Au丝键合改为Cu丝键合技术

现阶段Au丝作为内引线一直占着键合的主导地位,由于Cu丝具有优良的电性能和价格优势,随着键合技术的发展,以Cu丝代替Au丝作为键合用内引线已经成为必然,封装行业许多厂家正热衷于将原有的Au丝键合设备进行改造,但还存在这样那样的问题。以Au丝键合改为Cu丝键合的技术研究为出发点,首先介绍了键合技术的发展,然后通过工艺调整和设备改造,使得Cu丝作为内引线能够代替Au丝在该设备上使用,同时达到了节约生产成本,节约资金的目的。对改造过程中的气体流量、压力、功率、焊接时间等参数问题进行了详细地阐述,同时对芯片、键合劈刀等也做了相应调整,使得改造后的检测结果完全满足产品要求。大力推进以Cu丝替代Au丝键合技术,可节约生产成本,提高键合强度,增强导电率、导热率等,具有重要的经济技术效益,必将迎来封装业的又一次大变革。     

一种基于像素差值编码度量不确定SAR图像相似性的新方法

在SAR图像目标识别、图像匹配等应用中,定义合理可靠的相似度尤为重要。该文在分析现有SAR图像相似度基础上,提出一种基于像素差值编码的相似度准则。首先将SAR图像按照相邻像素灰度差异生成编码图像,然后以编码图像之间的一致性作为相似度。该文从理论上证明了该相似度对SAR图像中相干斑噪声、部分遮挡和模糊等因素的鲁棒性和适应性,还讨论了将该准则应用于SAR图像匹配时,如何针对不确定性,给出一定置信水平下所有合理的匹配位置。理论和实验结果表明该文提出的相似度准则对SAR图像上相干斑噪声、部分遮挡以及模糊不敏感,能有效应用于不确定SAR图像的匹配。     

从问卷调查看中国公众对转基因食品 的科技政策期待

转基因食品是社会上颇具争议的技术产品。最近的“黄金大米”事件将转基因食品安全性的争论在中国推向了一个高峰。过去关于中国公众对转基因食品的调查主要集中在认知度和购买意愿方面。本文调查了中国公众对转基因食品的科技政策期待。结果表明,被调查公众期待对转基因玉米进行标识;期待看到更多正式的政府官方信息;期待加强转基因食品的安全风险监管,慎重商业化;对转基因主粮作物商业化等重大食品政策问题,大部分被调查公众期待能参与政策决策;期待完善转基因食品风险监控体系、严格转基因食品审批程序,以及强化转基因食品质量追究责任,等等。     

一种Ka波段倍频器设计

采用肖特基势垒二极管DMK2790,利用ADS与HFSS,进行了Ka波段无源二倍频器的设计。输出频率为38GHz,仿真结果表明,倍频损耗小于5dB。     

耐电镀光致抗蚀干膜对化学镀镍镀层的影响

文章从FPCB生产案例金裂问题出发,研究讨论了耐电镀光致抗蚀干膜对化学镀镍药水pH值、镀层厚度、表面形貌和脆性的影响,并采用弯折法定性研究了干膜对化学镀镍镀层脆性的影响。结果显示干膜在化学镀镍药水中长时间浸泡使溶出物大量积累会增大化学镀镍镀层脆性。     

A new family of nonbinary sequences with three-level correlation property and large linear span

In this correspondence, we present a new family of nonbinary sequences with three-level nontrivial correlations and large linear complexity. The sequences may be considered as nonlinear analogues of the well-known sequences by Trachtenberg and Helleseth. It is shown that the family is optimal with respect to the Welch bound in terms of root mean square of all nontrivial correlations. We also determine the correlation distribution of the new family.     

Hallucinating face by eigentransformation

In video surveillance, the faces of interest are often of small size. Image resolution is an important factor affecting face recognition by human and computer. In this paper, we propose a new face hallucination method using eigentransformation. Different from most of the proposed methods based on probabilistic models, this method views hallucination as a transformation between different image styles. We use Principal Component Analysis (PCA) to fit the input face image as a linear combination of the low-resolution face images in the training set. The high-resolution image is rendered by replacing the low-resolution training images with high-resolution ones, while retaining the same combination coefficients. Experiments show that the hallucinated face images are not only very helpful for recognition by humans, but also make the automatic recognition procedure easier, since they emphasize the face difference by adding more high-frequency details.     

Inline frequency-non-degenerate phase-sensitive fibre parametric amplifier for fibre-optic communication

Error-free transmission of 2.5 Gbit/s data over 60 km of dispersion-compensated standard single-mode fibre is demonstrated by using an inline phase-sensitive fibre-parametric amplifier and double-sideband data modulation format. The power penalty for the phase-sensitive amplifier was found to be <0.5 dB compared to back-to-back for bit-error-rate >10/sup -6/ and <2 dB compared to that for an equivalent phase-insensitive fibre-parametric amplifier of the same gain.     

Low-complexity iterative equalization for EDGE with bidirectional processing

We present a new and simple iterative equalization scheme for the enhanced data rates for global evolution (EDGE) wireless system. This scheme can significantly reduce the number of trellis states in a maximum a posteriori probability (MAP) equalizer via delayed decision-feedback (DDF) approach. Relying on the mechanism of decision feedback in the DDF trellis, bidirectional processing can be applied to exploit the time diversity of the received signal bursts for a more reliable equalizer output. With mild increase in computational complexity over the more traditional single-directional (Si) DDF turbo equalizer, the bidirectional turbo equalizer can achieve a significant performance gain.