Research On The Delamination Detection Technology And Failure Mechanism For Power MOSFET

In recent years,with the rapid development of China's economy,the requirements of energy conservation and environmental protection and low-carbon life have become increasingly important,and people's demand for energy conversion and application management is increasing.In terms of power conversion,the demand for power MOSFET is also increasing.In the application of power MOSFET,the device reliability becomes more and more important,which determines the stability of the whole application system.At present,the delamination failure in power MOSFET packaging has attracted much attention and become a research issue.In this paper,the delamination failure and detection of power MOSFET will be studied.Firstly,the development of power devices is briefly analyzed.The classification and performance characteristics of power devices are introduced,and the development of the third generation wide bandgap semiconductors is briefly analyzed.The package of power MOSFET is introduced briefly.Then the delamination failure of power MOSFET is introduced,and the developments of power MOSFET delamination issues at home and abroad are analyzed.Secondly,the delamination of the device is analyzed,including the definition,causes and hazards of delamination.The importance of delamination detection is analyzed through the delamination criteria at home and abroad.In order to analyze and study the follow-up results,the ultrasonic scanning microscopy technology,which is commonly used in the delamination detection,is introduced.Thirdly,the delamination failure is studied.The delamination failure of plastic sealing material and lead frame is analyzed,and the influence factors of delamination area on the electrical and thermal properties of power MOSFET are studied.The results show that the larger the delamination area,the higher the junction temperature and the larger the thermal resistance in the device.The delamination failure of the bonding layer between the chip and the lead wire is analyzed.The increase of the thermal resistance causes the increase of the internal temperature,and leading to the decrease of the carrier mobility.This results in the increase on resistance R_dson by 111.5%,while for the normal chip only by the increase of 66.7%.In addition,the overheating effect may even provoke the chip EOS failure.Finally,the influence factors of the sample detection in delamination detection are analyzed.The influences of the probe frequency,the sample thickness,the scanning gain,the surface energy compensation and the sample immersion time on the detection results are studied.The results show that,for thicker sample,the probe with lower frequency is used.But for thinner sample,the probe with higher frequency is used.The scanning gain makes the echo energy between 60%and 80%,leading to higher resolution of scanned images.For the sample with the rough surface,the scanning mode of surface energy compensation should be used.The delamination crack will cause water immersion into the package.So it is necessary to control the immersion time of the water for SOP8 package devices within one hour for preventing the erroneous judgement of the delamination detection results.The research results of this paper have certain guiding significance for delamination failure analysis and detection in power devices.