| Fiber Bragg Grating(FBG)sensor has the advantages of small size and anti electromagnetic interference,so it is widely used in the field of structural health monitoring.However,for monitoring the working condition of high-precision electronic components,the adhesive used to fix FBG sensors is prone to produce stains on the tested components,affecting the appearance and performance of the product.In response to this problem,inspired by the self-adhesion function of the gecko toe microstructure,this paper proposes a method for fabricating PDMS microarray self-adhesive FBG temperature sensor.The fabricated FBG sensor has dual functions of self-adhesion and strain isolation,and has been successfully used to solve the problem of multi-chip junction temperature monitoring for IGBT module.The main research contents of this paper are as follows:1.Introduction to research status and principles.The current research status of IGBT module junction temperature monitoring,flexible substrate FBG sensors,and flexible substrate microarray self-adhesive structures is introduced.The principles of FBG and flexible substrate microarray self-adhesive structure are also described.2.Design and fabrication of PDMS microarray self-adhesive FBG.Based on the Van der Waals force adhesion principle,the PDMS microarray self-adhesive FBG is designed.Two types of package forms are proposed: a packaging form without PI capillary in which the FBG is solidly coupled to the packaging layer,and a packaging form with PI capillary in which the FBG and the packaging layer could be separated.At the same time,the RC thermal impedance network is used to establish a thermal simulation model to explore the thermal conductivity of the sensor,and a strain transfer finite element model is established to study the temperature and strain cross sensitivity separation technology of PDMS microarray self-adhesive FBG.A mold based on reflective diffraction gratings is designed,and a packaging process for fabricating PDMS microarray self-adhesive FBG is proposed.3.Performance test of PDMS microarray self-adhesive FBG.The adhesion performance,temperature measurement performance and strain isolation performance of PDMS microarray self-adhesive FBG were tested.The experimental result shows that the microarray self-adhesive structure fabricated by diffraction grating is able to improve the adhesion performance of the sample by about twice.The temperature measurement error of PDMS microarray self-adhesive FBG is less than 0.7℃.In addition,the PDMS microarray self-adhesive FBG has the function of strain isolation.The package without PI capillary is able to isolate 95.04% of strain,while the package with PI capillary is capable of isolating up to 99.51% of strain.Therefore,the PDMS microarray self-adhesive FBG can effectively avoid the temperature-strain cross-sensitivity.4.Research on IGBT module junction temperature monitoring based on PDMS microarray self-adhesive FBG.The embedded packaging process of PDMS microarray self-adhesive FBG placed in the IGBT module is proposed,as well as the placement of multiple FBG sensors on the surface of the IGBT chips and the extraction method of optical fiber.A single-phase inverter circuit with four IGBT chips is built,and a finite element thermal model of the IGBT module is established.At the same time,the temperature rise experiment of the IGBT module is conducted,and comparing the result with the finite element result,verifying the feasibility of using PDMS microarray self-adhesive FBG for junction temperature monitoring of IGBT module. |
