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We observed a linear behaviour of intermetallic compound (IMC) layer growth in electronic metallurgical interconnections, although the time required was twice that of commercial reliability standards for electronic packaging. This finding contradicts the classical parabolic growth law, which is widely reported to represent growth behaviour. We suggest that the parabolic growth law may be inadequate to thoroughly explain the IMC layer's growth by considering (a) one-directional growth and (b) reactions between elements for formation and growth. Further analysis has been carried out to analyse the logical judgment of the parabolic growth law and support our finding over linear IMC layer growth behavior.

Laser rework (LR) and hot air rework (HR) process impact on the nearby ball grid array (BGA) rework components with lead-free solder Sn3.0Ag0.5Cu (SAC305) solder joints were investigated in these studies. Reworking BGA components is a challenging procedure with additional implications for printed circuit board assembly (PCBA) reliability due to the thermal exposure affecting the nearby rework components’ solder joints’ qualities. In these studies, we examined thermal exposure effects on nearby BGA rework components and analyzed the solder joint qualities after the rework process by observing the dye penetration percentage along with the separation location on the solder joints. The successful outcomes of the dye and pull (DnP) tests show the LR method on BGA components is reliable for high-density PCBA design with up to 15% reduction on the impacted solder joints and 24 °C lesser on the peak temperature for the nearby BGA rework components compared to the HR performance.

The aim of this study is to identify the bonding mechanisms of the ultrasonic Al bond on the Mo back-contact layer (Al–Mo system) of a copper indium gallium (de) selenide (CIGS) thin-film photovoltaic (TFPV) solar panel. The bonding mechanism of the Al–Mo system was obtained from the identification of nonstick footprints of Al ribbon and the deformation of ultrasonic Al bonds on the Mo layer using an infinite focus microscope (IFM). The effect of Al bond deformation toward the bondability and electrical behavior of the bonds was evaluated by comparing the results obtained from IFM with the peel force, contact resistance from the transmission line method (TLM), and resistance from a micro-ohmmeter, respectively. It is observed that ultrasonic bonding parameters have a major impact on the deformation, bondability, and electrical properties of ultrasonic Al bonds on Mo layers. The bonding mechanism and failure mode can be identified through the IFM examination through the formation of footprints and the evolution of microwelds (remnant) of ultrasonic Al bonds and the occurrence of glass substrate cratering. It was found that arithmetical mean deviation of the assessed profile ( $R_{a}$ ) of more than 6 $\mu $ m indicates that the ultrasonic Al bond has been formed on the Mo layer. The contact resistance values are more toward representing the variation of intimate contact area, while resistance is more toward representing the resistance of two bonds and the straightness of the Al ribbon.

In this paper, the dynamic precipitation and dynamic recrystallization (DRX) behaviors of Mg-7Gd-2Nd-0.5Zr (wt.%) alloy during thermal compression were investigated by optical microscopy (OM), scanning electron microscope (SEM) and transmission electron microscopy (TEM). The hot compression tests were performed at 350–500 °C with strain rates of 0.003–1 s−1and a strain of 0.7. The results indicate that dynamic precipitation and DRX occur in the deformed region under appropriate conditions, and that dynamic precipitation precedes DRX. Elevated deformation temperature and strain rate facilitate DRX but weaken dynamic precipitation. The dynamic precipitates were β(Mg5Gd) phases and were mainly located at the grain boundaries in the deformed regions. DRX can be promoted when the size of the granular precipitates is larger than 200 nm. The second phase particles located at the grain boundaries of the recrystallized grains can pin the grain boundaries to refine the recrystallized grains. There are three mechanisms of recrystallization nucleation: grain boundary bowing nucleation, dislocation pile-up induced nucleation, and particle-stimulated nucleation (PSN). Moreover, a critical strain model and a kinetic model for the DRX of the alloy were developed.

