铜酚醛树脂导电油墨的研究

高性能导电油墨的开发是印制电子技术研究焦点之一。本文利用自制热固性酚醛树脂做联接剂,铜粉做导电填料来制备导电油墨。通过试验获得的最佳配方中各组分比例为:合成树脂组分中苯酚:甲醛溶液:氢氧化钠=1:(4-5):3,铜粉重量占固化后油墨总重的75%-80%。在此配比范围内,150℃加热固化后导电油墨的电阻率可以达到实际应用要求的100Ω/cm。     

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。     

用喷墨打印法直接形成铜导电线路图形

金属纳米粒子的喷墨打印直接形成金属导电线路,低成本、低消耗、工艺过程简单,是一个很具吸引力的方法。虽然目前大多数的研究集中在新金属方面,如金和银,但是本实验开发出一种廉价的导电材料作为替代品,即铜纳米粒子导电油墨。用多元醇过程制备出粒径为40nm～50nm的铜纳米粒子,把铜离子很好的分散在低粘度的导电油墨中。实验成功地演示了用铜导电油墨直接形成导电线路的方法。喷墨印刷形成的铜导电线路图形具有金属般的外观,并且在热处理后具有很好的导电性。薄膜在真空中以325℃的温度持续1h后,薄膜的电阻率达到17．2μΩm·cm。     

紫外光固化银包铜粉导电胶的制备及研究

以银包铜粉和环氧丙烯酸树脂为原料制备导电胶浆料,采用丝网印刷将浆料涂覆到载玻片上,置于紫外光下固化获得导电涂层。利用SEM和四探针电阻测试仪对固化后导电胶的微观结构和电学性能进行表征。结果表明:当银包铜粉质量分数为70%,导电胶固化完全,制得的导电胶电阻率最低为1.135×10~(–3)?·cm,涂层厚度为140μm。     

纤维状铜粉导电填料的制备及性能研究

采用水溶液配位沉淀-热分解法制备了纤维状铜粉,利用XRD和SEM对粉末物相和形貌进行了表征,并采用热重-差热-红外联用仪(TG-DSC-FTIR)分析了草酸铜盐的热分解过程。以该铜粉为导电填料,配制了铜导电胶,通过测定导电胶的渗流曲线和固化曲线对其导电性能进行了研究。结果表明,配位沉淀产物为棒状草酸氨铜,其在N2和H2混合气氛中的热分解依次经历两次脱氨、脱结晶水、草酸铜热分解四个阶段,产物为直径约1μm、长径比20的纤维状铜粉;在铜粉与环氧树脂质量比为3:1、常温固化24 h的条件下所制备的铜导电胶的电阻率最小,为4.45×10–3?·cm。     

柔性银包铜基导电线路的制备与性能

针对导电银浆价格高、导电铜浆易氧化等问题,采用银包铜粉作为导电填料,聚氨酯改性丙烯酸树脂为树脂基体,通过丝网印刷在聚酰亚胺薄膜上印制导电线路,并用热固化的方式进行固化,从而获得导电性能优良的柔性银包铜基导电线路。结果表明:当银包铜粉的含量为65%(质量分数)时,制备的导电胶各项性能达到最佳值,满足丝印要求,平均膜厚为29.25μm,固化后得到的导电膜电阻率达到最低值1.06×10~(-3)Ω·cm。     

新产品与新技术(53)

一种用丝网印刷制造可变电阻的碳油墨导电化合物(Conductive Compounds)公司开发出一种可采用丝网印刷形成可变电阻的碳油墨。该碳油墨通过运用模板或丝网印刷工艺,可以在聚酯(PET)和聚酰亚胺(PI)薄膜、FR-4基板上印刷形成可变阻器、电位器或分立电阻,电阻值范围可由混合成份差异而不同,每批电阻值为±5%的误差。该碳油墨电阻与铜或银油墨印刷导线结合良好,在高温和高湿环境中性能稳定。电阻表面有着特殊的耐机械磨损性,表面平滑和优良的线性电阻,能经受1百万线性或旋转磨损周期。     

无机导电油墨在电路板丝网印刷中的应用

导电油墨就是指印刷于非导电体承印物(如塑料、玻璃、陶瓷、纸板等)上,使之成为具有传导电流和排除积累静电能力的油墨。导电油墨是一种导电性复合材料,即在导电油墨体系中,有无数个导电粒子均匀地分散在液态料中,形成一种包含溶剂的浆状物,处于绝缘状态。当油墨印刷固化干燥后,溶剂挥发,导电材料和粘合剂等固化,使彼此之间紧密连结为一体,导电粒子间的距离变小,自由电子沿外电场方向移动而形成电流。导电油墨根据导电材料性质的不同可分为无机导电油墨和有机导电油墨。在电子丝网印刷中,无机导电油墨是其主要的印刷材料,从集成电路、线路板、按键、开关等的丝网印刷一般都使用无机导电油墨,它是目前电子丝网印刷中主要的应用材料。     

