图形电镀夹膜修理方法

图形电镀已经是PCB制造加厚铜的主要方式,夹膜问题是此工艺流程的一大顽疾,本文为各位同仁介绍一种有效、简便、实用的修理夹膜的方法.     

Electron microscopic visualization of collagen aggregates without chemical staining.

Lateral, uni-directional aggregates of collagen, segment-long-spacing crystallites (SLS), were made by dialyzing collagen solutions against acetic acid containing ATP, and were examined by transmission electron microscopes without electron staining. There detected were at least 20 dark (electron dense) cross-striations within SLS. The banding pattern was compared with the biochemical and biophysical properties of the amino acid side chains along the collagen molecule. The banding pattern of unstained SLS was mostly correlated with the intramolecular distribution of basic amino acid residues. Since basic amino acids have relatively large side chains, the distribution of mass (molecular weight of amino acids) along the molecule (local density profile) partially explained the cross-striation. Addition of fractions of molecular weight of ATP to basic residues made the local density profile much better correlate to the banding pattern. We conclude that the electron microscopic banding pattern of unstained SLS was generated by the local amount of material or local density profile along the collagen aggregates, which was enhanced by ATP bound to positively charged basic residues. The concept that the electron density correlates with the amount of material is fundamental in electron microscopy, and it has been proven with biological materials in this paper.     

Zerotree pattern coding of motion picture residues forerror-resilient transmission of video sequences

This paper describes a compression scheme for difference-image residues in video coding. Structured spatial patterns are used to map residue pixel values into a quadtree structure, which is then coded in significance order with the SPIHT algorithm. Thus the wavelet coefficient values of standard zerotree coding are replaced by untransformed (but carefully positioned) residue pixel values. The new zerotree pattern coding method compresses as well as zerotree wavelet coding and much better than DCT coding (as in MPEG) over error-free channels. Over noisy channels, zerotree pattern coding provides built-in error resilience, allowing transmission of residue data without error control overhead. A simple postprocessing technique provides additional error concealment     

Structure and formation of the twisted plywood pattern of collagen fibrils in rat lamellar bone

This study was designed to elucidate details of the structure and formation process of the alternate lamellar pattern known to exist in lamellar bone. For this purpose, we examined basic internal lamellae in femurs of young rats by transmission and scanning electron microscopy, the latter employing two different macerations with NaOH at concentrations of 10 and 24%. Observations after the maceration with 10% NaOH showed that the regular and periodic rotation of collagen fibrils caused an alternation between two types of lamellae: one consisting of transversely and nearly transversely cut fibrils, and the other consisting of longitudinally and nearly longitudinally cut fibrils. This finding confirms the consistency of the twisted plywood model. The maceration method with 24% NaOH removed bone components other than cells, thus allowing for three-dimensional observations of osteoblast morphology. Osteoblasts extended finger-like processes paralleling the inner bone surface, and grouped in such a way that, within a group, the processes arranged in a similar direction. Transmission electron microscopy showed that newly deposited fibrils were arranged alongside these processes. For the formation of the alternating pattern, our findings suggest that: (1) osteoblasts control the collagen fibril arrangement through their finger-like process position; (2) osteoblasts behave similarly within a group; (3) osteoblasts move their processes synchronously and periodically to promote alternating different fibril orientation; and (4) this dynamic sequential deposition of fibrils results in the alternate lamellar (or twisted plywood) pattern.     

从初论来看数学和实践之间的相互关系

数学和实践的关系是唯物辩证法一直研究和关注的一个问题.更加一般地,它涉及科学和实践的相互关系.本文仅从"矢量场论"课程中旋度(△)×(A→)着手初步认识:数学源于实践,而数学又有自身运动,它必然会反过来影响实践.因此,关于数学的自身运动及发展很值得我们在科研和教学中进一步探讨.     

Correlation between highly and moderately acceleratedelectromigration tests

Electromigration testing at the wafer level under very highly accelerated stress conditions offers the potential for significant savings in cost and test time over less accelerated package-level tests. However, the extremely large current densities and high temperatures used to achieve that acceleration add uncertainties in extrapolating test results to operating conditions. Also, the possibility exists that failure mechanisms other than those of interest may be excited. Data are presented showing good correlation between wafer- and package-level electromigration test results for a particular metal system, namely, Al-Cu(2 wt.%) with a TiW top and bottom layer     