This work assesses the bondability and temperature cycling reliability of ultrasonic Al bonds on Molybdenum (Mo) and Molybdenum (di)Selenide (MoSe2) layers of a Copper Indium Gallium (di)Selenide (CIGS) thin-film photovoltaic (TFPV) solar panel. The bondability and reliability of ultrasonic Al bonds were assessed using a qualitative load–displacement profile and quantitative peel force data obtained from a peel test, as well as contact resistance Rc measured using the transmission line method. It was discovered that using the peel test to examine the bondability and reliability of ultrasonic Al bonds and conductive adhesives was quite beneficial. Varied forms of ultrasonic Al bonds and conductive adhesives, either on Mo or MoSe2 layers, have different shapes of load–displacement profiles before and after the application of temperature cycling. Therefore, comparing the load–displacement profile, peel force, and Rc could offer a complete bonding mechanism, failure modes, and failure mechanism for ultrasonic Al bond on MoSe2 and Mo layers of CIGS TFPV solar panels before and after temperature cycling.

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.

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.

Coloured solders offer wide range of possible application on top of conventional usage related to solder and soldering. Coloured solder can be produced by adding colour pigment into solder formulation to form coloured solder composite. The performance of coloured solder joint typically determined by good solderability, which influenced by wetting properties. The objectives of this paper is to investigate the solderability of coloured lead free solder composite with different formulation type of colour pigment and variation of colour pigment composition. Green and “glow in the dark pigment” with composition of 5% and 10% respectively were added into the lead free solder paste. Each coloured solder paste was stencil printed on the PCB and then reflowed using reflow soldering process. The wettability of the solder composite was measured and observed using Infinite Focus Measurements (IFM). The results demonstrated that coloured lead free solder composite have a good wettability. This finding also indicates that use of green pigment into the solder composite has shown greater wettability as compared to glow in the dark pigment. Higher percentage of added colour pigment of 10% has significantly reduced the wettability of solder composite. Wettability of coloured solder composite with small amount of added pigment is in the acceptable range of contact angle, showing good solderability of joining.

Tin-Silver-Copper (SnAgCu) lead-free solder on Electroless Nickel Immersion Gold (ENiG) and Immersion Tin (ImSn) surface finish printed circuit board was subjected to blast test. A variation of intermetallic compounds (IMC) layer, hardness and reduced modulus of soldered sample exposed to blast test were intensively investigated using optical microscope and nanoindentation machine. Formation of IMCs due to reaction between solder and substrate during blast test provided deleterious effect of metallurgical bond strength and reliability on the solder joint. Microstructural analysis was evaluated via Infinite Focused Microscope (IFM). The findings of these studies indicate that best surface finished for blast test performance was not necessarily the best surface finish for optimum reliability. ENiG and ImSn surface finish can be advantage or a disadvantage depending on the application, package and reliability requirements. As a result, most component assemblers are using ENiG and ImSn in order to improve solderability as well as the wettability between solder and the substrate and to meet various package requirements.

Evaluating the growth kinetics is one of the most important characteristic in assessing the quality and reliability of metallurgical joining, especially in electronics packaging such as soldering and wire bonding technology. The growth kinetics is normally assessed using Arrhenius equation that involves diffusion activities due to thermally activated process. The well-known factors of thermal and time together with generally accepted growth exponent have been widely used for this assessment. The intermetallic compound layer which is the by-product of metallurgical reaction during soldering process has been exposed to high temperature to accelerate its growth. The cross-section of the joining was observed using optical microscope to quantify the layer of intermetallic compound. Morphological effect and shape factor of the layer have been analysed in complement with the effect of temperature and time on the growth behaviour. Directional growth and irregularities shape of the intermetallic layer show some inconsistency on the selection of growth exponent. The effect of initial size of intermetallic layer must also be considered in this assessment. This study suggests that the morphological effect must be analysed prior to the selection the growth exponent in assessing growth behaviour and kinetics of intermetallic layer in metallurgical joining.

The kinetic and isotherm studies of gas-solid system were represented by oil palm mesocarp bio-char as adsorbent and formaldehyde as adsorbate. Three kinetic model; i.e pseudo-first-order, pseudo-second-order and Elovich model and three isotherm model; i.e.Langmuir, Freundlich and Temkin isotherm were applied to evaluate the applicability of the equilibrium experimental data and the pyrolysis effect was studied. As a result, oil palm fiber carbonized at 500 °C and 700 °C was best presented by the Langmuir isotherm and oil palm mesocarp carbonized at 600 °C and 800 °C followed Temkin and Freundlich model, respectively. The formaldehyde adsorption was found favorable to happen at 25 °C with initial concentration of 0.5 ppm, 0.9 ppm, 0.75 ppm and 2.1 ppm as the Langmuir dimensionless constant, RLgave the value of 0 < RL < 1. Carbonization temperature of 500 °C, 600 °C, and 700 °C was kinetically presented by pseudo-first-order kinetic equation and carbonization temperature of 800 °C followed Elovich equation. As a conclusion, the pyrolysis of oil palm mesocarp does affect the isotherm and kinetic behavior of formaldehyde adsorption on oil palm char.

