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This study, mainly emphasis on effects of solder volume on interfacial diffusion kinetics and mechanical properties of Sn/Cu microbump solder joints. Different thicknesses i.e. 12 μm Sn (electrodeposited) and 100 and 200μm Sn is screen printed over 14 μm thickness Cu under bump metallization (UBM). The diameter of Cu UBM used in this study is 50, 110 and 240μm respectively. Solder joints are subjected...
In this study, Ag/NiNiP-plated Cu leadframes from two different processes are compared in terms of NiNiP surface morphology, composition of NiP layer, grain structures of Ni and NiP plated layers, and impurities in the interface of Ni/NiP plated layers. Their impacts were assessed after solder plating and baking. Scanning electron microscopy (SEM) shows that the grain size of Leadframe A (from Process...
Temperature and current density are two crucial factors in electromigration study. In order to investigate the effects of these two crucial factors deeply and separately. A temperature control device, employing forced convection with a constant direction, was adopted to control the chip temperature so that the chip temperature can be decoupled from the applied current density. With this temperature...
In this study, we study the metallurgical reactions at liquid state for different thickness Sn2.5Ag solder microbumps with Cu/Ni UBM. After 260°C reflow, we observed that the intermetallic compounds (IMCs) at chip side and interposer side both were Ni3Sn4 IMCs. As reflow time increased, the thickness of Ni3Sn4 IMCs and the concentration of Ag in the solder increased. We calculated the Ni3Sn4 IMCs...
A Cu/Ni UBM and Sn-2.5Ag lead-free solder for 20 μm pitch micro-bump was successfully fabricated via consecutive electroplatings of Cu, Ni, and binary SnAg. Materials characterizations such as Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Electron Probe Micro-analyzer (EPMA), and X-ay Photoelectron Spectroscopy (XPS) were carried out to obtain relevant materials properties. We observed...
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 effects of the rare earth Ce element on melting temperature, wettability of Sn-0.3Ag-0.7Cu low-Ag lead-free solder and the intermetallic compounds morphologies of Sn-0.3Ag-0.7Cu-XCe/Cu were investigated. The addition of the Ce element has an unconspicuous effect on decreasing the melting temperature of Sn-0.3Ag-0.7Cu solder. The results indicate that the addition of Ce element increases the wettability...
The interfacial reactions between (001) Ni single crystal and high-Sn solders were compared with those of polycrystalline Ni. The morphology of interfacial intermetallic compound (IMC) grains formed between (001) Ni single crystal and high-Sn solders (pure Sn, Sn-0.7Cu, Sn-0.7Cu-0.1Ni, Sn-1.5Cu and Sn-1.5Cu-0.1Ni, all in wt. %) at 250 °C and 300°C for various durations was investigated. Regular arrangement...
This study focused on the effect of solder volume on the interfacial reaction between Sn3.5Ag0.75Cu solder balls and Cu pads on PCB after various reflow soldering times. The diameters of the solder balls were 200, 300, 400 and 500 μm, respectively, and the opening diameter of the Cu pads was 250 μm. The solder volume ratio for the 200, 300, 400 and 500 μm balls was approximately 1:4:8:16. The interfacial...
Effect of solidification cooling rate on Ag3Sn formation and its morphological appearance in Sn-Ag based lead-free solder was investigated. Depends on cooling rate, three types of Ag3Sn compound with different morphologies may form by solidification. They are particle-like, needle-like, and platelike respectively. Small particle-like Ag3Sn in large amount was occurred by rapid cooling, where plate...
This work compared the interfacial reactions of single crystal Cu and polycrystalline Cu with the high-Sn solders. The morphology aspects of Cu6Sn5 intermetallic compound (IMC) grains formed between (001) single crystal Cu and high-Sn solder bath (pure Sn, Sn-0.7Cu, Sn-3Cu) at 250degC and 300degC for different durations ranging from 10 s to 10 min were investigated. The Cu6Sn5 grains formed in all...
The wetting behavior of Sn-Ag-Cu solder ball on nickel pad has been studied. SEM and EDX were employed to analyze the solder joint interfacial microstructure. Three zone-reactive wetting ring structure was found at the interface. To further study this kind of structures, solder ball attachment (SBA) and surface mount technology (SMT) were performed to prepare more samples. Experimental results show...
The changes of morphology and growth tropism of inter-metallic compound (IMC) and IMC growth rate at lead-free solders/Cu interface of solder joints often limit the reliability of the entire package during service. Furthermore, during thermal-shearing cycling process, the thickness of IMC at the interface grows significantly and growth tropism of IMC changes, resulting in in-service evolution of the...
The Cu pillar is a thick under bump metallurgy (UBM) structure developed based on the consideration of alleviating current crowding in a flip-chip solder joint in operation conditions. We present in this work electromigration reliability and morphologies of Cu pillar flip-chip solder joints formed by joining Ti/Cu/Ni UBM with largely elongated Cu at ~62 mum onto Cu substrate pad metallization through...
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