Blogs background
  1. Home
  2. > Blog
  3. > Mobile Phone Middle Frame Substrate: Aluminum vs Stainless Steel vs Liquid Metal

Mobile Phone Middle Frame Substrate: Aluminum vs Stainless Steel vs Liquid Metal

Updated : Jul. 06, 2023

For a long time, aluminum alloy has always been the protagonist of the middle frame material of mobile phones because of its advantages of light weight, low price, and easy processing.

With the development of mobile phones in the direction of full-screen and ultra-thin, to maintain the strength of the body and support the large screen, a higher-strength metal middle frame is required. High-strength aluminum alloy, stainless steel and liquid metal are all good candidates. .

The reason for the diversification of middle frame materials is that the materials themselves have their own advantages but all have shortcomings that are difficult to break through.

Compared with the three material characteristics of aluminum alloy middle frame, stainless steel middle frame and liquid metal middle frame, which side do you stand on?

Aluminum 7075-T6 Stainless Steel sus304 Liquid Metal EON1
Bending strength/MPa 570 590 2200
Yield strength/MPa 500 240 /
Vickers Hardness/HV 150 200 500
Density g/cm3 2.82 7.85 6.72
Processing difficulty Easy Disaster Easy
Process maturity Mature immature /
Yield 80% 30-40% Approaching "Net Shape"
Appearance Varied less Diverse in theory
Pprice/RMB 100-200 200-300 120-150
Application Model Representative iPhone5, iPhone6, OPPO R15 iPhone4,iPhoneX, Xiaomi 6, Hammer M1L Turing phone

NO.1 Physical properties of materials

Aluminum alloy

The aluminum alloy material is very light, and its specific gravity is only one-third of that of stainless steel;

Low strength, it is easy to cause the mobile phone to be bent or bent;

Since the "bending door" incident of the iPhone 6, the iPhone 6S has adopted a 7-series aviation aluminum alloy with a strength of 700 MPa, but this series of alloys has poor corrosion resistance and is prone to stress corrosion.

iPhone 6s aluminum middle frame

Moreover, the hardness of the aluminum alloy is only about 150. The relatively soft performance will cause bump marks on the aluminum alloy middle frame, which will affect the appearance.

Stainless steel

The most common 304 stainless steel has a strength of 520 MPa. The strength of common stainless steel is between 1300 and 1400 MPa. The Vickers hardness of stainless steel is about 200. The relatively high strength and hardness can meet the support of large-screen double-sided glass. iPhoneX The middle frame design also returns to stainless steel.

iPhone X stainless steel middle frame

However, the heat dissipation performance of stainless steel is poor, and its thermal conductivity is only 14 /W·(m·k) (14 /W·(m·k) for stainless steel VS 204/W·(m·k) for aluminum alloy). It will lead to accelerated aging of electronic components; and the larger specific gravity will increase the weight of the whole machine.

Liquid metal

The strength of liquid metal is 2 to 3 times that of traditional high-strength steel and 10 times that of magnesium-aluminum alloy. In addition, it has high hardness, high wear resistance, corrosion resistance, good heat dissipation, and is light and thin. box, Liquidmetal has significant advantages.

NO.2 Processing technology

Aluminum alloy

Due to the characteristics of the material itself, aluminum alloy can be combined with forging + a small amount of CNC, stamping + a small amount of CNC, etc., which can greatly reduce material costs and CNC processing time;

Aluminum alloy materials have strong dyeability and mature anodizing process, making it easier to process high-grade, beautiful and diverse appearance effects.

Stainless steel

Stainless steel has high hardness and poor CNC machining performance. Compared with aluminum alloy, the processing time and tool wear are doubled.

From a whole piece of stainless steel to the one-piece stainless steel middle frame, nearly 30 kinds of knives and hundreds of steps that require extremely high craftsmanship have to be experienced during this period. Complicated processes lead to low yield and low production efficiency.

In addition, the stainless steel middle frame is generally colored by PVD process. The mainstream design is to polish and then make a highlight effect through PVD. Compared with aluminum alloy, its color types are relatively simple.

Liquid metal

Liquid metal can be shaped like plastic through injection molding, die-casting and other processes. It is light, thin and compact, and can be molded at one time. It is close to "net shape" in technology and saves a lot of post-processing.

Liquid metal can theoretically make a variety of colors, but there are still few attempts. At present, the main coloring method is PVD coloring, and the color is relatively single. Anodizing is also possible in theory, but there is no actual mass production case.

NO.3 Cost and Manufacturability

Aluminum alloy

The aluminum alloy middle frame is still the most widely used metal middle frame at present. It has the characteristics of light weight, low production cost, mature technology, gorgeous color and good texture, and has already achieved mass production.

Stainless steel

Due to the high hardness of stainless steel, CNC processing is difficult, resulting in high cost, long time-consuming, and relatively low processing yield. Currently, it has not been popularized by mainstream manufacturers.

In addition to Apple, among the mainstream manufacturers, Xiaomi used stainless steel in MI4 and MI6, but gave up stainless steel in MI8 and switched to 7-series aluminum alloy. In order to achieve mass production of stainless steel middle frames, it is urgent to solve the problems of production technology and cost.

Liquid metal

Although liquid metal has many advantages, and the cost is lower than that of stainless steel, at present, no second manufacturer has really adopted it except for the Turing mobile phone;

Turing mobile phone liquid metal middle frame

Because the technical barriers of liquid metal are very high, the requirements for the equipment used are also high, and there are relatively few production companies, the production capacity is too low, and a complete industrial chain has not yet been formed. Therefore, there is still a long way to go before mass production of liquid metal way to go.

Comprehensive summary

To sum up, with the advancement of technology and changes in market demand, the mobile phone industry will continue to explore new materials and processing technologies to meet consumers' expectations for higher-quality and more stylish mobile phones. Therefore, stainless steel and liquid metals have emerged as potential candidate materials.

Stainless steel has high strength and hardness, which can meet the needs of large-screen double-sided glass design, but its heat dissipation performance, weight and processing cost become considerations.

Liquid metal has super strength, hardness, wear resistance and heat dissipation, and has the advantages of being light, thin, and one-time molding, but technical barriers and imperfect industrial chains limit its mass production and application.

In the selection of mobile phone middle frame materials, aluminum alloy is still the most widely used material at present. It is light in weight, low in cost, and mature in processing technology, and has achieved large-scale mass production.

Huawei P20 aluminum middle frame

As an enterprise focusing on the aluminum industry, CHALCO is mainly engaged in the production of aluminum strips, providing a rich selection of aluminum alloy materials for the mobile phone industry. Through continuous innovation and improvement of processing technology, the mobile phone industry can further improve the strength and aesthetics of the aluminum alloy middle frame. As an important aluminum supplier for 3C digital products, CHALCO will continue to give full play to its advantages in the field of aluminum sheets, provide diversified aluminum alloy materials for the mobile phone industry, and help the development and innovation of the mobile phone industry.

Do you have the aluminum you need?

Welcome to contact us

  • Contact us to get quotation information
  • Contact us for the details of the product
  • Contact us to get free samples
  • Product demand
  • Name
  • Phone number or WhatsApp
  • Email
  • content