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《电子元件与材料》2016,(6):98-102
基于内聚力模型,提出一种用于振动载荷下特种设备中电路板级焊点疲劳寿命预测的介观尺度模型。将单调载荷与振动周期载荷相结合,建立焊点累积损伤参数来表征焊点的剩余疲劳寿命,利用焊点损伤累积率来表征焊点损伤演化规律。以Sn3.0Ag0.5Cu(SAC305)细间距无铅焊点为例分析了模型参数确定方法,并通过振幅为5 mm与10 mm的定频振动试验对模型的预测精度进行了验证,寿命预测结果误差小于10%。由于模型参数为焊点钎料累积塑性应变的固有函数,与焊点尺寸与几何形态无关,通过小样本试验,数据一经确定即可应用于同种钎料不同尺寸焊点在不同振动等级下的疲劳寿命预测,节约了时间与试验成本,该模型能为特种设备中的电子组件提供一种评估板级焊点疲劳寿命的简洁、实用方法。 相似文献
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为减小振动因素对产品失效的影响,改进PCBA组件的结构参数,提高PBGA(塑料球栅阵列)振动可靠性。采用有限元法,运用模态分析,得出结论:固支数目越多,焊点的振动可靠性越好。此外,利用随机振动模块,分析了板级振动条件下,焊点位置、焊点材料、PCB厚度、BGA焊点高度对可靠性的影响,并且利用焊点的疲劳寿命模型计算出关键焊点的疲劳寿命。结果表明:焊点最容易失效的位置位于焊点的顶角处;相比于Pb90Sn10、Sn63Pb37、Mix、SAC387这四种材料,SAC305的疲劳寿命最高;PCB的厚度和焊点的疲劳寿命成正比;焊点高度和焊点的疲劳寿命成反比。 相似文献
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基于正交试验法研究不同温度与振动耦合条件下的板级焊点失效行为与模式,采用L9(34)混合水平正交表设计了不同温度(T)、加速度功率谱密度(PSD)与频率(V)条件下的加速寿命试验,结果表明三者对焊点可靠性影响程度为T>PSD>V,且温度是影响焊点失效模式的主要因素,随温度的升高,焊点裂纹逐渐从近封装侧的界面金属化合物(IMC)层向钎体内部扩展,焊点失效模式从脆性断裂向韧性断裂演化.基于焊点失效数据分析,发现焊点疲劳寿命对数值与PCB板背侧最大应变范围存在关联关系,并采用多项式拟合的方法建立了焊点疲劳寿命模型,拟合结果显示,该模型能较好的评估温度与振动耦合条件下的焊点寿命,预测精度较高. 相似文献
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PCBA结构参数与振动谱型对BGA焊点疲劳寿命的影响 总被引:1,自引:1,他引:0
为获得印制电路板组件(PCBA)的板厚、芯片布局等结构参数和随机振动谱型(功率谱密度,PSD)变化对球栅阵列(BGA)封装芯片焊点振动疲劳寿命的影响,利用HYPERMESH软件建立了带BGA封装芯片的PCBA三维有限元网格模型,并采用ANSYS软件对PCBA有限元模型进行了随机振动响应分析。结果表明,随着PCB厚度增加,BGA焊点振动疲劳寿命呈现明显提升的趋势,当PCB厚度由1.2 mm增加到2.2 mm时,BGA焊点振动疲劳寿命N由45363大幅增加到557386;合理的芯片安装间距能够明显增加焊点振动疲劳寿命,特别是当芯片安装在靠近固定约束并处于两个约束对称中间位置时;当PCBA的第一阶固有频率位于随机振动谱最大幅值对应的频率区间时,BGA焊点的振动疲劳寿命会明显降低。 相似文献
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电迁移致无铅钎料微互连焊点的 脆性蠕变断裂行为 总被引:4,自引:0,他引:4
研究了电迁移条件下不同电流密度(0.8~1.27×104A/cm2)和通电时间(0~96 h)对无铅钎料模拟微互连焊点的蠕变断裂行为的影响.研究结果发现,电迁移作用加速了焊点的蠕变断裂过程,随着电迁移通电时间的延长及电流密度的增加,其蠕变应变速率显著增大,而蠕变寿命逐渐缩短;电迁移还导致焊点蠕变断裂机制发生明显变化,在高电流密度或长时间通电的电迁移后,微互连焊点在服役条件下会发生由延性断裂向脆性断裂的转变. 相似文献
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《电子元件与材料》2017,(11):83-90
采用有限元分析、蒙特卡罗模拟和概率分析相结合的方法,研究了BGA(Ball Grid Array)封装焊点内部孔洞对焊点的热疲劳可靠性的影响规律。先用X-Ray检测仪对BGA封装进行无损检测,获得焊点内部孔洞尺寸及其分布规律,然后通过有限元软件建立BGA封装模型进行计算分析,针对危险焊点进行参数化建模,建立了含孔洞尺寸及位置呈随机分布的焊点有限元分析子模型。通过后处理获取塑性应变能密度作为响应值,构造随机孔洞参数与塑性应变能密度的代理模型,并运用蒙特卡罗随机模拟方法,研究了孔洞对焊点热疲劳可靠性的影响规律。结果表明,除了位于焊点顶部区域的小孔洞以外,大部分孔洞的出现都会提高焊点的热疲劳可靠性。 相似文献
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《电子元件与材料》2018,(3):64-67
为了获得微量元素Ag、Bi、Ni对无铅微焊点固-液界面扩散行为的影响规律,以低银无铅微焊点Cu/SAC0705+Bi+Ni/Cu为主要研究对象,并与Cu/SAC0705/Cu及高银钎料Cu/SAC305/Cu进行对比。研究了三种成分焊点固-液扩散后界面IMC的生长演变行为,并分析了Ag、Bi、Ni对微焊点固-液扩散的影响。研究结果表明:钎料中微量元素Ag、Bi、Ni添加可细化界面IMC晶粒,对提高界面强度有利。长时间的固-液时效过程中,界面IMC的生长速率主要取决于界面IMC的晶粒尺寸。Cu/SAC0705+Bi+Ni/Cu焊点界面IMC晶粒尺寸最小,界面IMC生长速率最大,为11.74μm/h。Cu/SAC0705/Cu焊点界面IMC晶粒尺寸最大,界面IMC生长速率最慢,其数值为1.24μm/h。 相似文献
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New lead-free,Sn-Zn-In solder alloys 总被引:11,自引:0,他引:11
In view of the need for a lead-free, drop-in replacement for the widely used 40Pb-60Sn near-eutectic solder (m.p. ~183°C),
new Sn-Zn-ln based alloys with substantially the same melting point have been developed. It is shown that the alloying additions
