In 2007, the first generation of iPhone was released. In the past ten years, Apple has released 19 iPhones in a total of twelve generations. This year marks the 10th anniversary of Apple's mobile phones, and Apple has released three iPhones in one go. The most eye-catching one is the iPhone X.
The three newly released iPhones all use double-sided glass + metal middle frame design
. The picture comes from The Verge
1. Why is stainless steel
IPhone X used as Apple's high-end flagship phone? It has changed to the front and rear covers similar to the iPhone 4 series with glass and stainless steel middle frame design. As we all know, aluminum alloy midframes have many advantages, as follows:
·Beautiful appearance, small aluminum alloy density makes the equipment light and thin. Aluminum alloy has excellent comprehensive performance
·Strong metal texture, easy to process high-end and beautiful. Aluminum alloy is cheap, stainless steel is expensive
·High temperature resistance, no handprints, anti-static, environmentally friendly and non-toxic. Aluminum alloy has strong dyeability
0 Aluminum alloy is known as a gift from God to the 3C industry. At the same time, it has so many advantages. Why should we choose stainless steel if we look far away?
iPhone 6's once controversial curved door
Pictures are from n-tv.de
Lenovo's once controversial "iPhone 6's bend door" has obvious disadvantages - aluminum alloy is softer, lighter bumps leave marks, and heavyer ones bend and deformed. At the same time, in the era of double-sided glass/ceramic mobile phones/full screens, all put forward higher requirements for mobile phone bezels, and stainless steel midframes are also a trend.
Advantages and disadvantages of stainless steel material as a mobile phone frame
Although stainless steel is difficult to process, the working hours will increase and the cost will be high. But some mobile terminal companies still choose stainless steel as the middle frame material. The iPhone 4 is of great significance.
From iPhone 4, Xiaomi 4 to iPhone X, Xiaomi 6, stainless steel has also made a remarkable and promising path in the world of mobile phone midframes where aluminum alloy is king.
2. If you use stainless steel, you cannot escape the process and other materials. Choose
. In the future, ceramics and glass will be the appearance dominant, and the requirements for the center frame will be higher. High-strength aluminum alloy or stainless steel must be used. From the perspective of strength, the latter is more inclined.
The mainstream surface treatment process of stainless steel materials is PVD (Physical Vapor Deposition) technology. After "sandblasting, brushing or polishing + PVD", the metal surface can be coated with high hard plating and high wear resistance decorative coatings.
PVD technology is an ion coating technology with high technological content and widely used internationally. It has the characteristics of dense and uniform coating layer, strong adhesion, good plating properties, fast deposition speed, low processing temperature, and wide range of plating materials. The selection of
PVD process puts forward new requirements for the selection of nano-injection molded parts: Taking the vacuum evaporation method as an example, it is necessary to heat the metal under high vacuum to melt and evaporate, and then form a metal film on the surface of the sample after cooling to obtain a mirror-like surface.
PVD process flow
Because the stainless steel middle frame post-treatment process involves PVD and radium engraving processes, the processing temperature reaches 180 degrees, which requires the nano injection molding material to be able to withstand high temperatures. High temperature resistant nylon (HPPA) came into being, especially when it comes to connection with stainless steel, composite metals and liquid metals.
3. Nano-injection molding material selection: high temperature resistant nylon (Huaying HPPA)
Because radio frequency signals cannot penetrate metal, special processing design is required in most cases. The commonly used method is to cut off the metal frame where there is an antenna and perform injection molding connections at the cutoff.
Commonly used nano injection molding materials include PPS ( polyphenylene sulfide ), PBT (polybutylene terephthalate), PA (nylon, polyamide) and PPA (polyphthalamide). Because the processing temperature of the stainless steel midframe post-treatment process is high, the nano-injection molded materials used in actual use must be resistant to high temperatures. High temperature resistant nylon HPPA is one of the emerging and cutting-edge materials that meet this requirement.
HPPA is a type of PPA, with excellent material properties, and is an excellent matching material for stainless steel midframes.At present, Huaying New Materials in China has successfully developed nano high-temperature nylon HPPA TG850ML1 that meets the PVD process, and has been used in famous mobile phone terminal manufacturers. This specification material can have excellent adhesion capabilities with stainless steel, liquid metals, powder metallurgy, etc., and adapt to ceramics, glass and other stainless steel materials that have high strength requirements for mobile phone frames. In the
pulling force test, Huaying New Materials HPPA high-temperature nylon has excellent performance. When the pulling force is about 200 kgf, the nylon in the test piece is evenly adhesive after it falls off, it is firmly combined with stainless steel, and has excellent performance. For details, please see the following figure
Huaying HPPA is firmly combined with stainless steel
Huaying HPPA excellent pulling performance
. I have said so much, I believe many friends are interested in this new material with excellent performance. What is the level of Huaying high-temperature nylon, what are the specific parameters, and can we explore more space for cooperation and expansion. The editor specially obtained the detailed physical parameters of Huaying HPPA for friends in the material circle to "taste".
Huaying HPPA compared with key performance indicators of a well-known international manufacturer
Stainless steel middle frame Huaying high-temperature nylon physical properties parameters
In addition to this nano high-temperature nylon HPPA, Huaying New Materials also has TG835 ML1 (35% glass fiber content/low dielectric constant) and TG840 ML1 (40% glass fiber content), excellent performance, comply with the PVD process and has been successfully used.
Huaying New Materials Co., Ltd. has developed a series of high-performance nylon materials for mid-to-high-end parts based on the structural characteristics of consumer electronic products. This series of products contains nylon materials with aromatic chemical structures, making this series of products excellent in fluidity, mechanical strength, and high temperature resistance. Including: high-strength nylon materials with low shrinkage and linear expansion coefficient; nylon materials for high appearance requirements of products; nylon materials for large-area metal-bound products.
4, future prediction
0 The current mobile phone frame material is still mainly aluminum alloy. According to the brand sequence, Apple uses 7000 series aluminum-magnesium alloy , Huawei's aviation-grade aluminum alloy and Vivo's special aluminum-magnesium alloy. At the same time, many mobile phones using stainless steel ( austenite 304 and austenite 316) have appeared, represented by Xiaomi's high-gloss stainless steel and hammer's breakpoint mirror all-metal stainless steel. There are also some niche categories, such as Nubia using titanium alloy and Turing phones using liquid metal.
Current mobile phone frame material overview
3D glass era, the middle frame will become narrower. As a key structural part, the middle frame needs higher strength materials to carry it. In the future that can be encountered, the penetration rate of metal midframes will continue to increase, because glass and ceramics also require metal midframes.
As the 5G era approaches, the signal requirements are getting higher and higher, and the need for wireless charging, the "metal shell + metal middle frame" will develop towards the "metal middle frame + double-sided glass". Materials with excellent structural performance such as 7-Series aluminum, stainless steel and even titanium alloys will be more widely used in metal midframes to maintain body strength and support for large screens. This type of material processing has higher technical barriers and higher value, which will definitely significantly increase the value space of the metal frame industry. Materials matching this (such as high-temperature resistant nylon) will also usher in greater development!
