Analysis of causes of mobile phone screen explosion

 On October 5, 2017, a consumer opened a mobile phone purchased online and found that the screen on one side of the SIM card device was cracked, but the screen was intact. The mobile phone purchased by this consumer was the first case of such mobile phone explosion discovered in mainland my country. Not long ago, incidents of this series of mobile phone explosions occurred in Taiwan, Japan, Toronto, Canada, Greece and other places. According to incomplete statistics, from September 28 to October 5, there were at least five cases of the phone bursting around the world. And the five confirmed models of explosions were all of the same model.

The company earlier responded to the explosion incident of the mobile phone in Taiwan, saying that it was learning about the situation and more details and had replaced the user's phone. As of today, the mobile phone company has not disclosed the cause of the phone explosion. The incident is still unfolding. Once the mobile phone product is recalled, it will bring huge economic losses to the mobile phone company.

A mobile phone is powered by a lithium battery, and the heat generated by the lithium battery is affected by the surrounding environment and temperature. This is its inherent nature. The screen of a certain mobile phone is made of glass base material, and the casing is made of stainless steel base material, which are bonded together by adhesive. The thermal expansion coefficients of glass and stainless steel are different. Due to space constraints and limited thermal conductivity efficiency, the lithium battery will cause a size difference between glass and stainless steel after heating, and the difference can be up to 0.1 mm. If the flexibility of the adhesive is not enough (the ability to withstand long-term shear relaxation deformation tanγ), and the design thickness of the adhesive layer is not enough (or the gap between the adhesive layers of individual mobile phone bonding joints is too thin due to manufacturing tolerances), it will not be exposed to heat for a long time. The adhesive will crack later. It can be said that this is the inevitable result of improper adhesive selection, bonding design and process control.

Bonding is a complex interdisciplinary system engineering. If the designer of the bonding joint of this mobile phone has participated in the EAE European bonding engineer training at Shanghai Yifa Bonding Training Center, he will be familiar with the bonding layer under various working conditions. The deformation requirements have been carefully analyzed and calculated, and the deformation capacity provided by the selected adhesive under various loading and aging conditions has been tested, and the design of "the deformation capacity provided by the adhesive layer is greater than the deformation requirements of the bonded joint" With a clear concept of the guidelines, such accidents would not happen.

Note: Shanghai Yifa Bonding Training Center conducts DIN6701&DIN2304 bonding certification consultation, conducts Chinese training and Chinese examinations at three levels: EAE European Bonding Engineer, EAS European Bonding Technician and EAB European Bonding Operator, and provides professional services to enterprises We provide comprehensive bonding project support, special training, bonded joint load and deformation calculation, test verification, process evaluation and other services.

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