镀银铜线的防变色处理新工艺

用于制造各种氟塑料导线的镀银铜线,由于银层光亮,表面电阻小,焊接性能良好等优点而经常受到各使用单位欢迎。但是,镀银铜线在大气中受到二氧化硫等硫化物作用后,就会失去光泽,并使表面电阻增大,焊接性能变差。因而,多年来防银变色,一直是银层表面     

运用价值工程降低银耗

改进工艺,提高效率,降低银耗,确保质量。白银在我厂用于生产耐高温导线所用的镀银铜线芯及屏蔽,是镀银铜线的主要材料之一。每年消耗量达两吨半之多,成本高。降低银耗已成为我厂生产此产品的主要课题。尤其近几年来随着电子工业的发展,对耐高温导线的需要量越来越大,为了满足社会生产的需要,适应经济发展的要求,既增     

以锡代银提高2CW 50—78、100—121的引线可焊性

2CW_(50_78、100_121)金属封装硅稳压管多年来一直采用镀银铜线作引线。一般在中库存放半年以后,引线即变黄,最后变黑,致使引线不可焊。分析其主要原因是银与空气中的硫化氢气体(即使只有千万分之一)反应而生成黑色的硫化银缘故。另外,镀银铜线在产品的生产过程中所受到高温老化、手汗沾污等因素的影响,也加剧了银     

确保石英谐振器蒸发银层厚度一致性的探讨与实践

叙述了石英谐振器真空蒸镀银层的机理,分析了在进口的串联式真空镀膜设备上造成银层厚度不均匀的原因,是由于石英晶片与蒸发源的距离不等,采取了在蒸发源与承载板之间加金属档板的措施,从而减少了中间部分石英晶片的蒸镀量,保证了最后所有晶片蒸镀银层的一致性。     

半导体封装行业中铜线键合工艺的应用

文章介绍了半导体封装行业中铜线键合工艺下,各材料及工艺参数(如框架、劈刀、设备参数、芯片铝层与铜材的匹配选择)对键合质量的影响,并总结提出如何更好地使用铜线这一新材料的规范要求。应用表明芯片铝层厚度应选择在0.025mm以上;劈刀应使用表面较粗糙的;铜线在键合工艺中使用体积比为95:5的氢、氮气混合保护气体;引线框架镀银层厚度应控制在0.03mm～0.06mm。     

镀银三防处理及其防银变色工艺研究

本文分析了镀银层易变色及其在恶劣环境条件下耐蚀性差的原因；探讨了防银变色的机理；按国军标、国标和通用方法对采用不同的工艺措施获得的镀银层的防银变色性能、三防性能、接触电阻、焊接性能进行试验、评定及对比；找到了一种可以进一步提高镀银层三防性能及其防银变色性能的工艺措施。     

菸酸镀银的应力及其控制

菸酸镀银属于无氰镀银工艺。许多文献报道了这种工艺具有镀液稳定,镀层细致,光亮等优点。有的文献还强调了这种工艺所制得银层具有良好的韧性。但是,本文作者在用菸酸镀银液制备镀银铜线时,发现在一定条件下,镀层会出现“脆性”。经过分析试验。证实这种脆性,是由于镀层内应力所引起的,它受电流密度,溶液组份,PH值等因素影响。同时,也可用镀后退火、时效等工艺来减小镀层内应力。文中结合试验情况,粗浅地讨论了应力产生原因。认为菸酸镀银的应力是由于镀银层在电沉积过程中银的点阵扭曲所造成的。     

防银变色试验总结

一、前言多年来,镀银变色一直是电子工业中的老大难问题。镀银层变色后不仅影响外观,更重要的是接触电阻增大,妨碍导电性能,造成焊接困难,影响器件的寿命和可靠性,降低实用价值。特别是电子设备中的高频及超高频元件由于银层变色而造成的导电性能下降更为突出。而镀银件在电子工业中应用既多、面又广,占有极为重要的位置。因此,防止     

防银变色综述

银镀层是一种光亮洁白的贵金属,可锻、可塑、具有良好的导电性,导热性和焊接性,化学性质比较稳定,几乎不与空气中的氧和水蒸汽作用,在电子工业中占有重要地位。镀银层在使用中存在的主要问题是:它容易受硫化物(如H_2S和SO_2等)气氛的腐蚀,银层表面很快生成浅黄     