The variation on mechanical properties and crystalline structure of gamma-irradiated Sn-rich lead-free solder (SAC) were intensively investigated using nanoindentation and X-ray diffraction (XRD) techniques. Samples of solder on a printed circuit board (PCB) with copper substrate were irradiated at low dose (5 Gray) of gamma from Co-60 source. The nanoindentation hardness for β-Sn phase of the solder was found to increase from 0.1935 GPa to 0.2210 GPa after the irradiation. Furthermore XRD peak intensity was also observed to increase as well indicating the occurrence of defect in β-Sn crystal structure due to gamma radiation. The defect contributes to the increment of the hardness by indicating the change in crystallite size of the grains. Microstructure analysis by FESEM-EDAX has also confirmed the indentation was performed with no cracks in subsurface on β-Sn area.

Magnesium (Mg) with a concentration range of 1 to 3 at% was successfully doped in zinc oxide (ZnO) and prepared via a hydrothermal process in powder form. X-ray diffraction patterns revealed a polycrystalline nature of the prepared powders. Images taken by a scanning electron microscope showed that the synthesized powders had clear solid hexagonal rod structures. Furthermore, the solid hexagonal structures were hollow because of the Mg ions introduced into the ZnO. The photoluminescence emission of the undoped and Mg-doped ZnO showed an enhancement of the ultraviolet emission with the Mg concentrations. Furthermore, the Gaussian fitting reveals that the UV band emission is consist of two emissions. The first peak was at 3.36 eV for the undoped ZnO that shifts to 3.4 eV, 3.43 eV for the 1 at% Mg and 2 at% Mg concentration, respectively. Thereafter the UV peak position reduced to 3.39 eV for the 3 at% Mg ions concentration. The results were studied, and the correlation of the results was attributed to the doping process.

The evaluation of the strength and bondability of gold, Au ball bond requires a new approach to provide a more detail data. Nanoindentation test was used as a new approach to evaluate the strength distribution and bondability of Au ball. Au ball bonds that experienced different value of wire bonding parameter namely bonding force, bonding time, bonding power, and stage temperature were used as samples for the present analysis. The distribution of strength based on hardness and reduced modulus values located at the bonding area of Au ball bonds were found to be related with the values of the wire bonding parameter. Nanoindentation test was found to be a suitable approach to analyze and evaluate the bondability of Au ball bond in a localized and detailed manner. In addition, the responsible mechanism for the thermosonic Au wire bonding can be identified and analyzed by using the results obtained from the nanoindentation test.

This work is a contribution towards the understanding of wire bond integrity and reliability in relation to their microstructural and mechanical properties in semiconductor packaging.The effect of surface roughness and hardness of leadframe on the bondability of Au wedge bond still requires detail analysis. Two type of leadframes namely leadframe A and leadframe B were chosen and scanning electron microscope (SEM) and optical microscope were used to inspect the surface morphology of leadframes and the quality of created Au wedge bond after wire bonding process. It was found that there were significant differences in the surface morphologies between these two leadframes. The atomic force microscopy (AFM) which was utilized to measure the average roughness, Ra of lead finger confirms that leadframe A has the highest Ra with value of 166.46 nm compared to that of leadframe B with value of 85.89 nm. While hardness value of different lead finger from the selected leadframe A and B obtained using Vicker microhardness tester are 180.9 VH and 154.2VH respectively.

The in-situ inspection of ultrasonic vibration of wire bonder capillary was carried out using laser interferometer in order to analyze the formation of Au wedge bond. It was observed that the changes in ultrasonic vibration can be used to describe process of bonding formation. The loss of ultrasonic energy was exhibited in ultrasonic vibration waveform of wire bonding on leadframe A. This observation is due to the low frictional energy and high deformation of Au wedge bond on leadframe A. The lower pull strength obtained by Au wedge bond further confirms the reduction of bond formation on leadframe A.

