Papers by Author: Azman Jalar

Abstract: This study discussed the effect of blast exposure distance of lead-free solder on micromechanical properties. Sn-Ag-Cu solder samples were exposed to 1000 g of Plastic Explosive. The soldered samples were placed at a distance of 1 m, 2 m and 4 m distance from the blast source. In order to study micromechanical properties in localized and more details, the nanoindentation approach was used. The indentation was performed at the center of the solder to examine the hardness and reduced modulus properties. The load-depth curve of indentation for 1 m distance from the blast source has apparent the discontinuity during loading as compared to the control sample. The hardness value increased as the distance from the blast source increased. The shortest distance from the blast source gives a high impact on the degradation of hardness properties as compared to others. This result is important in assessing the effect of exposure distance from the blast source.

Abstract: Electronic packaging is the technology concerning to the establishment of electrical interconnections and it is a major discipline within the field of electronics engineering. Packaging of an electronics system should considered the protection from mechanical damage, cooling, radio frequency noise emission and protection from electrostatic charge. Solder alloys have been extensively used as interconnection materials for microelectronic package. Solder joint in radiation environment requires higher reliability and resistance to any damage caused by ionizing radiation. The electrical failure during radiation has proved that the reliability of solder joint is importance and sensitive to the service condition. In this study, a lead-free solder alloy, SAC305 (96.5Sn3.0Ag0.5Cu wt.%) were prepared into two batches, which are unirradiated and irradiated batches with the various doses 5, 50, 500 Gy of gamma radiation. Nanoindentation was used in order to investigate the effect of the radiation to micromechanical properties such as hardness, H and reduced modulus, E of the solder. The results showed that the SAC solder changed when exposed to gamma rays. The hardness of the specimens calculated from the nanoindentation were decreased to 195.4 from 279.6 MPa with the increasing of radiation dose. These values of hardness are also lower than the hardness of non-irradiated sample indicating possible radiation damage and needs further related atomic dislocation study. The reduced modulus for irradiated specimens significantly increased as well, with values from 25.6 to 123.9 GPa after exposure. The increment of the reduced modulus occurred as a result of strain hardening or softening of the solder.

Abstract: The behavior of Fe-12Cr-2Mo stainless steel exposed isothermally in tube furnace at 700°C for 10 h had been studied in different environments; of mixed environment (Ar-20%O₂ with coated Na₂SO₄-50%NaCl salts), molten salt (Na₂SO₄-50%NaCl) and dry oxygen (Ar-20%O₂) atmospheres. The exposed samples were characterized by using optical microscopy (OM), scanning electron microscope (SEM), energy dispersive X-ray (EDX) and X-ray diffraction (XRD). The results indicated that, sample exposed in mixed environments undergoes highest corrosion rate compared with other samples. The main phase exists in all samples generally were iron-rich oxides which non-protective and thick. Conversely, EDX analysis on cross-sectional samples revealed the Cr-enrichment developed underneath the iron-rich oxide scales as the chromium concentration increases towards near the substrate. In presence of salt mixture, the oxide scales undergo spallation, however there is no crack observed. The catastrophic corrosion sample was occurred in combined environment due to the oxidation induced by the chloridation and sulfidation phenomena as well.

Abstract: Effect of gamma radiation (1.33 MeV) and high temperature storage of semiconductor package towards micromechanical properties has been investigated. The in-house fabricated Quad Flat No Lead was exposed to gamma radiation with the dose of 5 Gy. Afterwards, high temperature storage was performed at 150 °C for 10, 100 and 1000 hours. Subsequently, the three point bending technique was carried out to obtain the micromechanical properties of semiconductor package. The fracture of the packages caused by three point bending test was subjected to 3D CT scan to capture the image of the fracture. Irradiated package shows the decreasing in their strength with increasing doses of gamma radiation. However, the strength of the package was improved after high temperature storage for 10 hours and decreased as the storage period is extended. Further analysis exhibited that high temperature storage for 10 hours is reveal as good thermal treatment for package in radioactive environment application.

Abstract: Nanoindentation tests with loading rates of 0.05 mN/s, 0.1 mN/s, 0.5 mN/s, and 1.0 mN/s were conducted on the Au ball bond. The effect of different loading on the Au ball bond were analysed based on qualitative and quantitative results. The displacement burst was more pronounced with the increment of loading rates. The increase of hardness value and the decrease of the reduced modulus value when the loading rate was increased are due to the effect of creep. It was found that the loading rate of 0.5 mN/s is the appropriate and stable value for the nanoindentation test on the Au ball bond.