利用碱性蚀刻废液制备纳米铜导电浆料

利用液相还原的方法先在碱性蚀刻废液中制备成纳米级的铜粉,再通过对纳米铜粉表面的保护和真空干燥,然后将铜粉分散到聚氨基甲酸酯以及浆料助剂中得到纳米铜导电浆料。实验研究表明通过液相法制备出了的铜粉纯度比较高,大部分颗粒尺寸在100 nm以内,制备出来的导电浆料其体积电阻率可以达到18.35×10-3Ωcm。     

用纳米银棒和颗粒制备高导电性油墨

研制了一种高导电性油墨。首先,分别以乙二醇和N,N-二甲基甲酰胺为还原剂,还原硝酸银溶液得到纳米银棒和纳米银球形颗粒。用纳米银棒和纳米银球形颗粒混合银粉、双酚A环氧树脂/酚醛树脂、丁酮等其他助剂配制导电油墨。研究了不同固化温度、固化时间对所制油墨导电性能的影响。结果表明,在150℃固化20 min该油墨印刷的导电图形具有很致密的表面结构和丰富的三维导电网络,其体积电阻率达3.6 10–6.cm。     

铜蚀刻废液制备氧化铜

PCB行业主要存在酸性和碱性两种废液,当前对蚀刻废液的处理方法有许多种,其中沉淀法是经济的处理方法,而且去除铜率高。通过加入试剂,将废液中的铜离子转变成氢氧化铜沉淀,然后加热煅烧,得到最终产品氧化铜。分别采用单独对酸和两种废液混合二种方式制取氧化铜;讨论了酸度对沉铜量的影响,结果表明,铜离子沉淀的最佳pH分别为9和4.5,沉淀最佳的分解温度和时间分别为500℃和30 min。探讨了水洗量和次数对杂质的去除影响,分别得到水洗三次,纯净水两次为最佳结果。     

Double-level copper interconnections using selective copper CVD

Selective copper CVD technique involving hydrogen reduction of hexafluoro acetylacetonate copper has been used to fill vias for fabricating double-level copper interconnect structure. The surface morphology of selectively deposited copper on copper substrate of the via bottom depends strongly on via opening process. A two-step via opening process consisting of an reactive ion etching of the insulating interlayer and a wet removal of the interlayer metal results in smooth copper plug formation by CVD. Double-level copper interconnect structures have been fabricated using this technique and a via resistance as low as 100 mΩ has been obtained for a 1 μ diameter via.     

Comparison of copper acetylacetonate, copper (II) acetate, and copper chloride as lasants for copper vapor lasers

The operating characteristics of a neutral copper laser oscillating on the 5106 Å transition employing copper acetylacetonate, copper (II) acetate, and copper chloride oscillating on the 5106 and 5782 Å are described; and all three laser systems are compared in a fixed parameter system. The total output energies for optimum temperature, buffer gas pressure, dissociation pulse energy, and time delay were measured for each laser system. The total energies for the three lasants Cu(Ac)2, Cu(Ac), and CuCl under optimum lasing conditions are in the ratio of 3:2:1.     

Direct gold and copper wires bonding on copper

The key to bonding to copper die is to ensure bond pad cleanliness and minimum oxidation during wire bonding process. This has been achieved by applying a organic coating layer to protect the copper bond pad from oxidation. During the wire bonding process, the organic coating layer is removed and a metal to metal weld is formed. This organic layer is a self-assembled monolayer. Both gold and copper wires have been wire-bonded successfully to the copper die even without prior plasma cleaning. The ball diameter for both wires are 60 μm on a 100 μm fine pitch bond pad. The effectiveness of the protection of the organic coating layer starts from the wafer dicing process up to the wire bonding process and is able to protect the bond pad for an extended period after the first round of wire bond process. In this study, oxidization of copper bond pad at different packaging processing stages, dicing and die attach curing, have been explored. The ball shear strength for both gold and copper ball bonds achieved are 5 and 6 g/mil² respectively. When subjected to high temperature storage test at 150 °C, the ball bonds formed by both gold and copper wire bond on the organic coated copper bondpad are thermally stable in ball shear strength up to a period of 1440 h. The encapsulated daisy chain test vehicle with both gold and copper wires bonding have passed 1000 cycles of thermal cycling test (−65 to 150 °C). It has been demonstrated that orientation imaging microscopy technique is able to detect early levels of oxidation on the copper bond pad. This is extremely important in characterization of the bondability of the copper bond pad surface.     

Interpulse kinetics in copper and copper halide lasers

The various rate processes that govern the interpulse relaxation in metal vapor and metal halide vapor lasers are considered. Computer calculations indicate that the rapid metastable levels relaxation observed in copper and copper halide laser experiments requires the existence of a relatively small resonance in the cross section for metastable excitation or deexcitation near threshold. The accurate calculation of interpulse relaxation requires knowledge of rate constants presently not well known; this is especially so for metal halide lasers.     

