| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2005: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2004: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2003: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2002: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
In order to develop a new common-mode filter for advanced balance-mode digital interface, fabrication and characterization of the Mn-Zn ferrite particle/Polyimide composite material has been investigated. In addition, the new common-mode filters using ferrite based composite material have been developed, and their signal transmission characteristics have been evaluated.
(1) Fabrication method of Mn-Zn ferrite particle/Polyimide composite material
A possibility of the new composite material composed of Mn-Zn ferrite magnetic particle and Polyimide dielectric material for common-mode filter has been investigated. Two fabrication methods, one was a spin-coating method using slurry composed of Mn-Zn ferrite and Polyamic acid solution, the other was a screen-printing method using paste, were investigated. In either fabrication method, it was possible to fabricate the composite material by low temperature firing around 300℃. A volume fraction of the ferrite in the composites was around 50%. Th
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e typical fabricated composite material exhibited a static relative permeability of 5〜6, same tendency of high frequency property as the Snoek's limit line of the conventional bulk Ni-Zn ferrite. The relative permittivity was 50〜100 at several hundreds megahertz, this was 5〜10 times higher than that of the conventional bulk Ni-Zn ferrite.
(2) Fabrication of common-mode filter
By using two methods of spin-coating and screen-printing, the common-mode filters have been fabricated. In the former method, a device with coupled distributed lines in the same plane was fabricated, since it was very difficult to fabricate the complicated three dimensional structure. The latter method enabled to fabricate the complicated multilayer structure, and the device with a higher magnetic coupling between coupled signal lines by introducing upper and lower facing coupled line structure was fabricated. In the screen-printing method, in order to avoid the cracking of the magnetic composite material, a new nonmagnetic composite with SiO_2 filler and polyimide as a dielectric interlayer was introduced. Since both magnetic and nonmagnetic composite materials had same thermal expansion coefficient, the crack of the materials was markedly suppressed.
(3) Signal transmission characteristic
The fabricated common-mode filters have been evaluated using a four-port network analyzer. From experimental results, the common-mode decay was over 15 dB in GHz band, and the maximum decay was up to 50 dB at 3 GHz. The balance-mode decay was below 15 dB in GHz band. It was found that the new device functioned as a GHz common-mode filter with a large common-mode rejection.
(4) Future issues
Though the newly developed common-mode filter exhibited a large common-mode rejection in GHz band, the balance-mode decay was relatively large. In order to apply it to Gbps advanced digital interface, the balance-mode insertion loss should be less than 3 dB. We currently investigate a metal based magnetic composite material as a substitute for ferrite based material. Since the metal based composite material has two times higher permeability than that of ferrite based one. In the future, we will investigate the common-mode filter using metal based composite material. Less
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