Laser Marking For Anodized Aluminum on Mobile Phone Back Cover

In this blog, Focuslaser will explain seven things you should know before buying a fiber optic laser engraver or UV laser engraving machine — working area, focal length, pulse resolution, quality of the power source, automation functions, engraving speed and after-sales service are some of the facts that you should have on mind before you purchase this type of technology.

In the 21st century electronic information age, mobile phones are becoming more and more inseparable in our daily lives. In the mobile terminal market, mobile phones are playing an increasingly important role. It can be seen that the future market for mobile phones will be even broader. With the continuous change of consumer consumption concepts, the requirements for mobile phone manufacturing are also getting higher and higher. Many smart phone brands have strict requirements on the LOGO process of the body shell. Even the LOGOs that are as small as power adapters, headphones, and mobile power are processed by laser marking machines.

Evolution of phone body materials

Most of the earliest mobile phone bodies were made of plastic. The plastic material usually used on mobile phone cases is polycarbonate, including LG-G series, Nokia (Microsoft) Lumia, and Samsung S5. They are all mainstream plastics. The shell mobile phone has the disadvantages of poor texture, poor heat dissipation, cheap looking, and tight combination. Ceramic material has become a rising star of mobile phone backplanes in recent years. In September 2017, Xiaomi released MIX2. According to market research by professionals, ceramic materials are gradually becoming a competitive weapon for high-end consumer electronics differentiation. It is expected that the smart phone ceramic backplane market in 2018 The space will reach 11.6 billion yuan. However, due to factors such as manufacturing difficulty and high cost, it has not been widely used in the market. At present, most models on the market use an all-aluminum body, usually an aluminum alloy. After the aluminum alloy is anodized, it is the common material of the back cover of a mobile phone, commonly known as anodized aluminum.

Anodized aluminum black introduction

The back cover of the phone has the manufacturer’s logo and the black font in the serial number area. At first glance, it looks similar to the ink. But in fact, it is neither ink coding nor silk screen printing, which is also laser-treated, commonly known as alumina blackening. The traditional method is to use screen printing to print on the surface. The silk screen printing ink is heavy, not delicate, difficult to follow the color, and the printing effect is not ideal. The ink composition used for screen printing is a heavy metal chemical element. All businesses now specify low carbon and environmental protection. In the new technology, mobile phones use laser marking as a marking method, which can improve anti-counterfeiting capabilities and increase added value, making products look higher-level and more brand-conscious.

Anodized aluminum refers to the coating of a dense layer of aluminum oxide on the surface of aluminum and aluminum alloys. In order to prevent further oxidation, its chemical properties are the same as aluminum oxide. Anodizing can significantly improve the corrosion resistance of aluminum alloys, increase the surface hardness and wear resistance of aluminum alloys, and have good decorative properties after proper coloring treatment.

Anodized aluminum black principle

The mechanism of anodized alumina blackening is to further oxidize and change the surface material of the anodized alumina layer with a film thickness of 5-20um in a short time by focusing the high energy density laser. The principle of alumina blackening is based on nanometers. Effect, because the oxide particles are nanometer in size after laser treatment, so the light absorption performance of the substance is increased, so that visible light is irradiated to the substance and absorbed, and there is very little visible light reflected, so it is black to the naked eye, so it is called Blackening alumina. The thickness of the anodized aluminum oxide layer and the surface treatment process. Generally speaking, the film thickness is 5-20um, and the thickness of the film directly determines the effect and efficiency of blackening. Generally, the film thickness is 10-20um, which is easier to blacken. When it is less than 8um, the oxide film is too thin, it is easy to break, and white spots appear, which needs to be compensated by laser parameters. In addition, the anodized aluminum surface treatment process will directly affect the blackening effect. Sandblasting and surface drawing are common processes. The thickness of the sandblasting will have different effects on the marking effect. The finer the sandblasting particles, the better the blackening effect. . It is recommended that the thickness of the anode aluminum be 10-15 μm, so that the overall blackness effect will be better.

Use laser to mark black trademark, model, text on the surface of anodized aluminum material. This application has been widely used by electronics manufacturers such as Apple, Huawei, ZTE, OPPO, VIVO, etc. on the shell of electronic products for marking Engraved trademarks, models, etc. in black. For these applications, MOPA fiber lasers are currently used to process them. Because the MOPA laser has a wide range of pulse width and pulse frequency adjustment, the parameters of narrow pulse width and high frequency can be used to mark the effect of black on the surface of the material, and different gray levels can be marked by different parameter combinations.

With the development of the times and the needs of market applications, the past silk screen process has been gradually replaced by laser marking. focuslaser Laser marking is a modern precision processing method, and traditional processing methods such as printing, mechanical scoring, and electric discharge machining. Compared with that, it has unparalleled advantages. The laser marking machine has the characteristics of maintenance-free, high flexibility, high reliability, etc., and is especially suitable for areas with high requirements for fineness, depth and smoothness. Personal electronic products represented by mobile phones have positively changed and facilitated people’s lives. Functionalization, intelligence, and smartness are the development direction of mobile phones. With the technological progress of the microelectronics industry and people’s pursuit of personalization of mobile phones, fine laser marking processing technology will play an increasingly important role in mobile phone manufacturing.

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