Research On Packaging Technology Of Micro Electro-thermal Film Based Transient Electronic

Chip self-destruction technology means that electronic devices can achieve different degrees of self-destruction from multiple dimensions such as circuit function,device structure,and device materials under the influence of specific external signals or external environment under the condition of ensuring normal operation..Precisely because it can achieve the destruction of device functions and structures,and even the degradation of materials,chip self-destruction technology has a wide range of application prospects in the fields of information security,medical and health,and environmental protection.Taking information security as an example,the existing solutions focus on the complete destruction of circuits and structures,and a large number of highly corrosive liquids or energetic materials are used.Although these schemes are effective,they lack concealment,are not portable,and are harmful to the environment.Under the premise of ensuring the degree of device rupture,this thesis uses a safe,highly concealed,and environmentally friendly trigger to achieve chip rupture,and completes the corresponding research on key packaging technologies.Specifically,the heating of the micro-electric heating film triggers the thermal expansion of the microspheres to generate stress and realizes the selfdestruction of the chip.By optimizing the preset stress structure and the structure of the micro-electric heating film,the resistance value and the power-up method,the chip fracture efficiency is improved.First,the temperature expansion properties of thermally expandable microspheres are introduced,and the experimental route that uses microsphere expansion to apply stress to the silicon wafer to cause it to break is confirmed.Based on the principle of stress concentration,a plan for notching the back of the silicon wafer was designed.The cracking experiment was carried out by etching multiple types of patterns at the same depth on the back of the silicon wafer.It was found that the problem of poor cracking performance of the silicon wafer in the experiment.So,a limiting device was designed to compensate for the poor operation accuracy caused by the small silicon wafer in the experiment,and at the same time,more stress concentration points were introduced.In the end,a good breaking ratio and breaking time were achieved.The experimental results show that the square groove can make the thermally expandable microspheres have the best cracking effect on the silicon wafer.Then,according to the above experimental conclusions,experiments were carried out by etching a square groove on the back of the actual chip.Through experiments with different restriction devices,it was found that because the tensile strength of the actual chip is higher than that of the silicon wafer,the failure rate of rupture when a restriction device of a specific shape is used with insufficient precision of the restriction device.The experimental results show that the actual chip's anti-cracking ability is stronger than that of silicon wafers.Although the actual chip has a relatively high cracking rate above 5,the cracking time is longer,and the typical cracking time is more than 20 s.Finally,the micro-electric heating film is introduced as the heat source of the expansion agent,and the thermal uniformity and heating capacity of the micro-electric heating film are analyzed through COMSOL,and then the micro-electric heating film is made by magnetron sputtering and stamping processes respectively.Because of the defects of process stability,the uniformity and resistance of the manufactured electric heating film are quite different from expected.Through the adjustment of the capacitance value and the rated voltage,although the experiment has successfully achieved the destruction of the chip,the success rate is low,and the cracking effect still needs to be improved.