多层板制造中层压前铜的氧化工艺

多层电路板的成品率和最终可靠性的一个关键因素是防止由于高温引起的分层。温度的急剧变化以及由此而产生的内应力会造成内层铜与半固化胶片间分层。为保证铜线路与胶片间的结合力和耐热性,多层板生产采用氧化处理已有多年了。层压前铜表面氧化处理是给内层电路图形表面提供一氧化铜结构层。这样处理增加了层压后环氧胶片与铜箔层间的结合力。铜表面的钝化以及因为氧化铜使铜与环氧胶片接触面加大,促使了结合力的改善。对铜与     

印制电路板铜线路化学沉积NiCr合金表面结合力增强研究北大核心CSCD

通过对化学镀铬镍磷合金工艺的研究,在印制电路铜板上通过Ni的催化作用施镀一层铬或者含铬合金,改善印制电路铜线路板表面金属性质,提高印制电路铜板与PI覆盖膜之间的结合力。对化学沉积NiCr合金的速率和覆铜层压板的结合力进行系统分析确定合金最佳沉积参数。结果表明:化学沉积NiCr合金最佳实验条件为:温度85℃、时间20min、0.05mol/L硫酸镍、0.15mol/L三氯化铬。最佳实验条件下的合金镀层含铬量为8.85%(摩尔分数),与PI的线结合力为0.96N/mm,相比无NiCr合金层提高了12%。     

无胶单面挠性覆铜板与不流动粘结片结合力的考察

文章对刚挠结合印制板用无胶单面挠性覆铜板与不流动粘结片的结合力进行了考察,结果表明增加PI表面粗糙度和减小PI表面接触角可以提高结合力,但一般不大于0．6N／mm;对PI表面进行等离子处理可以将结合力提高到客户要求的大于0．8N／mm;而提高无胶单面挠性覆铜板与不流动粘结片结合力的最有效的方法是使用高锰酸钾溶液对PI进行表面处理,在合适的条件下,结合力可达到1．15N／mm。     

新产品与新技术(74)

低粗化度高结合力和绿色环保的化学镀铜工艺Atotech德国公司和日本公司开发出PCB生产用的低粗化度高结合力和绿色环保的化学镀铜药水:CovaBondTM和Printoganth FFS,适合于半加成法加工10 m以下线路的高密度IC封装载板。CovaBond TM是分子界面技术,用于绝缘树脂化学沉铜前处理。CovaBond TM工艺是经过喷淋、烘烤、氧化、清除过程,达到去除钻污和产生增强结合力的低     

超高导热金刚石铜复合材料在GaN器件中的应用

金刚石铜具有高导热率和低膨胀系数,可用于大功率芯片的散热热沉.未做处理的金刚石表面非常光滑,不易附着其他金属,由于金刚石性质非常稳定,不容易被强酸和强碱进行表面处理.采用JG-01金刚石铜粗化处理液对金刚石进行粗化处理,而对铜无损伤,提升了金刚石表面结合力.金刚石铜镀层对金锡(AuSn)和锡铅(PbSn)焊料的润湿性满足GJB548B-2005要求.GaN功率放大器芯片采用金刚石铜热沉比铜钼铜热沉结温可以降低12℃.金刚石铜载板镀层润湿性良好,焊接后芯片底部的空洞率不大于3％,热沉焊接后空洞率不大于5％,满足高功率芯片散热要求.按照产品环境适应要求,对GaN功率放大器做了高低温冲击和机械振动两种环境筛选实验,最终满足可靠性考核要求.     

超粗化工艺的优势及其实际应用所面临的挑战及解决

超粗化作为一种提高铜面粗糙度的工艺,常用于阻焊油墨前处理,可提高铜面与阻焊油墨的结合力,以防止表面处理后出现掉阻焊油墨现象。随着线路精细化要求越来越高,对铜面与干膜的结合力提出更高要求,超粗化工艺逐渐被引入线路制作前处理。本文简要介绍了超粗化应用于线路制作前处理在结合力等方面的优势,在生产实践中,透过干膜前处理引入超粗化工艺后出现的问题,探讨其根源,并提出改善措施,为后续厂商引入该工艺提供借鉴。     

一种超粗化表面处理用于改善沉锡脱油的工艺探讨

沉锡工艺是一种代替传统热风整平的新型环保工艺,但沉锡工艺中的脱油问题一直是难以解决的问题,现通常方法是使用专用耐沉锡油墨或前处理使用超粗化药水处理板面,提高油墨和铜面的结合力,前两种方法的生产成本大大升高;本文根据现有的前处理方式,实验出适合沉锡使用的阻焊前处理方式,并列举该方式的具体应用。     

