基于有机基板的化学镍钯浸金工艺应用与测评

有机基板被广泛应用于电子封装领域,常见的表面处理工艺包括电镀镍金、化学镍金、浸锡、浸银等工艺。在众多表面处理工艺中,化学镍钯浸金工艺因其具有较好的综合性能展现出显著优势。化学镍钯浸金工艺是在化学镍金工艺的基础上增加化镀钯处理,采用该工艺先对基板表面进行化镀镍处理,再进行化镀钯处理,最后完成化学浸金处理。钯镀层可以防止金在沉积过程中腐蚀镍镀层以及阻挡镍向金属间化合物（IMC）层扩散。利用X-Ray、电子扫描显微镜（SEM）、聚焦离子束（FIB）等图像分析方法,对比了不同厂商的化学镍钯浸金镀层的厚度、微观形貌及质量,结果表明,平整且致密的钯镀层可以有效避免镍腐蚀现象。     

国际酸性化学银的问题与新型微碱性化学银IAG-377工艺

化学银制程流程短、适用于水平与垂直线生产、且具有银层导电性好、焊锡性佳、可打铝线等优点。近来已为众多OEM首选无铅表面涂(镀)覆(Final Finishing)工艺。然而目前国际流行的化学银大都采用硝酸体系。它会咬蚀铜线路,使施镀时间不能长,这又导致孔处常露底铜。硝酸体系同时要用缓蚀剂或渗透剂,致使银层含杂质(碳)量很高,焊接时会产生气泡,影响焊接强度。CharterSILVER~IAG-377是一种崭新的无硝酸、无缓蚀剂和渗透剂的微碱性体系,它不会咬蚀铜线和在焊料中产生气泡,它可得到高纯度、高抗蚀性、易清洗、低接触电阻、无电迁移、高焊接强度和高打线强度的化学银层。CharterSILVER~IAG-377产品完全符合欧洲RoHS及WEEE要求,可满足OEM无铅与环保的需求,现已在欧洲的英国、意大利的印制板厂正常使用。     

化学镍/化学钯/浸金的表面涂覆层的可焊性和可靠性

概述了化学镍/化学钯/浸金(ENEPIG)表面涂(镀)覆层的优点。它比化学镍/浸金(ENIG)有更好的可焊接性和焊接可靠性。化学镍/化学钯/浸金表面涂(镀)覆层应该是有发展前景的。     

化学镍金工艺中金剥落问题的探讨

化学镍金工艺能够有效的保护导电和焊接表面而被广泛的应用于PCB行业.然而,针对该工艺的品质保证绝非易事.化学镍金工艺受药水等因素的影响,在品质上容易会出现甩金、渗镀等不良问题.本文利用SEM、EDS分析手段对化学镍金工艺中的甩金问题进行了分析探讨.结果发现:甩金处镍层被腐蚀而形成空洞,EDS分析发现镍层中含有铜元素.这很有可能是金缸受到污染,镀液中存在一定含量的Cu2+,镍层与Cu2+发生自发的置换反应置换出铜而沉积在镍层上面,从而腐蚀镍层形成大量孔洞,使之与金层的结合力下降,导致化学镍金后甩金.     

电镀镍金工艺中渗镀问题的探讨

在PCB行业产品的最终表面处理显得至关重要，其不但影响产品的最终外观，而且影响对下游装配的可靠性及可操作性。目前在PCB行业，最终处理方式多种多样，各种方式的特点也各有千秋，常见有热风整平、化学镍金、电镀镍金、有机保焊剂（OSP）、化学沉银等，电镀镍金工艺因其良好的抗蚀性能、优良的可焊性并且兼容各种助焊剂，并能进行多次焊接，故已经得到越来越多的应用。     

乐思化学推出更环保的表面处理产品

近日,确信电子旗下乐思化学有限公司（Enthone Inc）隆重推介OrmeSTAR Ultra印刷线路板表面处理制程。该有机金属基、注册专利的纳米表面处理技术与化学沉镍／金（ENIG）及其他传统的金属表面处理制程相比,有效减少约90％的能量消耗,产生废水更少。与ENIG相比,OrmeSTARUltra可缩短75％操作时间,减少30％成本,且无“黑焊盘”风险。     

