汉高发布更高生产效率电子组装材料

汉高电子（Henkel Technologies）推出的Multicore LF328免清洗无铅焊锡膏，及Loclite3548／3549可维修型CSP（芯片级封装）／BGA（球栅阵列）底部填充剂。Multicore LF328为不含卤素，免清洗无铅焊锡膏，专为细间距（0．5mm及0.4mmCSP）应用而设计，其低空洞焊点配方，可以非常有效地提高生产效率和产品的可靠性。该公司介绍，LF328具有很强的粘接力，     

铟泰公司在NEPCON深圳展出重大成果Indium8．9焊锡膏

Indium8．9免洗无铅焊锡膏是在空气中进行再流焊的焊锡膏,它的各方面性能比至今制造的任何无铅焊锡膏都好,用起来像是锡铅焊锡膏。     

铟泰公司推出卓越非凡的Indium8．9HFA无卤无铅锡膏

铟泰公司全新推出了其获得全球技术奖的卓越非凡的焊接材料Indium8．9HFA无卤无铅锡膏，Indium8．9HFA是使用在电子组装行业的第四代无卤素，无铅焊锡膏。由于工业界趋向于生产对环境无害的产品以及客户对在电子组装中使用无卤素材料的需求，     

新型焊接技术——免清洗焊剂和无铅焊锡膏

鉴于全球电子制造业正向着绿色生产的方向发展,美国、日本、欧洲等一些国家制定了专项法规,保护人居环境。为此,本文重点介绍了绿色焊接材料——免清洗焊剂和无铅焊锡膏的发展历程及其主要性能、特点以及存在的问题。阐述了国内外免清洗焊剂和无铅焊锡膏的研究现状及其在电子组装技术中的应用前景。     

焊锡膏黏度的影响因素研究

黏度是焊锡膏的主要性能指标之一。研究了助焊剂含量、焊锡粉种类、焊锡粉粒度、温度等对其黏度的影响。结果表明：助焊剂的质量分数在9％～12％时,焊膏使用效果较好;温度对黏度的影响很大,每升高1℃,黏度降低约10 Pa·s,其他因素也不同程度影响着焊锡膏的黏度。     

新品推荐——材料类

AQUANOX水基清洗剂,SN100C焊接材料系列产品,无铅焊锡膏Multicore LF600     

无铅焊锡丝用低含量改性松香型无卤助焊剂

针对现有无铅焊锡丝用助焊剂松香含量过高、含有卤素和残留过多等问题,研制了一种以DL-苹果酸等为主要活性剂组分,以有机溶剂和少量改性松香为载体的新型无铅焊锡丝用助焊剂。测试结果表明:本助焊剂不含卤素,焊后残留较少,表面绝缘电阻达3.6×108Ω,可焊性好,焊点光亮饱满,满足手工焊接的工艺要求。     

无卤焊锡膏对SMT清洗工艺的影响

根据欧盟的立法和法规,许多公司都努力在电子制造装配中放弃对卤素的使用,特别是溴化物和氟化物。最近Zestron首次就无卤焊锡膏在后续组装件清洗工艺中的影响进行了研究。本研究目的是为了找出替代性活化剂对后续清洗工艺可能造成的影响,确保在切换到无卤免洗焊锡膏后选择正,     

低银无铅焊膏板级封装工艺和焊点可靠性试验

针对低Ag无铅焊膏的市场需求,研究开发了一种适用于99.0Sn0.3Ag0.7Cu低Ag无铅焊膏用松香型无卤素助焊剂(WTO—LF3000),配制了相应的无铅焊膏(WTO—LF3000—SAC0307),并对其板级封装工艺适应性及焊点可靠性进行了考察,用测试后样品的电气可靠性作为接头可靠性评价条件。结果表明:所开发的低Ag无铅焊膏熔点和润湿性符合产品实际要求。配制的焊膏印刷质量良好,焊点切片观察其孔隙率<25%,满足行业标准IPC—A—610D之要求。样品分别经跌落、震动和温度循环试验后,无焊点脱落等现象,电气功能正常。     