PI调整液除去挠性多层板钻污的工艺参数优化

挠性多层线路板已经厂泛应用在通信、航空航天等领域。但是随着板厚／孔径比的增加，孔金属化工艺越来越难，去钻污不净，沉铜不良，造成产品合格率大大下降。本介绍了挠性板生产的去钻污工艺。通过正交实验方法研究了孔壁凹蚀量与PI调整剂含量、添加剂含量、溶液温度、时间的关系，优化了PI调整液的工艺条件。结果表明：在PI调整剂含量400ml／L、添加剂含量40g／L、时间3min、温度45℃条件下去钻污结果最好。该法应用在2—4层线路板中，获得的孔壁干净，凹蚀量在13μm左右，沉铜层附着力好，大大提高了产吊合格率。     

LS-DCL-1型印制板自动沉铜生产线

引言:化学沉铜是印制板生产中极为重要的一环。沉铜层的质量直接影响着印制板的质量。以前我们公司的印制板生产从沉铜前处理到沉铜一直采用手工操作,工人劳动强度大,工艺参数不易控制,使得印制板质量难以保证。为了改变这种状况,我们通过一年的时间,研制出了一条自动沉铜生产线。它将沉铜前处理和沉铜工艺融为一体,既提高了效率,又改善了印制板质量。本文就该系统的组成和电控原理作一简单介绍。     

5G用印制板低粗糙度导体的结合力挑战

文章评述了导体表面粗糙度对高频化信号传输的影响.提出加入偶链剂与铜表面进行化学的键合作用和树脂类聚合作用来提高低粗糙度铜表面与树脂类之间结合力方法,而采用氮杂环的咪唑类偶链剂是PCB制造中解决结合力的优选.     

聚酰亚胺无胶型挠性覆铜板的卷曲及其模型

用直接涂覆聚酰胺酸于铜箔的方法制作了聚酰亚胺无胶型挠性覆铜板,对无胶型挠性覆铜板发生卷曲的原因进行了分析推导,并建立了模型,用建立的卷曲模型公式成功地评估了挠性板的铜箔基材与覆于铜箔上的聚酰亚胺树脂的线性热膨胀系数之间的差值。文章还就聚酰亚胺的化学结构、聚酰亚胺薄膜的厚度及聚酰胺酸酰亚胺化工艺对卷曲程度的影响进行了初步分析和探讨。     

一种挠性印制电路基板的研制

以脂肪族二胺、芳香杂环二胺和芳香四羧酸二酐或芳香四羧酸二酐、芳香族二胺为原料,N-甲基吡咯烷酮为溶剂,合成两种聚酰胺酸。逐层涂覆,制备了表面为热可塑聚酰亚胺的三层聚酰亚胺复合膜,与铜箔热压复合制备了双面覆铜挠性印制电路基板。热塑性聚酰亚胺胶的玻璃化转变温度为133℃,三层聚酰亚胺复合膜的结晶熔融温度为222℃。该挠性印制电路基材平均剥离强度为7.1 N/cm。     

Copper/Polyimide Heterojunctions: Controlling Interfacial Structures Through an Additive‐Based,All‐Wet Chemical Process Using Ion‐Doped Precursors

Heterojunctions comprising copper thin films and polyimide underlayers are exploited as an important system for generating flexible microelectronic circuit elements. A fully additive‐based chemical method that allows metallization of polyimide films with copper by the in situ reduction of copper ions doped in surface‐modified polyimide precursors is reported. It is shown that dimethylamine borane is a good reducing agent for copper ions initially complexed with carboxylate anions in the hydrolyzed polyimide layers. This reduction allows diffusion of copper ions towards the film surface to form copper thin films, and simultaneously controls the fabrication of interfacial microstructures between the copper and underlying polyimide. The formation of copper thin films and composite layers is elucidated by glow‐discharge optical emission spectrometry depth profiling, scanning electron microscopy, and cross‐sectional transmission electron microscopy studies, and it is shown that the final microstructure at the copper/polyimide interface is dependent upon experimental variables: a larger amount of copper ions incorporated into the modified layers and a higher reduction rate result in the formation of a granular layer containing smaller copper nanoparticles near the film surface. The granular layers thus formed are found to play a critical role in achieving strong adhesion between metal thin films and the substrate, owing to the increased contact area and hence the increased work of adhesion between them. These results have important implications for realizing a novel adhesion scheme between deposited metals and underlying dielectrics based on nanoscale interlocking through metal nanoparticles.     

Metal Conductive Surface Patterning on Photoactive Polyimide

Current fabrication methods for metal interconnects and contacts are generally based on conventional photoresist fabrication procedures that require expensive equipment and multiple material/time‐consuming steps. In this work, a photopatternable polyimide is synthesized via the copolymerization of a functional diamine monomer with a 1,4‐dihydropyridine side‐chain which can decompose under UV irradiation into a pyridine group—a promising ligand for palladium ions. After the absorption of palladium ions, the electroless copper plating is carried out to form metal patterns of copper. Copper patterns with smooth boundaries are confirmed by scanning electron microscope and atomic force microscope. Robust interfacial bonding between the copper and the polyimide film is evidenced by Scotch tape adhesion tests. The photopatternable polyimide has the advantages of low Pd consumption, easy operation without expansive equipment. The linear thermal expansion coefficient of the photopatternable polyimide remains close to the one of copper wire, demonstrating the adaptability of the photopatternable polyimide for integrated circuit application. This work presents the approach of (i) the synthesis of a novel photopatternable polyimide and (ii) its application for making flexible conductive metal structures and patterned metal interconnects, which can be expected to have tremendous potential in the field of flexible electronics.     