以锡代银提高2CW50—78、100—121的引线可焊性

2CW50—78、100—121金属封装硅稳压管多年来一直采用镀银铜线作引线。一般在库中存放半年以后,引线即变黄,最后变黑,致使引线不可焊。分析其主要原因是银与空气中的硫化氢气体(即使只有千万分之一)反应而生成黑色的硫化银的缘故。     

RF Shielding Effectiveness and Light Transmission of Copper or Silver Film Coating on Plastic Substrate

RF shielding effectiveness and light transmittance of acopper or silver film coating on a plastic substrate is investigated. The dependence of the RF shielding effectiveness upon the surface resistance or thickness of a copper or silver film coating on a plastic substrate is calculated numerically by means of multireflection transmission-line theory over the frequency range of 100 MHz to 30 GHz. The light transmansmittance is determined by using the optical properties of the copper or silver film and plastic substrate. An optimum condition between the RF shielding effectiveness and the light transmittance is established for the copper or silver film coating on a plastic substrate.     

Silver Nanoparticle Paste for Low-Temperature Bonding of Copper

Silver nanoparticle (NP) paste was fabricated and used to bond copper wire to copper foil at low temperatures down to 160°C. The silver NP paste was developed by increasing the concentration of 50 nm silver NP sol from 0.001 vol.% to 0.1 vol.% by centrifugation. The 0.001 vol.% silver NP sol was fabricated in water by reducing silver nitrate (AgNO₃) using sodium citrate dihydrate (Na₃C₆H₅O₇·2H₂O). The bond was formed by solid-state sintering among the individual silver NPs and solid-state bonding of these silver NPs onto both copper wire and foil. Metallurgical bonds between silver NPs and copper were confirmed by transmission electron microscopy (TEM). The silver NPs were coated with an organic shell to prevent sintering at room temperature (RT). It was found that the organic shell decomposed at 160°C, the lowest temperature at which a bond could be formed. Shear tests showed that the joint strength increased as the bonding temperature increased, due to enhanced sintering of silver NPs at higher temperatures. Unlike low-temperature soldering techniques, bonds formed by our method have been proved to withstand temperatures above the bonding temperature.     

Acid Decapsulation of Epoxy Molded IC Packages With Copper Wire Bonds

Epoxy molded IC packages with copper wire bonds are decapsulated using mixtures of concentrated sulfuric acid (20%) and fuming nitric acid in an automatic decapping unit and, observed with minimal corrosion of copper wires (0.8–6 mil sizes) and bond interfaces. To attain maximum cross-linking of the molded epoxies, the post mold cured packages (175$^circ$C for 4 h) were further, aged at high temperature of 150$^circ$C for 1000 h. These packages are decapsulated using mixtures of higher ratio of concentrated sulfuric acid (40%) along with fuming nitric acid. The shear strength of copper wire bonds with 1 mil (25$mu$m) diameter of the decapsulated unit is higher than 5.5 gf/mil$^2$. The present study shows copper stitch bonds to Au, Cu, Pd, and Sn alloy plated surfaces are less affected on decapping, with a few grams of breaking load on stitch pull test, while stitch bonds on silver plated surfaces reveal lifting of wire bonds on decapping.     

浅谈镀钯铜线的特性

随着金线价格一路上涨并创下历史新高,大型封装厂正在加大对铜线制程的投入。通过封装厂多年的摸索,发现镀钯铜线是金线很好的替代品。文章分析了镀钯铜线作为键合线材料本身的基本性质,镀钯铜线引线键合的特征和镀钯铜线PCT实验的可靠性。通过分析发现镀钯铜线材料本身有优良的导电和导热特性,同时还有很好的抗氧化性。镀钯铜线在键合过程中需要保护气体的保护,通过硬度实验发现镀钯铜线的硬度较大,因此需要在键合过程中防止弹坑的出现。通过PCT实验证实镀钯铜线具有较好的可靠性。     

封装用抗腐蚀高可靠性银合金丝

介绍一种在封装工艺中可用于替代昂贵金丝的抗腐蚀高可靠性银合金丝。利用表面钝化和固溶合金、二次中频合金熔炼和定向连续拉铸工艺,分别从成分和工艺方面提高了银合金丝的机械性能、抗腐蚀性、可靠性等一系列键合性能,解决了普通银丝在使用过程中存在的电子迁移问题,推动了键合银合金丝的广泛使用。     

Comparison of the Microwave Performance of Transparent Wire Monopole Antennas Based on Silver Films