of In to the Sn-Zn binary system result in a suppression of the melting point to 175-188°C, and at the same time significantly
improve the wetting characteristics. While a relatively active flux may be required for good solderability in air atmosphere,
the recent manufacturing trend of using inert atmospheres is likely to allow acceptable manufacturability using less active
fluxes in the future. 相似文献
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John P. Ranieri Frederick S. Lauten Donald H. Avery 《Journal of Electronic Materials》1995,24(10):1419-1423
The aspect ratio (joint area/joint thickness) of thin (0.001-0.006 in.) surface mount solder (60S-40Pb) joints plays an important
role in determining the mechanical properties and fracture behavior of the joints. This study demon-strates that plastic constraint
of a large aspect ratio 60Sn-40Pb solder joint can develop triaxial (hydrostatic) stresses several times greater than the
average tensile strength of the bulk solder material. A four to sixfold increase in average joint stress and up to a tenfold
increase in peak stress was measured on joints with aspect ratios ranging from 400 to 1000. Although a direct relationship
of the aspect ratio to the average tensile stress is shown, as the Friction Hill model predicts, the observed stress increase
is not nearly as high but proportional to the classical prediction. This is attributed to the existence of internal defects
(oxide particles and micro-voids) and transverse grain boundaries which fail producing internal free surfaces. Thus, the actual
aspect ratio is thickness/d2, where d equals the distance between internal surfaces. The fracture of these constrained joints was brittle, with the separation
occurring between a tin-rich copper tin intermetallic at the interface and the solder matrix. Voids within the solder joint
are shown to relieve the plastic constraint and lower the average tensile stress of the joint. The Friction Hill model may
play an important role in explaining the small percentage of atypical solder joint failures which sometimes occur on electronic
assemblies. In particular, the sudden failure of a thin joint in a strain controlled environment may be attributed to the
development of a large hydrostatic stress component. Therefore, a flaw free, plastically constrained joint which develops
a high stress state will be a high risk candidate for failure. 相似文献
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F. Guo J. Lee J. P. Lucas K. N. Subramanian T. R. Bieler 《Journal of Electronic Materials》2001,30(9):1222-1227
The creep deformation behavior of eutectic Sn-3.5Ag based Ni particle rein forced composite solder joints was investigated.
The Ni particle reinforced composite solder was prepared by mechanically dispersing 15 vol.% of Ni particles into eutectic
Sn-3.5Ag solder paste. Static-loading creep tests were carried out on solder joint specimens at 25 C, 65 C, and 105 C, representing
homologous temperatures ranging from 0.6 to 0.78. A novel-design, miniature creep-testing frame was utilized in this study.
