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。     

Preparation and characterization of Cu and Zn modified nickel manganite NTC powders and thick film thermistors

A simple ball milling/thermal treatment procedure was applied to obtain fine thermistor powders. Three different powder compositions were analyzed–Cu_0.2Ni_0.5Zn_1.0Mn_1.3O₄, Cu_0.25Ni_0.5Zn_1.0Mn_1.25O₄ and Cu_0.4Ni_0.5Mn_2.1O₄. XRD analysis showed that all three powder compositions had a cubic spinel structure. Correlation between the sintering temperature, structure and resulting electrical properties was analyzed on bulk samples. Thick film pastes were composed and segmented thick film thermistors were screen printed on alumina, dried and fired. SEM analysis revealed a typical dendrite structure with small grains and a developed surface area. Thick film sheet resistance was measured on a test matrix and the resistance decreased with increasing Cu content. The temperature dependence of sample resistance was measured in a climatic chamber enabling calculation of the material constant and activation energy. Aging of the obtained segmented thermistors was analyzed and the resistivity drift was 0.23% for the Cu_0.2Ni_0.5Zn_1.0Mn_1.3O₄ NTC thick film thermistor confirming greater stability of thermistors containing Zn and Cu that in combination with the determined good thermistor characteristics make them good candidates for temperature and heat loss sensor applications.     

Preparation of polycrystalline CdZnTe thick film Schottky diode for ultraviolet detectors

High resistivity (3 × 10⁹ Ω cm) polycrystalline CdZnTe thick films with thickness of 25 μm–150 μm were grown on SnO₂: F-coated glass substrates by close-spaced sublimation method. The properties of polycrystalline CdZnTe films were studied by XRD, SEM and EDS, respectively. A CdZnTe film Schottky diode detector was also fabricated and investigated using current–voltage and capacitance–voltage methods. The photo-current density of the device was about 1508.69 nA/mm² under light illumination (λ = 260 nm), at an applied negative voltage of 15 V. The results showed that polycrystalline CdZnTe thick film was suitable for application in ultraviolet detectors.     

Preliminary data on compatibility between thick film perovskite electrodes and PLZT films

The possible use of electrically conductive perovskites SrRuO₃, La(Ni_0.6Co_0.4)O₃ and (La_0.5Ca_0.5)FeO₃ as electrodes for PLZT ((Pb,La)(Ti,Zr)O₃ solid solutions) thick films was evaluated. As the ceramic electrode is placed between an alumina substrate and a PLZT thick film layer possible interactions between Al₂O₃ on one side and PLZT on the other and the chosen perovkites were studied. Both SrRuO₃ and LaNi_0.6Co_0.4O₃ reacted at 1000°C with Al₂O₃ forming SrAl₂O₄ and RuO₂ in the first case and LaAlO₃ and La₂NiO₄ in the second case. At higher firing temperatures reactions between La_0.5Ca_0.5FeO₃ and Al₂O₃ resulted in small quantities of an unknown phase or phases. The results of reactions of all three perovskites with PLZT were perovskite solid solutions incorporating ions from the conducting perovskites into the PLZT structure.     

Preparation by sputtering of thick sendust film suited for recording head core

A 12 μm thick film with large saturation flux density, 11 000 G, and high effective permeability, such as 240 at 20 MHz, was prepared by using tetrode sputtering equipment from a ternary alloy that consisted of Si:10.5 wt.%, Al:5.6 wt.%, and Fe:bal. (Si rich Sendust alloy) at a target voltage of 1000 VDC. These were the best conditions for obtaining the minimum value of coercivity with the glass substrate in our experiments. The electric resistivity and Vickers hardness of the film became greater than the same qualities in bulk alloys. The increase in effective permeability at high frequencies, and the higher resistivity and hardness are believed to originate from the granular structure of the film. In this study, it was proved that the magnetic properties, especially the coercivity and the initial permeability of the film were due, not only to the effect of magnetostriction and crystalline anisotropy, but also to the effect of film structure.     

Preparation of ultra-fine copper powder and its lead-free conductive thick film

In this paper, non-agglomerated monodispersed ultra-fine copper metallic powders have been synthesized with chemical reduction method. Fine lead-free glass powders were also prepared by solid synthesis process. Thick film paste prepared by above-mentioned copper metallic powders and lead-free glass powders was applied as conductive paste of MLCC. Mixture of glass and zinc oxide give the thick film a high adhesion strength which is attributed to the rough interface from interfacial reaction between glass and chip, and a good densification. Diffusion of metal between copper thick film and nickel thick film is clear. Ni-Cu solid solution appears under high temperature firing.     

