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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...
Plated Ni is a commonly used barrier layer for direct bond copper (DBC) substrates used in high-temperature and high-power applications. The Ni plating method can be electrolytic or electroless, and the composition may be pure Ni, Ni:P, or Ni:B. With a melting point of 356 °C, eutectic Au88Ge12 (wt.%) solder preforms can be used for die attach in high-temperature applications up to 325 °C. The reactivity...
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...
Electroless nickel-phosphor (Ni-P) plating has been extensively used as a diffusion barrier layer in printed circuit board applications. However, the interfacial reactions between electroless Ni-P and lead (Pb)-free Sn solders during high temperature reflow are known to dissolve Ni-P excessively into Sn leaving behind a brittle Ni3P compound at the interface. This often causes various reliability...
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...
In this paper, the formation and growth of intermetallic compounds (IMCs) of Sn-8Zn-3Bi-0.3Cr solder on Cu, Ni and Ni-W substrates have been investigated. For the Cu substrate, only Cu5Zn8 intermetallic compound was observed. For the Ni substrate, a Ni5Zn21 film formed at the interface due to the fast reaction between Ni and Zn. For the Ni-W substrate, a thin Ni5Zn21 film appeared between the solder...
Wire bonding technology has been widely used in the semiconductor industry for interconnection between device and substrate. Gold wire has been used in industry for many years; however with the increase in the price of gold in the past few years, copper wire has become an alternative. Copper wires have better electrical and thermal performance than gold wire. However due to coppers hardness, the bonding...
The adoption of lead-free solders accelerates interfacial reaction because they have higher melting points and higher Sn content than the conventional Pb-Sn solders. In this work, we developed a ternary electroless Ni-W-P (6∼7 wt.% P, and 15∼16 wt.% W) alloy to be used as the soldering metallization due to its good thermal stability. Comparison was made with the results obtained from the conventional...
The effects of Ni element on the morphology of intermetallic compounds and some mechanical properties of SAC-Bi-XNi/Cu lead-free solder joints have been investigated. The corresponding mechanical and reliability behaviors were evaluated by performing shear test, fracture mode analysis, nanoindentation experiments and measurement of IMC before and after isothermal aging 200h and 400h at 160°C. The...
The failure mechanisms of Ni/Sn3.0Ag0.5Cu/ENEPIG flip chip solder joint were investigated during EM at 150 °C under a current density of 1×104 A/cm2. In as-soldered state, (Cu,Ni)6Sn5 IMCs formed at the both Ni/solder and electroless Ni-P/solder interfaces, and the spalled (Cu0.58Ni0.42)6Sn5 was observed in the solder at the chip side. After aging for 600 h, the interfacial IMCs at the both Ni/solder...
The Cu/Sn3.0Ag0.5Cu/Ni (Cu/SAC305/Ni) solder joints were designed to investigate the Cu, Ni atoms diffusion behavior and the interfacial reaction during electromigration (EM) at 180 °C under a current density of 1.0×104 A/cm2. For comparison, the Cu/Sn3.0Ag0.5Cu/Ni solder joints were aged at 180 °C for the same durations. In as-soldered state, the (Cu0.55Ni0.45)6Sn5 and (Cu0.92Ni0.08)6Sn5 IMCs formed...
Wide bandgap materials have become very attractive for power electronics due to their physical properties that allow junction temperatures up to a theoretical limit of 600°C. In contrast, the maximum operation temperature of conventional silicon semiconductors is limited to approximately 200°C. The high-temperature operation of wide bandgap switches allows an increasing power density of power converters...
In this study, varying amounts of Ni-CNTs were incorporated into the Sn-Ag-Cu matrix to form the composite solders. The interfacial intermetallic thickness formed on the Ni/Au metallized Cu substrate was determined under the as-soldered and isothermally aged (at 150°C for up to 42 days) conditions. The results of the interfacial intermetallic thickness showed that for the case of the unreinforced...
For high temperature automotive application, IC products are required to pass stringent high temperature storage stress test (e.g. 5000hrs at 150 deg C), hence requires reliable wire bonds. Such requirement is especially challenging with fine pitch Au & Cu wire bond (e.g. bond pad pitch <; 70um and bonded ball diameter <; 58um), more-so on low k wafer technology with bond-over-active requirement...
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...
In this work, IMC (Inter metallic compound) of lead free (Sn-Ag-Cu (SAC)) and lead (62Sn-36Pb-2Ag (SP)) solder joint on the four kinds of surface finished of ball grid array (BGA) pad, such as Immersion Tin (ImSn), Organic solderability preservatives (OSPs), Ni-P/Pd/Au (ENEPIG), and Ni-P/Au (ENIG) were investigated by Focus Ion Beam microscope (FIB). Sample after failure ageing conditions (Baking...
The Ni/95Pb5Sn/Cu ternary diffusion couples were used to investigate the cross-interaction between Ni and Cu across a layer of 95Pb5Sn solder. High-lead solder layers with thickness of 100 or 400 μm was electroplated over Cu foils. A pure Ni layer (20 μm) was then deposited over the as-deposited high-lead solder surface. The diffusion couples were then aged at 150 to 250°C for different periods of...
For satisfying the current industrial need of downscaling electronic devices, the die-to-die or die-to-package interconnects need to decrease in size accordingly. In view of that, flip chip bumps, which are currently the smallest interconnect type, have to be further miniaturized. In this study, Cu-Sn-Cu TLP (Transient Liquid Phase) bonded bumps that consist entirely of intermetallics (IMC) are studied...
The line-type Cu/Sn/Ni interconnects were used to determine the effect of electromigration (EM) on the Cu-Ni cross-interaction under the current density of 1.0×104 A/cm2 at 150 °C for 100 h and 200 h. For the purpose of comparison, the line-type Cu/Sn/Ni interconnects were also aged at 150 °C for 100 h and 200 h. After soldering, Ni3Sn4 and Cu6Sn5 IMCs formed at the Sn/Ni and Sn/Cu interfaces, respectively...
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