PCB的化学镀锡应用技术

本文阐述PCB的绿色表面涂覆的化学镀锡工艺的有关理论和技术,化学镀锡应用是实现取代热风整平表面涂覆绿色化的最重要的手段之一,化学镀锡应用也是实现取代内层板棕化和黑化表面涂覆的产品换代升级已成必然之势。     

甲烷磺酸型化学镀锡铅溶液添加剂的影响

随着电子产品的高密度化及小型化,锡铅作为可焊性涂层其涂覆方法已由电镀锡铅、热风整平向化学镀方向发展。化学镀锡铅通常采用氯化物型,氟化物型溶液,由于氯离子对基板具有腐蚀性,氟离子污染环境等问题,近年来研究了甲烷磺酸型化学镀锡铅。本文介绍甲烷磺酸型化学镀锡铅溶液各种添加剂的影响,其中包括能     

化学镀及化学处理取代热风整平工艺探讨

热风整平工艺一直是印刷线路板制作中重要的后处理工艺，但是，随着印刷线路板的精细化和环境保护的需要，热风整平工艺的应用已经受到限制，由此，产生了一些替代工艺，包括化学防氧化、化学镀镍金、化学镀锡及锡合金等，其中化学镀锡及锡合金最有可能成为取代热风整平的主流工艺。     

激光直接成像技术（V）—化学镀Sn和直接覆铜板上的LDI

4 在化学镀锡上的LDI 这是指经制备的在制板铜箔上涂覆上一层厚度为0.8/μm的锡箔,接着通过UV激光蚀去不需要的锡镀(涂)层及其底下的铜箔厚度3～5μm所形成的图形,最后以锡层为抗蚀剂进行碱性蚀刻(如常规的碱性CuCl_2蚀刻液),便可得到所期望的精细导体图形。     

激光直接成像技术(Ⅴ)--化学镀Sn和直接覆铜板上的LDI

4 在化学镀锡上的LDI 这是指经制备的在制板铜箔上涂覆上一层厚度为0.8μm的锡箔,接着通过UV激光蚀去不需要的锡镀(涂)层及其底下的铜箔厚度3～5μm所形成的图形,最后以锡层为抗蚀剂进行碱性蚀刻(如常规的碱性CuCl2蚀刻液),便可得到所期望的精细导体图形.     

化学沉银工艺的实践

化学沉银是近年新兴起的印制板表面处理工艺,预计沉银和浸锡会成为下一代主流的表面涂覆工艺。本文概述化学沉银工艺流程、工艺参数、制程要点,质量要求等,同时结合生产实际,对沉银工艺影响因素、常见问题及解决方法阐述了自己的实践应用体会。     

化学沉银工艺的应用实践—深圳恩达

化学沉银是近年新兴起的印制板表面处理工艺，预料沉银和浸锡会成为下一代主流的表面涂覆工艺。本概述化学沉银工艺流程、工艺参数、制程要点，质量要求等，同时结合生产实际，对沉银工艺影响因素，常见问题及解决方法阐述了自己的实践应用体会。     

常见PCB表面处理工艺的特点、用途和发展趋势

本文详细介绍了目前常见的五种PCB表面处理工艺（热风整平、有机涂覆、化学镀镍／浸金、浸银、浸锡）的特点、用途和未来的发展趋势。     

自催化型化学镀锡铅

近年来随着电子工业的发展、电子部件小型化、印制板薄型化和组装密度的提高,过去提供锡铅涂层的方法(热风整平、电镀锡铅)由于厚度不均匀及对某些孤立电路不适用等问题已不能满足要求,因此化学镀将成为新的提供锡铅涂层的方法。化学镀锡铅大多是利用基体金属与锡铅的置换反应,即以基体的溶解反应作为沉积的驱动力,当基体金属     

半柔性同轴电缆外导体整体镀锡专用助焊剂

经过对溶剂、活性成分和表面活性剂特性的分析,开发了一种半柔性同轴电缆外导体整体镀锡专用助焊剂。实验结果表明,所开发的#4助焊剂[w(己二酸)=1.0%、w(癸二酸)=1.0%、w(阳离子表面活性剂)=0.3%、w(非离子型表面活性剂)=0.1%、乙醇余量]在镀锡过程中气体释放量小,所获得的镀锡层表面连续、光滑,基本上消除了针孔缺陷,同时可以保证锡液能很好地渗透到编织网屏蔽层的内部,形成牢固的镀锡层。     

化学镀工艺在微电子材料中的研究和应用

简要综述了化学镀工艺在微电子材料中的应用,讨论了影响化学镀镍、铜、锡、钴和贵金属等的主要因素,阐述了化学镀微电子材料的特性、存在问题及研究动态。     

超细铜粉的化学镀锡及其抗氧化性能研究

以水合肼还原法制备出平均粒径约1μm的超细铜粉,并对其进行化学镀锡。研究了镀锡层对复合粉末微观形貌及抗氧化性能的影响。结果表明:镀覆质量分数50%的锡后,复合粉末平均粒径有所减小,但在空气中的氧化起始温度从120℃提高到220℃,与镀银层相比,镀锡层在较低温度区间对铜粉抗氧化具有优势。     

Lead-Free Solder Films Via Novel Solution Synthesis Routes

We report two novel routes, sol-gel and electroless plating, for the synthesis of lead-free solders. Novel processes with these routes were developed and demonstrated for Sn-Ag-Cu, Sn-Ag systems to achieve thin bonding layers for assembly of fine pitch integrated circuits onto substrates. Sol-gel route can be used to accurately control the final alloy composition and incorporate additives leading to the designed thermomechanical properties. In this process, the inorganic polymer solutions were spin coated and then heat-treated in a reducing atmosphere to form thin films of lead-free solders. The presence of Ag and Cu enabled easy reduction of tin oxide to tin at 400degC that was not possible with Sn precursor. With the alternate solution reduction (electroless plating) approach, bonding layers can be deposited at almost room temperatures directly on organic substrates. With this approach, the deposition selectively occurs on the metal bonding pads, which eliminates the need for any lithography. Using this approach, electroless Sn-Ag films were demonstrated on organic laminates. These thin film synthesis routes can enable short interconnections that are critical for high density, high frequency, and embedded active component packaging.     

