The 5g era is coming, and the materials of mobile phone shell are from plastic to metal to non-metal. Plastic is liked by the middle and low-end market because of its low cost. The evolution from IML to IMT process makes the plastic white and beautiful, which can be close to imitating the 3D optical texture of the glass back cover, and has become the choice of many CMF designers. LDS has been widely used in the plastic back shell antenna in the 4G period, but whether it can adapt to the high-end curved glass 3D back cover in the 5g period requires continued planning and research. IMT technology can also be further extended to ime technology, integrating electrical and decorative functions, and applied to the intelligent appearance of cars in the future.

LDS Technology

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

Manufacturing process of LDS Technology: integrated design of antenna and structural parts → injection molding → thunder carving → chemical plating → RF test → surface treatment → assembly / post decoration.

At present, LDS is widely used in smart phone terminal antenna, which is called LDS antenna. Ordinary mobile phone antennas are installed on the motherboard of the mobile phone. LDS antenna technology is laser direct forming technology. The computer controls the movement of the laser according to the trajectory of the conductive pattern, projects the laser onto the formed three-dimensional plastic device, and activates the circuit pattern in a few seconds. Such a technology can directly laser the antenna on the shell of the mobile phone, meeting the design requirements of light and thin mobile phones with small space.

Advantages of LDS Technology: mobile devices (smartphones, tablets and laptops) tend to have large screens, thin bodies, and integrated multi-function. The requirements for antennas are also increasingly stringent. LDS antenna technology provides flexible and complex three-dimensional design. This technology has surpassed the technical application of traditional flex antenna in small volume and mobile equipment. Its advantages are:

1. Integrate different types of antennas, such as global system of mobile communications (GSM), code division multiple access (CDMA), wireless network (WiFi), Bluetooth, and frequency modulated radio (FM radio);

2. Save space in the thin and complex structure of portable mobile equipment;

3. Reduce interference in different types of antennas, and reduce the probability of signal landing caused by users' direct touch to the antenna;

4. It can be widely used in smartphones, laptops and tablets;

Deployment trend: in the future 5g period, the antenna of high-end smart phone terminals needs to be on the back cover of 3D glass. The curved structure of 3D glass is not suitable for the placement of 5g antenna contacts, which is a technical problem at present. Recently, according to the media, BYD has been equipped with the mass production technology of 5g antenna in the 3D glass back cover. Whether the LDS antenna can comply with the curved 3D glass needs further planning and discussion.

IMR Technology

In mold transfer printing process is a kind of in mold decoration, which was developed by Nissha printing in Japan since the 1980s. Since 2006, it has cooperated with HP to launch color case notebook computers. IMR process has become the mainstream technology to deal with notebook computer shell, and has been widely used in mobile terminals.

The principle of IMR process: printing ink on a PE film, it can also steam the metal material on the PE film in a steaming way to become a whole roll type, and a positioning system is added on the molding machine. After aligning the printing position of the film with the position to be printed in the mold cavity, it is molded with plastic. After molding, the molded product and ink, but with the film, continue the molding action of the next the first mock examination respectively, The formed waste products are hardened after UV mapping.

IMR process can complete different decorative effects (leather, cloth, bamboo, stone, etc.), and its advantage is that changing the film can show patterns with different effects. The IMR back cover applied on Xiaomi 4 is called "grating back cover" by Xiaomi.

In addition to the raster texture effect, Xiaomi 4 is equipped with back shell accessories made of wood, bamboo, marble, leather and other materials, which can be changed manually by users.

Development trend: the most important thing in IMR product development is the successful condition of coating transfer. There are restrictions on height, corner radius and draft angle, so the products that used IMR process before can only be made into four corners that are round. We call it circular arc machine, which is intact without side wall height. In 2015, it was understood from the technical forum that Dell's newly launched Insprion new 17 has re adopted IMR, breaking the previously impossible height of the side wall, and the R angle is 12, making it lower (Nissha's specification is R20). At present, matte and high gloss have been shipped in large quantities, and soft touch leather IMR with soft touch is also used in the whole C key. The wear resistance specification is higher than that of paint.

IML Technology

The remarkable feature of in mold insert injection molding (IML) technology is that the outside is a hardened transparent film, the middle is a printed pattern layer, and the reverse is a plastic layer. Because the ink is clamped in the middle, the product can avoid scratches and external resistance. With strong friction, it can keep bright color for a long time and is not easy to fade.

IML technology manufacturing process: cutting --- plane printing --- ink drying and fixing --- sticking protective film --- punching positioning holes --- thermoforming --- cutting peripheral shape --- material injection molding process

IML technology product effect:

1. Diversification of printing appearance effect: through the transfer of soft touch and color, electroplating and other printing technologies, the diversification of various appearances is completed

2. Research and development of ultra-thin IML, the thinness can reach 0.80mm, and the deformation can be less than 0.5mm; The deformation of 6-inch battery cover can be less than 1.0mm; The thickness of partial glue reduction can be 0.6mm.

Development trend: in terms of the existing equipment and process flow of IML technology, the improvement has evolved into an IMT process that is more responsive to future user needs and technical requirements, thereby reactivating the development space of traditional plastic molding plants.

IMT Technology

In mold decoration (IMT) technology is a new process that combines in mold insert injection molding (IML) technology and in mold transfer printing (IMR) technology.

Its technology applies the separate technology of membrane and ink of IMR technology, and integrates the monomer forming and injection molding manufacturing methods of IML technology. Its multi-layer maintenance film can effectively maintain the quality of the main decorative layer.

Advantages of IMT process: 1 The thickness of the product can be as thin as 0.70mm;
2. Stable deformation;
3. No risk of spalling;
4. After the extension of the process, such as spraying UV, it can better complete the functional requirements of the product appearance, such as fingerprint prevention, wear resistance, gloss, and can pass through the 3D texture printing layer and apply the magnetron sputtering technology to complete the 3D optical texture effect.

At present, IMT technology is a popular disposal plan for the back cover of smart phones. Tongda said that the IMT project has won the victory and provided plans other than the glass backplane. In 18 years, more IMT plans will be launched to cooperate with the middle and low-end market. The presentation of IMT process will replace the oil spray, UV shading, electroplating, vacuum color plating, silk screen printing, pad printing and transfer printing processes in the current industry, and will drive the breakthrough innovation in the product appearance industry, completing the decorative effect of irregular products such as three-dimensional plane, color mutation, R angle, and providing a better innovation and platform for the appearance process design industry. The new IMT process is a popular 3D optical texture and PVD decoration method at present, which is more attractive and has a larger radian than the traditional process. The current IMT process has changed from the 3D optical texture PVD of the new process to the double-layer 3D optical texture PVD.

Development trend: oppo A79 used IMT process, which was once popular. At present, the problem encountered by IMT is that the straight through rate still needs to be improved. In the 5g period, IMT process may become popular. According to Xiaobian's understanding, many domestic manufacturers such as Tongda, Zhaoyi, Lianmao, Yuding nano, BYD, Jingfeng, Huanli, etc. are planning, and some enterprises begin mass production. IMT technology can be integrated with electronic technology and evolved into ime technology in the future, adding circuit layers and mounting electronic components, giving the diaphragm electronic functions and a variety of visual, tactile and sensory effects, which can be applied to the intelligent appearance of cars in the future.