Preparation of porous nickel electrodes for molten carbonate fuel cells by non-aqueous tape casting

The casting behaviour, ultimate tensile strength and the sintering process of tapes consisting of nickel powder, ethanol, po!yvinylbutyral as the binder, polyethylene glycol (molecular weight 200, PEG2) or dibutyl phthalate (DBP) as the plasticizer, and glycerol trioleate as the dispersant agent, were studied. On increasing powder content in the slurry the packing factor of nickel in the green increased, but the ultimate tensile stress and strain to failure decreased. Increasing binder to total binder ratio caused the green density and strain to failure to decrease, but the ultimate tensile stress increased for both PEG2 and DBP. The maximum strain to failure (about 35% for both PEG2 and DBP) in the case of DBP was obtained with an amount of plasticizer lower than that of PEG2. When tapes having different composition were sintered at various temperatures, a linear relation was found between packing factor and fired density, independently of the kind of binder and plasticizer used.     

BaTiO3填充PEO基复合聚合物电解质厚膜的制备与性能研究

采用溶液铸膜法制备PEO基复合聚合物电解质(CPE)厚膜,利用XRD、SEM、DSC、FTIR分析等多种结构测量技术对CPE的性能进行了表征和分析.本文研究的是在(PEO)6:NaPO3基导电聚合物电解质中加入质量分数为3～10 wt％ BaTiO3填料,从而分析性能的变化.(PEO)6:NaPO3在加入填料后玻璃化转...     

石墨衬底上多晶硅厚膜的生长及性质分析

以石墨片为衬底,利用磁控溅射技术生长多晶硅籽晶层,退火处理后用CVD制备多晶硅厚膜。XRD测试结果表明,在籽晶层上外延多晶硅厚膜具有高度的(220)取向,这说明外延层的择优取向延续了籽晶层的取向。SEM测试结果表明,石墨片上多晶硅外延层生长良好,说明石墨片作为廉价衬底之一,有望投入工业化生产,以降低太阳能电池的制作成本。     

Preparation of silver nanoparticles dispersed in polyacrylonitrile nanofiber film spun by electrospinning

Ag nanoparticles dispersed in polyacrylonitrile (PAN) nanofiber film spun by electrospinning were in situ prepared by reduction of silver ions in N₂H₅OH aqueous solution. The Ag/PAN nanocomposite film was characterized by UV absorption spectroscopy, transmission electron microscopy (TEM) and surface-enhanced Raman scattering (SERS) spectroscopy. UV spectrum and TEM image show that silver nanoparticles with average diameter of 10 nm were obtained and dispersed homogeneously in PAN nanofibers. SERS spectrum indicates that the structure of PAN has been changed after Ag nanoparticles are dispersed in PAN.     

Design and development of high voltage high power operational amplifier using thick film technology

Applications of power operational amplifiers (opamps) are increasing day by day in the industry as they are used in audio amplifiers, Piezo transducer systems and the electron deflection systems. Power operational amplifiers have all the features of a general purpose opamp except the additional power handling capability. The power handling feature can be achieved using an external circuitry around a regular opamp. Normally power opamps can deliver current more than 50 mA and can operate on the supply voltage more than ±25 V. This paper gives the details of one of the power opamps developed to drive the Piezo Actuators for Active Vibration Control (AVC) of aircraft/aerospace structures. The designed power opamp will work on ±200 V supply voltage and can deliver 200 mA current.     

Preparation of TiO2 thick film by laser chemical vapor deposition method

A TiO₂ film was prepared on Pt/Ti/SiO₂/Si substrate by a laser chemical vapor deposition method. The rutile TiO₂ film with pyramidal grains and columnar cross-section was obtained at a high deposition rate (R _dep = 11.4 μm h^?1). At 300 K and 1 MHz, the dielectric constant (ε _r) and loss (tanδ) of the TiO₂ film were about 73.0 and 0.0069, respectively. The electrical properties of TiO₂ film were investigated by ac impedance spectroscopy over ranges of temperature (300–873 K) and frequency (10²–10⁷ Hz). The Cole–Cole plots between real and imaginary parts of the impedance (Z′ and Z′′) in the above frequency and temperature range suggested the presence of two relaxation regimes that were attributed to grain and grain boundary responses. The ionic conduction in the rutile TiO₂ film was dominated by the oxygen vacancies.     

Polymer dispersed liquid crystal film for variable-transparency glazing

The transmission of visible light and thermal energy through variable-transparency switchable glazing can be varied. Polymer-dispersed liquid crystal (PDLC) has been the most widely used variable-transparency glazing technology in the architectural and automotive industries due to its excellent optical performance, durability, and ease of processing into large-area products. Here we describe the electro-optical performance, temperature stability, and electrical and environmental durability of commercial PDLC products.     

