用于PWB的高分散能力光亮酸性镀锡

现在,无氟无铅镀锡在PWB的电镀中已经成为主流,其中酸性硫酸盐镀锡因其镀液成份简单、成本低廉而尤其引人注目.本文报告了酸性光亮镀锡添加剂的选择和高分散能力全光亮酸性镀锡的工艺及其操作条件,讨论了影响光亮镀锡分散能力的因素,说明各种添加剂的协同作用以及合理的工艺条件有利于改善分散能力.并介绍了二液型添加剂的优点,这种添加剂综合了光亮剂、稳定剂、分散能力添加剂和无机添加剂的特点.     

柠檬酸镀镍工艺

适用于柠檬酸型镀镍溶液的光亮剂的开发，光亮镀镍与瓦特槽采用的光亮剂具有不同的特征。为此，两种类型的镀镍液进行对比试验。     

PCB酸性镀铜阳极泥与电镀添加剂关系的研究

PCB酸性镀铜磷铜阳极的阳极泥是电镀过程产生的,当阳极泥累积到足以阻挡阳极铜球时,会影响到阳极电力线的分布,导致电镀板件的镀铜均匀性变差,因而要求生产人员对生产线进行停产保养,清洗阳极,清洗阳极的过程会造成铜球的损耗,增加生产的成本。本文通过测试不同种类的电镀铜添加剂与电镀阳极铜泥的关系,发现在有机添加剂中电镀光亮剂对阳极泥的生成影响最大,在进一步研究中发现不同电镀光亮剂对阳极泥生成的促进效果也不一样,容易析出MPS结构的电镀光亮剂比较容易产生阳极泥,光亮剂SCCTB相比SPS可以减少阳极泥的生成。     

陈旧氰化镀银槽光亮镀银工艺探讨

光亮镀银比普通镀银有更多优越的性能，除了镀层美观外，在耐变色性、镀层细致性方面也都有明显的优势，此外还具有工艺操作简便、镀层结合力强、沉积速度快、成本低等优点。当前，各种功能镀银包括光亮镀银主要在氰化物镀银体系中得到，而且氰化镀银的光亮剂品种很多。本文对几种氰化光亮镀银工艺进行了比较，着重论述了用ＦＢ光亮剂作为陈旧氰化镀银添加剂的光亮镀银工艺及实践情况。实践证明，ＦＢ光亮剂不仅适用于新配制的氰化镀     

光亮剂和载体对脉冲图形电镀效果的影响

概述脉冲电镀工艺的原理、脉冲图形电镀工艺的优势,针对实际脉冲图形电镀工艺加工过程中出现的板面色差、深镀能力异常问题,使用鱼骨图进行分析,逐步排查,最后确认是光亮剂和载体含量异常所造成的,经过试验对比、数据收集,最终找到了光亮剂和载体的合理控制范围,彻底解决了色差、深镀能力等异常的问题。     

多种添加剂及电流密度对高径深TSV电镀影响研究

硅通孔(TSV)填充工艺是三维集成关键技术之一。通过分析对比TSV电镀填充药水光亮剂、整平剂的浓度以及电流密度等对于TSV电镀填充效果的影响,发现在光亮剂浓度10 ml/L、整平剂浓度30 ml/L条件下,填充效果呈底部生长且形貌较好;同时发现电流密度较低时,呈等壁生长,而电流密度较高时,底部产生孔洞。     

填孔电镀光剂研究进展

文章简述了填孔电镀的机理模型,分析了光亮剂、整平剂和载运剂的作用及失效机制,以期加深广大PCB业者对盲孔填孔电镀技术的了解。     

XNF光亮镍铁合金电镀工艺

本文着重就光亮剂XNF—1和温度对镀液的整平能力、深镀能力、分散能力、阴极极化和镀层组成及硬度的影响进行了初步研究。     

一种快速填盲孔的工艺及原理研究

消费电子的快速发展推动HDI需求的持续增长,电镀填盲孔是HDI制造中必不可少的工序之一。快速填盲孔对制作精细线路、控制成本、提高产能都是有利的。本文探讨了一种新的填盲孔工艺,在不改变现有电镀体系的基础上,仅通过改变工序,可以将填盲孔时间从60 min缩短到40 min,微凹<5 mm,面铜厚度控制在(12±0.5)mm。文章还采用电化学方法和SEM图对新工艺的快速填盲孔原理进行了初步研究,研究结果表明,采用新工艺,可以在电镀工序之前实现盲孔板不同位置添加剂的选择性吸附,具体表现为盲孔底部吸附有高浓度的光亮剂,而板面光亮剂浓度较低。     

无硫氰化光亮鍍银新工艺

目前,国内外光亮镀银工艺中所采用的添加剂(包括光亮剂)绝大部分是载硫的有机化合物,其镀层抗硫性能较差,容 (一)配方与工艺规范:易变色,致使镀层各项性能下降。     

Design of wideband circularly polarized aperture-coupled microstripantennas

Two variations of a novel feeding technique for a wideband circularly polarized aperture-coupled microstrip antenna are described. Prototype designs for wideband linearly polarized elements are first presented, and then used for circularly polarized designs. Techniques used for design of the feed network are detailed, for both series feed and parallel feed versions. Experimental results are shown for each antenna, and results for the two designs are compared. The impedance and axial ratio bandwidths for these antennas are among the best yet achieved for microstrip antenna elements. Several design variations are also discussed     

Robust estimators of the 2-parameter gamma distribution

The available estimators for parameters of the gamma distribution are moment estimators, maximum-likelihood estimators, and approximations to the maximum-likelihood estimators. These estimators are not suitable for small samples; however, they are still being used at the present time. The proposed robust estimators for scale and shape parameters are more suitable for small samples. They have RMS (root-mean-square) errors that are considerably smaller than those of the other estimators. In addition, they are easier to calculate, and are therefore appropriate in many applications     

