A blogger of Xiaoji recently returned to Tianjin and found that several smart phones used were not acclimatized to the local conditions and had problems, mainly including battery durability, slow response to calls, delayed response of LCD screen, and flashing screen. In fact, it is not an individual case that mobile phones and other electronic products are not resistant to freezing. For example, many people reported their iPhone Or the iPad can't be charged due to cold weather. On Apple's official website, we can also see similar tips about abnormal low-temperature operation:

In fact, most of the electronic products we use will undergo simulated environmental tests before leaving the factory. Usually, the standard atmospheric conditions required during the test are: temperature 15~35 ℃, relative humidity 45%~75%, air pressure 860~1060 mbar, to ensure that the products can be used normally under general conditions. Precision electronic products, such as mobile phones, which contain LCD screens, lithium batteries, chips and other components, are relatively delicate. The performance of these components at low temperatures will be affected to varying degrees, resulting in the overall "frost resistance" of mobile phones. According to the feedback from netizens on the performance of mobile phones in low temperature environment, we started from 1) screen problems; 2) Performance problems; 3) The battery problem is analyzed in three aspects.

1. LCD screen

The main component of the liquid crystal screen is the liquid crystal panel. In simple terms, two glass substrates are sandwiched with a layer of liquid crystal. The physical properties of liquid crystal materials will change differently at different temperatures. When the molecules are activated at high temperatures, the molecular reaction speed will be slower at low temperatures. Generally, the operating temperature of the LCD screen is about - 20 ° C to 70 ° C. When the temperature drops below zero, the LCD screen can still work, but the LCD brightness and response time will be greatly affected.

2. Chip and other electronic components

The chip is actually an integrated circuit made on a semiconductor substrate by technological means. The electronic components contained in the chip generally have a specific operating temperature range. Generally, the commercial grade is 0 ° C to 70 ° C, the industrial grade is - 25 ° C to 85 ° C, and the military grade is - 55 ° C to 150 ° C. If the temperature range is exceeded, the performance will become poor, or even not work.

Why is this? This is because the so-called semiconductor refers to the material whose conductivity is between conductor and insulator at room temperature. The change of temperature has a great impact on the conductivity, limiting voltage, limiting current and switching characteristics of the semiconductor. Now a chip often contains millions or even tens of millions of transistors and other components, and the accumulation of each small deviation may cause a huge impact on the external characteristics of semiconductors. If the temperature is too low, the chip will often be unable to open its internal semiconductor switch under the rated operating voltage, resulting in its failure to work normally.

3. Battery

At present, most mobile phones use lithium batteries, which use lithium compounds as cathode materials and graphite as anode materials. There is a non-aqueous electrolyte solution between the positive and negative electrodes. At present, the most widely used electrolyte in commercial lithium-ion batteries is to dissolve conductive lithium salt LiPF6 in binary or ternary mixed solvents based on ethylene carbonate (EC). These solvents are generally organic carbonate series, including dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), etc. Among them, the main component vinyl carbonate (molecular formula: C3H4O3, melting point: 35 ° C to 38 ° C) has poor low-temperature performance and is easy to precipitate at low temperatures, which leads to the decline of battery performance.

It can be seen that the "three major" LCD screens, chips and batteries in mobile phones will have different performance problems under low temperature conditions, which will affect the normal operation of mobile phones. In fact, it's not just the temperature. After all, mobile phones are still relatively "effeminate" electronic products. Users must be careful when using them. After all, not all mobile phones are called Nokia.

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