The Shear Stress–Strain Behaviour of Low-modulus Structural Adhesives

The shear stress–strain behaviour of two low-modulus structural adhesives has been measured using the butt-torsion test. The Nadai correction for non-linear shear behaviour is explained as it is necessary to understand how this correction can be applied to butt joints. The results for one adhesive were accurately used to predict the strength of a lap joint, and it was shown that the strength of such a joint can approach that of a conventional, modern, structural epoxy. Structural adhesives are usually reckoned to be those with a high strength (50 MPa and upwards) and (these days), a strain to failure of at least 10% in tension, and which usually have a tensile modulus of 2 GPa or so. However, adhesives which are significantly less stiff, less strong, but much more ductile are entering the ‘structural’ arena. In order to evaluate their effectiveness and use in design, it is necessary to be able to measure accurately their stress–strain behaviour. Two such materials are 3M 9245 Structural Bonding Tape (SBT) and 3M 7838 B/A.     

Evaluation of pressure-sensitive tape adhesion and backing directionality by excimer laser methods

The effects of 248 nm KrF excimer laser irradiation on a pressure-sensitive adhesive tape bonded to a glass substrate were investigated as a possible method to evaluate the quality of adhesion, as well as the directionality induced during manufacture. The model pressure-sensitive tape consisted of biaxially-oriented polypropylene (PP) tape coated with a hot-melt rubber resin. Analysis of the front-shot experiments, which were performed by irradiation through the PP backing, allowed correlation between the excimer laser irradiation-induced detachment and the peel adhesion strength. For this purpose, peel tests were performed before and after laser shots. The directionality induced during manufacture resulted in a more ablated area in the strength direction than in the transverse direction when the bonded tapes were irradiated with an elliptically-shaped laser beam above the ablation threshold. A correlation was found between the detachment bubbles created by irradiation below the ablation threshold and their respective peel adhesion values, which allows us to evaluate the quality of adhesion for pressure-sensitive tapes. Thus, a method to evaluate the quality of adhesion using an excimer laser is proposed based on the findings of this work.     

Tape casting of high dielectric ceramic substrates for microelectronics packaging

The production of ceramic green tapes is integral to the production of multilayer ceramic packages and capacitors. This article presents a batch type process for producing alumina ceramic green tape down to 150 μm thickness. The process parameters relevant to the precise control of the thickness of an aluminabased ceramic tape have been investigated using a float glass tape caster. Results indicate that the cast tape thickness was dependent on the blade gap until it reached a limiting value. This limiting thickness in turn was dependent on the casting speed, with a higher speed producing thinner tapes. Optimal casting was shown to exist when the blade gap was set at or beyond the limiting value, with the casting speed the controlling factor for the final thickness.     

Multi-pass serpentine flow-fields to enhance under-rib convection in polymer electrolyte membrane fuel cells: Design and geometrical characterization

The flow-field for reactant distribution is an important design factor that influences the performance of polymer electrolyte membrane fuel cells (PEMFCs). Under-rib convection between neighboring channels has been recognized to enhance the performance of PEMFCs with serpentine flow-fields. This study presents a simple design method to generate multi-pass serpentine flow-fields (MPSFFs) that can maximize under-rib convection in a given cell area. Geometrical characterization indicates that MPSFFs lead to significantly higher under-rib convection intensities and more uniform conditions, such as reactant concentrations, temperature, and liquid water saturation, compared with conventional serpentine flow-fields. The implications of the enhanced under-rib convection due to MPSFFs on the performance of PEMFCs are discussed.     

Estimation of the thermohydraulic efficiency of swirlers at small Reynolds numbers

To estimate the thermohydraulic efficiency of different types of swirlers of heat exchange in pipes, we have generalized the experimental data, which has made it possible to determine the optimal range of Reynolds numbers and the optimal geometric sizes of swirlers. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 82, No. 1, pp. 23–30, January–February, 2009.     

Failure analysis of leakage current in plastic encapsulated packages

Plastic encapsulated packages exhibit high leakage currents after a few hundred hours in the steam pressure pot test (SPP). The present study investigates two possible causes of leakage current. These are: (a) mold compound, (b) the polyimide tape used for co-planarity of lead frame fingers. The results of this study indicate that the leakage cur-rent is independent of the frame and is not caused by the mold compound. The data indicates that it is the ionic content and acrylic-based adhesive layer of the polyimide tape which cause the leakage current. To eliminate the leakage current, polyimide tape with low ionic content and non acrylic-based adhesive should be used. *Permanent address: School of Physics, Universiti Sains Ma-laysia, 11800 USM Penang, Malaysia.     

谈电视节目的制作方式

本文讨论了目前电视节目制作的两种方式,即电视影片和电视录像,井指出它们各自的优势及存在的问题。     

Investigations of nano- and macro-wear of magnetic tape head materials

The nano- and macro-wear characteristics of calcium titanate, single crystal ferrite and polycrystalline ferrite were investigated using nano-scratch testing and wear bar testing. Nano- and micro-indentations were made to determine nano- and micro-hardness, and nano-scratch testing was used to evaluate relative wear rates on the nano-scale. The macro-wear characteristics of the various head materials against metal particle tapes was investigated as a function of tape speed using wear bars mounted in a DLT tape drive. The micro-indentation method was used to investigate wear of the head/tape interface in a linear tape drive. The results from nano- and macro-wear tests were analysed and correlated with the microstructure of the materials.     

热熔压敏胶,用于OPP包装带优先技术

从包装带的历史，成本，生产率，性能（使用温度、对回收纸板粘合性、对非极性基材粘合、涂胶量控制），外观，环境污染问题等方面论证热熔压敏胶作为优先技术，应用于OPP包装带。     

流延工艺对BSZT-0.02MgO陶瓷微结构和性能的影响

采用溶胶凝胶法制备BSZT陶瓷粉,将Mg O粉体以2%摩尔比固相法掺入BSZT陶瓷粉中,研究不同流延工艺对Ba0.3Sr0.7Zr0.18Ti0.82O3(BSZT)-0.02Mg O陶瓷微结构和电学性能的影响。研究结果表明,适当的烧结温度和优化的流延成型工艺能有效改善陶瓷的电学性能,提高击穿强度和储能密度,本实验击穿强度达到233.33 k V/cm,储能密度达到1.539×106Jm-3。