材料

Indium Corporation Nf260不流动底部填充胶,确信电子ALPHA OM-338 Pt新型无铅焊膏--提供同类产品中最佳的探针可测试性,朝日化学及锡焊公司：无铅焊膏,无铅波峰焊助焊剂,     

材料类

Kester 295无铅无卤素免洗助焊剂；全新ALPHA PoP-959无铅焊膏；新型OSP有机保护剂U-108；Xf3新型无铅焊膏。     

无铅焊膏用松香型助焊剂活化点的研究

论述了无铅焊膏用松香型助焊剂活化点研究的重要性,探讨了活化点的物理意义及其影响因素.实验结果表明,无铅焊膏用松香型助焊剂的活化点就是松香树脂酸在有机溶剂中电离溶解平衡常数的升温曲线的拐点,松香种类对其活化点没有影响,决定其活化点的影响因素是松香本身的物理化学性质、溶剂以及有机酸的电离常数.     

无铅焊膏用助焊剂的制备与研究

无铅焊膏用助焊剂需要一定的黏性,选择有机酸和有机胺混合作为活性物质,配合一定量的松香配制出一种助焊剂。通过控制助焊剂中松香的含量,降低不挥发物的含量,减少残留物对元器件的腐蚀。依据标准对所配制的助焊剂进行了性能测试,并与一种松香含量较高的助焊剂比较。结果表明:助焊剂的松香含量降低约10%,在260℃焊接后不挥发物含量降低了近6%,黏度较好,无卤化物,无毒,环保,符合焊膏用助焊剂的要求。     

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。     

BGA无铅焊点零空洞缺陷控制研究

在无铅BGA封装工艺过程中,通过不同组分的BGA焊球合金与焊膏合金组合焊接、焊膏助焊剂活性剂不同配比及其不同再流焊接条件等实验,对焊料合金和助焊剂配比、再流焊接峰值温度、再流保温时间等参数变化,以降低BGA焊点空洞缺陷进行了研究。结果表明选用相同或相似的BGA焊球和焊膏合金组合焊接、选用活性强的焊膏、选择焊接保温时间较长均有助于降低BGA焊点空洞缺陷产生的几率和空洞面积,BGA焊点最佳再流焊接峰值温度为240℃,当峰值温度设置为250℃时,BGA焊点产生空洞缺陷几率会比240℃高出25%～30%。     

日本斯倍利亚推出新型无铅波峰焊接助焊剂

全球市场先进焊接与铜焊供应商日本斯倍利亚股份有限公司推出NS—F850无铅波峰焊接松香助焊剂。NS—F850可确保为所有PCB与元件基底提供卓越润湿效果,从而最大程度填充通孔。它还便于焊料排出,从而最大程度减少锡桥及锡尖。NS—F850是用于无铅波峰焊接的理想助焊剂。此外,松香助焊剂可确保完全实现SN100C无铅焊膏的潜在可靠性。     

SnAgCu无铅焊膏用活性物质研究

以SnAgCu无铅焊膏铺展性能为主要指标,通过回流焊接实验,对用于助焊剂的17种有机酸活性物质进行了筛选。选取两种性能较好的有机酸配成复合活性物质,并对该活性物质的组成进行优化。用湿热试验测试焊后残留物的腐蚀性。结果表明:以羧基官能团比例为3:7的丁二酸和一元酸A混合物作为活性物质,并添加质量约0.66%的乙醇胺调整酸度,得到了pH值约为3的助焊剂;此助焊剂性能优良,可使焊点铺展率达到84%。使用含有此助焊剂的焊膏,采用回流焊接工艺在PCB板上贴装片式元件,所得焊点光亮饱满,且焊后残留物无腐蚀性,可以实现免清洗。     

密间距WLCSP的无铅／锡铅组装及可靠性

把密间距晶圆级CSP（WLCSP）组件当作倒装片并采用助焊剂浸渍法进行组装，越来越吸引厂商选用以取代传统的焊膏印刷组装。本文将讨论0．4mm和0．5mm密间距无铅WLCSP的焊膏印刷和助焊剂浸渍组装法，及其相应的组装效果和热循环可靠性。此外也对在相同条件下采用SnPb焊料组装相同组件的结果进行了可靠性比较。     

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。     

Ethylene glycol ether free solder paste development

There are growing concerns in the electronics industry for not only finding alternatives to lead but also other potentially hazardous materials as well. This paper summarizes the development of ethylene glycol ether (EGE)-free solder flux for the formulation of lead-free solder pastes. Replacing the toxic components in the flux was only the first challenge, the criteria of commercially proven pastes also had to be met. Both commercial and in-house solder paste formulations were evaluated for printability, reflow, wetting, flux residue removal, and solder void characteristics. Two critical issues, solder bump boids and flux residue removal, were identified and associated with the high temperature reflow of Pb-free pastes. These issues were not effectively improved by the existing commercial EGE-free solder pastes. New solder paste formulations were developed utilizing alternative chemistry than those found in traditional solder paste fluxes. These pastes, some, of which are also water soluble, reduced void frequency and size by more than 4x as compared to vendors' pastes. Solder bump height uniformity of 135 4 m within each die was consistently achieved. Thermal-mechanical reliability tests were performed on various lead-free solder alloys using the new flux formulations. The reliability of flip chip assembled DCA on organic boards with both OSP/Cu and Cu/Ni/au pad metallizations were comparable to eutectic Sn63Pb37 bumped assemblies using commerical pastes.     