双量子阱OLED正负磁电阻的调控

通过改变发光层的厚度,制备了一种双量子阱结构的有机电致发光器件(OLEDs),其结构为ITO/2T-NATA(20nm)/NPBX(50nm)/[Alq3:2%C545(dnm)/Alq3(3nm)]2/Alq3(17nm)/LiF(0.9nm)/Al。在常温下研究了器件的发光层在不同厚度(d=10,15,20和25nm)时的磁电阻(MR,magnetoresistance)特性。实验结果表明,在10V驱动电压的作用下,在相同磁场强度下,器件的厚度越大,电阻率也越大;在驱动电压为10V时,随着磁场强度的增加,10nm厚器件的MR随着磁场的增加而增大,表现正MR特性;而15、20和25nm厚3种器件的MR随着磁场强度的增强先减小后增加并趋于饱和状态,发光层越厚,MR减小的幅度越大,且都表现出负MR特性;获得最大的MR为-10.32%。     

Correlation between induced grid noise and tube noise

The correlated and uncorrelated parts of the induced grid noise of a triode can be measured by plotting the equivalent saturated diode current of a tuned stage as a function of its input capacity after neutralizing the anode-grid capacitance. Measurement results on 6AC7, 7AF7, and 6V6 tubes are presented. The large uncorrelated part found with the 6V6, which has a relatively large grid-cathode distance, indicates that the uncorrelated part cannot be explained by a breakdown of the Llewellyn-Peterson theory at close grid-cathode spacings. The large uncorrelated part may be explained by considering the tube as made up of a large number of small independent diodes in parallel. The percent of correlation increases when the grid is made more negative since the spread in electron paths is reduced. The noise figure of a stage cannot be improved by detuning if the correlated part is small.     

蓄电池容量与电导相关性的研究

通信电源系统中,蓄电池是直流供电系统的重要组成部分,是保证通信直流供电系统正常的最后一道防线,能否准确把握蓄电池容量现状,对保障通信具有重要指导意义。文中简要介绍蓄电池结构、模型及工作原理,阐述了蓄电池充放电机理,并通过对一组蓄电池电导、内阻进行长期跟踪测试,从大量实测数据中定量分析了蓄电池容量与电导之间的内在联系。最后利用福光蓄电池在线放电仪表FBI对目标蓄电池组进行容量测试,并得出蓄电池容量与电导具有相关性的结论。     

Correlation between current-voltage and capacitance-voltagecharacteristics of Schottky barrier diodes

A correlation between the current-voltage (I-V) and the capacitance-voltage (C-V) characteristics of Schottky barrier diodes (SBDs) is revealed and claimed to be a general property of SBDs for the first time. Analytical expressions explaining the correlation based on the electric field dependence of the Schottky barrier height are derived, yielding novel approaches to evaluate Schottky barrier height lowering and to model the device behaviors     

Correlation between substrate and gate currents in MOSFET's

A correlation between substrate and gate currents in MOSFET's is described and analyzed. Both of these currents are the result of hot-electron mechanisms. Theory for these mechanisms has been applied to derive an expression for gate current in terms of substrate current and parameters that can be calculated from processing data and bias conditions. The theory is successfully applied to a series of n-channel MOSFET's with a range of geometries and bias values.     

相关免疫函数和Hamming重量之间的关系

相关免疫性是设计流密码和分组密码的重要准则之一.在对布尔函数的特征矩阵研究的基础上,利用Hamming重量分析法和相关免疫的充要条件从Hamming角度方面给出了相关免疫的一些性质,同时得到一个n元布尔函数f(x)是m阶相关免疫的充要条件,该充要条件进一步扩充了Siegenthaler关于相关免疫的,必要条件.     

Correlation between chemistry of polymer building blocks and microelectronics reliability

Among various materials, polymers are widely used in microelectronics as different product constituents, such as encapsulants, conductive or non-conductive adhesives, underfills, molding compounds, insulators, dielectrics, and coatings. The behavior of these polymer constituents determines the performance, such as functionality and reliability, of the final products. Therefore, the successful development of microelectronics depends on, to some extent, the optimal design and processing of polymer materials. Due to the development trends of microelectronics, characterized mainly by ongoing miniaturization down to the nano scale, technology and functionality integration, eco-designing, shorter-time-to-market, development and application of polymers become one of the bottlenecks for microelectronic industry. Aiming at optimizing the product/process development, we have been spending a lot of effort to understand and design polymer behavior in microelectronics, such as material pre-selection, processing, characterization and modeling. Although these efforts are necessary, the ultimate benefits can only be realized if the relationship between chemistry and the behavior can be understood and predicted. This paper presents some results of our effort to establish the links between chemical details of the polymers and microelectronics reliability.