In 2007, the first generation of iPhone was released. In the past ten years, Apple has released 19 generations of 19 iPhones. This year is the 10th anniversary of Apple's mobile phone, Apple released three iPhones in one breath. One of the most eye-catching is the iPhone X.
IPhone X uses stainless steel middle frame
Image from Apple's official website
The three newly released iPhones are double sided glass + metal middle frame design
Image courtesy of The Verge
1. Why use stainless steel?
As the high-end flagship machine of Apple, IPhone X changed back to the front and rear covers of the iPhone 4 series, which were made of glass and supplemented with a stainless steel middle frame. As we all know, aluminum alloy frame has many advantages, as follows:
l Beautiful appearance, low density of aluminum alloy makes the equipment light and thin l
l Metal texture is strong, easy to process high-grade, beautiful feeling l Aluminum alloy is cheap, stainless steel is expensive
l High temperature resistance, no fingerprints, antistatic, environmental protection and non-toxic l Aluminum alloy material has strong dyeability
Aluminum alloy is known as a gift from God to the 3C industry. At the same time, there are so many advantages. Why should we choose stainless steel?
The iPhone 6 has been swelled by curved doors
Image courtesy of n-tv.de
The "iPhone 6 curved door" that Lenovo once boasted, the shortcomings are obvious - the aluminum alloy is soft, the light one touches the mark, and the heavy one bends and deforms. At the same time, the double-sided glass/ceramic mobile phone/full screen era has put forward higher requirements on the mobile phone frame, and the stainless steel middle frame is also a trend.
Advantages and disadvantages of stainless steel materials as the middle frame of mobile phones
Although the processing of stainless steel is difficult, the working hours are increased and the cost is high. However, there are still some mobile phone terminal companies that choose stainless steel as the middle frame material. Among them, the iPhone 4 has contributed.
iPhone 4 sturdy, eye-catching and avant-garde stainless steel border
Picture from Pisapapeles
From iPhone 4, Xiaomi 4 to iPhone X, Xiaomi 6, stainless steel in the aluminum alloy is the king of the mobile phone in the box world also has a fascinating and promising road.
Stainless steel middle frame development history
2, using stainless steel, can not escape the process and other material selection
In the future, the future of mobile phones will be dominated by ceramics and glass. The requirements for the middle frame will be higher. High-strength aluminum alloy or stainless steel must be used, and from the perspective of strength, the latter is more inclined.
Stainless steel makes the phone no longer afraid of bending
Image courtesy of GSMDome.com
The main surface treatment process of stainless steel materials is PVD (Physical Vapor DeposiTIon). After “sandblasting, drawing or polishing + PVDâ€, the metal surface can be coated with high-hard plating and high abrasion resistance decorative coating.
PVD technology is a high-tech and widely used ion plating technology in the world. It has the characteristics of dense coating uniformity, strong adhesion, good plating performance, fast deposition speed, low processing temperature and wide plating materials.
PVD coating effect
Image from public information
The selection of PVD process puts forward new requirements for the selection of nano-injected parts: taking vacuum evaporation as an example, it is necessary to heat metal under high vacuum to melt, evaporate and form a metal film on the surface of the sample after cooling. Get a mirror-like surface.
PVD process
Because the stainless steel middle frame post-treatment process involves PVD and laser engraving process, the processing temperature reaches 180 degrees, which requires the nano-injection material to withstand high temperature. High temperature resistant nylon (HPPA) came into being, especially in connection with stainless steel, composite metal, liquid metal.
Subsequent laser engraving process also requires matching of other related materials.
Image from YouTube
3, nano-injection material selection: high temperature resistant nylon (Hua Ying HPPA)
Since RF signals cannot penetrate metals, special handling designs are required in most cases. A common method is to cut the metal frame where there is an antenna and perform an injection joint at the cut.