Abstract: Wollastonite, CaSiO₃ material was prepared from rice husk ash, as the source for SiO₂ and limestone, source for CaO using sol-gel method. Rice husk ash and CaO powder was mixed together in 100ml distilled water with the rice husk ash/CaO ratios of 45:55 and 40:60. The mixed solution was place in the autoclave and heated at 135°C for 4 hours and calcined at 950°C for 1 and 2 hours. From the XRD results,ratio of 45:55 exhibited that b-wollastonite is the major phase and the minor phase is only contributed by cristoballite and by calcining the mixture for 2hrs would yield better crystallinity. Both of the rice husk ash:CaO ratios produced wollastonite materials in cylinder structures. Wollastonite with nano size grain was obtained for an hour calcination and 2 hrs of calcination would increase the grain size over 100 nm for ratio, 45:55 and 40:60.Therefore in order to get the nano size of wollastonite material, period of calcination process has to be controlled.

Abstract: Grape-like tin dioxide (SnO₂) structures have been grown on p-type silicon (Si(100)) substrate synthesized by thermal evaporation of tin (Sn) without use of metal catalyst. The experiment were conducted in a three-zone tube furnace at a constant temperature of 1080°C,under 1.6% of oxygen (O₂) gas in an atmospheric ambient with a controlled flow rate of 1.0L/min. The prepared SnO₂ film was characterized by using X-ray diffraction diffractometer (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy(EDX) and photoluminescence (PL) measurement. The grape-like SnO₂ structures were highly crystalline with particle size (resemble grape fruit) ranging from 120-550 nm and diameter of wire (resemble grape stem) around 120-160 nm.The PL spectrum of the grape-like SnO₂ structures exhibits a broad visible light emission with a peak centered at around 623 nm, corresponding to 1.99 eV and usual near band edge emission of SnO₂ is not observed.

Abstract: Nanosilica powder produced from rice husk ash (RHA) via NaOH treatment has particle size in the range of 10-20 nm as revealed by transmission electron microscopy (TEM). The inhibitive action of nanosilicate from RHA on the corrosion of carbon steel SAE1045 in 0.5M HCl solution was studied using weight loss and potentio dynamic polarization methods. Result shows that the inhibition efficiency was increased with increasing of the inhibitor concentration. Nanosilicate was tremendously effective on carbon steel; exhibiting high inhibition efficiency attained 99%at optimum concentration of 175 ppm. Pitting was not observed on surface of carbon steel when the inhibitor was present. This finding was confirmed from surface morphology by scanning electron microscopy (SEM).

Abstract: The aim of the study was to synthesis the CdS nanoparticles via AOT-water-n-heptane microemulsion technique. Ternary phase diagram was constructed to obtain the concentration range of oil, surfactant and water. Three main phases form on the ternary phase diagram of AOT-water-n-heptane, which were gel, cloudy and clear phases. The clear phase was heptane rich region. Meanwhile, cloudy phase have consisted two phases and the gel phase was due to high concentration of AOT. The result showed that clear phase region shrink when the Cd²⁺ and S^2-solvent was added or replaced the water component of the tertiary system.The existence of CdS nanoparticles with average size of 14.0 nm has been calculated by using UV-Vis Spectrometry meanwhile the TEM image showed that the size of CdS nanoparticles was about 49-89 nm. It also have concluded that the same concentration at solvents Cd²⁺ and S^2- does not effected the size of nanoparticles.

Abstract: Metal/polymer/metal laminate composite is of great patent due to their excellence physical and mechanical properties. In this work, linear low density polyethylene (LLDPE) was used as matrix between aluminium sheets to produce aluminium/LLDPE/aluminium (APEA) laminate composite. The maleic anhydride grafted polyethylene, PE-g-MAH, with concentration between 0% - 3% was used as coupling agent. The -glycidoxy propyl trimethoxy silane (-GPS) has been used to enhanced the mechanical properties of laminate composite. The lap shear strength increased with the increasing percentage of PE-g-MAH with the application of -GPS. Surface analysis suggested that this increment was associated with the chemical state of the compound involved.