The five major technology changes in mobile phone shells must be known (Part 1)

The 5G era is approaching. Mobile phone shell material from plastic to metal and non-metal material cycle, plastic because of the low cost, favored by the low-end market

The evolution from the IML to the IMT process has made plastics more useful, which can approach the 3D optical texture of the simulated glass back cover, and has become the choice of many CMF designers. LDS has been widely used in plastic rear case antennas in the 4G era, but whether it can be adapted to the high-end curved glass 3D back cover of the 5G era needs to continue to be developed.

IMT technology can be further extended to IME technology, which integrates electrical and decorative functions and is applied to the intelligent surface of future cars. Injection molded transparent PC back cover, as a lower cost and more efficient product form, with better impact strength and durability, is attracting more and more attention from traditional plastic factories.

1.LDS technology

The principle of LDS technology is to excite the metal particles of a plastic case containing metal components by laser, and use environmental protection electroplating technology to float a copper sheet on the plastic. This copper sheet can be used in three-dimensional space and directly turn the mobile phone case into an antenna. Signal.

LDS technology production process:

Integrated design of antenna and structural parts → injection molding → laser engraving → chemical plating → radio frequency testing → surface treatment → assembly / post decoration

At present, LDS is widely used in smart phone terminal antennas, called LDS antennas. Ordinary mobile phone antennas are installed on the mobile phone's motherboard. The LDS antenna technology is Laser-Direct-structuring, which uses a computer to control the movement of the laser according to the trajectory of the conductive pattern, and projects the laser onto the molded three-dimensional plastic device in a few seconds. To activate the circuit pattern. Such a technology can directly irradiate the antenna on the mobile phone casing, and meet the design requirements of mobile phones with thin and light space.

Advantages of LDS technology:

Mobile devices (smartphones, tablets, and laptops) are trending toward larger screens, slimmer bodies, and integrated functions, and increasingly stricter antenna requirements. LDS antenna technology provides flexible and complex three-dimensional design. This technology has exceeded the technical requirements of traditional physical antennas (Flex-antenna) in small size and mobile devices. Its advantages are:

Integrate different types of antennas; such as: Global System for Mobile Communications (GSM), Code Division Multiple Access (CDMA), Wireless Network (WiFi), Bluetooth, and FM Radio

Save space on slim and complex portable mobile device structures.Reducing interference in different types of antennas and reducing the chance of users dropping signals directly by touching the antennas.Can be widely used in smart phones, laptops and tablets.

development trend:

In the future 5G era, high-end smart phone terminal antennas need to be covered with 3D glass. The curved structure of 3D glass is not suitable for the placement of 5G antenna contacts, which is currently a technical problem. According to recent media reports, BYD has the technology to mass-produce 5G antennas on the 3D glass back cover. Whether LDS antennas are suitable for curved 3D glass requires continued layout research.

2.IMR technology

The in-mold transfer process is a type of in-mold decoration. It was developed by the Japanese photo printing (Nissha Printing) from the 1980s. Since 2006, it has cooperated with HP to launch color-case notebook computers. Technology, and a large number of applications in mobile terminals.

The principle of IMR process:

After printing the ink on a PE film, it can also vaporize the metal material on the PE film to form a full-roll type on the molding machine plus a positioning system. After the printing position of the film is aligned with the position to be printed in the cavity, Combined with plastic molding, the molded product is combined with ink but separated from the film to continue the molding operation of the next mold. The finished product is cured after UV irradiation.

The IMR process can achieve different decorative effects (leather, cloth, bamboo, stone, etc.). The advantage is that changing the film can express patterns with different effects. The IMR back cover applied on Xiaomi 4, which Xiaomi refers to as the "grating back cover".

In addition to the grating texture effect, Xiaomi Mi 4 is equipped with back shell accessories of various material effects such as wood, bamboo, marble, leather, etc., which can be replaced manually by the user.

development trend:

The most important development of IMR products is the conditions for successful coating and transfer. The height, corner radius, and draft angle have restrictions. Therefore, the products using the IMR process can only be made into four corners. We call them arc machines. , No side wall height at all. In 2015, I learned from the technical forum that Dell's newly launched Insprion New 17 has adopted IMR again, breaking through the previously unachievable side wall height, and the R angle is 12 or lower (Nissha's standard is R20). At present, matt and high-gloss have been shipped in large quantities, and the soft touch leather IMR is also used throughout the C key. The wear resistance standard is higher than that of paint.

From zhushizhijia

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