Abstract
Effects of reflow time on the interfacial microstructure and shear strength of the SAC/FeNi-Cu connections were investigated. It was found that the amount of Cu6Sn5 within the solder did not have a noticeable increase after a long time period of reflowing, indicating that the electro-deposited FeNi layer blocked the Cu atoms effectively into the solder area during a long period under liquid-conditions. The ball shear test results showed that the SAC/FeNi-Cu joint had a comparable strength to the SAC/Cu joint after reflowing, and the strength drop after reflowing for 210 s was less than that of the SAC/Cu joint.
Highlights
IntroductionSolder bump connection is an important interconnect in flip chip packages, where the solder bumps deposited on metal terminals on the chip are connected to the metal pads on the substrate [1]
Solder bump connection is an important interconnect in flip chip packages, where the solder bumps deposited on metal terminals on the chip are connected to the metal pads on the substrate [1].The metal terminals consist of successive layers of metal, under bump metal (UBM), which provides a strong mechanical and electrical connection
When the SAC After solderReflow reacted with the deposited FeNi film under the same conditions, by contrast, a flat and thin intermetallic compounds (IMCs) in sub‐micrometer thickness was formed at the interface of SAC and the FeNi layer, see Figure 2b
Summary
Solder bump connection is an important interconnect in flip chip packages, where the solder bumps deposited on metal terminals on the chip are connected to the metal pads on the substrate [1]. The shear resistance behavior of an SAC solder joint can be slightly improved by using the FeNi alloy rather than the Cu substrate [9,10]. It is found that only FeSn2 phase with minor Ni solubility formed between the FeNi substrate and Sn solder during liquid reactions at 270 ̋ C [11,12,13,14]. The microstructure and the shear properties of SAC/FeNi‐Cu connection were investigated to Metals 2016, 6, 109 discuss the potential application of FeNi layer as UBM layer for a Sn‐based solder. SAC/FeNi-Cu connection were investigated to discuss the potential application of FeNi layer as UBM °C for different time: 90, 150, 210 and 270 s respectively.
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