Research On Heat Dissipation And Packaging Technology Of Pre-stressed Chip

Chip self-destruct technology refers to the ability of electronic devices to selfdestruct circuit function,device structure and device material in different degrees under specific signals,so it can be widely used in information security,biomedical and environmental protection.There is an effective and safe method to realize chip selfdestruct by presetting stress.At present,it is urgent to solve the packaging problem of pre-stressed chip.The thesis designed the chip heat dissipation performance test scheme,tested the chip heat dissipation performance of different samples and the thermal parameters of microcolloid,established and verified the chip heat dissipation model,studied the various factors affecting the chip heat dissipation;The packaging structure of pre-stressed chip was designed.Firstly,the chip temperature and the thermal parameters of microcolloid of four samples were tested.Then,the chip heat dissipation model was established in accordance with the experiment,and the effects of the groove filling,the contact between different parts and the convective heat transfer coefficient on the chip heat dissipation performance were studied.The results show that compared with the sample without filler,the fluted microcolloids reduce the thermal conductivity between the chip and the probe by 8 times,thus greatly reducing the heat dissipation performance of the chip.Then,based on the above research results,a package structure which can simultaneously satisfy the two working states of the pre-stressed chip was designed based on the package thermal resistance theory,and the structure was compared with the traditional package structure by numerical method.Results show that compared with the traditional encapsulation structure,the pre-stressed encapsulation structure improves the chip before not yet received the self-destruct signals the working hours of cooling performance and the same electrothermal film heat transfer to the proportion of the micro colloid,puff micro colloid reached the minimum threshold required the electrothermal power reduced 1/2,shorten time of 35 s,And with the increase of chip power,its advantages become more obvious.Finally,the thermal properties of different packaging materials and sizes based on the package structure were studied.The results show that the chip temperature does not decrease unrestricted with the increase of substrate thermal conductivity and bond thermal conductivity.When the substrate thermal conductivity exceeds 148 W/（m·K）and the bond thermal conductivity exceeds 41 W/（m·K）,increasing the chip temperature has little effect on improving the heat dissipation capacity of the package.The temperature of the chip decreases first and then increases with the increase of the thickness of the bonding layer,and the temperature is the lowest when the thickness is 0.01 mm.The smaller the electrothermal film thickness is,the faster the microcolloid temperature rises to 120 ℃.The electrothermal film thickness of 0.005 mm is 2 times faster than that of 0.01 mm,which accelerates the self-destruction of the pre-stressed chip correspondingly and ensures the information security on the chip to a greater extent.