Mate 8 phone case as an example—there are countless varieties of phone cases available on the market, leaving consumers overwhelmed and confused. Moreover, the quality of these cases varies widely, causing considerable headaches for many people who are looking to buy a protective case for their beloved Mate 8. Among the factors influencing people’s choice of phone cases, material is one of the most important, as its physical and chemical properties significantly affect the overall user experience.

II. Silicone

1. What is silicone?

Silicone protective cases are arguably the most familiar and widely used type of protective case among consumers. They have a soft texture and a slightly smooth feel, and have been popular in the market for many years. From low-quality, poorly made products sold at street stalls to finely crafted, personalized brands, this product category has consistently maintained a leading market share.

Silica gel (also known as silica) is a highly active adsorbent material that is amorphous in nature. Its chemical formula is mSiO2·nH2O. Except for strong alkalis and hydrofluoric acid, it does not react with any other substances. It is insoluble in water and all solvents, non-toxic, odorless, and chemically stable. Different grades of silica gel exhibit varying microporous structures due to differences in their manufacturing processes. The chemical composition and physical structure of silica gel endow it with numerous characteristics that are difficult for other similar materials to replicate: high adsorption capacity, excellent thermal stability, chemical inertness, and relatively high mechanical strength. Based on pore size, silica gel can be classified into the following types: macroporous silica gel, mesoporous silica gel, Type B silica gel, and microporous silica gel.

2. Silicone raw materials

3. Silicone phone case

Silicone protective cases generally have a soft texture, good tensile strength, and a slightly slippery feel. If the high-tensile material added to the silicone is insufficient, the case can easily tear. How can you tell whether the silicone has sufficient tensile strength? Simply pull on the product with moderate force under natural light. If the product shows noticeable whitening when pulled, it means the tensile strength is too low. On the other hand, if the product only exhibits slight whitening or no whitening at all when pulled firmly, then it’s a qualified product.

4. Silicone Production Process

The production process for silicone phone cases, like that for other silicone gift products, involves several steps: material preparation, molding, edge trimming, secondary vulcanization, and surface pattern printing. The specific steps are as follows:

(1) Material Preparation: A silicone phone case is a phone case made from silicone material. Typically, silicone comes in two colors—semi-transparent and grayish-white—and has a texture similar to the modeling clay kids used to play with as children. To produce colorful phone cases, it’s essential to add appropriate colorants to the silicone material—what the industry refers to as color masterbatches (color pastes). However, even after adding color masterbatches, the silicone material still doesn’t meet the requirements for molding into phone cases. Therefore, a crosslinking agent (vulcanizing agent) must also be added, and the color masterbatch and crosslinking agent need to be thoroughly mixed and dispersed evenly in a rubber-mixing machine. Once the material has been cut to the required dimensions and weight, it’s ready for the next stage of molding.

(2) Molding: Now that the raw materials for the silicone phone case are ready, we can proceed with “shaping” these silicone materials—what the industry commonly refers to as vulcanization molding. First, the mold for the silicone phone case must be securely fixed onto the vulcanization molding machine, and the required parameters such as temperature, pressure, and molding time must be set accordingly. Once the molding machine reaches the set temperature, the prepared silicone phone case material is injected into the mold. Then, the molding machine is activated to apply pressure and initiate the vulcanization process. When the vulcanization time has reached the required duration, the silicone material will have solidified into the shape of the phone case. At this point, the mold is opened, and the silicone phone case is carefully removed from the mold.

(3) Trimming: After the silicone phone case is removed from the molding die, some burrs may still remain, affecting the case’s appearance. These burrs need to be carefully trimmed away using a blade or scissors. This process is called trimming—or alternatively, deburring or finishing. Trimming silicone phone cases is a purely manual task that requires operators to be meticulous and patient. If the operator isn’t careful, the burrs may not be completely removed, spoiling the case’s appearance. And if the operator lacks patience, the case could easily get nicked or even torn. That’s why almost all those engaged in trimming silicone phone cases are extremely meticulous and highly patient!