Indium公司推出CW-801锡线焊接材料

CW-801是使用在电子组装行业的第三代无卤素,无铅含助焊剂芯的锡线。Indium公司继将它业界领先的无卤素及无铅技术应用于它的无铅锡膏产品以后,又将其应用于含助焊剂芯的锡线产品上。由于工业界趋向于生产对环境无害的产品以及客户对在电子组装中使用无卤素材料的需求,对无卤素产品的需求有了很大的增长。     

无铅焊膏的设计与展望

分析了无铅焊膏的构成和技术要求。对无铅焊膏用焊粉及助焊剂配方设计的现状进行了讨论,焊粉的成分多为Sn、Ag和Cu,粒度越来越多地采用20μm;助焊剂多为改性松香、有机酸活化剂等。展望了无铅焊膏的研究与发展趋势。     

无铅焊膏工艺适应性的研究

无铅焊膏是适应环保要求的一种绿色焊接材料,其质量的优劣直接决定着现代表面组装组件品质的好坏,为了检测与评价无铅焊膏的性能,研究影响其焊接可靠性的因素,实验研制了一种Sn-Ag-Cu无铅焊膏,并根据其本身的材料特性和实际工艺性能结合IPC的有关标准设计了整套试验,包括:焊膏黏度测试、塌陷实验、焊球实验以及铜板腐蚀测试等。研究结果表明:焊粉的质量分数与焊膏黏度呈正比关系;高温高湿环境下焊膏的可靠性降低,焊后残留物的腐蚀性增强;焊膏过多暴露在氧化环境中易引起焊料成球等焊接缺陷。     

有铅焊料焊接无铅BGA回流参数探索

航天电子产品尚未允许采用无铅焊接,而航天电子产品中采用的进口元器件多为无铅器件,因此需要对有铅焊料焊接无铅元器件进行研究。通过对无铅焊球和有铅焊料的焊接特性分析,设计数种回流参数,进行回流焊接试验,并对试验结果进行焊接分析,得出回流峰值温度为228℃~232℃,液相线(217℃)以上时间为50s~60s的回流曲线能较好完成有铅焊料对无铅BGA的焊接。     

Sn42Bi57Ag1无铅焊膏用活性剂的优化设计

针对Sn42Bi57Ag1无铅焊料开发出一种低温无铅焊锡膏,着重研究助焊剂中活性剂对焊锡膏润湿性能的影响。以铺展性能作为主要评价指标,通过回流焊接实验,对用于助焊剂的7种有机酸进行了筛选。最终选取了性能较好的甲基丁二酸、己二酸、水杨酸与丁二酸四种有机酸进行正交试验,通过量化分析选取正交试验水平,根据方差分析确定助焊剂中活性剂的最佳组合。结果表明:有机酸的复配能显著改善焊点铺展情况,当甲基丁二酸、己二酸、水杨酸与丁二酸质量比为2∶3∶5∶2时,Sn42Bi57Ag1无铅焊膏的润湿性能优异,焊点铺展率达86.52%。     

烷基羟基胺在无铅焊锡膏制备中的应用

探讨了一种无铅焊锡膏的制备方法.它是由Sn-Cu-Ag锡基合金粉和作为载体介质的焊剂均匀混合制成,其特点是在载体介质中加入羟基烷基胺;用羟基烷基胺作为活性催化剂,可得到高度可靠的焊锡膏,其可焊性不降低,在温度变化条件下不变质,活性提高,增加了无铅锡基合金的润湿性,提高了焊点的光亮度.     

A new bumping process using lead-free solder paste

In this paper, we report development of a new process for lead-free solder bumping with no flux residues, using stencil printing and hydrogen radicals, which can lessen both the environmental load and the manufacturing cost of solder bumping. In this process the reduction of the hydrogen radicals, instead of the flux, will eliminate the surface oxides of the stencil printed lead-free solder paste. Sn-3.0Ag-0.5Cu lead-free solder paste, which contains no residue flux was printed on an 8-in wafer. Hydrogen plasma was radiated for a minute during the reflow process, and the printed paste formed a bump. Reflow experiments without hydrogen radicals treatment were also carried out for comparison, where no successful reflow could be observed.     

