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 (Tea) 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 Teak of 246 and 260°C. This is due to the inadequate reflow profile and insufficient heating input during the p 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.
A comprehensive study on the spin-on-glass (SOG) 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.
CaxZn(1_x)Al204thin films (x = 0.00; 0 .05 ; 0.10; 0.15 and 0.20) were prepared by sol-gel method with the substitution of Zn2+ by Ca" in the framework of ZnAl204. The effect of Ca addition on the structure and morphology of CaZnAl204thin films was investigated by x-ray diffraction (xRD), field-emission scanning electron microscope (FESEM), energy-dispersive x-ray spectroscopy (EDx), ultra-violet visible (uv-Vis) and atomic force microscope (AFM). The xRD patterns showed the characteristic peaks of face-centred cubic (fcc)ZnAl204and CaZnAl204. The addition of Ca increased the crystallite size from 8.9 to 302 nm. The bandgap of CaxZnuld204 thin film was found in the range of 3.40 to 3.84 eV. sEm micrograph shows the morphology of all thin films is sphere-like, with the grain size increased from 33 to 123 nm. The AFM images show the roughness of surface morphology increased. The substitution of Zn2+ by Ca" increased the crystallite size, grain size and surface roughness which evidently increased the density (4.59 to 4.64 glcm3) and dielectric constant (8.48 to 9.54). The composition of CaxZn(1_x)Al204is considered as suitable material for GPS patch antennas.
Kaedah sol gel digunakan untuk menghasilkan filem nipis CoxZn(1-x)Al2
O4 berstruktur nano pada suhu 600°C. Corak
pembelauan XRD menunjukkan pembentukan struktur tunggal spinel ZnAl2
O4 dan CoAl2
O4
. 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
ZnAl2
O4
dan CoAl2
O4
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)Al2
O4
. 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.