Effect of copper seed aging on electroplating-induced defects in copper interconnects

Voids in copper thin films, observed after electroplating, have been linked to seed aging that occurs when a wafer is exposed, over time, to clean-room ambient. Oxidation of the copper seed surface prevents wetting during subsequent copper electroplating, leading to voids. Several surface treatments were employed to counteract the seed aging effect, including reduction of the copper oxide film by hydrogen, reverse plating of the copper surface, and rinsing the wafer surface with electrolyte. Each treatment was applied to wafers increasingly aged from 2 to 14 days, just prior to electroplating. Results showed a significant decrease in postelectroplating defects with all three treatments. The reduction of copper oxide by hydrogen exhibited the most marked results. An increase in surface wetting is shown by a decrease in contact angle measurements and an increase in film reflectivity for treated versus untreated copper wafers. This study shows that, although the copper surface exhibits strong aging effects over a short period of time, using proper surface treatments can eliminate such effects and voids.     

CEM-3型覆铜板用于多层板的研究

由于主要原材料价格不断上涨,印制电路板市场竞争日趋激烈,促使客户以及PCB厂商不断寻求低成本材料以及生产工艺。CEM-3型覆铜板成本则相对较低,若将CEM-3型覆铜板应用于多层板制作并能满足产品品质需求,将是一个降低成本的新方法。然而传统的CEM-3型覆铜板由于材料特性限制,一般用于制作单双面板,用于多层板制作则由于其机械加工性能及可靠性等方面存在很大的制作难题,且无对应的半固化片,业内暂无此应用研究。根据CEM-3覆铜板的特性从板材的制前准备、压合参数优化、钻孔参数制定等方面进行分析试验,通过采用CEM-3基板与FR-4合适的半固化片成功压合,并制作出机械加工性及可靠性均完全符合制作标准的多层板,并成功导入批量制作。解决了行业内CEM-3板料用于多层板制作难题,降低了PCB产品的制作成本。     

Investigation on copper diffusion depth in copper wire bonding

Due to the dramatic price increase of precious metals, the replacement of Au with Cu in wire bonding has become an emerging trend for IC packaging nowadays. Similar to the Pb-free soldering transition, such a replacement is not just a simple drop-in material change. Comprehensive processing and reliability investigations are required before a mass production of electronic devices with Cu wire bonding can be implemented. However, among the existing studies on Cu wire bonding, it appears that most researchers just focused on issues above the wire bond pads. In fact, the Cu in the wire bonds may diffuse into the Si chip and impose reliability threats to the electronic devices. So far there was no research on the Cu-to-Si diffusion issue in Cu wire bonding. In this paper, an experimental study on the Cu-to-Si diffusion in Cu wire bond is reported. The Cu diffusion depth was characterized with the secondary ion mass spectrometry (SIMS) technique. Specimens with various configurations were designed and fabricated to investigate the effects of several parameters on the Cu-to-Si diffusion depth. The issues of concern include the amount of Cu supply, the bond pad deformation, and the barrier layer under the bond pad. In addition, some samples with conventional Au wire bonding were fabricated and tested in parallel for comparison.     

新型碱性精抛液对300mm铜膜全局平坦化的影响

The copper removal rate and uniformity of two types copper slurries were investigated, which was performed on the 300 mm chemical mechanical planarization （CMP） platform. The experiment results illustrate that the removal rate of the two slurries is nearly the same. Slurry A is mainly composed ofa FA/OI1 type chelating agent and the uniformity reaches to 88.32%. While the uniformity of slurry B is 96.68%, which is mainly composed of a FA/OV type chelating agent. This phenomenon demonstrates that under the same process conditions, the uniformity of different slurries is vastly different. The CMP performance was evaluated in terms of the dishing and erosion values. In this paper, the relationship between the uniformity and the planarization was deeply analyzed, which is mainly based on the endpoint detection mechanism. The experiment results reveal that the slurry with good uniformity has low dishing and erosion. The slurry with bad uniformity, by contract, increases Cu dishing significantly and causes copper loss in the recessed region. Therefore, the following conclusions are drawn： slurry B can improve the wafer leveling efficiently and minimize the resistance and current density along the line, which is helpful to improve the device yield and product reliability. This investigation provides a guide to improve the uniformity and achieve the global and local planarization. It is very significant to meet the requirements for 22 nm technology nodes and control the dishing and erosion efficiently.     

覆铜板用厚铜箔产品的性能及其应用

介绍了覆铜板用厚铜箔的定义、应用特性以及厚铜箔覆铜板市场,并重点讨论了厚铜箔所需达到的关键性能,以及它与PCB加工性、品质提高的关系.