厚膜电阻的研究现状及发展趋势

首先描述了厚膜电阻的基本结构,介绍了制作厚膜电阻的各种材料,然后详细地阐述了厚膜电阻的制备工艺,探讨了厚膜电阻的导电机理和近年来的发展趋势。     

厚膜电阻材料的物化特性对钌系厚膜电阻应变系数的影响

通过对厚膜电阻导电相、玻璃相的粒径控制、粒径比搭配以及在导电相、玻璃相中掺杂,研制成一种厚膜力敏电阻浆料,其应变系数GF可达15～17、工作温度可达150℃.介绍了厚膜力敏应变系数的测量方法,研究了厚膜电阻材料的物化特性对钌系厚膜电阻应变系数的影响,探讨了提高应变系数的技术途径,同时,对其导电机理作了简要的阐述.     

纤维基ZnO/Ag/ZnO多层膜的制备、结构及性能研究

利用射频磁控溅射法,室温下通过交替溅射ZnO和Ag,在PET纤维基材上制备ZnO／Ag／ZnO纳米结构多层膜。运用扫描电镜和原子力显微镜对薄膜表面形貌进行分析,用分光光度计测试其透光性能,用四探针电阻测试仪测试其方块电阻。结果表明：纤维基Zno／Ag／ZnO多层膜致密、均匀,对紫外光表现为较强的吸收能力;Ag膜厚度的改变可以调控多层膜的光电性能;ZnO（40nm）／Ag（20nm）／ZnO（40m）多层膜呈现多晶结构,方块电阻为4．4Ω;透光率接近30％。     

汽车油位传感器厚膜电阻的力学性能

通过对汽车市场应用最广的油位传感器核心部件厚膜电阻导带进行分析和样品准备,利用纳米压痕法对常用的三种油位传感器厚膜电阻导带:C4303GCD(银/钯导体浆料)、C4303M(银/钯导体浆料)和5800B(陶瓷铂金导体浆料)及其基片进行了力学性能测试,得到了厚膜电阻导带的硬度、弹性模量等力学特性参数。结果表明:C4303GSD型导带的硬度值和弹性模量最大,而且导带中银/钯含量比越低,导带硬度值越高。该研究对于油位传感器质量提高有着十分重要的意义,不但解决了目前生产厂家无法测出厚膜电阻导带力学性能的问题,也为新型油位传感器的触头导带的合理配对选型和性能改进,厚膜电阻导带的质量和耐磨性评价提供了重要的理论和试验依据。     

纳米Al2O3掺杂对厚膜应变电阻性能的影响

采用粒子尺寸为８ｎｍ的纳米Ａｌ２Ｏ３作掺杂改性剂，通过选择合适粒径和配比的导电相、玻璃及烧结工艺，得到一种ＧＦ为１３、电阻温度系数小、稳定性良好的在厚膜应变电阻，并从厚膜电阻导电机理和纳米材料特性出发。     

基于接触电阻法测量润滑油膜厚度的方法研究

提出了一种基于接触电阻法测量润滑油膜厚度的方法，研制了一台可实时测量接触电阻以评价润滑膜厚的旋转摩擦试验机，分析了边界润滑与混合润滑区域中油膜厚度与接触电阻的相关性。该装置实现了在高精度加载与速度控制下，获得确定工况下的润滑状态，通过精密电路设计实时测量接触区内部接触电阻，并与相同工况下光干涉法测得的润滑膜厚进行对应，获得了接触电阻-润滑膜厚对应关系，拟合曲线相关系数为0.98,剩余标准差为4.56 nm。为在实际工况中表征润滑状态提供了技术支撑和数据支持。     

Pt/TiO2表面状态对气敏特性的影响

通过浸渍法用H2PtCl6溶液修饰TiO2厚膜,经过不同的处理工艺,获得表面负载Pt粒子的Pt/TiO2厚膜.采用XRD和SEM分析了Pt/TiO2的物相结构和表面形貌,并通过电阻氧分压关系计算Pt/TiO2厚膜活化能.然后分别通过静态和动态测试法,表征了Pt/TiO2厚膜在H2/O2中的稳态阻值和动态响应时间.结果表明:受"spill-over"机制影响,Pt/TiO2厚膜在H2/O2气氛下的稳态电阻与Pt的散布状态有关.而样品响应时间不仅与Pt粒子的分布有关,还受表面活化能的影响,在Pt散布基本相同情况下,活化能越低,样品响应速度越快.     