钛酸钡改性及其聚酰亚胺复合材料的性能研究

采用化学还原法在直径100 nm的钛酸钡表面沉积直径约5~20 nm的铜纳米颗粒,分析了BaTiO3-聚酰亚胺复合材料的介电性能和作用机理。研究结果表明:铜纳米颗粒通过化学键与钛酸钡表面的晶体结构结合在一起,与聚酰亚胺组合成两相复合材料,这有别于BaTiO3/导电粒子/聚酰亚胺三相复合材料。另外,虽然铜纳米颗粒有部分被氧化,导电性能降低,但改性后的BaTiO3-聚酰亚胺的复合材料还是具有低损耗、高介电的性能,充分说明了这种新型的两相复合材料能够实现高介电、低损耗的目标。     

Optimal design toward enhancement of thermomechanical reliability of polyimide layers in a flip-chip-on-lead-frame dual flat no-leads package with copper pillar bumps

Thermomechanical reliability of polyimide layers in a flip-chip-on-lead-frame dual flat no-leads package subjected to thermal cycling test condition was studied by the finite element method and the Taguchi method. Different control factors were considered for optimal design toward enhancement of the thermomechanical reliability of polyimide layers, including diameter of the Cu pillar bumps, polyimide opening, and size of the Al pad. Conforming to design rules, the largest Al pad diameter, the smallest size of bump diameter, and the largest polyimide opening were found to be beneficial to enhance the thermomechanical reliability of polyimide layers. And the optimal design was experimentally verified.     

Laser-assisted via hole metallization in PCB materials

A novel via hole metallization method is presented, where the vias are drilled in polyimide/copper (PI/Cu) flexible printed circuit boards (PCBs) using KrF excimer pulses, and then pre-metallized using a scanned Ar⁺ laser. In the premetallization step, a thin (20–50 nm) and narrow (2–10 μm) palladium layer is deposited on the polyimide-covered side of the PCB and on the wall of the vias using the laser-induced chemical liquid-phase deposition method. After the pretreatment, the Pd covered holes are immersed into a Cu electroless plating bath. Plated copper vertical and horizontal interconnects are analyzed by optical microscopy, focused ion beam, profilometry and resistivity measurements. The results show that the copper deposits formed on the pre-metallized surface of PCBs have high chemical purity, excellent adhesion and almost bulk conductivity, but, so far, due to unclear reasons, high through hole resistance.     

Fabrication and adhesion strength of Cu/Ni-Cr/polyimide films for flexible printed circuits

The adhesion strength of a Cu/Ni-Cr/polyimide flexible copper clad laminate (FCCL), was evaluated according to the thickness of the Ni-Cr (Ni:Cr = 95:5 ratio) seed layer using the 90° peel test. The changes in the morphology, chemical bonding and adhesion properties were characterized by SEM, AFM and XPS. The peel strength of the FCCL increased with increasing thickness of the Ni-Cr seed layer, due to the increase in the ion bombardment caused by the higher power used in the Ni-Cr sputtering process. This increase in the FCCL peel strength was attributed to the lower proportion of C-N bonds and higher proportion of C-O bonds in the polyimide surface. The adhesion strength between the metal and polyimide was mostly attributed to the chemical interaction between the metal layer and the functional groups of the polyimide.     

Ultra-violet direct patterning of metal on polyimide

Copper micro-patterns have been fabricated on polyimide substrates by ultra-violet (UV) lithography without the use of evaporation techniques or photoresist materials. Using a photoreactive polymer-reducing agent, methoxy poly(ethylene glycol) (MPEG) as a thin film coating, a novel light-directed metal-patterning method in air atmosphere was realised. The interaction of UV light and MPEG in ethanol film enabled the photoreduction of mobile silver ions available within the surface-modified polyimide substrates. The silver nanoparticle patterns thus formed served as active catalytic seed layers for subsequent electroless copper plating. Narrow copper tracks with low resistivity close to that of bulk copper were achieved. MPEG is a nontoxic, low cost and commercially available polymer which can be easily spin-coated and washed off after the patterning process. These attractive properties of MPEG together with its photoreactivity provide great potential for developments of UV direct-metallisation methods.     

一种MEMS复合牺牲层工艺的研究

以MEMS滤波器中的MEMS开关牺牲层的工艺为例,通过同时运用聚酰亚胺和正胶作为牺牲层材料的方法,避免了牺牲层单独使用聚酰亚胺做材料难于去除,或单独使用光刻胶做材料,叠层旋涂光刻胶时会出现龟裂的缺点.改善了牺牲层固化和刻蚀的效果,减小了刻蚀的时间.此研究应用在表面微细加工工艺中,对MEMS加工工艺具有一定的参考价值.