With the development of communication technology, mobile 5G signals are likely to be commercialized in early 2020. At that time, 5G smartphones will also develop towards thinness and portability, and the transmission speed of signals will become faster and faster. To truly unleash the perfect performance of 5G signals, one cannot do without the good performance of a mobile phone. So, what kind of mobile hardware can meet the demand for 5G signals?
Modification and Rebirth of Engineering Plastics
In the 5G era, mobile phones have higher requirements for engineering plastics. Yao Weizhong, the technical chief engineer of Hefei Huitong New Materials Co., Ltd., introduced that the future 5G mobile phones will develop towards a lighter, thinner, and more portable direction. This requires materials to have good fluidity and high rigidity, as well as color stains and drop resistance, to ensure that the phone can withstand certain impact forces even in extremely light and thin situations, and not be "easily damaged". In addition, the transmission speed of signals in the 5G era will also be much faster than that of 4G signals. From a software perspective, it is required that materials have low interference with the signal and low dielectric constant to ensure that big data transmission is not disturbed.
Engineering plastics have always been one of the mainstream materials for manufacturing mobile phones due to their advantages of mature technology, strong plasticity, and high stability. Currently, PC (polycarbonate) materials are mostly used for the front frame, middle frame, and battery back cover of mobile phones. PC is prone to decomposition under increasing temperature or certain pressure, resulting in paint peeling and cracking. This is something that 5G phones must avoid.
Yao Weizhong introduced that super tough PC materials can effectively solve the above problems. The modified super tough PC material has good flowability, thermal stability, and cosmetic resistance, with excellent spray performance and impact resistance. For example, fiberglass reinforced PC materials have good anti drop performance and toughness, as well as advantages such as minimal damage to molds, making them highly competitive in 5G mobile phone applications.
In addition, excellent modified engineering plastics also include high glass fiber reinforced PPA (polyphosphate) materials, which have extremely low dielectric constant, excellent color resistance, anisotropy, dimensional stability, flowability, and surface appearance. They are now widely used in the front and middle frames of mobile phones.
With the advent of the 5G era, mobile phone covers will also become a new research hotspot. At present, metal back covers have been gradually phased out, and glass back covers have become the new mainstream. But in the 5G era, thicker glass back covers cannot meet the requirements of thinness and impact resistance. At that time, plastic back covers will have the opportunity to be reborn.
With the development of plastic texture technology, composite panels such as PC/PMMA (polymethyl methacrylate) will provide a solution for mobile phone casings. Industry experts have introduced that PC/PMMA composite boards are made by co extrusion of PC and PMMA. Due to the good hardness and wear resistance of PMMA, it is generally used for external purposes, while PC has good toughness, so it is used as the inner layer. PC/PMMA composite board combines the advantages of PC and PMMA, with good adhesion, high hardness, and scratch resistance, making it a perfect substitute for glass.
 
Combining metal and plastic to create new products
For the various requirements put forward by mobile applications in the 5G era, NMT (nano injection molding technology) materials that combine metal and plastic, and LDS (modified plastic containing organic metal composites) materials have also ushered in their development opportunities.
NMT materials are processed by combining metal and plastic with nanotechnology and can be used for phone frames and back cases. Yang Jianjun, Marketing Director of Shenzhen Zhongsu New Materials Co., Ltd., stated that NMT material is a combination of metal and plastic at the nanoscale level, with higher bonding strength. In terms of product technology and design, it can make products have both the strength and appearance of metal and the plasticity of plastic, allowing them to develop towards lighter, thinner, and more miniature directions. NMT materials with good insulation performance have a very low dielectric constant, which can fully meet the requirement of a dielectric constant below 3.0 for 5G smartphone micro slot antennas.
5G signals also pose higher requirements for the signal transmission capability of mobile phone casings. Zhou Hongwei, Chairman of Shenzhen Micro Aviation Magnetoelectric Technology Co., Ltd., stated that 5G uses millimeter wave technology, which has a short transmission distance and can block connections when encountering obstacles. It has high requirements for the material of mobile phones, and if the phone shell is made of metal, the interference is very severe. Ordinary mobile phone antennas are installed on the motherboard, while 5G phone antennas can only take a different approach.
At present, the best solution is to use LDS antennas. Simply put, LDS antennas are formed on a molded plastic bracket, using laser technology to directly deposit metal antennas onto the bracket, allowing for direct laser irradiation of the antenna onto the phone case. After laser irradiation, the organic metal complexes in LDS materials can release metal particles, just like they grow from a plastic substrate after laser irradiation, meeting the volume requirements of mobile phones for antennas.
Meng Xingbing, Product Manager of Shenzhen Zhongsu New Materials Co., Ltd., believes that 5G antennas have higher transmission frequencies and shorter wavelengths, which pose higher requirements for LDS materials. High dielectric LDS materials based on special nylon, PPO, and PC can meet the new needs of 5G antennas.
 
Adhesive helps with waterproofing
Waterproofing will become the most basic requirement for 5G smartphones. The simplest and most intuitive way to waterproof mobile phones is to seal any possible gaps on the phone with adhesive. According to the survey, there are epoxy adhesives, thermal conductive adhesives, organic silicone adhesives, UV adhesives, acrylic adhesives, etc. suitable for 5G mobile phones.
Zhang Liwen, General Manager of Yantai Xinyou New Materials Co., Ltd., introduced that compared to traditional silicone strips, UV glue has faster dispensing, lower viscosity, better elasticity, and better sealing and waterproofing effect, which can help meet the needs of 5G mobile phone component waterproofing and circuit board waterproofing.
The UV adhesive mentioned by Zhang Liwen, also known as UV cured adhesive, is a type of adhesive that must be cured by ultraviolet light irradiation. It is a solvent-free adhesive, so its curing process does not produce toxic and harmful volatiles, and does not pollute the ambient air. In addition, the curing speed of UV glue is very fast. Under UV irradiation, it can be cured in just a few seconds, and after curing, it can be detected and transported, which is very conducive to the automated production of 5G mobile phones and greatly helps to improve the production efficiency of mobile phones.
Cui Bin, Market Promotion Manager of Yantai Xinyou New Materials, further introduced that UV glue has strong moisture-proof, dust-proof, and salt spray resistant properties. When used on circuit boards, it can effectively protect them from erosion. In addition, an important factor affecting the quality of mobile phones is the reliability of chip solder joints on the phone motherboard, and using UV adhesive to fill and bind the bottom can help improve the reliability of chip solder joints.
In addition, acrylic adhesive has good waterproof performance, which not only quickly sticks the screen, but also has high resistance to push out. Therefore, acrylic adhesive is also used to bond phone shells. Cui Bin introduced that for the bonding of mobile phone shells, it is necessary to improve the performance of two-component acrylic acid to increase toughness and bonding strength, in order to achieve better results.