Now showing 1 - 6 of 6
  • Publication
    Comparative wetting study of Sn-0.7Cu solder on dimple and pillar micro-texture fabricated by the photolithography technique
    ( 2024-12) ; ; ; ;
    Nurul Aida Husna Mohd Mahayuddin
    ;
    Siti Faqihah Roduan
    The study focused on exploring the impact of micro-textured surfaces on the wetting behaviour of Sn-0.7Cu solder. Dimple and pillar micro-textures, each with a diameter of 100 μm, were fabricated on the copper substrate using a photolithography technique. The Sn-0.7Cu solder was melted onto the micro-textured copper substrate during the soldering process. The spreading time, spreading area, and spreading rate of the solder on the copper substrate were investigated. The copper substrates with dimple textures exhibited a prolonged spreading time of 51 seconds, a smaller spreading area of 60.54 mm², and a slower spreading rate of 1.44 mm²/s than the pillar-textured copper substrates. However, the presence of micro-textures resulted in a reduced spreading area, indicative of enhanced solderability. This improvement is attributed to the textured substrate promoting higher copper diffusion during the soldering process. The controlled application of micro-textures holds promise for optimising wetting behaviour and solderability in electronic assembly processes, presenting avenues for further exploration and application in the realm of materials science and electronic manufacturing.
  • Publication
    The effect of Ni and Bi additions on the solderability of Sn-0.7Cu solder coatings
    (Springer, 2019)
    Mohd Izrul Izwan Ramli
    ;
    ;
    P. Narayanan
    ;
    ;
    J. Chaiprapa
    ;
    ;
    S. Yoriya
    ;
    K. Nogita
    The present investigation explores the influence of Ni and Bi on the solderability of Sn-0.7Cu solder coatings. The minor addition of 0.05 wt.% Ni into the Sn-0.7Cu solder alloy results in an improvement in the wettability based on dipping tests. The solderability investigation using a globule mode shows the influence of Ni and Bi on the interfacial intermetallic compound (IMC). The addition of Ni to a Sn-0.7Cu solder coating resulted in a (Cu,Ni)6Sn5 interfacial IMC, which enhanced the solderability performance during the globule test. With an increasing amount of Bi in the Sn-0.7Cu-0.05Ni-xBi solder ball, the surface energy of the solder alloy can be reduced, and this improves the solderability. The synchrotron micro-XRF results indicate that Ni is found in a relatively high concentration in the interfacial layer. Additionally, Bi was found to be homogenously distributed in the bulk solder, which improved solderability.
  • Publication
    Effects of multiple reflow on the formation of primary crystals in Sn-3.5Ag and solder joint strength: experimental and finite element analysis
    ( 2023)
    Siti Farahnabilah Muhd Amli
    ;
    ;
    Mohd Sharizal Abdul Aziz
    ;
    Hideyuki Yasuda
    ;
    Kazuhiro Nogita
    ;
    ;
    Ovidiu Nemes
    ;
    Andrei Victor Sandu
    ;
    Petrica Vizureanu
    The growth and formation of primary intermetallics formed in Sn-3.5Ag soldered on copper organic solderability preservative (Cu-OSP) and electroless nickel immersion gold (ENIG) surface finish after multiple reflows were systematically investigated. Real-time synchrotron imaging was used to investigate the microstructure, focusing on the in situ growth behavior of primary intermetallics during the solid–liquid–solid interactions. The high-speed shear test was conducted to observe the correlation of microstructure formation to the solder joint strength. Subsequently, the experimental results were correlated with the numerical Finite Element (FE) modeling using ANSYS software to investigate the effects of primary intermetallics on the reliability of solder joints. In the Sn-3.5Ag/Cu-OSP solder joint, the well-known Cu6Sn5 interfacial intermetallic compounds (IMCs) layer was observed in each reflow, where the thickness of the IMC layer increases with an increasing number of reflows due to the Cu diffusion from the substrate. Meanwhile, for the Sn-3.5Ag/ENIG solder joints, the Ni3Sn4 interfacial IMC layer was formed first, followed by the (Cu, Ni)6Sn5 IMC layer, where the formation was detected after five cycles of reflow. The results obtained from real-time imaging prove that the Ni layer from the ENIG surface finish possessed an effective barrier to suppress and control the Cu dissolution from the substrates, as there is no sizeable primary phase observed up to four cycles of reflow. Thus, this resulted in a thinner IMC layer and smaller primary intermetallics, producing a stronger solder joint for Sn-3.5Ag/ENIG even after the repeated reflow process relative to the Sn-3.5Ag/Cu-OSP joints.
