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Ni plating is a commonly used barrier layer for direct bond copper substrates used in high-temperature and high-power applications. The Ni plating method can be electrolytic or electroless and the composition options include pure Ni, Ni:P, Ni–Co, or Ni:B. BiAgX solder paste is a promising lead-free solder for applications below 200 °C. The reactivity of these different Ni layers with the BiAgX solder...
Increasing I/O counts have led to ever decreasing cross sectional contact areas or, by default, an increase in solder performance expectations. A recognized measure of solder joint integrity is gained through High Speed Shear testing, (HSS). This article will statistically evaluate the solderability of the dominant final finishes with reference to some real life variables. The only skew is that only...
In this study, the influence of adding Sn-0.7Cu, Sn-1.2Cu, Sn-3.0Ag-0.5Cu and Sn-4.0Ag-0.5Cu coating into Sn-58Bi/Cu interface was investigated during thermal aging by scanning electron microscopy with Energy Dispersive X-ray. And the coatings of the Sn-based solder on the Cu were made by using hot-dip method. The result showed the Sn-based coating on the Cu was effective at suppressing the IMCs'...
In these study, the effect of Bi content on shear strength of Sn-xBi (x=0, 2.5, 5, 15) solder balls were investigated. The Bi addition could improve the shear strength of solder balls, added 2.5wt.% Bi into pure Sn solder alloys had a greater increase in shear strength. The fracture mode always remained the same and the shear strength had no obvious changes with increasing the aging time. The Sn-2...
Thermal aging effects on the fatigue life of Sn-3.0Ag-0.5Cu (wt%, SAC305) solder joint are investigated. Two series of experiments were conducted: 1) at different temperatures after aging for 72 hours; 2) with different aging time at the cryogenic temperature. The fatigue life of SAC305 solder joint were analyzed statistically by using a modified Weibull distribution model, which takes the thermal...
In the current study, the size effect of Sn3.0Ag0.5Cu solder joints on intermetallic growth is investigated. Experiments were performed to solder joints with a diameter of 2 mm and the solder thickness ranges from 2 mm to 50 µm. The thickness of intermetallic compound (IMC) of solder joints with different thickness as reflowed are found to be dependent on the size of solder joints. The IMC of small...
In order to study the electromigration characteristics of the butting solder joint in microelectronic packaging devices, this paper designs a Cu/Solder/Cu electromigration experiment to observe the change of the microstructure of the interface by scanning electron microscopy (SEM). It is found that the evolvement of the IMC at anode follows a parabolic growth rule under the condition of electric current...
The voiding phenomenon at the interface has been proven to weaken the mechanical properties of solder joints. The aim of this study was to investigate the influence of grain size on voiding propensity. Two kinds of substrates were used: high purity oxygen free copper (HPOFC) substrate and electrolytic tough pitch copper (ETPC) substrate. Grain size and voiding propensity were characterized by introducing...
The interfacial reaction and the growth kinetics of intermetallic compounds between 63Sn37Pb (wt.%) solder and the electroplated silver layer during the solid-state aging were studied in this paper. To measure the growth kinetics of Ag3Sn, the product of the interfacial reaction, more accurately, we used the quasi in situ method. And three same joints between solar cells and solder were annealed at...
The high temperature storage test (HTST) was conducted on the SnAgCu/Ni-W-P and Ni-Fe solder joints. While the conventional Ni-P solder joints were used as comparison to study the diffusion barrier effect of Ni-W-P and Ni-Fe under bump metallization (UBM). Both cross section and top view for the microstructural evolution of solder joints during 150°C aging were observed by the scanning electron microscope...
In the present paper the influences of design and technological preparation process of SMT test samples and the variation of parameters of shear tests on test results were examined. SMT samples with different sizes of electronic components (1206. 0805, 0603) and different lead-containing and lead-free solder materials were used and their ageing behavior in a temperature cycling process was studied...
In this work, we have used nanoindentation methods to explore the creep behavior, and aging effects of SAC305 solder joints at several elevated testing temperatures from 25 to 125 oC. A special high temperature stage and test protocol was used within the nanoindentation system to carefully control the testing temperature, and make the measurements insensitive to thermal drift problems. Solder joints...
In this investigation, Scanning Electron Microscopy (SEM) and Scanning Probe Microscopy (SPM) have been utilized to examine aging induced microstructural changes occurring within lead free solders. Unlike many prior studies, fixed regions in the solder joint cross-sections were monitored throughout the aging process, rather than examining different samples and/or different regions after the various...
This study was aimed at quantifying critically relevant topics about the influence of intermetallic compounds (IMC) within power electronics reliability such as the influence of soldering profile on the growth rate of IMC in large area solder joints, estimation of IMC thickness during non-isothermal ageing and the impact of IMC thickness on reliability. To this end, test samples were soldered using...
The effect of the variation of processing parameters such as thermal history, or the composition of Sn-Ag-Cu solder joints, on microstructure and reliability performance depends strongly on joint geometry, in particular length scale. The advent of 2.5/3D packaging technologies in microelectronics has further decreased joint length scales and changed interconnect aspect ratios to reduce I/O pitch....
The elevated working temperature of high temperature electronics can inevitably cause potential excessive growth of interfacial intermetallic compounds (IMCs), which can significantly deteriorate the mechanical integrity of electronic devices. Therefore, a robust diffusion barrier that can operate reliably under elevated temperature is highly demanded to retard the interfacial reaction between solder...
Isothermal aging of lead-free Sn-Ag-Cu (SAC) solder joints leads to growth of intermetallic (IMC) particles in the solder bulk as well as growth of intermetallic layers at the joint interfaces with copper bond pads. Fracturing near the interfacial IMC layers is often found to be the primary reason for failures caused by drop impacts. The IMCs in SAC joints are primarily AgsSn and Cu6Sn5 binary compounds...
Two types of additive combinations are used in the Cu plating solution to prepare the Cu deposits. The Cu deposit prepared with PEG and Cl− results in the formation of a specular structure composed of voids, Cu-impurity compounds, and intermetallic compounds when it reacts with Sn. The specular structure exhibits a very fast growth rate which is unusual for the Sn/Cu interfacial reaction. Introduction...
In this study, the effect of substrate metallization on the impact strength of Sn-Ag-Cu solder bumps, produced by a fluxless soldering process in a formic acid atmosphere, was investigated. The interfacial reaction between Sn-3.0Ag-0.5Cu solder and two different substrates (Cu and electroless nickel-immersion gold (ENIG)) during isothermal aging at 150 °C were studied. In the case of the Cu substrate,...
Low temperature bonding of Au-electroplated Cu and Cu electrodes with Sn-57Bi-1Ag solder was examined. Longer bonding time gave a Au/Cu joint higher melting point. In the joint bonded at 170 °C for 1 min, a large scallop-shaped AuSn4 layer formed in the joint interface of Au and solder. A Au-diffused layer formed in the tip of the AuSn4 layer. The Sn-Cu-Au layer including approximately 20 mol% Au...
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