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For some applications like ship, aircraft and car, electronic systems are submitted to salt environment. In this case, the main reliability issue is the corrosion of the metals from the pads and the solder alloys. More than 20% of failures in microelectronic devices can be attributed to corrosion. Nevertheless this phenomenon is little studied on microelectronic assemblies. This paper presents ageing...
In this study, palladium coated copper core wire is evaluated and a series of bond quality test is carried out on Aluminum (1.5μm Al) bond pad and Nickel Palladium (2.5μm Ni/0.3μmPd) bond pad with Ø0.6mil palladium-coated copper core wire. From the optimization with mechanical chips, it is found that NiPd has larger bond parameters windows than Al bond pad. Ball shear strength of NiPd samples becomes...
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 order to study the growth of electrochemical migration along the thickness direction, paper/phenol-resin composite on printed wiring boards was aged at 85 °C and 85 %RH by applying of a dc voltage. Then, the sample was observed by a scanning electron microscope with a function of energy dispersive spectroscopy (SEM-EDS) analysis. Space charge distributions in the sample were also measured by the...
Sn-Ag-Cu (SAC) and Sn-Ag alloys are considered to be the most promising Pb-free solders for electronics applications. The properties of these solders can be improved by the addition of minor alloying elements to control the intermetallic compounds (IMCs) that are formed during soldering and high temperature storage/cycling. Additional alloying elements into the solder alloys change the solidification...
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...
This paper details the outgassing process during epoxy degradation and evaluates the corresponding influence on adjacent PWB pads for immersion Ag (ImAg) plated circuit boards. Three commercial epoxy adhesives used for edge-bonding of surface-mount (SMT) components were investigated. Scanning electron microscope (SEM) analysis and electron dispersive spectroscopy (EDS) was carried out to investigate...
SiC power devices were die bonded to a AlN/Cu/Ni(Au) direct bonded copper (DBC) substrate with a Au-Ge eutectic solder in a vacuum reflow system. The long term joint reliability of the bonded chips was evaluated at 330degC in air for up to 1600 hours. The bonded samples were inspected with a micro focus X-ray TV system. The microstructure of the samples was observed and analyzed by the scanning electron...
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,...
Wire bonding is the most applied technology to realize an electric chip-to-package interconnection and to provide electrical paths from and to the substrate for power and signal distribution. Established in the 1970s, wire bonding has been well documented and researched as a result of continuous process improvement and through the development of sophisticated, automated equipment over the years, [1-2].
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...
To enhance the ability of lead-free solder joint to resist failures induced by mechanical impact and shock, some researchers have introduced low-Ag lead-free solder. In this study, the formation and evolution of IMC, the fracture morphology and performance of solder joint between SAC 105 solder and Under Bump Metallization (UBM) have been studied after different temperature storage aging and multi-reflow...
The thermal stability of flip chip solder joints made with Al/Ni(V)/Cu-UBM and SAC-405 solder bumps on substrates with either electroless Ni(P)-immersion gold (ENIG) or Cu surface finish (Cu-SOP) was determined at 170C. On ENIG, the resistance changed by more than one order of magnitude after 400 hours of high temperature storage, whereas on Cu-SOP, no change in resistance was observed up to 2400...
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