表面处理工艺的新发展简

文章简述了当下流行的有机涂覆（OSP）、化学镀镍浸金（ENIG）、化学镀镍镀钯浸金（ENEPIG）等表面处理技术的发展现状;并对浸银（IAg）、浸锡（ISn）和直接浸金（DIG）以及自组装单分子（SAM）等新工艺进行了简单讨论,并提出了一些降低工艺成本,改进技术,提高工艺可靠性的方法。     

印制线路板专用化学银表面处理的介绍

一、前言。印制线路板的最终表面处理是为保护铜线路，在零件组装焊接时，确保优良的焊接性为目的的一种做法。目前该做法主要包括以下一些工艺。HASL(HotAir Solder Leveler／喷锡)、OSP(Organic Solderability Preservative／耐热有机处理)、ENIG(Electroless Nickel and Immersion Gold／化学镍金)     

化学镍钯金表面处理工艺研究

采用扫描电子显微镜、润湿性、拔/撞锡球和打金线测试等分析手段,比较研究了四家化学镍钯金药水表面处理焊盘的焊接可靠性,同时比较研究了化学镍钯金表面处理和化学镍金表面处理焊盘的焊接可靠性差异.研究表明,化学镍钯金表面处理相对化学镍金表面处理可有效防止镍腐蚀(黑盘)缺陷引起的连接可靠性问题.     

无铅焊接的高耐热型OSP（有机保焊剂）技术

一、前言 面对无铅焊接时代的来临，各种取代传统的喷锡技术的表面可焊处理日趋发展。针对电路板板面焊盘、电镀通孔、IC载板腹底焊锡球焊盘而言，目前较为成熟、可上线量产者计有化学浸金ENIG、化学银Immersion Silver、有机保护焊剂OSP（Organic Solderability Preservatives）等。随着耐热型有机保焊剂的推出，OSP工艺的成本低、焊接强度高、可耐多次回焊处理、制作简单、废水处理容易等优点，日益获得业界重视及使用。[第一段]     

满足无铅化应用需要的热风整平技术

在PCB组件中，现在仍有超过60％的组件大量采用热风整平（HAL）工艺技术，但人们大多数的研究工作还是针对ENIG、OSP、浸银和浸锡等。无铅化热风整平PCB组件往往会被忽视。那么热风整平技术能否胜任无铅化应用的要求呢？丈章试图予以简单介绍。     

关于沉金镍腐蚀问题的研究

近年来,在无铅化的大背景下,PCB产业随之发生重大变化,表面处理工艺亦然如此。沉金工艺在诸多选择中可谓异军突起,因其固有的优点,其所占比重迅速提高,当前已经占据PCB总量的半壁江山。但沉金工艺又有其难以克服的顽疾,镍腐蚀问题就是一直困扰沉金的难题。关于镍腐蚀问题,国内外同行都做了许多方面的研究,尽管对镍腐蚀控制取得长足的进步,然而对此问题的认识、理解依旧不尽而一。实际生产中镍腐蚀问题仍是难以根除,沉金焊接性投诉还是时有发生。本章由生产实际出发结合相关实验测试,对镍腐蚀问题的关键影响因素进行了独特的探讨,分析其内在机理,以期能够帮助生产实际,为业内同行改善沉金工艺品质提供切实、有效的参考。     

浅析化镍金焊接后黑垫产生原因

化学沉镍金是一种能满足大多数的组装要求的可行的表面涂层,不仅具备抗氧化功能,并有平整的PAD表面,在电子\通讯领域有十分广泛之用途,但化镍金焊接后存在黑垫问题一直困扰PCB制造商、药水供应商以及下游SMT客户,目前PCB业界对化镍金焊接后黑垫产生原因比较模糊未有明确定义,本文将通过试验对比对化镍金板焊接后出现黑垫产生原因进行分析及探讨。     