0.5mm间距CSP/BGA器件无铅焊接工艺技术研究

芯片级封装器件因其小尺寸、低阻抗、低噪声等优点广泛应用于电子信息系统中.从器件封装、印制板焊盘设计、焊膏印刷、贴装以及回流焊接等方面探讨了0.5 mm间距CSP/BGA器件无铅焊接工艺技术.     

On the absence of the β to α Sn allotropic transformation in solder joints made from paste and metal powder

Until July 2006, most solder joints in the electronics industry were made of the alloy 63Sn37Pb or 62Sn36Pb2Ag. After this date, the European environmental Restriction of Hazardous Substances directive (RoHS) forced many manufacturers to use Pb-free alloys. These substitutes for SnPb are Sn-rich alloys (over 90% Sn) of various compositions. Below 13.2 °C, Sn potentially transforms into a different phase. This occurs with catastrophic effects, as the transforming material becomes extremely brittle and falls apart. The purpose of this paper is to investigate if this allotropic transformation also occurs in samples prepared from solder paste or metal powder. This work compares the transformation propensity of samples prepared with bulk solder, solder paste, and tin powder. Different conditions and geometries are used in the investigation and experiments with both commercial and specifically prepared solder pastes are carried out. Samples prepared from bulk solder transform into the α phase as expected, whilst samples prepared from solder paste and tin powder do not transform. The residual organic compounds from the flux are believed to be responsible for this behaviour. The tin oxide (SnO₂) retained in the bulk after melting could also play a role. This paper shows, for the first time, a relationship between the ability of tin to transform and the nature of the starting material and in particular that the tin β/α allotropic transformation does not occur when samples are prepared from paste or powders. The new lead-free alloys can therefore be used with more confidence in mission-critical applications.     

BGA混合焊点热循环负载下的可靠性研究

焊料从有铅向无铅转换中,不可避免会遇到二者混合使用的情况,有必要对生成的混合焊点进行可靠性研究。通过对不同工艺参数下形成的混合焊点和无铅焊点进行了外观检测、X射线检测和温度循环测试。结果显示,只要工艺参数控制得当,混合焊点是可行的。在焊球合金、焊料合金、峰值温度、液相线以上时间和焊接环境五个关键因素中,前四项对焊点可靠性比较重要,焊接环境对焊点可靠性的影响不很显著。     

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.     

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。     

Self-assembly of Sn-3Ag-0.5Cu Solder in Thermoplastic Resin Containing Carboxyl Group and its Interconnection

The self-assembly of solder powder on pads is attractive as a novel interconnection method between chips and substrates. However, the solder used in this method is limited to Sn-58Bi and Sn-52In. In contrast, Sn-3Ag-0.5Cu has been relatively less studied despite its wide use as a lead-free solder in assembling semiconductor packages. Hence, here, polymeric materials incorporating Sn-3Ag-0.5Cu solder powder were investigated for the self-assembly of the solder on pads at temperatures up to 260°C in a lead-free reflow process. The self-assembly of the solder was observed with an optical microscope through transparent glass chips placed on substrates covered with the polymeric materials incorporating the solder powder. Differential scanning calorimetry measurements were performed to confirm the behaviors of the reaction of the resins and the melting of the solder. When epoxy resin with a fluxing additive was used as a matrix, self-assembly of the solder was prevented by the cross-linking reaction. Conversely, when thermoplastic resin containing carboxyl groups was used as a matrix, the self-assembly of solder was successfully achieved in the absence of fluxing additives. The shear strength of interconnection using reflowfilm with lamination was sufficient and significantly increased during the reflow process. However, the shear strength of the reflowfilm showed cohesive failure, possibly because of the brittle intermetallic compounds (Ag₃Sn, Au₄Sn) network in bulk was lower than that of conventional solder paste that showed interfacial failure after the reflow process with a rapid cooling rate.     

低卤素无铅焊锡膏研制

针对当前高卤素无铅焊锡膏腐蚀性较大的缺点,研制出一种低卤素无铅焊锡膏,并测试其主要性能参数,如黏度、润湿性、卤素含量、坍塌性等。结果表明:该焊锡膏的黏度为195Pa·s,卤素质量分数为0.023%,其他性能符合IPCJ—STD—005等行业要求。