The effect of high temperature storage of gold ball bonds towards micromechanical properties has been investigated. Gold wire from thermosonic wire bonding exposed to high temperature storage at 150 °C for 10, 100 and 1000 hours. The nanoindentation test was used in order to evaluate the high temperature storage effect on wire bonding in more details and localized. Prior to nanoindentation test, the specimens were cross-sectioned diagonally. The constant load nanoindentation was performed at the center of gold ball bond to investigate the hardness and reduced modulus. The load-depth curve of nanoindentation for the high temperature storage gold wire has apparent the discontinuity during loading compared to as-received gold wire. The hardness value increased after subjected to high temperature storage. However, the hardness decreased when the storage period is extended. The decreasing in the hardness value may due to the grain size of Au metal which recrystallized after subjected to high temperature storage. The results obtained from nanoindentation is important in assessing the high temperature storage of wire bonding.

This study used nanoindentation technique in order to examine the micromechanical properties of Sn3.0Ag0.5Cu (SAC305) on Electroless Nickel Immersion Gold (ENIG) surface finished Cu substrate subjected to high temperature storage. Lead free solder paste of SAC305 were soldered on ENIG substrate by reflow soldering at 215 °C for 8 second. The soldered samples were exposed to high temperature storage at 180 °C for 0, 200, 400, 600, 800 and 1000 hours. Micromechanical properties show that the solder hardness is decreasing with the HTS time from 239.13 MPa for 0 hour to 178.96 MPa for 1000 hours while the reduce modulus results has increased from 62. 16 x 103 MPa for 0 hour to 82.13 x 103 MPa for 1000 hours. The value of hardness and reduced modulus from nanoindentation approach indicate the occurrence of plastic and elastic deformation throughout the test.

Directional growth behavior of intermetallic compound (IMC) layer of Sn3.0Ag0.5Cu (SAC305) on immersion tin (ImSn) surface finished Cu substrate was investigated. The samples of SAC305 on ImSn/Cu substrate were subjected to thermal cycling at temperatures between 0 °C and 100 °C for 0 cycle up to 500 cycles. The cross-sectioned microstructures of soldered samples, SAC305 on ImSn/Cu were observed using optical microscope. The shape and orientation of IMC growth on the SAC305 on ImSn/Cu indicates that the orientation of IMC growth were observed to be non-uniform and dispersed throughout the solder joint with longer thermal cycling test.

Electrochemical migration (ECM) of solder joining can result in the growth of a metal deposit with dendrite structure from cathode to anode. In electronic device, this phenomenon potentially leads to the incompetence or failure of whole devices. In this paper, the ECM behaviour of printed circuit boards (PCBs) with SAC 0307, one of the low-cost lead-free solder alloys with less silver content, has been studied. The corrosion behaviour of SAC 0307 has been investigated by using sodium chloride solution in different concentrations which is between 0.01 M to 1.0 M as a medium. A Water Drop Test (WDT) was carried out and the time-to-failure of each sample has been recorded. After WDT test, the dendrite phase was identified using Variable Pressure Scanning Electron Microscope (VPSEM) with Energy Dispersive X-ray Spectroscopy (EDX) and X-ray Photoelectron Spectroscopy (XPS) to investigate its surface morphology and corrosion products. As results, it has been found that the corrosion susceptibility of SAC 0307 is greatly influenced by the concentration of the medium solution used. The voltage drop occurred was due to the dendrite grew at the cathode electrode on the PCBs and expanded to the anode electrode, indicating a significant effect of aggressive behaviour of the medium used. The rate of the dendrite growth was affected by the concentration of the medium used. The main element found in the dendrites on the SAC 0307 on PCBs was Tin as it is more mobile than Cu.

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.

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).

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.

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 S2-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 S2- does not effected the size of nanoparticles.

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.

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.

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.

