Reflow soldering process for Sn3.5Ag solder on ENIG using rapid thermal processing system

A study on reflow soldering process for Sn3.5Ag solder on ENIG substrate was performed using the rapid thermal processing (RTP) system. The reflow soldering process by RTP system can be successful, but it is sensitive to some typical defects. A poor RTP system design can lead to significant temperature differences where non-uniform heating or cooling may result in material failure due to increase in thermal stresses or serious damage. From this study, it was found that at a peak temperature (Tpeak) of 251°C, the reflowed solder was observed to be smooth joint appearance over the solder pad and formed a regular joint shape of the solder due to the efficient reflow profile and sufficient heating input during the reflow process. The Ni3Sn4 intermetallic compounds were found to be continuous, thus resulting in a good metallurgical bonding between Sn3.5Ag solder and ENIG substrate. Meanwhile, an uneven reflowed solder and defect mechanism was detected at Tpeak of 246 and 260°C. This is due to the inadequate reflow profile and insufficient heating input during the reflow soldering process in the RTP system. Visual micrographs of reflowed solder and cross-sectional micrograph and elemental analysis were presented in this paper for better understanding of the defect mechanism in order to optimize the reflow soldering process using RTP system. The reflow soldering process can be performed better with appropriate reflow profile in the RTP system in order to achieve a good solder joint of Sn3.5Ag solder and ENIG substrate

Application of building information modelling (BIM) in design and build (D&B) projects in Malaysia

Design and Build (D&B) is one of the most suitable types of project delivery method that are being used to implement BIM. However, there is a lack of documented evidence to show on how BIM is being implemented in D&B project. This paper aims to explore the current practices of BIM in D&B projects in the Malaysian construction industry. A literature review was done to explore on application of BIM in construction projects and D&B project concept. Furthermore, semi-structured interviews with construction players were conducted as a primary data for this paper. The interviews were conducted with construction players that are currently involved and have experiences in D&B BIM projects. The findings revealed that the BIM process in D&B projects is much similar with activities in conventional D&B project. The differences were by the used of BIM software, the process of developing project design into a 3D model and the involvement of BIM related designation in the project. In addition to that, the process of BIM in D&B has been highlighted in this paper

Spin-on-Glass (SOG) based insulator of stack coupled microcoils for MEMS sensors and actuators application

A comprehensive study on the SOG (Spin-on-Glass) based thin film insulating layer is presented. The SOG layer has been fabricated using simple MEMS technology which can play an important role as insulating layer of stack coupled microcoils. The fabrication process utilizes a simple, cost effective process technique as well as CMOS compatible resulting to a reproducible and good controlled process. It was observed that the spin speed and material preparation prior to the process affect to the thickness and surface quality of the layer. Through the annealing process at temperature 425oC in N2 atmospheric for 1 h, a 750 nm thin SOG layer with the surface roughness or the uniformity of about 1.5% can be achieved. Furthermore, the basic characteristics of the spiral coils, including the coupling characteristics and its parasitic capacitance were discussed in wide range of operating frequency. The results from this investigation showed a good prospect for the development of fully integrated planar magnetic field coupler and generator for sensing and actuating purposes

Fabrikasi GPS antena menggunakan bahan zink aluminat berstruktur nano didopkan dengan kobalt

Kaedah sol gel digunakan untuk menghasilkan filem nipis CoxZn(1-x)Al2O4 berstruktur nano pada suhu 600°C. Corak pembelauan XRD menunjukkan pembentukan struktur tunggal spinel ZnAl2O4 dan CoAl2O4. Saiz hablur dan ketumpatan bahan berkurangan apabila kepekatan bahan dopan Co bertambah, iaitu masing-masing daripada 19.52 kepada 10.39 nm dan 4.609 kepada 4.585 g/cm3. Parameter kekisi pula meningkat daripada 8.085 kepada 8.098 Å apabila Co meningkat. Analisis FTIR menunjukkan ikatan ZnO, Co dan Al-O berlaku antara 487 hingga 550 cm-1, manakala ikatan spinel bagi ZnAl2O4 dan CoAl2O4 pula terbentuk pada 655 cm-1. Imej AFM menunjukkan kekasaran permukaan menurun apabila Co bertambah iaitu daripada 30.21 nm (×=0.00) kepada 14.83 nm (×=0.30). Nilai pemalar dielektrik (εr) menunjukkan penurunan secara linear apabila Co meningkat iaitu daripada 8.53 kepada 7.31. Seterusnya, GPS antena difabrikasi menggunakan sampel CoxZn(1-x)Al2O4. Prestasi dan frekuensi operasi GPS antena diukur menggunakan penganalisis rangkaian siri PNA pada frekuensi kenaan 1-2 GHz. Analisis mendapati antena beroperasi pada frekuensi 1.570 Ghz dengan kerungian pulangan -15.6 hingga -21.2 dB dan lebar jalurnya pula adalah 80 hingga 315 MHz. Kesemua antena yang telah difabrikasi memenuhi keperluan minimum antena untuk beroperasi pada aplikasi GPS

