The growth kinetics of the reaction layers formed in the flip chip joints using Cu-cored Sn-5 mass%Ag balls was investigated. In particular, the effect of Ni coating over the Cu core was investigated on the microstructures of flip chip joints with Ni/Au plated Cu pads after reflow soldering and the subsequent heat exposure at 373 K, 398 K and 423 K. A Ni-Sn reaction layer formed at the Cu core/Sn-5Ag interface in the joint using the Cu-cored Sn-5Ag ball with Ni coating over the Cu core with reflow soldering. A similar Ni-Sn reaction layer formed at the joint interface between the Sn-5Ag solder and the Ni/Au plated Cu pad with reflow soldering. The growth rates of those Ni-Sn reaction layers following the subsequent heat exposure were slower than that of the Cu-Sn reaction layer formed at the Cu core/Sn-5Ag interface in the joint with the Cu-cored Sn-5Ag ball without Ni coating over the Cu core. In this study, the activation energies of the growth of the reaction layers and the shear load of the joint were also investigated.
Effect of Ni coating over the Cu core of Cu-cored Sn-5mass%Ag balls was investigated on the microstructures of flip chip joints with Ni/Au plated Cu pads after reflow soldering and the subsequent heat exposure at 423 K. For joints using Cu-cored Sn-5Ag balls with Ni coating over the Cu core, a Ni-Sn reaction layer forms at the Cu core/Sn-5Ag interface. A similar Ni-Sn reaction layer forms at the interface between the Sn-5Ag solder and the Ni/Au plated Cu pad. Although the Ni-Sn reaction layers grow with increasing the thermal exposure time, the growth rate is slower than that of a Cu-Sn reaction layer formed at the Cu core/Sn-5Ag interface in the joint with the Cu-cored Sn-5Ag ball without Ni coating over the Cu core.
In this presentation, we show some experimental results of binder-free WC with Nano WC sintered by Pulsed Electric Current Sintering (PECS) process also known as Field Assisted Sintering Technology (FAST). The particle size of WC powder is almost 80 nm. These binder-free WC have extremely hardness and stiffness. However, these mechanical properties are dependent on the sintering condition, e.g., maximum temperature, applied presssure, etc. We show some relationship between mechanical properties and sintering condition to improve to sinter the binder-free WC
In this paper, we show some experimental results of binder-free WC sintered by Pulsed
Electric Current Sintering (PECS) also known as Field Assisted Sintering Technology (FAST). These
binder-free WC have extremely high hardness and stiffness. However, these mechanical properties
are dependent on the sintering condition, e.g., maximum temperature, applied pressure, etc. We show
some relationship between mechanical properties and sintering condition to improve to sinter the
binder-free WC.
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