掺杂Al2O3纳米粉对ZnO厚膜气敏传感器性能的影响

以ZnO纳米粉(平均粒径30 nm)和Al2O3纳米粉(平均粒径5 nm)为原料,利用传统的厚膜气敏传感器制备工艺制备了纯ZnO厚膜气敏传感器和掺杂Al2O3(掺杂量为2wt%和5wt%)的ZnO厚膜气敏传感器.对这三种厚膜传感器的本征电阻及对乙醇蒸汽的敏感特性进行了测试.结果表明:掺杂少量Al2O3纳米粉可明显降低ZnO气敏传感器的本征电阻,改善传感器的烧结性能,同时还可降低其最佳工作温度,提高器件对乙醇的灵敏度.结合厚膜气敏传感器的显微结构分析结果,对出现上述差异的原因进行了讨论.     

用激光微细熔覆法直写电阻浆料制备厚膜电阻

介绍了一种激光微细熔覆法直写电阻浆料制备厚膜电阻的新技术,并利用该技术在陶瓷基板上制备出厚膜电阻。文章中展示了部分实验结果．并分析了其附着机理。由于激光微细熔覆直写电阻技术具有无需掩模、图形由计算机控制、分辨率高、柔性化制造程度高等优点,显示谊技术在电子工业中将具有广阔的应用前景。     

纳米TiO2膜的制备及电学性能研究

本文通过采用丝网印刷法制备了以)α－Al2O3基片为衬底的纳米和微米级TiO2厚膜，气敏性测试表明，纳米TiO2膜的电阻略高于微米TiO2膜，在实验温度范围内，电阻随氧分压的变化率明显高于微米膜，同时还以XRD，SEM对膜材料的结构和形貌进行了表征．     

A new model for electron movement in a thick film resistor and its application to analysis of the structure and conduction mechanism in these resistors

A new model has been developed to explain the strain behaviour of thick film resistors. In this model, the electron moves in a meandering way through the resistor. By measuring the strain sensitivity and applying the meander model on it, information is obtained about the structure of the thick film resistor and the strain sensitivity of the micro-electron paths in the resistor. The latter can be a useful tool in testing models that describe conduction mechanisms in thick film resistors.In this research, measurements on the strain sensitivity of thick film resistors were made using a four-point-bending bridge and the four-point-resistance measurement was made using special probes. Long, narrow enamel-coated steel substrates were used to enhance the accuracy of the measurements.     

Infrared absorption in thick film resistors

Infrared absorption in polymer and glass-based thick film resistors has been measured between 400 and 1500 cm^–1. Sample structures are discussed on the basis of X-ray, Fourier transform-infrared and resistance-temperature data. It is shown that in polymer-based thick film resistors, the particulate phase is mostly responsible for the infrared absorption between 400 and 900 cm^–1, whereas the infrared absorption at higher wave numbers is related to the continuous phase. In glass-based thick film resistors, absorption is mostly determined by the highly doped glass. The results indicate that thick film resistors can be used as an absorbent coating in the 400–1500 cm^–1 region by suitable selection of the continuous and particulate phases.     

溅射功率对TaN薄膜电阻电性能的影响

本文利用直流反应磁控溅射技术,通过调节溅射功率于200℃、3％的氮分压条件在Al2O3基片上沉积了一系列TaN薄膜,并使用光刻工艺制备出相应的TaN薄膜电阻,研究了溅射功率对TaN薄膜电阻率、电阻温度系数（TCR）和功率容量的影响。实验结果表明：当溅射功率从200W增大到1000W,TaN薄膜电阻率逐渐减小,TCR绝对值从几百ppm／℃降为几十ppm／℃,功率容量呈现逐渐增大趋势。     

Thermal impedance of thick-film resistance thermometers below 0.2 K

Contributions to the thermal impedance of thick-film resistors (TFRs) are discussed. Measurements of the heat flow along the resistance layer, through the substrate and through the glass overcoating, are presented for commercial resistors mounted on a copper plate in the 30–170 mK temperature range. Because of the relatively good thermal conductivity of the film material (three orders of magnitude higher than that of alumina), the contribution to the heat flow of the resistance layer is never negligible in spite of the thinness of the latter. Suggestions are given for the best mounting of the TFRs as low-temperature thermometers. Less conventional uses of TFRs as thermometers in bolometers are also considered.     

