Research On Non-Destructive Testing Method For Electrical Interconnection Structure Quality Of Power Package

With the continuous development of power semiconductor devices,the forms of power packaging are becoming more and more diverse.In the electrical interconnect structure of power packages devices,failure caused by the damage of solder layer and bonding wires is an important cause of device failure.Therefore,damage detection of electrical interconnect structure of power packages,which is particularly important.Traditional mechanical inspection will inevitably introduce micro-damage,the equipment cost of topography detection is too high and the detection process is complicated and cumbersome;Electrical detection is a low-cost and effective detection method to realize the structure without introducing damage,and has gradually become an effective means of damage detection of packages interconnection structures.This paper takes the package of IGBT device as the research object,and carries out the research on non-destructive testing methods for the quality of the electrical interconnection structure of power packages and the implementation of testing hardware.The specific research content and conclusions are as follows:（1）Based on the theory of small signal equivalent circuit of power devices,the electrical performance analysis of IGBT power packages is carried out as the basis for simulation analysis and experimental verification.In the electrical parameter extraction experiment,the parameters such as reflection S₁₁and impedance Z₁₁under different bonding wires damage conditions are obtained by the detection equipment,and the parasitic parameters of each part of the equivalent circuit of the IGBT power chip are obtained through the calculation and experimental data of the equivalent circuit,so as to realize the extraction of electrical parameters of the chip and parallel bonding wires.（2）Taking the damage detection of the bonding wires of the power packages as a typical example,the electrothermal performance of the IGBT power packages was modeled and analyzed.The influence of key damage characteristics such as shunt bonding wires mutual inductance and number of breaking lines on the parasitic parameters of the package was analyzed,and the relationship between the corresponding impedance value and the reflection coefficient was obtained.The electrothermal simulation results show that when the power device is working in the switching state,the temperature difference between the parallel bonding wires is within 0.4°C,and the mutual inductance change caused by the different fracture positions of the bonding wires is within 0.7%.The minimum change caused by the number of bonding wires breaks is greater than 5%.The experimental results show that as the four parallel bonding wires break one by one,the increase in impedance increases from 0.64Ωto 2.51Ω.The number of break lines in the bonding wires of the packages increases,and in a 50Ωhigh-speed system,the reflectance coefficient decreases as the impedance of the device increases.（3）Research on non-destructive detection method for bonding wires damage of power packages and implementation of software and hardware of testing device.Combined with the signal analysis results of the electrical parameter model and the relationship between the impedance value of the test at different frequencies and its corresponding reflection coefficient,the specific requirements of the test frequency,sampling rate,number of sampling points and other specific requirements of the detection device were analyzed and explored,and the circuit module of the detection device was developed.Carry out detection tests such as lines length and bonding wires damage,and study and analyze performance such as detection error and accuracy.The results show that 200MHz is the most effective test frequency for this detection device.In this paper,the base-2FFT is selected as the core algorithm of the programming software,and the development of nondestructive testing device for the electrical interconnection structure of power packages is finally realized through code debugging and hardware circuit optimization.The results show that the length detection error of the microstrip line of the detection device is less than 0.9mm,and the terminal impedance detection accuracy is 0.1Ω,which can effectively detect the damage degree of the bonding wires of IGBT device and complete the precise positioning of the damaged device.In this paper,the non-destructive testing method for the electrical interconnection structure quality of power packaging is studied in depth,and the development of testing hardware modules is realized.The research results show that the electrical non-destructive testing and quality characterization of power packaging have certain application value.