Abstract: The bonding mechanisms of gold, to give the desired strength of wire bonding, still require detailed investigation, including establishing adequate and reliable testing procedures. The current practices for analysing the mechanisms of wire bonding are inadequate and do not provide a comprehensive picture. This is because the focus of the tests is not clear, which causes variation in the results obtained, changing the conclusions about the responsible mechanism. Furthermore, as the size of Au wire bonds decreases, the mechanism responsible for thermosonic Au wire bonding may change. This paper provides a comprehensive analysis of the current and possible future methods for elaborating the bonding mechanism and strength of thermosonic Au wire bonds. We discuss the testing methods, their limitations and advantages, and suggest ways in which they can be improved.

SnO2 has been successfully grown on Si substrate using a thermal evaporation method, under different percentages of argon and oxygen gases. High purity Sn metal was used as reactants with deposition temperature were set at 900ºC. Different oxygen concentrations range between 1.6 and 10% were used during thermal evaporation process. The as-prepared metal oxides were analyzed using SEM-EDS, XRD and UV-VIS. SnO2 nanowhiskers were obtained at lower oxygen concentrations (1.6 to 6% oxygen), while nanowires structures were formed at higher oxygen percentages. XRD results revealed SnO2 produced were highly crystalline and no other impurity phase diffraction peaks were detected. EDS analysis revealed that only Sn and O elements were present in the sample which are consistent with XRD results. UV-VIS result revealed that the optical band gap energy of the metal oxides produced have low significant effect with increasing oxygen concentration. Optical band gap energy for was within 3.3 eV, which was lower than the optical band gap energy of bulk SnO2.

A plate of Fe-30Cr (wt%) were subjected to isothermal furnace at 600 °C in flowing CO2 gas at total pressure of approximately 1 atm. The reacted samples morphology and microstructure were characterized by using visual inspection, optical microscope, SEM and EDAX. The weight change measurement showed a fluctuating result during the exposure. The significant weight loss was observed after five hours exposure due to oxide scale exfoliation. Formation of different oxide and element presents on the interface of the specimen such as Cr2O3, C and Fe3C were revealed by X-ray diffraction and with supported by EDAX analysis. This behavior of the high temperature corrosion on Fe-30Cr was discussed based on morphology and microstructure observation.

Using a simple solution route based on the reaction between magnesium tetrahydrate ((CH3COO)2Mg.4H2O)) and hexamethylenetetramine (C6H12N4), MgO films were grown on Mg and MgO. Morphological observations revealed that porous MgO films were obtained on Mg, while sheet-like films were produced when MgO was used as the substrate. The EDX results indicated that only Mg and O were present in all of the films. When Mg was used as the substrate, the resistivity of the MgO film decreased from 2.060 x 102 Ω cm to 1.990 x 102 Ω cm as the temperature was increased to 150° C. In contrast, the resistivity decreased to 1.820 x 102 Ω cm when MgO was used as the substrate at 150° C. The morphology and crystallinity of the material likely played a role in the reduced resistivity of the films. The bandgap of MgO films was dependent on the type of substrate and the reaction temperature. The bandgap of MgO films grown on Mg increased from 5.18 eV to 5.27 eV as the temperature increased from 90° C to 150° C. A similar increase was also observed when a film of MgO was grown on MgO. However, the bandgap energies obtained in this study were well below that of bulk MgO due to the non-stoichiometry of the deposited layers and crystallinity of the samples, as shown by EDX and XRD, respectively.

Welded AA6061 Al alloy using ER5356 (Al-5Mg) filler was oxidized in flowing air gas for 40hrs at 600oC at a total pressure of approximately 1 atm. The morphology and microstructure of welded joint after exposure was characterized by using optical metallurgy microscopy and Scanning Electron Microscope (SEM). Different oxide morphologies and textures were observed on parent and fusion metal due to the differences of the alloying element. The oxidation mechanism represented a complex reaction occur where the morphology and phase formation of the oxide shows the protective oxide scales showed the protective oxide were developed on parent metal side, meanwhile non-protective oxide scale formed on fusion metal of the welded Al alloy. It can be concluded that the welded area failed to resist oxidation behavior compared to the parent metal. The differ results are discuss in term of microstructure changes caused by high temperature oxidation exposure and alloying element.