Effect of surface finish material on printed circuit board for electrochemical migration

This study investigates whether the electrochemical migration (ECM) is affected by factors such as the printed circuit board (PCB) surface finish, distance between the electrodes and bias voltage under water drop (WD) and polarization tests. The main element of the dendrite structure for ENIG (electroless nickel and immersion gold), electroless Ag and electroplate Sn was nickel, silver and tin, respectively. The order of speed in which the dendrite structure was formed from the cathode electrode to the anode electrode on the PCB with various surface finishes was electroless Ag, electroplate Sn and ENIG, irrespective of the distance between the electrodes and the bias voltage. The ECM rate was increased by decreasing the distance between conductors of the opposite polarity and increasing the bias voltage. The order of corrosion rate in distilled water with pH 6.5 and NaCl 1.0 wt% solution was electroless Ag, electroplate Sn and ENIG. This trend was corresponded with the tendency for ECM rate.     

The influence of temperature and humidity on printed wiring board surface finishes: Immersion tin vs organic azoles

Substitution of lead-free solders in electronic assemblies requires changes in the conventional Sn:Pb finishes on substrates and component leads to prevent contamination of the candidate lead-free solder. Options for solderability preservative coatings on the printed wiring board include organic (azole or rosin/resin based) films and tin-based plated metallic coatings. This paper compares the solderability performance and corrosion protection effectiveness of electroless tin coatings vs organic azole films after exposure to a series of humidity and thermal cycling conditions. The solderability of immersion tin is directly related to the tin oxide growth on the surface and is not affected by the formation of SnCu intermetallic phases as long as the intermetallic phase is underneath a protective Sn layer. Thin azole films decompose upon heating in the presence of oxygen and lead to solderability degradation. Evaluations of lead-free solder pastes for surface mount assembly applications indicate that immersion tin significantly improves the spreading of Sn:Ag and Sn:Bi alloys as compared to azole surface finishes.     

次亚磷酸钠还原化学镀铜工艺研究及展望

化学镀铜是印制电路制作中重要工序,开发新的非甲醛体系化学镀铜工艺是当前化学镀铜领域中的热点。文章根据化学镀铜的基本原理,分析了以次亚磷酸钠为还原剂的化学镀铜工艺的特点、以及该技术的研究情况,并提出了该工艺未来的研究方向。     

纳米化学复合镀的开发及在PCB制造中的应用研究

化学镀表面处理技术使用范围很广,镀层均匀、装饰性好;在防护性能方面,能提高产品的耐蚀性和使用寿命;在功能性方面,能提高加工件的耐磨性和导电性、润滑性能等特殊功能,因而成为表面处理技术的一个重要部分。钠米化学复合镀是在化学镀液中加入纳米粒子,使其与化学镀层共沉积的工艺技术。文章主要研究在化学镀Ni-P中加入纳米颗粒,在基体表面沉积具有镀厚均匀、耐磨、耐腐蚀、可焊的纳米复合镀层,阐明镀液组成和工艺条件对沉积速率、镀液稳定性、镀层与基体的结合力的影响,获得钠米化学复合镀技术的工艺参数,并对纳米复合镀层的性能进行了研究。     

铝合金化学镀镍工艺研究与应用

报道一种在铝合金元件上实施化学镀镍的工艺方法。该方法包括在改进的锌酸 溶液中经二闪浸锌处理后,以碱性化学镀镍作底层,然后进行酸性化学镀镍,能在铝合金（ＬＹ１２ｃｚ、ＬＤ３１等）表面获得光亮的、具有优异附着力和良好的防腐蚀性能及其综合物理、化学特性的化学镀镍（Ｎｉ－Ｐ）层。     

An Assessment of Immersion Silver Surface Finish for Lead-Free Electronics

The worldwide transition to lead-free electronics has increased the usage of several lead-free pad finishes for electronic assembly manufacturers, including immersion silver, immersion tin, electroless nickel-immersion gold, and organic solderability preservatives. This study assesses and compares immersion silver as a circuit board finish in terms of its ease of use, wettability, solderability, shelf life, appearance, solder joint strength, intermetallic and void formation, reliability, and costs.     

化学镍金UBM沉积差异探讨

UBM（under bumping metallization凸点下金属）的制作是整个FlipChip和WLCSP封装工艺中的关键。化学镍金UBM技术以其成本低、可靠性高而受到越来越多的关注和应用。对于不同功能和大小的I／O金属电极,化学镍金UBM的沉积会出现差异和不同。文中用混合电位理论解释了半导体晶圆化学镍金UBM沉积差异的现象。搅拌因素对于面积大小不同的I／O电极混合电位的影响是不同的,面积小的I／O电极其UBM沉积速度高于面积大的I／O电极。不同功能的I／O电极有着不同的起始电势,从而影响I／O电极的混合电位,表现为最终UBM沉积厚度和表面形貌的差异。