Effect Of Ultrasonic Bonding And Interlaminar Thermal Force On MEMS Devices

MEMS technology has a very important position in many fields and it has many advantages that traditional electromechanical technology does not possess.Silicon chip and circuits are connected by ultrasonic bonding technology in the manufacturing process.Chopper hits the chip at a certain speed and vibrates at high frequency when in the ultrasonic bonding process.When the speed is too high or the vibration frequency is close to the natural frequency of the MEMS chip,the MEMS chip may be damaged.At the same time,the MEMS sensor is often used in a high temperature environment and the materials have different thermal and mechanical properties,so it may leads thermal mismath stresses.Large thermal mismath stresses can damage MEMS devices.To explore the specific effects of ultrasonic bonding and thermal stress between layers on MEMS devices,we study various modal and response analyses of accelerometers and the damage to pad and chip caused by guillotine at different speeds.Then we study the influence of different factors on the thermal stress between layers and derive a formula for calculating peel stress.The conclusions obtained are of great significance and reference value for studying the failure of MEMS devices.The main work of the dissertation is as follows:(1)Firstly,analyzing the modal harmonic response of the cantilever in the microaccelerometer and getting the frequency range of resonance.Then analyzing the impact of the guillotine and the pad and obtain the stress and deformation of the pad and the chip at different speeds by the finite element method.(2)Firstly,analyzing the effect of chip,adhesive layer,and substrate on thermal stress between layers under different sizes.Then deriving a formula for calculating peel stress.Comparing with the finite element simulation and an existing stripping stress calculation method,the accuracy and validity of the results are verified.