In this study, brushite (CaHPO4·2H2O) has been coated on a stainless steel substrate using dip-coating technique. This technique offers uniform and crack-free film over entire surface of the substrate and easy to perform. Layer of brushite coated surround the stainless steel is very much affected by the parameters used namely concentration of the coating solution, speed of coating, stirring time etc. Results show that a smooth thin film is obtained when 1.5M of brushite solution is used and stirred at 50 °C for 2 hours. The optimum withdrawal rate used was 1.5 mm s-1. Thickness of the coating obtained was around 51.37 µm which would enable the apatite to growth.

In semiconductor packaging, conventional test procedures for evaluating mechanical properties of ball bonded gold wire bonding are well established. However these tests do not provide clear understanding related to the strength mechanism leading to improper reliability data. The nanoindentation approach, uses equipment called nanoindenter, gives advances mechanical (sub-micromechanical) characterization, particularly the combination effect of elastic and plastic deformation. Wire bonding process was prepared using thermosonic-wire bonding technology with 25m diameter gold wire and copper as substrate. To obtain mechanical properties, ball-bonded was cross-sectioned diagonally before indented at various locations. Results show that mechanical properties vary according the locations throughout the surface; at the centre, at the edge and at the area near intermetallics layer. This indicates test location plays important role in determining ‘meaningful’ mechanical properties.

The effect of different doses of gamma radiation (0.5 Gy, 1.5 Gy, 5.0 Gy, 10.0 Gy and 50 kGy) on the maximum load and deflection of the Single Die Quad Flat No Lead (SDQFN) semiconductor package has been investigated. The three-point technique was carried out to obtain the maximum load and deflection of the package. The results of irradiated SDQFN show the decreasing in their maximum load and deflection with the increasing of gamma irradiation dose. The higher gamma irradiation dose produced the more significant change in the load-deflection behaviour of the irradiated SDQFN. The package becomes prone to failure when exposed to the radiation environment.

In this paper, porous flower-like nickel oxide (NiO) on glass substrates were prepared by an aqueous chemical growth based technique. The morphology and optical observed were found to be influence by the reaction time. Field Emission Scanning Electron Microscopy (FESEM) revealed a porous flower-like structure growth on the substrates investigated. The optical band gap for NiO thin film calculated from transmission spectra has increased from 3.72 eV to 3.91 eV with the increasing of reaction time. This result shows that the growth time have some influence on morphology and optical of NiO films.

A simple solution route employing the reaction of magnesium acetate tetrahydrate ((CH3COO)2Mg.4H2O) and hexamethylenetetramine (C6H12N4) has been demonstrated to successfully grown MgO thin film on both Mg and MgO substrates at two different temperature i.e 90 °C and 150 °C for 4 h. Morphological observations revealed that the porous structure of MgO film was obtained on Mg substrate while sheet-like structure film was observed when using MgO substrate. EDX indicated only Mg and O were present in all films. The MgO bandgap obtained varies with type of substrate used and temperature. The MgO film growth on Mg substrate bandgap increased from 5.18 eV to 5.27 eV with temperature increased from 90 °C to 150 °C. Similar increased was also observed with MgO film growth on MgO substrate. However the results obtained are well below of MgO bulk energy bandgap. This was probably due to non-stoichiometry of deposited layers and crystallinity of the samples as shown by EDX and XRD results respectively.

The aim of the research was to establish the relationship between stress-strain behaviour of single die Quad Flat No lead (SDQFN) and degradation by gamma irradiation. The SDQFN was exposed to Cobalt-60 with different doses from 0.5 Gy, 1.5 Gy, 5.0 Gy, 10.0 Gy and 50.0 kGy. The three-point bending technique was used to measure the flexural stress and strain of the package behaviour relations. After exposing with gamma radiation, the result showed the decreasing in the strength of the package behaviour of irradiated SDQFN when increasing the dose of gamma irradiation. The highest gamma irradiation dose used in this work produced the highest change in stress-strain behaviour of irradiated SDQFN.

As-welded AA6061 Al alloy using Al-Si-Mg (ER 4043) filler metal was subjected to oxidationexposure in flowing air gas for 40hrs at 600oC at a total pressure of approximately 1 atm. SEM andEDAX were chosen to characterize the morphology microstructure of oxide formation on welded jointafter oxidation process. Different oxide morphology were found on parent and fusion metal due to thedifferences of the alloying element. The morphology of the oxide shows the protection oxide surfacewere developed on parent metal while non-protective oxide formed on fusion metal.