Lead-free chip scale packages: assembly and drop test reliability

Three underfill options compatible with lead-free assembly have been evaluated: capillary underfill, fluxing underfill, and corner bond underfill. Chip scale packages (CSPs) with eutectic Sn/Pb solder were used for control samples. Without underfill, lead-free and Sn/Pb eutectic drop test results were comparable. Capillary flow underfills, dispensed and cured after reflow, are commonly used in CSP assembly with eutectic Sn/Pb solder. With capillary flow underfill, the drop test results were significantly better with lead-free solder assembly than with Sn/Pb eutectic. Fluxing underfill is dispensed at the CSP site prior to CSP placement. No solder paste is printed at the site. The CSP is placed and reflowed in a standard reflow cycle. A new fluxing underfill developed for compatibility with the higher lead-free solder reflow profiles was investigated. The fluxing underfill with lead-free solder yielded the best drop test results. Corner bond underfill is dispensed as four dots corresponding to the four corners of the CSP after solder paste print, but before CSP placement. The corner bond material cures during the reflow cycle. It is a simpler process compared to capillary or fluxing underfill. The drop test results with corner bond were intermediate between no underfill and capillary underfill and similar for both lead-free and Sn/Pb eutectic solder assembly. The effect of aging on the drop test results with lead-free solder and either no underfill or corner bond underfill was studied. Tin/lead solder with no underfill was used for control. This test was to simulate drop performance after the product has been placed in service for some period of time. There was degradation in the drop test results in all cases after 100 and 250 h of storage at 125/spl deg/C prior to the drop test. The worst degradation occurred with the lead-free solder with no underfill.     

Understanding the process window for printing lead-free solderpastes

Solder paste is primarily used as a bonding medium for surface mount assemblies (SMA) in the electronics industry, and is typically deposited using the stencil printing process. Stencil printing is a very important and critical stage in the reflow soldering of surface mount devices, and a high proportion of all SMA defects are related to this process. This is likely to continue with the drive toward the introduction of lead-free solder pastes. Work is continuing on the metallurgical properties of these lead-free solders, including solder joint strength and material compatibility. However, the initial challenge for the new Pb-free formulations is in achieving repeatable solder deposit from print to print and from pad to pad. To meet this challenge, new flux formulations are being developed. For a smooth transition to Pb-free soldering formulations, a proper understanding of the solder paste printing performance is necessary. The key parameters that affect solder paste printing have been identified and are the subject of numerous studies. In lead-free solder paste, the replacement of lead with other elements (including Bi, Cu) changes the density of this dense suspension. In this paper, we investigate the effects of printer parameters, i.e. squeegee speed and pressure (defined as the process window) on the printing performance of a variety of lead-free solder pastes. A three-level design of experiment on these factors was used. Comparisons are presented with lead-rich solder pastes. The metal content of the lead-free solders had a significant effect on the process window     

A reliability study of the lead-free solder connections of miniature chip components on hybrid circuits

The results of the influence of lead-free solder paste, design and process parameters on the attachment reliability of chip surface-mounted components (SMCs) on thick-film conductor pads are presented. The purpose of the investigation was to compare the quality of the soldered joints made with new solder pastes that do not contain lead with joints soldered with standard SnPb solders. The miniature zero-ohm chip resistors were soldered with selected lead-free solder pastes. The visual appearance of the solder joint according to the standards of lead-free soldered components was compared with components soldered with SnPb solders. On the test sample with soldered chip resistors connected in series, the solder-joint resistance was measured before and after temperature cycling. On the same test sample the solder-joint resistance changes were measured with impedance spectroscopy. After temperature cycling the damaged samples were analysed with SEM and EDS. The reliability test results after temperature cycling indicate two lead-free solder pastes that are the most convenient for chip-component soldering on thick-film conductor pads with the reliability of the joints being equal or better than solder joints with Pb-containing solder paste.