Commonly used nano-injection materials are PPS (polyphenylene sulfide), PBT (polybutylene terephthalate), PA (nylon, polyamide) and PPA (polyphthalamide). Due to the high processing temperature of the stainless steel middle frame post-treatment process, the actual nano-injection material needs to withstand high temperature, and the high-temperature resistant nylon HPPA belongs to one of the emerging and cutting-edge materials that meet this requirement.
HPPA, a kind of PPA, has excellent material properties and is an excellent matching material for stainless steel middle frames. At present, China Huaying New Materials has successfully developed a nano-high temperature nylon HPPA TG850ML1 that meets the PVD process, and has been applied to famous mobile phone terminal manufacturers. The specification material has excellent adhesion with stainless steel, liquid metal, powder metallurgy, etc. It is suitable for stainless steel materials such as ceramics and glass that have high strength requirements for the middle frame of mobile phones.
In the pull-out test, Huaying New Material HPPA high temperature resistant nylon has excellent performance. When the drawing force is about 200 kgf, the adhesive is even after the nylon is detached in the test piece, and it is firmly combined with stainless steel and has excellent performance. Please see the picture below
Huaying HPPA is firmly combined with stainless steel
Huaying HPPA's excellent drawing performance
Having said that, I believe many of my friends are interested in this new material with excellent performance. How is Huaying High Temperature Nylon achieved? How can the various parameters be specific? Xiaobian specializes in the detailed physical parameters of Huaying HPPA, for the friends of the material circle to "taste".
Comparison of key performance indicators between Huaying HPPA and a famous international manufacturer
Stainless steel medium frame with Huaying high temperature nylon physical parameters
In addition to this nano-high temperature nylon HPPA, Huaying New Materials also has TG835 ML1 (35% glass fiber content / low dielectric constant), TG840 ML1 (40% glass fiber content), excellent performance, in line with PVD process and has been successful Terminal application.
Huaying New Materials Co., Ltd. has developed a series of high-performance nylon materials for medium and high-end components for the structural characteristics of consumer electronic products. The series contains nylon materials with aromatic chemical structure, which makes the products in flow and machinery. Excellent performance in terms of strength and high temperature resistance. These include: high-strength nylon materials with low shrinkage and coefficient of linear expansion; nylon materials for high-profile appearance; nylon materials for large-area metal-bonded products.
4. Future forecast
At present, the material of the mobile phone frame is still mainly made of aluminum alloy. According to the brand sequence, there are 7000 series aluminum-magnesium alloy used by Apple, Huawei's aviation-grade aluminum alloy and special aluminum-magnesium alloy of vivo. At the same time, many mobile phones using stainless steel (austenitic 304 and austenitic 316) have emerged, represented by millet's high-gloss stainless steel and hammer-free mirror-free all-metal stainless steel. There are also a few smaller categories, such as the Nubian and titanium metal Turing phones.
Current phone frame material overview
In the 3D glass era, the middle frame will be narrowed, and the middle frame as a key structural component requires a higher strength material to carry. In the future that can be met, the permeability of the metal middle frame will continue to increase, because glass and ceramic also require metal. In the middle box.
As the 5G era approaches, the signal requirements are getting higher and higher, and the need for wireless charging, "metal casing + metal middle frame" will develop in the direction of "metal frame + double-sided glass". Materials with excellent structural properties such as 7-series aluminum, stainless steel and even titanium alloys will be more widely used in metal frames to maintain the strength of the fuselage and support for large screens. This kind of material processing technology has higher barriers and higher value, which will definitely increase the value space of the metal frame industry. Matching materials (such as high temperature nylon) will also usher in even greater development!
If you are concerned about high temperature nylon and pay attention to new materials for mobile phones, please contact us.
If you have any questions, please call Mr. Xiang (WeChat with the same)
For product details, please contact us by email.
Mr. Chen Chengchen, Huaying New Materials (WeChat)
Website: www. szjerry.com
Email: cheng.
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