The most comprehensive new surface treatment technology and new market in the mobile phone industry
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What is surface treatment
Surface treatment is a kind of technology that USES the frontier technology of physics, chemistry, material science and manufacturing science to change the condition and property of parts surface.
Surface treatment is applied in various fields, such as industrial articles for human production, daily articles for daily use, consumer goods, handicrafts and so on. Different products have different requirements, the corresponding surface treatment is different.
Industrial products, More for the purpose of changing superficiality. Mainly for the enhancement of surface stiffness, hardness, strength, wear resistance, corrosion resistance, high temperature and other performance requirements.
Manufactured consumer goods, Modification meets the functional requirements while also paying attention to decorative. For example, the surface treatment of the external surface of the car, use of electrostatic spraying, both to protect the functional needs of the car body and beautiful decorative properties.
Daily supplies, Attach importance to decoration, to meet the customer experience, but also need to meet the corrosion resistance, wear resistance, ph and other performance requirements.
Application of surface treatment technology in consumer electronics industry
The surface treatment of smart phone consumer electronics adopts the most advanced technology. At present, the most commonly used mobile phone shell is plastic shell and metal shell. Mobile phone surface treatment is mainly for the shell, cato, keys, charging interface and other precision structural parts. Surface treatment methods can be roughly divided into physical and chemical methods, physical methods include: spraying, PVD, NVCM, magnetron sputtering, evaporation plating, ion injection molding, radium carving, etc. Chemical methods mainly include electrophoresis, water electroplating, anodic oxidation, micro-arc oxidation, chemical corrosion, etc.
Vacuum coating and anodic oxidation are two common surface treatment methods.
Physical vapor deposition (PVD) is the main vacuum coating method in the surface treatment of mobile phone consumer electronics. Its principle is: under vacuum conditions, the metal gasification into atoms or molecules, or ionisation into ions, directly deposited on the surface of the workpiece, forming a coating, the deposition of particle beam from non-chemical factors, such as evaporation plating, sputtering plating, ion plating and so on.
Vacuum non-conductive electroplating, NCVM, It is a new and high technology of vacuum electroplating. It is also one of the physical surface treatment processes widely used in plastic shell. Using the new coating technology and new materials, the general vacuum electroplating of different colors of metal appearance effect, play a role in beautifying the surface of the workpiece.
Radium carving process is a surface treatment process introduced in 2014. Similar to screen printing pad printing, are printed on the product words or patterns and so on, is a surface treatment process using optical principles. 3D radium carving has been successfully applied in the surface treatment of smartphone shells.
NCL (NCVM coating laser) : electroplating + spraying + laser engraving is the most popular new surface treatment technology for plastic shell, which can make plastic parts highly simulate the effect of metal. NCL process can make aluminum alloy sandblasting anodizing and highlighting metal effect from advanced polycarbonate, so as to achieve highly simulated metal luster and texture.
Anodic oxidation can only be applied to metal shell, mostly aluminum, aluminum alloy material. The common sulfuric acid anodizing method is widely used at present.
Hard oxidation: anodic oxidation with the hardness and wear resistance of anodic oxidation film as the primary performance target. There is no essential difference between hard anodic oxidation and ordinary anodic oxidation in terms of principle, equipment, process and detection, except for different emphases. Hard anodic oxidation is to try to reduce the solubility of the oxide film to thicken its film thickness and enhance the hardness of the film layer.
IPHONE 6S, 7 series aluminum alloy shell is anodized for surface treatment
The main technological process of anodic oxidation: degreasing, degreasing, alkali corrosion, polishing, anodic oxidation, dyeing and hole sealing. Among them, the purpose of alkali corrosion is to remove the dense but uneven oxidation film on the surface of aluminum alloy. HN03 and HF mixed solutions are used for high-silicon aluminum alloy, and NaOH solution is used as the basic tank solution for other aluminum alloys.
Surface treatment application for mobile phone structural parts with different materials
The surface treatment quality of mobile phone structural parts is related to the texture of the basic structural parts. Different surface treatment methods are required for mobile phone structural parts with different materials produced by different processes. Currently, the commonly used materials include plastics, metals, glass and ceramics. The commonly used processing methods include die-casting, CNC processing, forging and stamping.
Plastic shell is mainly prepared by injection molding
Plastic parts are mainly completed by means of injection molding. Injection molding is the method of injecting heated and melted materials into the mold and obtaining molding products after cooling and curing. It is suitable for mass production of products with complex shapes. The main processes include mold closing, injection, pressure maintaining, cooling, mold opening and removal.
