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Huang C.-W.,Chung Yuan Christian University | Chen B.-T.,Chung Yuan Christian University | Chen K.-Y.,National Taipei University | Hsueh C.-H.,National Taipei University | And 2 more authors.
International Journal of Applied Ceramic Technology | Year: 2015

A three-dimensional finite element model describing the thermal-mechanical stress distribution in multilayer ceramic capacitors (MLCCs) during termination firing, soldering, and bending tests is presented. Numerical results indicate that the thermal residual stresses originating from the soldering process are approximately one-fifth to half of the magnitude of the flexural stresses at the crack occurrence during the board flex test. The peak tensile stress from numerical simulations correlates with the crack initiation site observed in situ in board flex tests. The effects of inner electrode number, solder wicking height, lateral margin length, and the thickness of nickel in the termination component on mechanical failure during the board flex test are also investigated. Numerical results demonstrate that the maximum tensile stress could be effectively relieved by increasing the length of the lateral margin. In addition, a judicious combination of the solder wicking height and nickel termination thickness can further diminish the peak tensile stress during the board flex test. Finally, better design criteria are also developed by modifying the geometric parameters of MLCCs using Taguchi orthogonal arrays to decrease the peak tensile stresses that occur during board flex tests. © 2013 The American Ceramic Society. Source


Wong K.-L.,National Sun Yat - sen University | Lyu C.-A.,National Sun Yat - sen University | Chou L.-C.,Yageo Corporation Nantze Branch
Microwave and Optical Technology Letters | Year: 2012

A small-size multiband planar antenna can be obtained using a long parasitic shorted strip and a monopole feed encircled by the same. Such a configuration can lead to a small antenna size for multiband operation, and a promising design with a small size of 12 × 35 mm 2 for covering three-band LTE700/2300/2500 operation (704-787/2300-2400/2500-2690 MHz bands) in the tablet computer is presented. The antenna is easy to fabricate on one surface of an FR4 substrate and is composed of an inverted-L strip as the monopole feed and a long parasitic shorted strip encircling the inverted-L monopole. The long shorted strip is parasitically excited to generate a 0.25-wavelength resonant mode at about 750 MHz to cover the LTE700 operation, while the inverted-L monopole generates a 0.25-wavelength resonant mode at about 2.5 GHz to cover the LTE2300/2500 operation. Details of the proposed antenna are described. Radiation characteristics of the antenna and its body specific absorption rate results for tablet computer applications are also presented. © 2011 Wiley Periodicals, Inc. Source


Wong K.-L.,National Sun Yat - sen University | Wei W.-J.,National Sun Yat - sen University | Chou L.-C.,Yageo Corporation Nantze Branch
Microwave and Optical Technology Letters | Year: 2011

A WWAN/LTE printed loop antenna for tablet computer application is presented.The printed loop antenna is a half-wavelength loop strip coupled-fed by a patch monopole, which performs not only as a coupling feed but also as an efficient radiator for the antenna. By embedding a printed distributed inductor in the loop strip, dual-resonance excitation of the half-wavelength mode of the coupled-fed loop antenna is obtained, which forms the antenna's lower band at about 800 MHz to cover the LTE700/GSM850/900 operation (704-960 MHz). The antenna's upper band is formed by both the resonant modes contributed by the patch monopole and the higher order resonant modes contributed by the loop strip. The upper band shows a large bandwidth (>1 GHz) to cover the GSM1800/1900/UMTS/LTE2300/2500 operation (1710-2690 MHz). Further, with a planar and compact structure (12 × 75 mm 2), the antenna is suitable to be disposed in the limited space inside the tablet computer and meets the body specific absorption rate (SAR) requirement (<1.6 W/kg for 1-g body tissue) for practical applications. Details of the proposed antenna and its body SAR results are presented. © 2011 Wiley Periodicals, Inc. Source


Kang T.-W.,National Sun Yat - sen University | Wong K.-L.,National Sun Yat - sen University | Chou L.-C.,Yageo Corporation Nantze Branch
Asia-Pacific Microwave Conference Proceedings, APMC | Year: 2010

A coupled-fed shorted monopole with its feed structure as an effective radiator for 8-band LTE/WWAN operation in the laptop computer is presented. The radiating feed structure capacitively excites the shorted monopole. The feed structure mainly comprises a long feeding strip and a loop feed therein. The loop feed is formed at the front section of the feeding strip and connected to a 50-ω mini-cable to feed the antenna. Both the feeding strip and loop feed contribute wideband resonant modes to combine with those generated by the shorted monopole for the desired 8-band operation. The antenna size above the top shielding metal wall of the laptop display is 4 × 10 × 80 mm3 and is suitable to be embedded inside the casing of the laptop computer. The proposed antenna is fabricated and tested, and good radiation performances of the fabricated antenna are obtained. Details of the proposed antenna are presented and discussed. © 2010 IEICE Institute of Electronics Informati. Source


Wong K.-L.,National Sun Yat - sen University | Chen W.-J.,National Sun Yat - sen University | Chou L.-C.,Yageo Corporation Nantze Branch | Hsu M.-R.,Yageo Corporation Nantze Branch
IEEE Transactions on Antennas and Propagation | Year: 2010

By embedding a parasitic open slot in the antenna ground of a small-size internal laptop computer antenna, enhanced bandwidth for the antenna's lower band to cover the GSM850/900 operation (824960 MHz) can be achieved. The internal laptop computer antenna in this study is a small-size coupled-fed shorted T-monopole, whose length along the top edge of the display ground of the laptop computer is 43 mm only. The antenna can also provide a wide upper band to cover the GSM1800/1900/UMTS operation (17102170 MHz). With the inclusion of the parasitic open slot, the total antenna length along the top edge of the display ground is 48 mm only, and the occupied antenna volume is 10 × 3.5 × 48 mm3 above the top edge of the display ground, which is the smallest for the internal penta-band WWAN laptop computer antenna that have been reported for the present. Detailed results of the proposed parasitic open slot on bandwidth enhancement of the internal WWAN laptop computer antenna are presented. © 2010 IEEE. Source

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