Applied Mechanics and Materials Vols. 754-755

Abstract: . Pattern design transfer is the most crucial step in fabrication. Even a small mistake in fabrication can result in device damage or poor performance. To ensure the device performs perfectly, exact design and dimension pattern should be perfectly transferred onto wafer substrate. In this paper, optimization of conventional photolithography process of 0.98μm gap design for micro gap biosensor application is presented. The micro gap pattern on chrome mask is used and the effect of coating profile, UV light, and Post Exposure Bake (PEB) process are investigated. The conventional photolithography process (using a micro gap mask) starts after the silicon oxide, polysilicon and aluminium have been deposited on top of the substrate. Each set of experiment conducted by pairing the element investigated coating profile, UV light, and PEB, with the normal specification of photolithography process. It was observed that 0.98μm gap size can be achieved by choosing suitable process parameters i.e. thickness of coating profile, time and temperature used for UV light and PEB.

Abstract: This research has investigated the solder performances of Sn-0.7Cu lead-free solder reinforced with silicon nitride (Si₃N₄). The Sn-0.7Cu + Si₃N₄ composite solder were fabricated via powder metallurgy (PM) technique with five different weight percentages (0, 0.25, 0.5, 0.75 and 1.0). Results showed that distribution of Si₃N₄ along the grain boundaries has increased the hardness of the Sn-0.7Cu + Si₃N₄ composite solders compared to monolithic Sn-0.7Cu solder alloy. Addition of Si₃N₄ reinforcement had no significant effect to the melting temperature of the solder. Overall, the entire range of Sn-0.7Cu + Si₃N₄ composition greatly improves the microhardness of the eutectic solder.

Abstract: This research has investigated the microstructural analysis and shear strength of Sn-1.0Ag-0.7Cu (SAC107) alloy used as matrix while silicon nitride (Si₃N₄) as reinforcement particles with different weight fractions (0, 0.25, 0.5, 0.75 and 1.0 wt. %). The composite solders were fabricated using powder metallurgy (PM) method consisting of mixing, compaction and sintering process. With additions of Si₃N₄ particles, the composite solders experienced a corresponding increase in strength due to fine and homogeneous microstructure. This is signified that the presence of Si₃N₄ particles effectively refines the microstructure.

Abstract: This paper review based on the organic solar cell (OSC). In this review we investigates on the performance perspectives and theoretical of the solar cell using both simulation and spin coating fabrication technique. This paper reviews on progress several organic materials which use as active layer and issues on device efficiencies. This paper also review on development in device structure to get desired higher output in OSC.

Abstract: The effects of SiC on wettability and intermetallic compound (IMC) formation of Sn-Cu-Ni solder paste composite were systematically investigated. Lead-free solder paste composite was produced by mixing silicon carbide (SiC) particle with Sn-Cu-Ni (SN100C) solder paste. The wettability of composite solder was studied by observing the contact angle between solder and copper substrate. The IMC phase formation on copper substrate interface was identified using X-ray diffraction (XRD). The phase as detected in the composite solder is Cu₆Sn₅.The wettability of composite solder was observed through contact angle between solder and copper substrate and Sn-Cu-Ni + 1.0 wt.% SiC shows improvements in wetting angle and suppresses the IMCs formation.

Abstract: This paper reports on the effect of activated carbon (AC) addition on the properties of Sn-Cu-Ni (SN100C) solder paste. The composite solder was prepared by mixing reinforcement particles (0, 0.25, 0.5, 0.75 and 1.0 wt. %) into SN100C solder paste. The melting temperature of composite solder was determined by using differential scanning calorimetry (DSC). Wettability of fabricated solder was studied through contact angles between solder and copper substrate interface. The intermetallic compound formation was studied after reflow soldering process.With increased carbon particles addition, the composite solder was found to have a slightly lower melting temperature compared to monolithic solder while the wettability of composite solder effectively had improved. The activated carbon particles in solder paste composite have significant effects on the formation of intermetallic compounds (IMCs) at the solder/Cu substrate interfaces by suppressing the IMCs thickness.

Abstract: A composite solder with Sn-0.7Cu based solder was successfully fabricated via powder metallurgy routes which consist of mixing, compacting and sintering. Varying amount of activated carbon (AC) was used as reinforcement to obtain a novel lead-free composite solder. Following fabrication, the sintered composite solder was analyzed in terms of their microstructure, microhardness and solderability properties. The distribution of the various percentages of AC particles along the grain boundaries was observed. The addition of AC particles into the Sn-0.7Cu solder matrix has increased the hardness values up to 22.9%, while reducing the contact angle of composite solder up to 12.9% for a good wettability performance. As overall, addition of AC into Sn-0.7Cu based solder has indicated an enhancement of reliability performance of Sn-0.7Cu/AC composite solder for electronic application.

Abstract: This paper presents the characteristics of the doped polysilicon nanowire for pH sensors. The fabrication involved two chromium mask designs. Example the first mask is used for the polysilicon nanowire pattern and the other one is for pad patterning. It involved of photolithography, deposition, etching and wet oxidation process. Different length, number of polysilicon are fabricated and then subjected to voltage, current and pH measurement. APTES is being introduced to improve the sensitivity of the polysilicon nanowire. For the low pH, the conductivity is high, while for the high pH, the conductivity is low. The impact on investigating length is insignificant to the sensitivity of the doped polysilicon nanowire.

Abstract: This project deals with the experimental results of leaching of Sn from solder dross by means of leaching using different concentration of hydrochloric acid (HCl). Solder dross was sieved to obtain a mean particle size of 75 μm. The solder dross powder obtained was leached by using HCl acid aqueous solution. To optimize the parameter required for recovery of Sn from solder dross, initially the bench scale studies were carried out using varying acid concentration, stirring time and temperature. The experimental indicate that 98.7% of Sn was leached out from solder dross using 0.1M of HCl, 24 hours of stirring time at60°C solution temperature.

Abstract: Solder dross containing Sn, Ni, Cu, Zn, Fe and other impurities was leached with 0.1-1.0 M citric acid at 60 °C for 24 hours stirring times. Parameter affecting the tin recovery of suggested method such as acid concentration, stirring time and temperature were investigated. Results obtained revealed that the optimum leaching parameter were achieved using 250ml of citric acid (C₆H₈O₇) and 10 acid/g drossfor 24 hours at 60°Cof solution temperature. Recovery of tin from solder dross was 99.0%.