Study Of Patterning Transfer And Sensors On Curved Substrates Based On MEMS Technology

With the successful fabrication of the domestic commercial large aircraft-C919,we have to promote the technology of the aero-engine.Under the work of the aero-engine,the real-time monitoring and acquiring the surface of the blade is vital for engine safety and performance.Therefore,the thin-film thermocouple sensors should be fabricated on the curve substrate.The novel thermocouple sensors,which are based on the curve patterning technology,have been investigated to form the low cost and high precision microstructure on the curve substrate.The acquiring the surface of the curve aero-blades is very significant to increase the performance of the aero-engine.With the purpose of fabricating the temperature sensor on the surface of the blades,the thin-film patterns are deposited on the curve substrate.It is not easy to overcome the challenge that patterns transfer on the curve surface of the blades.The main challenge is that high-precision and large-area pattern may be difficult to transferred on the arbitrary surface.The high-precision curve patterning technology,which is other than the mature microelectronic transfer technology on the planar substrate,has several urgent problems: fabrication of the flexible mask;optical failure of the shadow mask lithography;lift-off process of the metal pattern.The attention of the material properties and fabrication process of the flexible mask should be focused.The flexible masks are investigated to optimize the parameter of the properties.The patterning technology,which is applied in the three-dimension structure,can be used to make the static nickel mask consistent to the curvature of the curve substrate.The pattern transfer technology plays the key role to fabricate the sensor on the non-planar surface.The key work of the article is monitoring the real-time temperature on the curve surface of the aircraft blades.Based on the MEMS technology,two kinds of the fabrication processes,which are the dry film photoresist(DFR)technology and nickel shadow mask technology,are proposed by optimizing key individual aspects including the process sequence and the technology parameters.They lead to fabricate the high reliability and performance thin-film thermocouple on the curve substrate.The distortion of the exposure on the curve surface is investigated to analyze the parameter of the exposure and development from the UV light with the dry film photoresist by MATLAB simulation.The optical model is built to research the distortion of the pattern.What's more,the thick of the photoresist,the distance between the mask and the photoresist and the different incident angles are optimized in the relative intensity diffusion.To research the non-planar patterning transfer with the dry film photoresist,the parameters of the exposure and development are optimized and the micro metal structures are deposited by sputtering with the lift-off technology.The 27?m and 75?m thickness dry film are used as negative photoresist to analyze the technology of the curve photolithography.In addition,the nickel shadow mask lithography,which is fabricated by the FPC UV laser cutting machine,is optimized to transfer the desired micrometer-feature pattern on the non-planar substrate.The flexible nickel mask is meshed with the nonplanar blade in favor of making the micro pattern high fidelity on the curve surface.With this novel nickel-DFR-substrate tri-layer technology,micro-structures with high aspect ratios and high spatial resolution can be fabricated on a wide range of non-planar surface.It is worth mentioning that nickel shadow mask can be reused to decrease the cost and simplify the process.Finally,based on the above-mentioned curve patterning technology,the Pt-Pt/Rh R-type thin film thermocouple is fabricated on the non-planar surface of the aeroengine blades.The test system is built to acquire the curve of the thermal electromotive force-temperature.The experimental results show that the thin film thermocouple can be work at the 20?-850? in the high temperature drying oven repetitively.With the failure test and the recycle test,the reliability and the performance of the thin film thermocouple,are demonstrated to be fabricated on the non-planar surface successfully.