In the surface mount technology, Ball Grid Array(ELGA) has been used in a production of PC hoards, because of their excellent characters such as high density of the lead pin pitch, better lead rigidity and self-alignment d'uing re-flow processing. This paper deals with the detection of defects at BGA solder joints in PC hoards by osing X-ray imaging. In the conventional IC boards, it is possible to detect defects of solder joints by visual inspection, because the lead of IC package is set .at its outside. However, we can not to detect visually defects at BGA solder joints, because they are hidden under the IC package. In a production line, the inspection of IBGA in PC boards depends on the function test of electric circuits in the final process. To improve a cost performance and reliability of PC boards, an inspection of BGA is required in the surface mount process. lypes of defects at BGA solder joints are solder bridge, missing connection, solder voids, open connection and misregistration of parts. As we can find mostly solder bridge in these defects, we pick up to detect solder bridge in a production line. The problems of image analysis for the detection of defects at BGA solder joints are the detection accuracy and image processing time according to a production line speed. To get design data for the development of the inspection system used easily in the surface mount process, it is important to develop image analysis techniques based on X-ray image data. At the first step of our study, we attempt to deteci: the characteristics of the solder bridges based on an image analysis.
We propose a microwave kinetic inductance detector consisting of an NbN rewound spiral resonator (spiral-MKID) as a possible broadband terahertz detector operating with a conventional cryogen-free 4He refrigerator. The spiral-MKIDs fabricated with NbN films reveal high-Q microwave resonation with loaded Q factors on the order of 104 at 3 K, and the temperature dependence of the microwave resonance frequency is well fitted by the Mattis–Bardeen theory. The optical response was confirmed in the terahertz range below 2.4 THz. We also discuss the expected noise equivalent power of the NbN-based MKIDs.
Synchrotron powder X-ray diffraction (XRD) experiments and transmission electron microscopy (TEM) observations of heat-treated sillimanite at various pressures were conducted to clarify the detailed phase relation between sillimanite and mullite. Under TEM, heat-treated sillimanite frequently showed anti-phase boundary (APB)-like textures with a displacement vector of ½[001]sil. Additional scanning TEM energy-dispersive X-ray spectroscopy analysis of regions with APB-like texture showed that they were clearly enriched in Al and accompanied by very fine, Si-rich glass inclusions, which indicates that the APB-like textures are composed of fine mullite. Moreover, synchrotron XRD patterns of these samples clearly showed double peaks of newly formed mullite and remnant sillimanite, indicating that the compositional transformation from sillimanite to mullite and glass is discontinuous. We separately determined the cell parameters of the sillimanite and mullite from the XRD pattern and found that the b axial length of the sillimanite increased with the treatment temperature, reflecting disordering of tetrahedral Al and Si in the sillimanite. In contrast, the positions of the deconvoluted mullite peaks indicated that the a axial length of mullite decreased as experimental pressure increased, owing to enrichment of the Si component. By projecting the cell parameters onto the a–b axial plane, the detailed changes in the crystallographic state of the sillimanite and mullite could be easily and comprehensively identified. On the basis of our results, we propose a new P-T diagram for the Al2SiO5 system that shows the transformation boundary between sillimanite and mullite + SiO2-rich melt and the contour of the Al/Si order parameter of sillimanite.
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