Test material of welded AA6061 Al alloy using ER5356 (Al-Mg-Si) filler metal was oxidized inflowing air gas for 40hrs at 600oC at a total pressure of approximately 1 atm. The morphology andmicrostructure of oxide formation on welded Al alloy was characterized using SEM and EDAX.Different oxide morphologies were observed on parent and fusion metal due to the differences of thealloying element. The oxidation mechanism represented a complex reaction where the morphology andphase formation of the oxide shows the protective oxide were developed on parent metal side, whilenon-protective oxide formed on fusion metal of the welded Al alloy.

Average roughness is an increasingly important method in material sciences. The searching for a possible correlation between average roughness and impact energy are current interest. This paper present the results of an experimentally study made on the correlation between the average roughness and the impact energy in aluminum alloy by using scatted diagram. The impact energy of aluminum alloy was obtained by using Charpy Impact Test. The micrographs of fractured aluminum alloy were analyzed with the IFM (Infinite Focus Measurement) profile to determine the parameter of average roughness. The result shows the relationship maybe established between average roughness and impact energy.

The changes of microstructure in eutectic sn-3.8ag-0.7cu during moderate current stressing have been investigated. The current stressing values were 102 and 103 a/cm2. The tests were carried out for 24, 216, 576 and 1008 hours. Sn-rich phases and eutectic phases appear immediately after soldering process. However, thermal rise during current stressing has coarsened sn-rich phases and altered the microstructure of the solder. Higher current density leads to larger snrich phase coarsening. The microstructures for current stressing test were also compared with the series of microstructure for isothermal annealing test since there is similarity in coarsening effect for both tests. The effect of thermal rising during current stressing as well as during isothermal annealing to sn-rich phase coarsening is established and will be discussed further.

The experiment discusses the issue of high-energy implant to the resist thickness and how the resist etched away during implantation process. The resist that is use as a mask or material to block the dopant ion such as Phosphorous, Boron or Arsenic introduces into silicon substrate. It is a common practice by all semiconductor industrial players to use photoresist as their protection on desired area in which purposely set as non-implanted area. The research benefits the engineer on determine the sufficient photoresist thickness for specific implant energy.

It is compulsory to have a good fatigue life to a component that is heavily subjected to cyclic loading. One of the good examples is parabolic spring, which is one of the components in suspension system for large vehicles. It serves to absorb, store and release back the damping energy due to road irregularity, bump and holes. These activities involve a lot of camber deflection that caused by the tension and compression loads. In reality, the loading that subjected to parabolic spring is variable amplitude loading, but most of the manufacturer used constant amplitude (CA) loading for the fatigue test. The objective of this paper is to relate the simulation result with the microstructure behaviour of the leaf spring that failed due to fatigue. A full scale fatigue test was carried out until that parabolic spring meet failure. In order to investigate the fatigue life, CA signal was generated based on an actual fatigue test on the parabolic spring, and it was then analysed using the FEA-based fatigue simulation. A microstructure study was then performed for both fracture and non-fracture area. From the FEA-based simulation, it gave the prediction on damage that occurred at the critical area and also the prediction on the lowest cycle with respect to the FEA model. In the actual fatigue test, the failure was occurred at the centre part of the spring, which is at bolt join of assembly hole. The microstructure analysis showed that the grain at the fracture area indicated some different from the non-fracture area in term of size, phase and precipitation of carbon.

In the last decade, failure of microelectronic devices has become a prominent field of research all across the world. The results of this of failure analysis allow an engineer to choose package geometries and materials which reduce the risk of failure. This paper is meant to relate the stress effect on material properties during Quad Flat No-Leads (QFN) stacked-die packages manufacturing processes. To achieve the study, the finite element technique was used to perform an extensive structural analysis on a QFN package design once it was verified by related experiments. A QFN unit was developed in three dimensional geometry with various materials be will simulated in order to determine the location of failure. The induced stress results were also measured in the maximum value, indicating the low modulus and coefficient of thermal expansion (CTE) in the packaging material were important for reducing high stress during the manufacturing stages. However, numerical simulation demonstrated that the stress developments increased exponentially when the die attach temperature increased. Therefore, the induced stress can be relieved by having high die attach process temperature with an adequate bonding force and time. It was vital to control the induced stress in package materials during die attachment process for ensuring the reliability level of QFN packages.

