As electronic devices have been increasingly reduced in size and height and provided with more functions, electronic parts which comprise the devices are highly required to be reduced in size and height (thickness), increased in functionality and integration. For example, a bandpass filter (hereinafter sometimes referred to as the “BPF”) employed in a communication device such as a portable phone, a wireless LAN device, and the like, plays an important role of selecting frequencies while removing unwanted waves for the communication device. For responding to such requirements, the bandpass filter may be provided as a filter chip which has a resonator formed within a laminated ceramic board that is more beneficial for a reduction in size and height and for higher integration.
A laminated ceramic board may employ, for example, an LTCC (Low Temperature Co-fired Ceramics) board, inductor electrodes and capacitor electrodes are distributively placed on a variety of wiring layers within the board, and a plurality of stages of resonators are disposed between an input terminal and an output terminal, thereby forming a predetermined pass band.
Then, the filter chip thus constructed is electrically and mechanically connected to the surface of a mother board or a board which forms part of a module (hereinafter referred to as the “mounting board”).
Additionally, the following patent documents 1-4 disclose such electronic parts.
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USPTO Backgrounds