MEMS集成应用的纳米结构PZT厚膜形成工艺研究

提出了制备PZT厚膜的一种新的旋转涂覆方法.采用0-3复合法将PZT溶胶与PZT纳米粉混合形成浆料,并与PZT溶胶交替涂覆在Pt/Ti/SiO2/Si衬底上,使PZT厚度达2μm,并且使PZT表面质量得到了改善.利用XRD和SEM对PZT厚膜的组织和结构进行了表征.得到的薄膜无裂纹,结晶和表面平整度良好,可用于MEMS中微型传感器和微型驱动器的制作.     

高黏度聚乙烯醇缩丁醛树脂及薄膜的制备

通过添加适量的扩链剂制备了高黏度的聚乙烯醇缩丁醛(PVB)树脂及薄膜.讨论了扩链剂的加入对PVB树脂及薄膜性能的影响.实验证明,合成树脂时加入相对于正丁醛体积3%左右的扩链剂;加工成膜时,加入相对于PVB树脂质量3%以下的扩链剂,可明显提高PVB的分子量,降低PVB薄膜与玻璃的粘结性能,所得薄膜的拉伸强度可由2～3MPa提高到20MPa左右,而且制得的夹层安全玻璃的耐冲击性能没有受到影响.     

Preparation of hexa-aluminate catalyst thick films on α-SiC substrate for high temperature application

The coating of Mn-substituted hexa-aluminate catalysts (BaMnAl₁₁O_19-α and Sr_0.8La_0.2MnAl₁₁O_19-α) on α-SiC substrates was investigated for high temperature application above 1000 °C. The thermal stability of the hexa-aluminate catalyst films on the α-SiC substrates was significantly affected by reactivity between the oxidized layer (SiO₂) of the surfaces of the substrates and the coated layers. The Mn-substituted hexa-aluminate films were thermally less stable due to their high reactivity than unsubstituted hexa-aluminates. The Sr_0.8La_0.2MnAl₁₁O_19-α film directly coated on the substrate exfoliated from the substrate even after heating at 1200 °C due to its high reactivity to the SiO₂ layer, whereas the BaMnAl₁₁O_19-α film was stable after the same treatment. The thermal stability of the Mn-substituted hexa-aluminate film could be improved by insertion of an Al₆Si₂O₁₃ intermediate layer between the film and the SiC substrate. Additional coating of a highly crystallized Ba_0.75Al_11.0O_17.25 intermediate layer underneath the BaMnAl₁₁O_19-α catalyst layer was also effective. The Al₆Si₂O₁₃ and Ba_0.75Al_11.0O_17.25 intermediate layers suppressed the diffusion of SiO₂ from the substrate and subsequent reaction between SiO₂ and the hexa-aluminate film. This revised version was published online in November 2006 with corrections to the Cover Date.     

Electrical properties of nickel electrodes for high-k MOS structures

Together with high-κ dielectric films, metal gate electrodes have to be employed in advanced CMOS technologies. The metal gate material should be carefully selected with respect to work function, stability of metal-dielectric stack and compatibility with the CMOS process. In our investigation Ni gate electrodes grown on thermal SiO₂, atomic-layer deposition HfO₂ and Al₂O₃ dielectric films have been analyzed by means of high-frequency capacitance-voltage measurement on MOS capacitors. Ni gate materials were prepared by RF diode sputter deposition. Work function of the investigated gate material and density of effective defect charge of the gate oxide film were extracted from the measurements. These properties are discussed with regard to application of Ni metal gates in CMOS technology.     

V2O5－x薄膜电极材料的氟化及性能研究

用脉冲激光沉积法制备了V2O5-x氧化物薄膜电极材料，用XeF2对其进行了氟化改性，并对比了电极材料氟化前后的充放电性能的变化。实验结果表明：氟化后的V2O5-x薄膜氟化后循环性能明显得到改善，经过200次循环充放电依然保持较高的充放电容量。     

Method for specific heat measurement of thick film layers

A method of simple implementation is presented for the measurement of the specific heat of thick film layers. It has to do with a system, operating at room temperature in accordance with a dynamic non-adiabatic technique, whose function regards the transient phase of a heating process between two steady states. It consists of a compact ensemble of three elements: a small plate thermistor serving as a heater, an alumina disk as a sample support and a tiny calibrated thermistor as a temperature sensor. The voltage across the heater and temperature from the sensor are monitored. An accurate evaluation of the dissipated energy allows the absorbed energy, responsible for the temperature variation, to be brought out. That makes possible the determination of thermal capacity of a small mass material deposited on a substrate. The achievement of the result simply involves the recording of a voltage and temperature during the transient phase, a fitting procedure with given analytical functions and a mathematical elaboration. The measuring system, its calibration procedure together with the transient operation are described. An application concerning screenprinted ferroelectric thick films on alumina substrate is presented and the results discussed.