Perisai tahap PCB telah digunakan dalam industri elektronik secara meluas untuk mengurangkan masalah gangguan elektromagnet dan mematuhi piawai Keserasian Elektromagnet (EMC). Namun, peranti yang nipis, kecil, dan laju, beroperasi pada frekuensi Giga-Hertz telah menyebabkan gangguan elektromagnet antara jalur elektrik dan komponen. Berdasarkan pengetahuan terbaik penulis, kebanyakan penilaian keberkesanan pemerisaian tahap PCB hanya dilakukan dalam medan berjauhan. Oleh itu, kaedah pengukuran keberkesanan pemerisaian dalam medan berdekatan untuk tahap PCB dengan menggunakan pengimbas 3D elektromagnet dicadangkan di dalam tesis ini. Beberapa papan ujian PCB direkabentuk dengan dimensi yang berbeza dan dinilai. Keputusan mengesahkan kebolehpercayaan kaedah pengukuran dalam kawasan berdekatan berdasarkan keserasian antara keputusan pengukuran dan simulasi. Selain itu, penilaian kesan ciri-ciri perisai seperti ketebalan dan ketinggian dinilai melalui simulasi. Keputusan mencadangkan bahawa keberkesanan pemerisaian boleh ditingkatkan dengan mempunyai perisai yang lebih tinggi dengan jarak antara ‘ground via’ yang lebih kecil. Dengan setiap tambahan 0.5 mm pada ketinggian perisai, keberkesanan pemerisaian boleh ditingkatkan sebanyak 1 dB. Sebaliknya, keberkesanan pemerisaian akan berkurang sebanyak 0.5 dB untuk setiap peningkatan 1 mm dalam jarak antara ‘ground via’. Di samping itu, perisai yang lebih tebal boleh meningkatkan keberkesanan pemerisaian pada frekuensi di bawah 300 MHz.
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PCB level shield cans had been widely used in electronic industry to mitigate electromagnetic interference and to comply with Electromagnetic Compatibility (EMC) standard. However, the thinner, smaller, and faster, operating up to Giga-Hertz range devices led to electromagnetic interference among traces and components. To the best of author’s knowledge, most of the shielding effectiveness in PCB level was done in far field evaluation. Thus, measurement method in near field for PCB level shielding effectiveness by using electromagnetic 3D scanner is proposed in this thesis. Several test boards were designed with different shields’ dimension, evaluated for shielding effectiveness. Comparable results between the measurement and simulation justified the reliability of the measurement method in near field. Besides that, the evaluation of the impact of shield’s characteristic such as shield’s height and thickness, were modeled through simulation. Results suggested that shielding effectiveness could be improved by having greater shield’s height with smaller ground via spacing in shielding ground tracks. With every step of 0.5 mm increase in shield’s height, shielding effectiveness can be improved by 1 dB. On the other hand, shielding effectiveness would be degraded by 0.5 dB for every step of 1 mm increase in ground via spacing. In addition, greater shield’s thickness can contribute better shielding effectiveness for operating frequency below 300 MHz.
Evaluation and characterization of pcb shielding effectiveness in near field region_Chuah Yih Jian_E3_2017_MYMY