Heat Flux Sensor Based On PCB Process For Heat Monitoring Of Chip On PCB

With the continuous improvement of microelectronics manufacturing technology,chips are developing towards the direction of high integration,high performance,multi-function,and the resulting chip heating problem has become a bottleneck restricting the development of chip manufacturing technology.Effective heat management is an important guarantee for chip to work with higher integration,faster frequency,more reliability and longer life.The chip heat management mainly includes the chip heat monitoring technology and chip heat dissipation technology.At present,the heat monitoring of chip mainly focuses on the temperature of the chip,while the heat flux,as a physical quantity that can characterize the speed and direction of heat transfer,is rarely monitored.However,the Heat flux sensor(HFS)which can be used for chip heat monitoring has some disadvantages,such as poor embedding and great influence on chip heat dissipation,which is not conducive to chip heat flux monitoring.To solve the above problems,a thermopile-type HFS based on printed circuit board(PCB)process is proposed and implemented for heat flux monitoring of chips.The research work and achievements of this thesis mainly include:(1)The working principle and structure design of thermopile-type HFS based on PCB process for heat monitoring of chips and other electronic devices are presented and studied.The equivalent circuit model of the thermopile with nickel-plated copper conductor is established.On this basis,a mathematical model of the static characteristics of the HFS is established,and the structure and size parameters affecting the static characteristics of HFS are extracted.A one-dimensional transient heat transfer model of HFS under two heat dissipation boundaries of constant temperature and natural convection was established,and the boundary conditions and dimensional parameters affecting the dynamic characteristics of HFS were analyzed by numerical simulation.To improve the dynamic performance of HFS,MCHS based on PCB process was introduced as the thermostatic boundary of the heat sink.(2)The effects of the thickness of FR4 thermal resistance layer,the distance of via holes and the thickness of nickel plating layer on the static characteristics of HFS under thermal-electric coupling physical field are studied by using the finite element method,and the three parameters above are analyzed by numerical simulation.The effect of inlet flow rate in MCHS on the response time of HFS based on PCB process was analyzed by finite element conjugate heat transfer simulation.The simulation results show that the introduction of MCHS reduces the response time of HFS.(3)The preparation and integration process of HFS and MCHS were studied.HFS and MCHS are prepared and integrated using standard PCB processes,including nickel plating and milling.(4)The static and dynamic characteristics of the proposed HFS based on PCB process are tested and analyzed.The principle of one-dimensional heat flux generation was analyzed and an experimental device for testing HFS was set up.Three different static characteristics of HFS were experimentally and analyzed.A small heating system was built,and the measurement of heat flux and thermal power transferred from heat source to the substrate was studied under actual HFS conditions.The experimental results show that the proposed HFS has high sensitivity and good measurement repeatability,and the response time of HFS is shortened by 30% with the introduction of MCHS.The research in this paper promotes the development of on-board chip heat flux monitoring technology and provides a new idea and reference for the realization of on-board heat management.