In this paper, transparent printed lines used in microwave radiating structures are studied. Two transparent wire monopole antennas and an opaque reference counterpart are presented, compared, and discussed. The first transparent antenna was fabricated from a transparent conductive AgGL coating (silver grid layer: a silver/titanium bilayer deposited on a glass substrate and meshed by a standard photolithographic wet etching process). It exhibits optical transparency T of 59.2 ± 0.1% in the visible-light spectrum and sheet resistance R _□ of 0.017 ± 0.001 Ω/□. The second transparent antenna was fabricated from a usual transparent conducting multilayer of indium tin oxide/silver/indium tin oxide, also deposited on a glass substrate. It exhibits optical transparency T of 71.3 ± 0.1% and sheet resistance R _□ of 5.05 ± 0.05 Ω/□. Both transparent wire monopole antennas have been characterized for microwave performance and compared with an opaque reference counterpart made from a continuous silver/titanium bilayer deposited on the same glass substrate (T = 0%, R _□ = 0.0025 ± 0.0002 Ω/□). Microwave measurements show similar performance for the transparent AgGL antenna and opaque reference counterpart. At 2.05 GHz, their maximum measured gains are both 4.4 ± 0.3 dBi. Conversely, the transparent indium tin oxide/silver/indium tin oxide antenna presents significant ohmic loss due to its sheet resistance value and consequently a low measured gain value (?2.1 ± 0.3 dBi maximum). This study demonstrates the relevance of the AgGL coating in the fabrication of transparent wire monopole antennas.     

Intermetallic Reaction of Indium and Silver in an Electroplating Process

The reaction of indium (In) and silver (Ag) during the electroplating process of indium over a thick silver layer was investigated. It was found that the plated In atoms react with Ag to form AgIn₂ intermetallic compounds at room temperature. Indium is commonly used in the electronics industry to bond delicate devices due to its low yield strength and low melting temperature. In this study, copper (Cu) substrates were electroplated with a 60-μm-thick Ag layer, followed by electroplating an In layer with a thickness of 5 μm or 10 μm, at room temperature. To investigate the chemical reaction between In and Ag, the microstructure and composition on the surface and the cross section of samples were observed by scanning electron microscopy (SEM) with energy-dispersive x-ray spectroscopy (EDX). The x-ray diffraction method (XRD) was also employed for phase identification. It was clear that indium atoms reacted with underlying Ag to form AgIn₂ during the plating process. After the sample was stored at room temperature in air for 1 day, AgIn₂ grew to 5 μm in thickness. With longer storage time, AgIn₂ continued to grow until all indium atoms were consumed. The indium layer, thus, disappeared and could barely be detected by XRD. Jong S. Kim now with Applied Materials.     

Gold Coating of Silver Nanoprisms

Core–shell Ag@Au nanoprisms are prepared through a surfactant‐free seed‐mediated approach by taking advantage of the anisotropic structure of silver nanoprisms as seeds. The gold coating on the silver nanoprism surface is achieved by using hydroxylamine as a mild reducing agent, and the final fully gold‐coated prism structures are confirmed by microscopic and spectroscopic characterization. The resulting Ag@Au core–shell structure preserves the optical signatures of nanoprisms and offers versatile functionality and particularly better stability against oxidation than the bare silver nanoprism. The surface plasmon resonances of the core–shell Ag@Au nanoprisms can be tuned throughout the visible and near‐IR range as a function of the Au shell thickness. Such tailorable optical features and surfactant‐free gold shells have great potential applications in biosensing and bioimaging.     

电镀废液回收铜粉的化学镀银工艺及其电磁屏蔽性能

采用高频超声脉冲电解法从电镀铜废液中回收制备枝晶状的铜粉,并在铜粉表面进行化学镀银以制备电磁屏蔽用银包铜粉,采用SEM、EDS、XRD、TEM等对其进行形貌和组分分析,研究了银包铜粉复合涂层的导电性能和电磁屏蔽性能。结果表明,经过表面化学镀银可以有效地避免铜粉的氧化;涂层的电磁屏蔽性能与银包铜粉的添加量紧密相关,当涂层中银包铜粉质量分数为60%时,其电磁屏蔽效率高达52 dB。     

一种工业核磁共振高灵敏度探头设计

核磁共振探头的灵敏度影响因素很多,包括探头的机械结构,电气参数等,本文着重从如何降低核磁共振探头的电气参数方面的影响因素出发,从理论上分析影响关系,到实际操作中,选择结构简单,场均匀的螺线管线圈,材质上选用具有空心结构的镀银铜线,采用具有低介电损耗和低介电常数的石英玻璃作为线圈骨架并固定,通过测试后达到了预期的目的.