【作者】 刘亮；

【导师】 胡泓；

【作者基本信息】 哈尔滨工业大学 ， 机械电子工程， 2013， 硕士

【摘要】 气体测量在航天、能源、医学、食品、汽车工业以及能源等领域中都至关重要。热式气体质量流量计，由于其原理简单，可测量的流量范围很广，对气体的干扰极小，而得到广泛的应用。但是，随着人们对气体测量的精度要求越来越高以及微电子技术的发展，采用MEMS工艺制造的热式流量传感器已经开始取代传统的金属外壳流量传感器，因其与后者相比在测量精度和功耗方面都有绝对的优势，同时采用成熟微电子制造技术，可以降低制造成本。本文设计了一种柔性MEMS流量传感器，采用PI材料做为基底，避免采用硅基材料需要刻蚀空腔的复杂工艺，同时结合FPC工艺，简化制作工艺的同时，增加传感器的可靠性。本文采用镍作为热敏材料，PI材料作为基底。通过工艺可靠性、数学模型和流体仿真软件进行模拟确定关键设计参数：溅射线宽、基底厚度以及不同的敏单元到热源的距离。采用FPC工艺制造PI基底和外围电路，将热敏金属直接溅射在上面，工艺简单，可靠性高。然后进过热处理和电流老化，使热敏金属具有良好的温度电阻特性，温度电阻系数达到2450ppm/℃。本文也设计了传感器的测试电路和程序，采用PID算法控制热源的温度，实现超调小，调节时间短。最后在管道中对传感器进行测试，测试结果显示，传感器的测量精度为±0.1m/s，在更低流速时测量精度可以达到±0.05m/s。充分体现了MEMS流量传感器在测量微小流量的优势。功耗测试显示，在零流速时，要维持热源比环境温度高60℃，需要在热源上加载24mW的功率；在流速为10m/s的时候，在热源上加载的功率为45.7mW。这一功耗值低于传统金属外壳流量传感器一个数量级以上。更多还原

【Abstract】 Gas measuring is of great important in the fields of aerospace, energy,medical, food and automobile. Thermal mass flow meter has been widely usedbecause of its simple principle and wide measuring range. And also because itcause little disturbance of the gas. However, as the requirements of gas measuringbecome higher and the great development of semiconductor technology, flowsensors fabricated by MEMS technology begin to replace traditional metal-shellthermal flow sensor. Because MEMS flow senor has great advantages than thelatter in accuracy and power consumption. Also, the cost of fabrication is lowerby using MEMS technology. This paper designed a new type of flexible MEMSflow sensor. The material of the substrate is PI rather than bulk silicon in order toavoid etching cavity which is a complicate fabrication process. The PI substate ismade by FPC which is simple and highly reliable. And nickle is used as thermalmetal because of its high TCR.The vital parameters such as the wideness of the Ni film, the thickness of thePI substrate and the distance between heater and thermal metal unit are designedby mathematical model and simulation. The nickel is directly spur on the substateon which there is signal circuit. And the TCR of nickle film reach2450ppm/℃with heat treatment. This paper also gives the principle of test including testcircuit and program. We use PID algorithm to control the temperature of heater toget higher accuracy and less response time. The test shows that the sensor canreach the accuracy as±0.1m/s and even higher as±0.05m/s at the situationlow air speed which is a great advantage of MEMS flow sensor in measuringmicro-flow. The power consumption is also much lower than metal-shell ones asit is only24mW at zero point and45.7mW at10m/s flow speed.更多还原