Several different groups of filler metal are known to be compatible in welding of AA6xxx series. The aim of this investigation is to study the effects of different filler alloys toward mechanical properties and microstructure of welded AA6061 aluminium alloy using gas metal arc welding. Single V butt joint configuration has been used for joining the plate’s. Butt-joint welds were made on 6 mm thick plates using 21 – 22 V arc voltage. Tensile test was carried out using 100kN, electro-mechanical controlled hydraulic Instron 8801 universal testing machine. The results showed that the yield strength of base metal were 330 MPa and while the yield strength of ER5356 joints and ER4043 joints were 200 MPa and 235 MPa, respectively. The difference properties of strength in both weld metal was due to the difference major element in the both filler composition. The amount of silicon content in ER4043(Al-Si5%) filler is believed to play a role in the mechanical strength on weld metal. Microstructural examination was carried out using a light optical and electron microscope. The different filler alloys give different weld metal microstructure.

The corrosion of four Fe-Cr alloys (Cr: 9, 12, 20, and 25%) with different Cr contents were subjected to cyclic oxidation furnace in Ar-10%O2 atmosphere at 950oC for 120 h. The samples after oxidation were investigated by using X-ray diffraction (XRD), optical metallography and SEM/EDS. The results indicated that increasing Cr content reduced the oxidation rate and the scale cracking. Alloys with less Cr content occurred breakaway oxidation due to formation of Fe-rich oxide scale. However, a thin protective chromia scale was observed on alloys with Cr > 20%. The corrosion behaviour on Fe-Cr alloy was then discussed based on experimental observation.

Underfilling is the vital process to reduce the impact of the thermal stress that results from the mismatch in the co-efficient of thermal expansion (CTE) between the silicon chip and the substrate in Flip Chip Packaging. This paper reported the pattern of underfill’s hardness during curing process for large die Ceramic Flip Chip Ball Grid Array (FC-CBGA). A commercial amine based underfill epoxy was dispensed into HiCTE FC-CBGA and cured in curing oven under a new method of two-step curing profile. Nano-identation test was employed to investigate the hardness of underfill epoxy during curing steps. The result has shown the almost similar hardness of fillet area and centre of the package after cured which presented uniformity of curing states. The total curing time/cycle in production was potentially reduced due to no significant different of hardness after 60 min and 120 min during the period of second hold temperature.

Over the years the methods for checking bonding quality during volume production still remains the same. These inspection methods like ball shear to test the first bond quality and wire pull to test the second bond integrity and quality have proven to be acceptable and achievable for many current industrial needs. However, driven by the relentless pursuit of dimensional reduction in wire bonding technology which calls for reduction in wire diameter, these conventional methods may not be sufficient. The interaction between machine, bonding tools, materials and the different categories of failure modes and mechanism during this quality test has become much more sensitive. The intent of this paper is to study and define the different categories of failure modes during 2nd bond test for ultra fine gold wire from 15 micron diameter up to 50 micron diameter. Therefore, lifted stitch or lifted 2nd bond which is a failure description known to be a ‘reject’ before can be re-visited. Analysis found that the two different test locations revealed that test location B or placing the hook as near possible to the leads where the 2nd bond was bonded is the better method to test the 2nd bond strength and performance as compared to the earlier bond pull method (location A).

The Reduced Modulus value for the bonded Au ball bond that have undergone three different time intervals of high temperature storage (HTS) have been obtained by using nanoindentation test. Twelve indentations have been made at three different locations (Au, IMC and Si area) across the bonded ball bonds to evaluate the variation of Reduced Modulus with the location of indentation. It was shown that the Reduced Modulus value for the indentations at IMC area is increased with the increment of HTS time interval. It was also observed that the Reduced Modulus at the Au area was increased with the increment of the HTS exposure time. No particular pattern was noted to describe the changes of Reduced Modulus with the location of the indentations that have been made. It was also found that the average Reduced Modulus for Au obtained through nanoindentation with value of 107 GPa has higher value compared to that of the Young’s modulus value obtained through actual tensile test with value of 79 GPa.