      14  37
  • Publication
    Mixed Assembly of Lead-free Solder Joint: A Short Review
    (IOP Publishing Ltd, 2022-01-24) ; ;
    Ramli M.I.I.
    ;
    Saud N.
    ;
    ;
    Razak N.R.A.
    ;
    Ismail A.N.
    The transition from lead (Pb) to Pb-free solder has arisen the need for the development of the reliability of mixed assemblies solder joint research. Mixed assemblies are defined as solder joints that joint together with different compositions or solder forms for example Ball Grid Array (BGA) and solder paste. During the transition period of solder materials, mixed assemblies are still used in electronic packaging. In addition, Pb-free manufacturing has been forced to release some of the product categories since legislation banning the use of lead solder in electronic assemblies. This phenomenon causes health and environmental concern of the Pb solder used in electronic assembly. Hence, some electronic assemblies will continue to use traditional eutectic Sn-Pb solder paste while others will use Pb-free solder paste. This situation indicates that the use of mixed assemblies in electronics manufacturing is still inevitable. This paper presents a projection of the reliability of mixed assembly's Pb-free solder joint.
      2  4
  • Publication
    Effect of Ni on the suppression of Sn whisker formation in Sn-0.7Cu solder joint
    ( 2021) ; ;
    Andrei Victor Sandu
    ;
    ; ;
    Noor Zaimah Mohd Mokhtar
    ;
    Jitrin Chaiprapa
    The evolution of internal compressive stress from the intermetallic compound (IMC) Cu6Sn5 growth is commonly acknowledged as the key inducement initiating the nucleation and growth of tin (Sn) whisker. This study investigates the effect of Sn-0.7Cu-0.05Ni on the nucleation and growth of Sn whisker under continuous mechanical stress induced. The Sn-0.7Cu-0.05Ni solder joint has a noticeable effect of suppression by diminishing the susceptibility of nucleation and growth of Sn whisker. By using a synchrotron micro X-ray fluorescence (µ-XRF) spectroscopy, it was found that a small amount of Ni alters the microstructure of Cu6Sn5 to form a (Cu,Ni)6Sn5 intermetallic layer. The morphology structure of the (Cu,Ni)6Sn5 interfacial intermetallic layer and Sn whisker growth were investigated by scanning electron microscope (SEM) in secondary and backscattered electron imaging mode, which showed that there is a strong correlation between the formation of Sn whisker and the composition of solder alloy. The thickness of the (Cu,Ni)6Sn5 IMC interfacial layer was relatively thinner and more refined, with a continuous fine scallop-shaped IMC interfacial layer, and consequently enhanced a greater incubation period for the nucleation and growth of the Sn whisker. These verification outcomes proposes a scientifically foundation to mitigate Sn whisker growth in lead-free solder joint.
      1  28
  • Publication
    Effect of Ni on the suppression of sn whisker formation in Sn-0.7Cu solder joint
    ( 2021) ; ;
    Andrei Victor Sandu
    ;
    ; ;
    Noor Zaimah Mohd Mokhtar
    ;
    Jitrin Chaiprapa
    The evolution of internal compressive stress from the intermetallic compound (IMC) Cu6Sn5 growth is commonly acknowledged as the key inducement initiating the nucleation and growth of tin (Sn) whisker. This study investigates the effect of Sn-0.7Cu-0.05Ni on the nucleation and growth of Sn whisker under continuous mechanical stress induced. The Sn-0.7Cu-0.05Ni solder joint has a noticeable effect of suppression by diminishing the susceptibility of nucleation and growth of Sn whisker. By using a synchrotron micro X-ray fluorescence (µ-XRF) spectroscopy, it was found that a small amount of Ni alters the microstructure of Cu6Sn5 to form a (Cu,Ni)6Sn5 intermetallic layer. The morphology structure of the (Cu,Ni)6Sn5 interfacial intermetallic layer and Sn whisker growth were investigated by scanning electron microscope (SEM) in secondary and backscattered electron imaging mode, which showed that there is a strong correlation between the formation of Sn whisker and the composition of solder alloy. The thickness of the (Cu,Ni)6Sn5 IMC interfacial layer was relatively thinner and more refined, with a continuous fine scallop-shaped IMC interfacial layer, and consequently enhanced a greater incubation period for the nucleation and growth of the Sn whisker. These verification outcomes proposes a scientifically foundation to mitigate Sn whisker growth in lead-free solder joint.
      1  25