Spares for 3C product

Application of magnesium alloy in modern electronic products

The development of modern electronic technology has placed increasing demands on the performance of structural materials and components for electronic devices. In order to adapt to the development direction of light, thin and miniaturized electronic devices, materials required as electronic device housings have low density, high strength and rigidity, good impact and vibration damping, strong electromagnetic shielding capability, good heat dissipation performance, and easy forming. Processing, beautiful surface, durable, low cost, easy to recycle and meet environmental requirements. Traditional plastics and aluminum materials have gradually become difficult to meet the requirements of use. Magnesium and its alloys are ideal materials for the manufacture of electronic device housings, and have broad application prospects in electronics and household appliances.

Electronic device housings made from magnesium and its alloys have a number of advantages.

First, the structure is light

The housing of the electronic device is generally made of engineering plastics, such as PC, PC/ABS, Nylon/PPE, carbon fiber reinforced plastic, etc., and some aluminum alloy parts. In order to reduce the weight of the casing, a method of reducing the wall thickness of the casing is mainly employed. However, after the wall thickness reaches 1 mm or less, the rigidity, impact resistance and deformation resistance of the above materials are greatly reduced, and it is difficult to meet the use requirements. Magnesium alloy has the advantages of low density, high specific strength and specific stiffness, good impact resistance, etc. It is an ideal material for making electronic device housings. Table 1 lists the performance comparisons of various housing materials, and Table 2 lists the performance requirements for magnesium alloy materials for different portable electrical products.表1  外壳材料性质对比

注：PC为聚碳酸酯；GF为玻璃纤维；CF为碳纤维。

表2  不同便携式电器产品对镁合金性能的要求

Note: √ indicates that the product has higher performance requirements.

The typical plastic wall of a personal computer has a wall thickness of 2.2 mm and is replaced by a magnesium alloy with a wall thickness of 0.82 mm, which can reduce weight by 46% and tensile strength by 1.4 times. In March 1995, Japan's SONY Corporation limited the thickness of the notebook's casing to 1.0mm for the first time. Japan Steel Workers has successfully produced a MD and laptop case with a wall thickness of 0.6 to 0.7 mm using a magnesium alloy semi-solid injection molding process. The 3C product body of a portable computer, camera, etc. made of magnesium alloy can improve the accuracy and durability of the product, making the camera lighter, smaller in structure, and easy to carry.

First, the heat dissipation is good

The computer generates a lot of heat during operation, which causes the internal temperature of the machine to rise. Therefore, the heat must be quickly dissipated in order to maintain the temperature of the critical components within a reliable range to ensure the stability of the system.

Generally, the thermal conductivity of metals is one to two orders of magnitude higher than that of plastics. For example, the thermal conductivity of AZ91D alloy is 79W·(m·K)ˉ1, which is hundreds of times that of plastic. IBM A4 resin was used in ABS resin and AZ91D magnesium alloy to make the A4 notebook computer case. The heat dissipation performance comparison test was carried out. When the power of the computer was 27W, the temperature in the ABS resin case was 62.5 °C, and the inside of the magnesium alloy case was The temperature is 56.5, which indicates that the heat dissipation effect of the magnesium alloy casing is better.

Although the thermal conductivity of magnesium alloy is slightly lower than that of aluminum alloy and copper alloy, it is much higher than that of titanium alloy and steel material, and the specific heat capacity is lower in common alloys. Therefore, the magnesium alloy casing has the remarkable advantage of quick heat dissipation, and is a notebook. The first material of the computer case.

The current power consumption limit of the notebook computer is 15W, and it is expected that the power of the notebook computer will reach 25W, and the heat dissipation design may mainly depend on the heat dissipation effect of the magnesium alloy casing. The portable computers CF25 and CF-25MarkII, which are marketed in 1997 by the Japanese company Matsushita, are very popular. After 1998, all the models in Japan and Taiwan, the current size of the model below 38cm has been fully used magnesium alloy shell. The computer case of 610mm×610mm, which is produced by White MetalCasting Company of the United States, is die-casted from magnesium alloy. China's Lenovo, Asus and other notebook computers have also adopted magnesium alloy casings since 1999.

The use of magnesium alloy to make LCD TV casing not only has excellent strength and appearance, but also has excellent heat dissipation performance, which can save the heat dissipation hole of the plastic casing, and protect the original electrical components from dust and external moisture, and extend the original of the electrical appliance. life.

Second, the electromagnetic shielding ability is strong

Mobile phones and personal computers emit high-frequency electromagnetic waves during use. When they pass through the outer casing of the body, they not only cause harm to human health, but also interfere with radio signals. When using plastics to manufacture electrical device housings, in order to improve its electromagnetic shielding capability, surface spraying of conductive paint, surface coating, metal spraying, adding conductive materials in plastics or assisting metal foil or metal plates is generally adopted, but this will increase production. The complexity of the process, the production cost and price of the product are increased, and the electromagnetic shielding effect is still limited. Compared with plastics, magnesium alloys have excellent electromagnetic shielding properties, and magnesium alloy electronic device housings can achieve good shielding effects without the above surface treatment.

Japan's IBM company compared the shielding ability of ABS resin and magnesium alloy casing (AZ91D, wall thickness 1.4mm) to electromagnetic waves of 30~200MHz on a notebook computer. The latter's shielding capability over the entire frequency range can be stabilized at 90 to 100 dB, while the ABS resin case with a plating layer (Cu2μm + Ni 0.25 μm) is 35 dB at 30 MHz and approximately 55 dB at 200 MHz.

Third, high damping and shock absorption, shock absorption performance

Magnesium alloy has excellent energy absorption capacity, absorbs vibration and noise, and ensures that the equipment can work quietly. The damping capacity of magnesium alloy is several times larger than that of aluminum alloy, and the shock absorption effect is very remarkable. The base of computer hard disk is replaced by magnesium alloy instead of aluminum alloy, which can greatly reduce the weight (about 70%) and greatly increase the stability of the hard disk. It is very beneficial for the computer's hard disk to develop in the direction of high speed and large capacity.

Fourth, good impact resistance and compression resistance

Its impact resistance is 20 times that of plastics; when magnesium alloys are impacted, the scars on the surface are much smaller than iron and aluminum. The magnesium alloy notebook computer display case adopts the display case to provide the pressure protection effect on the road, and the outer casing is 20 times stronger than the plastic case.

Since there is not enough supply of magnesium alloy sheet on the market, the outer shell of most electronic products is still made of magnesium alloy die-casting and powder metallurgy. With the breakthrough of the production technology of magnesium alloy sheet of our company, the shell of electronic products is stamped with magnesium alloy sheet. It can effectively improve the strength of the outer casing, shorten the processing process and reduce the price of the product.

     Other fields: Magnesium sheets are used to make magnesium cells such as sonar buoys, zinc electrolytic cathode plates, various hand tool casings, advanced suitcases, textile shuttles, heavy machinery, signage stamps, etc.