Generation of 1/f spectrum by relaxation process in thin film resistors

Relaxation processes with various time constants generate a 1/f spectrum when they are driven by a single random time series. Such simple processes may be the origin of the noise generated in some kinds of thin film resistors. © 1998 John Wiley & Sons, Ltd.     

Microstructure and electrical performance of eco-friendly thick film resistor compositions fired at different firing conditions

Perovskite ruthenates, viz. CaRuO₃, SrRuO₃, BaRuO₃, etc. although exhibit many interesting physical properties, have been seldom used in thick film resistors. In the preliminary attempts, we have formulated lead free thick film resistor paste compositions using CaRuO₃. Five different paste compositions by varying the ruthenate concentration were prepared. Thick film resistors were screen printed onto an alumina substrate. Different thick film firing conditions were adopted to fire the resistors. Although, for TFRs, the standard conventional firing cycle is 850 °C, our TFR compositions can be fired even at a peak temperature of 800 °C. The evolution of microstructure and electrical performance of these resistors were studied. The resistors fired in conventional thick film firing furnace (BTU make) were found to be morphologically more uniform than the resistors fired in normal tube furnace. However, the sheet resistance value ‘R_s’ is lower (54–1.36 kΩ/□) in case of resistors fired in tube furnace. On the other hand, resistors fired in thick film firing furnace exhibit higher range of sheet resistance (1.36–800 kΩ/□). The hot and cold TCR range is 180–560 ppm/°C in case of tube furnace fired resistors and 120–235 ppm/°C for BTU furnace, which is comparatively lower than those reported earlier (>600 ppm/°C) for other lead free resistors.     

Influence of the contacts and firing process on the properties of thick film resistors on alumina and dielectrics

This paper describes the behaviour of thick film ruthenium resistors when printed and fired onto standard 96% alumina substrates and onto alumina substrates covered with a dielectric film during long-term thermal ageing. It was observed that the behaviour of the resistors on alumina and dielectric depends upon the firing process of the resistors and the kind of terminations. An analysis of the effects of thermal ageing was made as well as some SEM observations of diffusion processes between the resistor and its terminations.     

A characterisation of thick film resistors for strain gauge applications

Some commercial thick film resistors with sheet resistivities from 1 kohm/sq. up to 1 Mohm/sq. were evaluated for strain gauge applications. Temperature coefficients of resistivity, noise indices and gauge factors (GFs) were measured. For the same resistor series GFs and noise indices increase with increasing sheet resistivity. However, both GFs and noise indices are different for resistors with the same nominal sheet resistivity but from different resistor series. The results indicated that the microstructure rather than the different chemical composition of the conductive phase in thick film resistors is the primary reason for the different gauge factors.     

Chemical constitution and conduction mechanisms in thick film resistors

This paper re-examines the data produced in a study of the behaviour of thick film resistors on dielectrics. It uses the published data to investigate the physicochemical nature of the conduction in six combinations of resistors on dielectrics and alumina. The results appear to confirm earlier observations that the presence of barium oxide in thick film resistor glass matrices has a major impact on the conduction mechanism. It is suggested that the cause is the totally different nature of two ions of similar size, possibly giving rise to localized regions of barium-lead compounds.     

RuO2-based thick-film resistors as high sensitivity thermometers for millikelvin temperatures

RuO₂-based thick-film resistors were designed for use as low temperature thermometers in the millikelvin temperature range. The thick films were printed in geometries providing 600 Ω and 2 kΩ units from 10 kΩ/□ and 100 kΩ/□ RuO paste, respectively. The sensitivities of these films below 1 K are comparable with germanium thermometers usually used in this temperature range and their reproducibilities are within 1% error in temperature.