(4) Secondary Vulcanization: To eliminate the odor of the crosslinking agent added to the silicone phone case material and to stabilize the dimensions of the silicone case, the phone case needs to undergo a second vulcanization after edge trimming. Typically, this is done by baking in a vertical oven at a temperature of 200°C for 2 to 4 hours. If the silicone case does not require printing or coating treatments, it can be packaged and shipped immediately after the secondary vulcanization is complete.

(5) Surface Pattern Production: When many people buy phone cases, they often notice that numerous silicone phone cases on the market feature stunning patterns or designs. In fact, these intricate designs are created using techniques such as screen printing, oil spraying, and laser engraving on the case’s surface.

5. Classification and Characteristics of Silicone

The chemical composition and physical structure of silica gel determine its many unique properties that are difficult for other similar materials to match: high adsorption capacity, excellent thermal stability, chemical inertness, and relatively high mechanical strength. According to pore size, silica gel is classified into the following types: macroporous silica gel, mesoporous silica gel, Type B silica gel, and microporous silica gel.

Currently, silicone cases are mainly divided into two types: organic silicone and inorganic silicone. Most silicone cases for digital devices available on the market today are made of organic silicone. These cases feature high temperature resistance, excellent weatherability (unaffected by UV radiation or ozone degradation), superior insulation properties, and stable material characteristics.

Advantages: low price, high adsorption performance, good buffering capacity, resistant to wear, and provides relatively comprehensive protection.

Drawbacks: The texture is relatively thick, there are few styles available, it tends to become greasy easily, and its fit with the device body is slightly loose. Additionally, materials of lower quality tend to attract and trap dust more readily.

6. Protecting your mobile phone

Silicone cases also offer a pleasant tactile feel; even some phones with stiff buttons can see an improvement once fitted with a silicone case. Moreover, these cases can absorb some of the impact from bumps and knocks, thereby reducing damage to the phone to a certain extent. Additionally, silicone cases boast excellent water resistance, which has become one of their biggest selling points. However, silicone cases themselves have a slight tackiness. After prolonged use, they tend to attract a significant amount of dust onto the phone. Over time, this not only detracts from the phone’s aesthetic appeal but also runs counter to the original purpose of protecting the device.

III. TPU

1. What is TPU?

TPU is the primary material used to manufacture clear protective sleeves. It stands for Thermoplastic Urethane, a thermoplastic polyurethane elastomer. An elastomer is defined as a polymer material whose glass transition temperature is below room temperature, with an elongation at break exceeding 50%, and which exhibits excellent recoverability after the removal of external forces. Polyurethane elastomers represent a particularly unique class within the broader category of elastomers. They offer an exceptionally wide range of hardness and performance characteristics, making them a type of polymer that lies somewhere between rubber and plastic. TPU can be heated and molded, and its chemical structure features either no crosslinks or very few crosslinks; its molecular chains are essentially linear yet still exhibit some degree of physical crosslinking. This particular type of polyurethane is referred to as TPU.

2. TPU raw material

3. TPU phone case

TPU’s soft and hard characteristics fall somewhere between those of rubber and plastic. TPU boasts a remarkably wide hardness range; by adjusting the proportions of its various reactive components, products of different hardness levels can be produced. Moreover, as the hardness increases, these products still maintain excellent elasticity and wear resistance. TPU is well-known for its outstanding wear resistance, tear resistance, and flexural strength. Other notable advantages of TPU include high tensile strength, large elongation at break, and low long-term compression set.

4. TPU Features

As an elastomer, TPU is a material that lies between rubber and plastic. It exhibits excellent resistance to oils, water, and mold. TPU products stand out for their outstanding load-bearing capacity, impact resistance, and shock-absorbing performance. TPU belongs to the category of thermoplastic plastics; its products are manufactured using injection molding—a process in which granular plastic pellets are heated and melted, then injected into a plastic mold via a screw extruder to form the final product.