Major factors to the solder joint strength of ENIG layer in FC BGA package

Since electroless nickel and immersion gold (ENIG) process was implemented as the surface finish of printed circuit board (PCB) substrate, there have been lots of reports on the brittle fracture between the Ni–P (phosphorous) layer and solder which results in the poor solder joint strength performance. Galvanic corrosion during immersion Au plating process and P-content in Ni–P layer were considered as major factors in the solder joint strength of ENIG layer in this investigation. The attempt to reduce the galvanic corrosion attack in Ni–P layer was made by changing immersion Au plating process to partial electroless Au plating process. Reducing the galvanic corrosion attack was proved to be effective to improve the solder joint strength of ENIG layer. Evaluation of the solder joint performances in variation with the thickness of the Ni layer leads to the conclusion that the thicker Ni layer has the better solder joint strength performances. The result also showed that higher P-content in Ni layer is more favorable to the solder joint strength.     

ENIG焊点的失效机理及镀层重工方法研究

采用显微形貌、微观结构和元素成分分析等物理分析方法,以不同类型的化镍浸金(electroless nickel/immersion gold,ENIG)基板为对象,分析了其焊点在不同情形下的失效模式和失效机理,阐述了"黑盘"缺陷的主要失效特征,研究了具有黑盘缺陷的化镍浸金基板的重工工艺.研究结果显示,Ni层断裂表面单一的高P含量或轻微Ni层腐蚀不能作为黑盘缺陷的唯一依据,已形成良好金属间化合物(intermetallic compound,IMC)层的Ni层腐蚀位置的焊接界面仍具有良好的机械结合强度,采用喷锡工艺(hot air solder level,HASL)对具有黑盘缺陷的化镍浸金基板进行重新处理切实可行.     

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.     

浅析V槽上金

无铅时代的到来,板材也正在逐步向无铅体系板材过渡,随之也带来一些负面影响;有铅板材开V槽后进行沉镍金,没有出现V槽上金;无铅板材开V槽后进行沉镍佥,断续出现V槽上金;从板材、刀具、沉镍金工艺三个方面实践论述V槽上金的原因分析及解决办法。     

Intermetallics Characterization of Lead-Free Solder Joints under Isothermal Aging

Solder interconnect reliability is influenced by environmentally imposed loads, solder material properties, and the intermetallics formed within the solder and the metal surfaces to which the solder is bonded. Several lead-free metallurgies are being used for component terminal plating, board pad plating, and solder materials. These metallurgies react together and form intermetallic compounds (IMCs) that affect the metallurgical bond strength and the reliability of solder joint connections. This study evaluates the composition and extent of intermetallic growth in solder joints of ball grid array components for several printed circuit board pad finishes and solder materials. Intermetallic growth during solid state aging at 100°C and 125°C up to 1000 h for two solder alloys, Sn-3.5Ag and Sn-3.0Ag-0.5Cu, was investigated. For Sn-3.5Ag solder, the electroless nickel immersion gold (ENIG) pad finish was found to result in the lowest IMC thickness compared to immersion tin (ImSn), immersion silver (ImAg), and organic solderability preservative (OSP). Due to the brittle nature of the IMC, a lower IMC thickness is generally preferred for optimal solder joint reliability. A lower IMC thickness may make ENIG a desirable finish for long-life applications. Activation energies of IMC growth in solid-state aging were found to be 0.54 ± 0.1 eV for ENIG, 0.91 ± 0.12 eV for ImSn, and 1.03 ± 0.1 eV for ImAg. Cu₃Sn and Cu₆Sn₅ IMCs were found between the solder and the copper pad on boards with the ImSn and ImAg pad finishes. Ternary (Cu,Ni)₆Sn₅ intermetallics were found for the ENIG pad finish on the board side. On the component side, a ternary IMC layer composed of Ni-Cu-Sn was found. Along with intermetallics, microvoids were observed at the interface between the copper pad and solder, which presents some concern if devices are subject to shock and vibration loading.