Various creep parameters such as the global and localized creep strain, steady-state creep rate, onset of tertiary creep and
the activation energy for creep were quantified by mapping the distorted laser ablation pattern imprinted on the solder joint
prior to testing. The Ni-reinforced composite solder joint showed improved creep resistance compared to the results previously
reported for eutectic Sn-3.5Ag solder, Sn-4.0Ag-0.5Cu solder alloys, and for eutectic Sn-3.5Ag solder reinforced with Cu or
Ag particle reinforcements. The activation energy for creep was ∼0.52 eV for Sn-3.5Ag and Sn-4Ag-0.5Cu solder alloys. The
activation energies ranged from 0.55–0.64 eV for Cu, Ag, and Ni reinforced composite solder joints, respectively. Most often,
creep fracture occurred closer to one side of the solder joint within the solder matrix. 相似文献
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Hsiao-Yun Chen Chih Chen Pu-Wei Wu Jia-Min Shieh Shing-Song Cheng Karl Hensen 《Journal of Electronic Materials》2008,37(2):224-230
Eutectic Sn-3.5wt.%Ag alloy is one of the most promising lead-free solders in low temperature processes for wafer bumping.
Near eutectic composition of deposited alloy films could be readily acquired by pulse electroplating with a proper combination
of active ingredients including K4P2O7, KI, Sn2P2O7, and AgI, as well as polyethylene glycol (PEG), with molecular weights of 200, 600, 2,000, and 4,000, as an inhibitive agent.
Pulse electroplating was carried out with current in alternating polarity to conduct electroplating and electropolishing sequentially.
As a result, alloy films with grains of less than 1 μm and uniform surface morphology can be obtained. The addition of PEG was necessary for the stabilization of the plating baths
to promote a wider process window for the desirable eutectic composition. Electrochemical characterization established that
PEG with molecular weight of 4,000 exhibited the strongest inhibition behavior. In contrast, PEG with molecular weight of
200 demonstrated the least interference. Energy dispersive X-ray and differential scanning calorimeter data confirmed the
formation of eutectic alloy as a function of deposition current density. X-ray diffraction results indicated that a biphasic
structures of β-Sn and ε-Ag3Sn was present in the as-deposited film. 相似文献
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L. Snugovsky C. Cermignani D. D. Perovic J. W. Rutter 《Journal of Electronic Materials》2004,33(11):1313-1315
Early studies of Ag-Sn and Cu-Sn binary alloys showed very low values, 0.04 wt.% for Ag and 0.0063 wt.% for Cu, for the solid
solubility of these elements in Sn at the eutectic temperature. In recent work on “as-cast” Sn-Ag-Cu solder alloys, much higher
values have been reported for the Ag and Cu content of the Sn phase. In the present study, wavelength dispersive x-ray microprobe
measurements made on a near-equilibrium sample confirmed the earlier solubility values. It was concluded that higher values,
some of which are reported in the current paper, represent nonequilibrium, supersaturated solid solutions. 相似文献
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C. Y. Liu Jian Li G. J. Vandentop W. J. Choi K. N. Tu 《Journal of Electronic Materials》2001,30(5):521-525
The wetting behavior of SnAg based Pb-free solders on Cu and Cu substrates plated with Au, Pd, and Au/Pd thin films have been
studied. The wetting angle and kinetics of interfacial reaction were measured. The Au-plated substrates exhibit better wetting
than the Pd-plated substrates. In the case of SnAg on Pd-plated Cu, SEM observation revealed that the solder cap was surrounded
by an innerring of Cu−Sn compound and an outer ring of Pd−Sn compound. This implies that the molten SnAg solder had removed
the Pd and wetted the Cu directly in the equilibrium state. The effects of pre-doping Cu in the SnAg solder on wetting behavior
were also investigated. We found that wettability decreases with increasing Cu content in the solder. We also observed that
the SnAgCu solders have a lower Cu consumption rate than the SnAg solder. 相似文献
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The creep behavior of In-Ag eutectic solder joints 总被引:7,自引:0,他引:7
The addition of 3 wt.% Ag to In results in a eutectic composition with improved mechanical properties while only slightly
lowering the melting temperature. Steady-state creep properties of In-Ag eutectic solder joints have been measured using constant
load tests at 0, 30, 60, and 90°C. Constitutive equations are derived to describe the creep behavior. The data are well represented
by an equation of the form proposed by Dorn: a power-law equation applies to each independent creep mechanism. Two parallel
mechanisms were observed for the In-Ag eutectic joints. The high-stress mechanism is a bulk mechanism with a thermal dependence
dominated by the thermal dependence of creep in the Inrich matrix. The low-stress mechanism is a grain boundary mechanism.
Results of this work are discussed with regard to creep behavior of typical eutectic systems. 相似文献