Relationship between students’ attitudes in space science with their achievements in the field

The purpose of this study is to identify the relationship between students’ attitude in space science with their achievement in the field. This study also examines students’ performance in space science. A total of 458 of secondary school students participated in this study. The questionnaire for this study was divided into two parts. The first part contains 9 items about students’ attitudes towards space science while the second part consists of 20 questions of general knowledge about space science. The findings show that students’ general knowledge about space science is at moderate level. The result also shows a significant relationship between students attitude with their achievement towards space science

Analysis of electrical responses of MEMS piezoresistive microcantilever

In this paper, an optimization of mechanical and electrical performance of single-layer silicon piezoresistive microcantilever (PRM) sensor in which both piezoresistor and microcantilever structures are made of the same material of single-crystalline silicon was discussed. Using CoventorWare 2008, the mechanical and electrical behaviors of the PRM structure was investigated by studying few contributing factors that affect the performance of the device. The performance of PRM sensor was investigated by observing the effects of applied loads to the current change and sensitivity of the device. Apart from that, the effects of thermal noise to the device’s performance were also investigated. From the simulation results, at applied loads between 1 to 10 µN, significant current increase of about 0.094% was observed. This current increase can be translated into an increase of sensitivity in the device. Simulation results also revealed that at temperature change between 290 K to 300 K, the PRM sensor shows insignificant change to sensitivity

VECTOR ALGEBRA QIBLA DETECTION IN AN INDOOR, SEMI-OPEN AND OUTDOOR ENVIRONMENT

There are myriad of methods used in determining the direction of Qibla and calculation using basic spherical trigonometric formula is the most accurate way that is used for centuries. Previous studies have successfully shown an alternative method using vector algebra formulas (VA) for Qibla determination to improvise the spherical trigonometric formula but only through the estimation software of Mathematica 8.0. Hence, this paper aims to extend the existing Qibla determination using VA on actual hardware implementation via integrated development environment (IDE) programming along with field test to confirm its capabilities. The prototype development in order to utilize of VA for Indoor Qibla Marking System comprises two modules: indoor and outdoor. The outdoor module includes a global positioning system (GPS) to provide location information, which is fed into the indoor module inside the building via wireless communication. The location information is then encoded into a format that is understood by the user and processed using VA to generate Qibla angle. While the indoor module consists of True North Finding System (TNFS) placed on the horizontal rotating laser mounted on the micro stepper motor to minimize motor disturbance as well as improving pointing accuracy. The results of the field test proved that the hardware and software implementation with VA method for Qibla determination obtained percentage accuracy of 99.95% compared to Qibla direction verified by Department of Survey and Mapping Malaysia (JUPEM) in collaboration with Department of Islamic Development Malaysia (JAKIM)

Fabrication of dual- and single-layer piezo resistive micro cantilever sensor

In this paper, the fabrication of piezoresistive microcantilever (PRM) sensor was realized through the utilization of bulk micromachining technology. Through a sequence of photolithography and etching processes, the device fabrication is realized. The fabrication of two PRM designs, dual-layer and single-layer has opened up the opportunity for device improvement especially in fabrication methods for simpler and reduced process steps. In single-layer design, the fabrication at reduced process steps which offers simpler and reproducible device has been successfully realized. This design offers simpler fabrication process by not only reducing the number of process steps but also eliminating the common fabrication issues encountered in bulk micromachining technology. With the development of single-layer doped silicon PRM sensor, the thermal strain issue, due to mismatch in coefficients of thermal expansion of multi-layered structure is not an issue. The novelty of this work lies in the design itself, in which the single-layer dual leg design not only simplifies the fabrication work, but also promotes an efficient current distribution along the piezoresistive dual-leg structure which is integrated with Wheatstone bridge configuration

Simple microcantilever release process of silicon piezoresistive microcantilever sensor using wet etching

In this paper, a simple microcantilever release process using anisotropic wet etching is presented. The microcantilever release is conducted at the final stage of the fabrication of piezoresistive microcantilever sensor. Issues related to microcantilever release such as microscopic roughness and macroscopic roughness has been resolved using simple technique. By utilizing silicon oxide (SiO2) as the etch stop for the wet etching process, issues related to microscopic roughness can be eliminated. On the other hand, proper etching procedure with constant stirring of the etchant solution of KOH anisotropic etching significantly reduces the notching effect contributed by the macroscopic roughness. Upon the completion of microcantilever release, suspended microcantilever of 2µm thick is realized with the removal of SiO2 layer using Buffered Oxide Etching (BOE)