Advantages: High wear resistance, high strength, outstanding cold resistance, oil resistance, water resistance, mold resistance, and excellent flexibility.

Disadvantages: Prone to deformation and yellowing.

5. Protecting your mobile phone

In terms of feel, TPU generally feels harder than silicone. When pinched by hand, TPU exhibits stronger elasticity, while silicone’s elasticity is slightly weaker. Visually, TPU can be made extremely transparent, whereas silicone cannot— even the most transparent silicone products have a hazy, misty appearance, akin to thick fog. It’s precisely because of this transparent quality that TPU has become increasingly popular among users. Moreover, high-end TPU products offer a wide variety of options, providing greater choice and more diverse pattern variations compared to silicone.

6. TPU Surface Treatment Process

(1) Vacuum plating process: The TPU is plated, and after plating, some patterns are engraved. The texture is quite good; however, after vacuum plating, it needs to be coated with a UV varnish.

(2) Coating process: UV varnish can be applied to enhance the scratch resistance of the TPU surface.

IV. PC

1. What is a PC?

PC is the abbreviation for polycarbonate. In English, polycarbonate is called Polycarbonate, and it’s often referred to as PC engineering plastic. PC material is actually one type of engineering plastic we commonly talk about. As a material widely used around the world, PC has its own unique characteristics as well as advantages and disadvantages. PC is an amorphous thermoplastic resin with excellent overall performance, boasting outstanding electrical insulation properties, elongation, dimensional stability, and resistance to chemical corrosion. It also exhibits high strength, heat resistance, and cold resistance. Additionally, PC boasts advantages such as self-extinguishing, flame retardancy, non-toxicity, and colorability. You can find traces of PC plastic in every corner of your life. Its large-scale industrial production and ease of processing also make it extremely cost-effective.

2. PC raw material

3. PC phone case

PC (polycarbonate) itself is a robust thermoplastic resin. PC material boasts excellent impact resistance, as well as high strength and toughness. Whether subjected to heavy pressure or ordinary drops and bumps—so long as you're not trying to smash it with a stone—it will last remarkably long. Additionally, it has high transparency, though its surface is relatively prone to scratches.

4. PC Features

Advantages: Excellent light transmittance, high hardness, drop resistance, lightweight and thin, with good strength and toughness.

Disadvantages: Not scratch-resistant, not resistant to strong acids, not resistant to strong bases, and not resistant to ultraviolet radiation.

5. Protecting your mobile phone

PC material protective cases differ from silicone and TPU cases in that they are rigid. PC plastic boasts excellent toughness and outstanding light transmittance. Pure PC plastic comes in a variety of colors, including crystal clear, transparent black, and transparent blue—each one is quite impressive.

6. PC Surface Treatment Process

( ) Vacuum plating process: The PC shell is plated, and after plating, some patterns are engraved. The texture is quite nice; however, after vacuum plating, it needs to be coated with a UV topcoat.

( ) PC spray coating process: You can apply a rubber-like feel oil, which many people find appealing. For an even more sophisticated look, you can first spray a base coat onto a colored (such as transparent red, transparent blue, or transparent yellow) transparent PC case, then use laser engraving to create intricate patterns, and finally apply a layer of rubber-like paint. Products made this way appear exceptionally high-end.

( ) PC water transfer and thermal transfer processes: Patterns and designs are transferred onto the PC shell, after which a UV topcoat or a soft, rubber-like oil is applied. If a UV topcoat is applied after transfer, the surface UV coating tends to crack easily when pinched by hand. Therefore, for transfer processes, it’s best to opt for the rubber oil application—it offers a soft, tactile feel and a matte finish. When executed well, this technique can give the product a high-end appearance. The downside is that the surface isn’t scratch-resistant; if paint chips off in one spot, the damage can quickly spread along the chipped area. On the other hand, the transfer process boasts an incredibly rich variety of patterns and colors.

