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For a limited solder volume interconnect structure, bump interconnect reliability is more sensitive to the growth behavior of the interfacial intermetallic compounds(IMCs). The study of the effect of solder cap thickness on the interfacial diffusion reaction is of great importance to the application of copper pillar bump. Here, we investigated the effect of different solder cap thicknesses on IMCs...
As the electronic packaging density continues to increase, flip chip or stacked packaging via bump bonding is gradually replacing traditional wire bonding and will become the mainstream packaging form in the future. For copper bumps, this new type of electronic interconnection has not yet been fixed by industry standards. Therefore, this paper has made a preliminary study on the reliability of this...
In high power automotive electronics copper wire bonding is regarded as most promising alternative for gold wire bonding in 1st level interconnects and therefore subjected to severe functional requirements. In the Cu-Al ball bond interface the growth of intermetallic compounds may deteriorate the wire bond. The thermo-mechanical properties of these intermetallic compounds are crucial in the prediction...
In this study, we would analyzed the solid state reaction between Sn2.5Ag solder bump and Cu/Ni under-bump-metallization (UBM). After 150°C thermal aging, we observed that the intermetallic compounds (IMCs) at chip side and interposer side both were Ni3Sn4 IMCs. It indicated that the solder did not react with Cu and the Cu layer was completed. As thermal aging time increased, the thickness of Ni3Sn...
The experimental samples mainly are the assembled OSP PCB with the Plated-Through-Hole (PTH) components which leads are manufactured with Sn/Ni/Cu substrates and the soldering process is Wave-Soldering (W/S) with two kinds of lead-free SAC solder bars categorized as Sn-3.0wt%Ag-0.5wt%Cu (SAC305) and Sn-0.3wt%Ag-0.7wt%Cu (SC0307). In addition, the test conditions are defined that the experimental temperatures...
Intermetallic compounds (IMCs) that grow on the interface between the solder alloy and its bonding pads play a crucial role in the reliability of solder joints. It has been identified that the cracking around the IMC layer is the primary failure mode in lead-free solder joints. Therefore the mechanical behavior of the IMC has attracted great attentions. In this paper, mechanical properties of two...
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...
The current study revealed that the growth kinetics and the interfacial reaction of the Cu/Sn/Ag couples with different thickness solder. For the Cu/Sn/Ag couples, plate-type Ag3Sn was firstly formed at the Sn/Cu interface rather than at the Sn/Ag interface for the Cu/Sn/Ag couple at the initial state of the reflow procedure when the solder thicknesses is 150 μm or 300 μm. Besides, the microstructure...
The η-η' transformation of interfacial Cu6Sn5 in solder joints was studied. Two cooling rates were selected to obtain different grain sizes of intermetallic compounds (IMCs). In the case of air cooling, the compounds were tiny and no η-η transformation was detected in the as-soldered state. Under furnace cooling, however, thick and coarse interfacial IMCs were obtained and η was still stable. After...
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...
In flip chip technology, the Ni(V)/Cu multi-metallic thin-films is a widely used under bump metallization (UBM), for doping 7 wt.% V into the Ni target can eliminate the magnetism of Ni during sputtering. It was noted that V in the Ni(V) layer did not react with solders and intermetallic compounds (IMC) during reflow and aging process, yet a Sn-rich phase, as the so-called "Sn-patch", would...
This paper investigates the growth of intermetallics in Sn-3.8Ag-0.7Cu (SAC) solder with and without Co nanoparticle reinforcement. Co reinforced composite was prepared by mechanically mixing 0.5 wt% and 1.5 wt% Co nanoparticles respectively into Sn-3.8Ag-0.7Cu solder paste. The formation and growth of the intermetallic compounds (IMC) at the solder joint interface were evaluated after thermal aging...
The microstructure of the eutectic SnBi/Cu interface was investigated by transmission electron microscopy (TEM). In-situ and ex-situ thermal aging were conducted to study the nucleation and growth of Cu3Sn and Cu6Sn5 on both polycrystalline and single crystalline Cu substrates. The growth kinetic analysis showed that although the growth of total IMCs (Cu3Sn + Cu6Sn5) was similar on single and polycrystalline...
Pure Sn, Sn-0.7Cu, Sn-1.5Cu and Sn-3.0Cu solder joints were fabricated by a laser reflow soldering method, and then they were aged at 125degC for various periods. After 600 hours treatment, we found that thickness of Intermetallic Compounds (IMCs) in the pure Sn solder joints was 54mum. However, in the solder joints with Cu addition, formation of AuSn4 IMCs was inhibited, and other two kinds of Sn-Cu-Au...
The present study investigates the effect of 1~5 wt.% Indium additions on microstructure, properties and interfacial IMC's formation of Sn-3Ag-2Sb(SAS) lead-free solder alloys. Experimental results show that addition of indium results in formation of intermetallic compounds of Ag-Sn-In phase and InSb phase. Sn atoms in Ag3Sn compound formed originally in Sn-Ag solder system are replaced by In atoms...
Gradually diminishing solderability and potential risk of whisker growth are two major concerns in using immersion tin as a final finish for printed wiring boards. Both phenomena are attributable to the spontaneous formation of intermetallic compounds (IMC) of Cu6Sn5 and Cu3Sn between the tin coating and copper substrate. The formation of IMC consumes the free tin in the coating that is essential...
84Sn-3Ag-3Bi-10In and 89Sn-3Ag-3Bi-5In solders were subjected to reflow and solid state aging. The intermetallic compounds that formed at the interfaces between the solders and the Cu substrates and those that formed in the bulk solders in both test conditions were investigated. In the as-reflow samples, the intermetallic compounds were identified as Cu3Sn and Cu6Sn5. After solid state aging, these...
To meet the urgent demands of future electronic packages, the solder joints have to become increasingly miniaturized. Compared to the large solder joints, mechanics behavior for the samll solder joints is very different, resulting in a series of reliability issues. Therefore, it is very important to understand the mechanics behavior of the small solder joints. In this paper, the shear test of the...
In this study, Sn3.0Ag0.5Cu solder bump was jointed on Ni(V)/Cu UBM and then aged at 125 degC for 500-2000 h. The heat treatment samples were employed to investigate the interfacial reaction and the mechanical properties between solder and UBM. (Cu,Ni)6Sn5 IMC formed at the interface between solder and Ni(V) layer after assembly. The thickness of (Cu,Ni)6Sn5 gradually increased to 4 mum during aging...
The microstructures of SnBi/Cu interconnect after reflow and its evolution during solid-state aging at 393 K were investigated using transmission electron microscopy (TEM). It was found that after reflow there were two kinds of intermetallic compounds (IMCs) - Cu6Sn5 and Cu3Sn in solder joint. Above these IMC layers there was a Bi-rich layer which consisted of discontinuous Bi particles. During solid...
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