Metal shell is mainly prepared by CNC or die casting method
Metal shell precision structural parts are mainly prepared in four ways: die casting, CNC machining, forging and stamping. The first two are more commonly used, led by South Korea's samsung, LG and other manufacturers, mainly using die-casting method to process metal shell; The manufacturers represented by apple mainly use CNC to process metal shells.
The cost of die casting method is lower than CNC method, but the quality of structural parts is difficult to control. Similar to plastic injection molding, the molten metal liquid is high-pressure injected into the mold with the shape of the mobile phone shell and cooled to form; This method has obvious cost advantage for mass production, but due to the sand hole, flow mark, grain inconsistency and other difficult problems of die-cast aluminum, its surface treatment is more difficult, compared with the lowest yield.
CNC method is a high cost for high quality process. Adopt numerical control machine tool, carry on rough milling, fine milling, polishing and so on to the inner cavity and outer cavity of the metal, so as to form the precision structure parts. CNC method has the longest processing period, but it has the highest yield and the best appearance texture, which is a typical process of exchanging high cost for high quality.
The forging process is difficult to design. Heat the metal to a certain temperature and then use a tool to forge it into shape. Forgings of mobile phone shell cost medium, medium quality, but the design space is small
Stamping has the worst designability and is often used in low-end mobile phones. Metal processing technology at room temperature, the main object is metal plate. Most of the performance parameters of the stamping mobile phone shell are excellent. Its processing cost is the lowest, the processing cycle is the shortest, and the yield rate is the highest. The appearance texture is second only to the full CNC, but the designability is the worst. That is to say, stamping is difficult to shape the complex structure of the shell of the mobile phone, often used in low-cost mobile phones.
The above methods can be used alone or together to complete the preparation of metal shell structural parts.
Mobile phone surface treatment development trend
At present, the shell of mobile phone is mainly made of plastic and metal, while glass and ceramic materials, as rising stars, are expected to be the shell material of the next generation of mobile phone.
The new NCL process should hopefully be used in the plastic casing of mid-range mobile phones. In July 2017, OPPO released a new mobile phone A77 with the official guidance price of 2,199 yuan. Its mobile phone shell is plastic parts processed by NCL. According to grassroots research: mobile phone shopping guide in the metal case to promote. Through this phenomenon, it can be seen that: 1.NCL process is a popular surface treatment process for high-end plastic shell, which can completely achieve the visual effect of metallization; 2. 2. The official price is 2,199 yuan, which is one of the most expensive plastic shell models in the market at present, indicating that the plastic mobile phone can break through the bottleneck of low-end mobile phone and is expected to extend to the mid-end model.
OPPO in the middle end new model use plastic shell with metal effect
The main surface treatment method of mobile phone glass shell: screen printing, spraying, coating, radium carving, AF treatment, among which the glass coating is coated on the glass surface of a layer or multiple layers of metal film or metal compounds, in order to change the optical and physical properties of glass. Advantages of glass coating: prevent paint oxidation, enhance toughness and extensibility, high temperature resistance, easy cleaning, scratch resistance, corrosion resistance.
Due to the smooth surface and high degree of curved surface, 3D glass does not have strong adhesion and is more difficult to be coated. At present, the following methods can be adopted: 1. Adhesion film scheme: screen printing, spraying and radium carving the color of a film in advance on a film, then 3D forming it, and then fitting it on the glass back shell; 2. 2. Direct coating +3D spray painting: the surface treatment is directly carried out on the glass, the latter treatment effect is better, but the difficulty is greater.
The principle of ceramic surface treatment is similar to that of plastic surface treatment. Both ceramics and plastics use physical surface treatment technology, the difference is that the surface adhesion of ceramics is not as good as plastic. Therefore, the ceramic surface needs to be pretreated. Pretreatment can increase the bonding area and adhesion by increasing the surface roughness of ceramics. Or through the ceramic surface and the first layer of film chemical reaction, forming a fine hole, and increase the adhesion.
Anodic oxidation plays a pretreatment role in the ceramic surface treatment process. The purpose is to form tiny pores on the ceramic surface through chemical reactions, so that the coating can increase adhesion after entering the pores. The main surface treatment processes of ceramic shell include polishing, wire drawing, sandblasting, radium carving, PVD and AF treatment, among which AF treatment, also known as fingerprint coating treatment, is used to prevent fingerprints and oil stains, and has good wear resistance.