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In electric power transmission, copper and aluminum are mainly used as conductor materials. To improve the contact behavior, the contact surfaces of e.g. high-voltage switching devices are often coated with silver or nickel. Due to economic reasons, connecting conductors are usually uncoated. In that case, an electrical joint with only one coated contact partner is formed. With respect to the permissible...
Electroplated Ni/Au over Cu is a popular metallization for printed circuit board (PCB) finish as well as for component leads, especially for wire-bondable high frequency packages, where the gold thickness requirement is high (≥ 20 µinches) for wire bonding. This study examines the effect of redeposition of bulk AuSn4 IMC as a function of varying gold content (2–5 nominal weight-%) in the solder joint...
Since miniaturization of electronic devices makes the joint height of solder joints shrink to tens of microns. IMCs take noticeably high volume ratio in solder joints, which seldom happens in BGA or bulk solder joints. Growth of IMCs volume ratio will definitely affect mechanical integrities of micro-scale solder joints, which is rarely covered in pervious publications. In this paper, copper/SAC305/copper...
Joint properties of Au stud bumps joined with Sn-3.5Ag solder by flip chip bonding were investigated. Au stud bumps were bonded on SOP (solder on pad) at bonding temperature of 260°C and 300°C for 10sec, respectively. Aging treatment was carried out at 150°C for 100 and 300 hrs. After flip chip bonding, intermetallic compounds (IMCs) of AuSn, AuSn2, and AuSn4 were formed at interface between Au stud...
The interfacial micro structure and creep behavior of the single BGA structure Cu/Sn-3.0Ag-0.5Cu/Cu joint of different standoff height (i.e., solder volume) values and undergoing isothermal aging were studied by using the lap-shear test. The experimental results show that the thickness of the intermetallic compounds (IMC) layer at the solder/Cu interface increases with decreasing the standoff height...
The mechanical properties and interfacial microstructure of Cu/Sn3Ag0.5Cu3Bi0.05Cr/Cu (Cu/SACBC/Cu) and Cu/Sn3.0Ag0.5Cu/Cu (Cu/SAC/Cu) joints were comparatively investigated after isothermal aging at 85 °C, 120°C and 150°C for 24, 168, 500 and 1000 h, respectively. The mechanism of Bi addition affecting the intermetallic compounds (IMCs) growth was discussed. Results show that the tensile strength...
A new lead-free solder alloy Sn3Ag0.5Cu3Bi0.05Cr (SACBC) was prepared by adding 3.0 wt.% Bi and 0.05 wt.% Cr on the basis of the composition of Sn3Ag0.5Cu(SAC). The tensile strength and the growth behavior of the interfacial intermetallic compound (IMC) of SAC/Cu substrate and the SACBC/Cu solder joints during isothermal aging at 150°C for 0, 24, 168, 500 and 1000 hours were comparatively investigated,...
The influence of the standoff height, pad size and isothermal aging on the microstructure and shear fracture behavior of Cu/Sn-3.0Ag-0.5Cu/Cu BGA structured interconnects were investigated using the lap-shear test. The experimental results show that the thickness of intermetallic compounds (IMC) layer at the solder/Cu interface increases with decreasing standoff height of the joints. The size of Kirkendall...
In flip chip technology, Cu thin-film is a widely used under bump metallization (UBM). However, the major disadvantages of Cu UBM are fast consumption of copper, rapid growth of IMCs and easy formation of Kirkendall voids. Many efforts have been focused on suppression of Kirkendall voids which are detrimental to solder joints reliability in the microelectronics industry. In this study, a novel Cu(Mn)...
The formation and growth of intermetallic compounds (IMC) is a key factor to the reliability of soldering joints in modern electronic mounting and packaging industry. In this paper, by means of Olympus, scanning electron microscope (SEM) and Energy Dispersive X-ray (EDX) analysis methods, the morphology and growth mechanisms of IMCs between SAC305-xNi and Cu joint during soldering as well as aging...
Sn-Ag-Cu (SAC) solders are susceptible to appreciable microstructural coarsening due to the combined effect of thermal and mechanical stimuli during service and storage. This results in evolution of joint properties over time, and thereby influences the long-term reliability of microelectronic packages. Accurate prediction of this aging behavior is therefore critical for joint reliability predictions...
Demand for high speed, high density, small size, and multifunctional electronic devices has driven the development of 3D integration. Cu pillar bumps have received great attentions in ultra fine pitch 3D packaging. In this study, Sn-3.5Ag and Sn-58Bi cap bumps were fabricated on Cu pillar for fine pitch bonding of 3D packaging. Sn-Ag and Sn-Bi cap bumps with eutectic composition were fabricated with...
In the present study, the interaction between thin film Cu and non-eutectic Sn-In is studied. The effects of the bonding and aging temperature on microstructure, IMC formation and also shear strength are investigated by SEM/EDX, XRD and shear testing. The bonding mechanism is proposed based on the obtained results. The bonding mechanism is proposed to occur over 2 stages: (1) An increase in bonding...
In this work, the SAC solder joints with minor Mn or RE (rare earth) additions were bonded on the substrate of OSP Cu surface finishes for evaluating the influence of minor alloying on BIT (ball impact test) behavior. The Mn-doped samples had a better resistance to the degradation in BIT performance suffering long time aging at 150??C. The greater impact force and toughness compared to the other samples...
The morphological features and growth kinetics of interfacial IMCs have shown significant effect on the mechanical properties, and hence, on the reliability of lead free solder joints. The growth behavior of the interfacial IMCs of SnAgCu/Cu solder joint, in reflow and thermal cycling, was investigated with the focus on the influence of reflow dwell time and the cyclic parameters on the growth kinetics...
The growth behaviors of interfacial intermetallic compound for the solder joints of Sn-3.0Ag-0.5Cu/Cu substrate and Sn-3.0Ag-0.3Cu-0.05Cr/Cu substrate during isothermal aging at 150deg for 0, 24, 168, 500 and 1000 h respectively have been investigated. The results showed that the intermetallic compound layer at the Sn-3.0Ag-0.3Cu-0.05Cr/Cu joint is much thinner than that at the Sn-3.0Ag-0.5Cu/Cu joint...
Sn-Ag-Cu (SAC) solders are susceptible to appreciable microstructural coarsening during storage or service, resulting in evolution of joint properties, and hence reliability, over time. Although the problem of microstructural coarsening in joints has been studied extensively, the effect of joint scale on aging kinetics has never been investigated. Understanding the scale dependence of aging is particularly...
Conventional assessment of solder joint reliability uses either ball shear test or solder ball pull test. The test results are reported in terms of materials strength in either shear or tensile mode, and the strength values are size-dependent. Therefore these test results are largely useful only for qualitative comparison and qualification of the products. In the current effort, we aim at developing...
SnPb solder joints are an essential part for microelectronic packages manufacturing industrial for a long time. In recent year, environmental concerns and RoHS (Restriction of Use of Hazardous Substances) has demanded elimination of lead from electronics products by July 1, 2006. However, base on increasing pressures to achieve environmentally friendly electronic materials and processes, and indeed,...
The reliability of lead free electronic devices depends strongly on the reliability of the soldered joints while the later one was controlled, mainly, by the formation and growth of the interfacial intermetallic compounds (IMCs) between the solder matrix and the substrates. The morphological features, microstructural evolutions and growth kinetics of the IMCs on the interfacial of SnAgCu/Cu soldered...
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