5. Leather case

1. Leather Case Instructions

Among various types of phone cases, leather cases are also very popular. Compared to the monotonous styles of silicone cases, business professionals who are active in the workplace prefer leather cases that exude elegance and sophistication. Unlike young people who embrace a casual style, carrying a phone with a plain, single-colored exterior would be considered inappropriate for them.

The quality of leather cases varies widely. Although leather cases are readily available even at street stalls, you really do get what you pay for—items priced at just a dozen yuan or so naturally won't be made from genuine leather; most are either synthetic leather or imitation leather, and they’ll start cracking and coming unglued after only a short period of use. In contrast, genuine leather is durable and long-lasting, but of course, it comes with a higher price tag—typically ranging from several dozen to several hundred yuan.

2. Leather case phone shell

3. Features of the leather case

Advantages: Good tactile feel, superior quality, and excellent protective performance.

Disadvantages: High price, relatively limited color options.

4. Protecting your phone

Leather phone cases are primarily made from genuine leather or faux leather. Genuine leather cases are meticulously crafted by hand, offering exceptional quality in terms of both feel and durability, as well as exquisite design. At appropriate locations, the case can be folded up to serve as a stand, providing an ideal angle for propping up your tablet and making it easy to watch videos and slideshows.

The leather case styles are relatively simple yet elegant, making them perfectly suited for business professionals. Its key selling points are its chic and refined design, its ability to protect your phone from scratches, and its excellent heat dissipation. In particular, wallet-style leather phone cases—which can hold cash, transit cards, and other essentials—have always been extremely popular. While synthetic leather or faux leather tends to crack easily, genuine leather is durable and long-lasting!

Six, Metals

1. Metal

The texture of the metal protective case is undoubtedly excellent and gives a sense of high-end sophistication. Currently, aluminum-magnesium alloy is the primary material used for metal casings, and surface treatment technologies have become highly mature. Aluminum-magnesium alloy boasts corrosion resistance, electrical insulation, durability, wear resistance, light weight, and structural stability.

2. Metal phone case

3. Features of the metal protective casing

Advantages: Rich texture, drop-resistant.

Disadvantages: Relatively inconvenient to install and relatively heavy.

In terms of material, metal clearly offers greater durability than other materials. That’s why there are many tablet protective cases on the market made from metal. Although metal feels great to the touch, it tends to feel slippery and cool in winter.

May affect mobile phone signals.

7. Wooden

1. Wooden

Thanks to the wide variety of wood species, natural grain patterns, and diverse colors, coupled with modern wood-processing technologies that enable the creation of an array of hues and designs, wood has become a visually appealing decorative material for phone cases, perfectly meeting consumers’ multi-layered needs.

Manufacturers can tailor processing techniques to suit the unique characteristics of different types of wood, carrying forward and incorporating the distinctive features and qualities of art pieces into innovative digital products, thereby making our daily lives more distinctive and full of charm.

2. Wooden phone case

Currently, woods commonly used for phone cases include cherry wood, maple wood, and pearwood. These woods have excellent coloration, are easy to carve into intricate patterns, and boast a relatively hard texture that makes them resistant to damage. Both maple wood and pearwood emit the natural scent of raw wood, helping to relieve the work fatigue experienced by white-collar workers who spend long hours sitting in office environments.

3. Features of the wooden protective case

Advantages: It’s distinctive and has a very traditional feel;

It shows little response to cold and heat—doesn't feel cold in winter—and is dirt-resistant and easy to clean.

Disadvantages: They are generally thicker, and their prices tend to be relatively high.

VIII. Summary

Each type of protective case has its own unique advantages, so you can totally choose according to your personal preference: if you like soft cases, go for silicone; if you prefer harder cases, opt for PC material; and if you’re looking for lower elasticity, go for TPU. Of course, the most important thing is to select protective cases or covers that are safe and made by reputable manufacturers—don’t be tempted by cheap, counterfeit, low-quality alternatives.