Maximum Likelihood Estimation of Label Imperfection Probabilities and Its Use in the Identification of Mislabeled Patterns

This paper presents the problem of estimating label imperfections and the use of the estimation in identifying mislabeled patterns. Expressions for the maximum likelihood estimates of classification errors and a priori probabilities are derived from the classification of a set of labeled and unlabeled patterns. Expressions also are presented for the asymptotic variances of probability of correct classification and proportions. Simple models are developed for imperfections in the labels and for classification errors and are used in the formulation of a maximum likelihood estimation scheme. Schemes are presented for the identification of mislabeled patterns in terms of thresholds on the discriminant functions for both two-class and multiclass cases. Expressions are derived for the probability that the imperfect label identifi'cation scheme will result in a wrong decision and are used in computing thresholds. Furthermore, the results of practical applications of these techniques in the processing of remotely sensed multispectral data are presented.     

Adaptive filters suitable for real-time spectral analysis

New cascade structures for adaptive filters are presented. They are especially suitable for real-time applications. Since the new structures are intended to be realized using single-chip DSP ICs or single-chip custom VLSI circuits, the requirements for memory and divisions are minimized. The new structures are based on state-variable biquads that in addition to having good SNRs and low sensitivities (for fixed-point implementations) can also have their resonant frequencies and Q-factors independently tuned. The special cases of using the adaptive filters for tracking sinusoids corrupted by noise and for formant based speech compression are described in detail.     

近场头相关传输函数及其应用

综述了近场头相关传输函数(HRTF)及其应用问题,讨论了近场HRTF的测量、理论计算及其物理特征。最后讨论了近场HRTF在双耳听觉和消费电子领域的应用。     

Throughput and packet error probability of cellularfrequency-hopped spread-spectrum radio networks

The authors characterize multiple-access interference for cellular mobile networks, in which users are assumed to be Poisson-distributed in the plane and use frequency-hopped spread-spectrum signaling with a transmitter-oriented assignment of frequency-hopping patterns. Exact expressions for the bit error probabilities are derived for binary coherently demodulated systems without coding. Approximations for the packet-error probability are derived for coherent and noncoherent systems and these approximations are applied when forward-error-control coding is used. In all cases, the effects of varying interference power are accurately taken into account according to some propagation law. Numerical results are given in terms of bit-error probability for the exact case and throughput for the approximate analyses. Comparisons are made with previously derived bounds, and it is shown that these tend to be very pessimistic     

Phased Mission Analysis: A Review of New Developments and An Application

Both exact and approximate methods for obtaining the unreliability of a nonrepairable system undergoing a phased mission are presented. The techniques are applied to an emergency core cooling system for a boiling water reactor. The estimates for the example agree well with the exact solution. The accuracy and ease of implementation are compared for both methods. The approximation techniques for unavailability estimates for phased missions contained in this paper are useful for industrial applications. The techniques are implementable and existing computer programs such as MOCUS, PREP, and KITT can be used for the analysis although such use is not efficient at this time. These programs are currently being modified, for efficient use in phased mission problems, at the Idaho National Engineering Laboratory. MOCUS, PREP, and KITT are obtainable from the Argonne Code Center; 9700 South Cass Avenue; Argonne, IL 60439 USA.     

Frontal methods for the space-time processing of ultra-wideband signals in exploration seismology and ground penetrating radar

Methods for the space-time processing of ultra-wideband signals used in short-range and ground penetrating radar as well as exploration seismology for execution of migration transformation procedures are analyzed. Procedures for obtaining the geometricalal parameters (position, shape, and orientation) of reflecting boundaries and diffracting objects from signals recorded during scanning in some spatial zone are proposed. Different methods for the implementation of linear and nonlinear migration transformations are analyzed. Frontal migration transformation methods are analyzed in more detail and advantages of these methods are demonstrated. Interactive and computer-aided versions of such methods are presented. Analytical relationships for the implementation of these versions of the space-time signal processing are presented.     

Detection of Modulated Gaussian Signals in Noise

A method using Hermite polynomials is utilized for analyzing the outputs of νth-law devices for inputs of modulated Gaussian signals and zero-mean Gaussian noise. New results are developed for the output correlation functions, and techniques for obtaining closed-form expressions are pointed out. Output signal-to-noise ratios for various input carrier-to-noise-power ratios are calculated, and plots are shown for a single sinusoidal modulating signal. Results are derived to show the existence of a theoretical maximum for the output signal-to-noise ratio. The method can be directly applied for the case of general Fourier expandable signals modulating a Gaussian carrier.     

Noise-figure calculations for crossed-field forward-wave amplifiers

The problem of finding an adequate model for derivation of noise-figure expressions for crossed-field forward-wave amplifiers is investigated. The modified Llewellyn-Peterson equations are used for the portion of the beam near the cathode. Four waves, two cyclotron waves and two space-charge waves, are used for the space connecting the gun and interaction region. Noise-figures are found by considering five waves in the interaction region. The results are very close to those found when only the space-charge waves are considered in the development of the equations for both drift and interaction regions. A matrix, like the space-charge-wave matrix for O-type beams, giving the transformation of beam fluctuations along a drifting, crossed-field stream including the effects of four waves is presented. Expressions for fluctuations of transverse velocity and beam center of gravity are derived to account for all the excitation quantities which are believed to be important in crossed-field amplifiers. The transformation of fluctuations of beam position, or center of gravity, along an accelerating stream is derived. Calculated values of noise figures are far in excess of experimental values. The reasons for the discrepancies are discussed.