Looking at the current mobile phone advertisements, you will find that "full screen" and "borderless" have become the key promotional content of almost all well-known mobile phone manufacturers.

The full screen does not just enlarge the screen. On the back of the invisible mobile phone screen, high temperature resistant nylon provides a stronger mid-frame structure for the full-screen mobile phone, which brings a sense of grip and visual comfort, while also ensuring The strength of signal transmission is not affected.

 Excellent rigidity provides support for the screen

The full screen can make the phone look cooler and more visually immersive, providing users with the ultimate user experience. When playing games, a full-screen mobile phone has a wider field of vision than an ordinary mobile phone ; when watching a movie, it can bring a better visual experience ; when browsing the web or brushing Weibo, a full-screen mobile phone can display more web content.

With the popularity of large-screen mobile phones, the portability of mobile phones has been criticized. The development of a full-screen mobile phone can improve the portability of a large-screen mobile phone without reducing the user experience, and make the mobile phone feel better.

Mobile phone screens are getting bigger and bigger, satisfying people's visual enjoyment, but increasing the burden on hands. In order to reduce weight, a narrow bezel or even no bezel design needs to be adopted on the outside of the phone screen. Without the support of a circle around the screen, the mobile phone must have a stronger middle frame structure to ensure the stability of the screen. This requires that the plastic parts behind the screen that provide support have super-rigidity to meet the support needs of the screen.

In addition, the post-processing temperature of the middle frame of the mobile phone can reach 180 ℃, which requires that the nano-injection material used in the middle frame can withstand high temperatures. At this time, high temperature nylon can show its strength well.

High temperature resistant nylon is a high temperature resistant nylon made by polycondensation of terephthalic acid and hexamethylene diamine. It has low water absorption, excellent heat resistance, good processing fluidity, low expansion coefficient, excellent chemical resistance, and is comparable to metals High bonding strength, etc., is the best choice for manufacturing the middle frame of mobile phones. The heat deformation temperature of high temperature resistant nylon exceeds 270 ℃, and the high crystallinity makes it still maintain excellent rigidity at high temperature, which can ensure that it provides sufficient support for the screen.

 Extensibility makes the design of mobile phones diverse

All along, polycarbonate (PC) and glass fiber are widely used in the middle frame of mobile phones. With the rise of borderless large-screen mobile phones, the middle frame of mobile phones has higher requirements for dimensional accuracy, dimensional stability and low warpage, but glass fiber reinforced PCs have insufficient rigidity, are prone to distortion or tensile deformation, and mobile phones The metal part has low binding force and other shortcomings, which cannot meet the needs of borderless mobile phones.

Dr. Cao Yanxia, ​​Shenzhen Hualixing New Materials Co., Ltd. introduced that, compared with ordinary nylon 66 and nylon 6 , high temperature resistant nylon has a water absorption of 2/3 , and the dimensional change caused by moisture absorption is small. At the same time, due to its outstanding temperature resistance, the coefficient of thermal expansion is comparable to that of metal or aluminum, and its rigidity is good. The high and low temperature changes cause little warpage and dimensional deformation, and have excellent dimensional stability and low warpage. Therefore, high temperature resistant nylon is fully capable of being used as a structural part of a full-screen mobile phone to provide the support required by the mobile phone.

Cao Yanxia said that high temperature resistant nylon is suitable for nano-injection molding, which can not only achieve integrated molding, so that the product appearance not only takes into account the metal texture, but also ensures the overall structural strength and makes the product details more perfect. The high temperature resistant nylon aluminum has the same strength, the same hardness as the steel, and the rubber has the same flexibility, ductility and impact resistance, so that the design space of the mobile phone is greater.

In addition, PC plus fiber is sensitive to stress. It is easy to crack when glacial acetic acid is tested before spraying, and it is not resistant to acids and alkalis. The high temperature resistant nylon has excellent crystalline arrangement and high permeability, so it has excellent resistance to chemical solvents and can resist the erosion of acids, alkalis and other chemical substances without cracking. After the high temperature resistant nylon is added with glass fiber, the suspended fiber is small or no floating fiber, and it can be sprayed or electroplated without affecting the surface quality.

Cao Yanxia believes that in the full-screen plastic material, high temperature resistant nylon just makes up for the shortcomings and defects in the performance of glass fiber reinforced PC . It has high cost performance and is particularly suitable for high precision mobile phone frame materials.

 Co-modified communication signal is not affected

The design of mobile phones is getting thinner, and the popularity of full screens has made the space for parts inside the mobile phone smaller, and the signal transmission of mobile phones is increasingly restricted. The influence of the dielectric constant of the middle frame material on the mobile phone signal has become more obvious than before. Only materials with a dielectric constant below 3.5 can meet the requirements of mobile phone signal transmission.

Wang Aiguo, general manager of Jiangmen Dezhongtai Engineering Plastic Technology Co., Ltd. introduced that the dielectric constant of high temperature resistant nylon is between 3.3 ~ 3.8 . In order to simplify the process flow and save manufacturing costs, some mobile phones adopt a structure without steel sheet reinforcement, which puts higher requirements on the strength of plastic materials. After copolymerizing a small amount of PA12T semi-aromatic nylon with high temperature resistant nylon , it can be used to produce steel-free middle frame. While ensuring the rigidity of the middle frame, it will not weaken the antenna signal and ensure normal communication is not affected.

Ordinary mobile phones generally have built-in antennas, while full-screen mobile phones use LDS antennas printed directly on the phone case . LDS is a technology that uses a CNC laser to directly print circuit patterns three-dimensionally on the surface of plastics. It has the advantages of short processing time, high accuracy, and the circuit patterns are not limited by the geometric shape of physical devices. For mobile phones to use LDS antennas, the processing requirements of LDS must be considered , such as thermal expansion coefficient, water absorption, etc., to ensure that the plastic case can meet the processing conditions of LDS antennas.

Xue Xiaoping, application development manager of Emmans ( Suzhou ) Engineering Plastics Co., Ltd. introduced that high temperature resistant nylon has high melting temperature, high stiffness and strength at high temperature, low creep, and also has good dimensional stability and high flame retardant performance , It can still maintain a good appearance under the condition of low mold temperature. This feature is very suitable for LDS processing needs, suitable for lead-free soldering SMT process.

According to reports, high temperature resistant nylon has no foaming and low warpage after lead-free soldering, and the radio signal loss is very low. High temperature resistant nylon can also be used for smart watch LDS three-dimensional circuit laser laser engraving antenna and plastic shell materials to ensure GSM , WIFI , GPS , Bluetooth and other antenna signal functions, so that smart watches are not only stylish and diverse, but also soft, feel good and comfortable .

Article link: China Plastic Online http://info.21cp.com/Gaixing/Zixun/201810/1468575.htm