Patent Publication Number: US-2009236692-A1

Title: Rc filtering device having air gap construction for over voltage protection

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an RC filtering device, specifically to an RC filtering device that has air gap construction for over voltage protection. 
     2. Description of Prior Art 
     It is known to public that today&#39;s electronic device is focusing on speed of signal transferring, for example, signal frequency of HDMI has reached 742.5 MHz, its electrostatic discharge (ESD) demand for better over voltage protection device is higher than before, with low capacitance, such over voltage protection device can avoid high frequency signal from reducing in high speed transmission. 
     Moreover, the noise of electromagnetic wave in the atmosphere is coupled to the circuit via coupling function, that causes misjudgment of signal from IC, therefore, the combination of filtering and over voltage protection for signals on high speed transmission line is very important. 
     SUMMARY OF THE INVENTION 
     Therefore, the object of present invention is to provide an RC filtering device having an air gap construction for over voltage protection, it consists constructions of RC filtering and over voltage protection structure that has air gap construction, so as to solve the dual problems of electrostatic discharge (ESD) and electromagnetic interference (EMI) faced by signal during high speed transmission. 
     According to the RC filtering device having an air gap construction for over voltage protection of present invention, it consists of: a lower substrate, an electrode layer formed on the top surface of the said lower substrate, this electrode layer is formed by a cross electrode. Wherein, one of the electrode in an orientation has two grooves at both end portions, the said grooves cut through the electrode layer and extend into the interior of lower substrate; an intermediate substrate, on the substrate is a second pair of grooves, the second pair of grooves correspond in location with the grooves formed in the lower substrate, and the second pair of grooves have the same length and width as the grooves formed in the lower substrate; a second intermediate substrate, its top surface contains a transmission wire, the said transmission wire lays in the same direction as the lower substrate electrode layer having the grooves; and an upper substrate that is put onto top of the said second intermediate substrate. 
     A more complete understanding of these and other features and advantages of the present invention will become apparent from a careful consideration of the following detailed description of certain embodiments illustrated in the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a decomposited three-dimensional view showing the structure of RC filtering device having air gap construction for over voltage protection of present invention. 
         FIG. 2  is a cross-sectional view showing the RC filtering device having air gap construction for over voltage protection of present invention. 
         FIG. 3  is a three-dimensional view showing the RC filtering device having air gap construction for over voltage protection of present invention. 
         FIG. 4  is an equivalent electric circuit of the RC filtering device of present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As shown in  FIGS. 1 &amp; 2 , the RC filtering device having air gap construction for over voltage protection of present invention consists of: a lower substrate  1 , a first intermediate substrate  2 , a second intermediate substrate  3  and an upper substrate  4 . An electrode layer  11  is formed on the top surface of the lower substrate  1 , the electrode layer  11  is formed in cross shape, one of the electrode layer in one orientations forms a pair of groove  121 ,  122  at its end portions, the said first pair of grooves  121 ,  122  not only cut through the electrode layer  11 , but also cut into the interior of lower substrate  1 ; 
     the first intermediate substrate  2  is formed on the lower substrate, at the position corresponding to the said grooves  121 ,  122  formed on the lower substrate  1 , the first intermediate substrate  2  forms a second pair of grooves  21 ,  22 , and the second pair of grooves  21 ,  22  cuts through the first intermediate substrate  2 . The second pair of grooves  21 ,  22  not only correspond to said first pair of grooves  121 ,  122  in position, they also have the same length and width as said first pair of grooves  121 ,  122 . 
     Referring to  FIGS. 1 &amp; 2  again, a second intermediate substrate  3  is formed on the top surface of said first intermediate substrate  2 , and an transmission wire  31  is formed on the upper surface of the second intermediate substrate  3 , both ends of the transmission wire  31  have electrode layers  32 ,  33 , the transmission wire  31  between the said electrode layer  32 ,  33  can be a metallic oxide layer, the metallic oxide layer is made up with material having electric resistance; the orientation of said transmission wire  31  is same as the electrode formed on the lower substrate having said grooves  121 ,  122 . 
     An upper substrate  4 , is formed on the upper surface of the second intermediate substrate  3 . 
     As shown in  FIG. 3 , after the lower substrate  1 , the first intermediate substrate  2 , the second intermediate substrate  3  and the upper substrate  4  are put together in order. The terminal electrodes  51 ,  52 ,  53 ,  54  are respectively formed at the four sides of the body, wherein, the terminal electrodes  51 ,  52  are formed as ground terminals, and the terminal electrodes  53 ,  54  are respectively formed as input terminal and output terminal. 
     The electric circuit equivalent to the RC device having air gap construction for over voltage protection is shown in  FIG. 4 . It is very clearly to see that the lower substrate  1  and the first intermediate substrate form a pair of capacitors C 1  &amp; C 2 , the air gaps  21 ,  22  &amp;  121 ,  122  respectively forms an over voltage protection construction, the transmission wire  31  forms a resistor between the capacitors C 1  &amp; C 2 , while  32 / 53  and  33 / 54  are respectively forms input and output terminal. 
     Regarding to the materials for above mentioned RC filtering device having air gap construction for over voltage protection of present invention, its lower substrate  1 , the first intermediate substrate  2 , the second intermediate substrate  3  and the upper substrate  4  are formed by the insulate materials of aluminum compounds (such as alumina), titanium or silicon, etc. The RC filtering device having air gap construction for over voltage protection of present invention can also be formed in multi-layer thin film. 
     The aforesaid electrode layer  11  of lower substrate  1  and the transmission wire  31  of second intermediate substrate  3  can be formed of one of the following materials: gold, silver, palladium, platinum, wolfram or copper, and can be formed by any alloy of said metallic elements or any composite material of said metallic elements. 
     The said grooves  121 ,  122  and  21 ,  22  formed in the lower substrate  1  and the first intermediate substrate  2  can be made by cutting, after the substrates are put together in order, grooves  121 ,  122 ,  21 ,  22  together form an air gap to provide over voltage protection to electronic circuit. Also, in accordance to the needs and requirements, the size of the air gap can be adjusted, such as the depth and width, that would not be limited by production. 
     According to the above mentioned construction, RC filtering device can easily obtain the function of over voltage protection, it is easy in production and would have the electrical properties of RC filtering device. 
     In conclusion of the above, since the RC filtering device having an air gap construction for over voltage protection of present invention is not disclosed previously and it does not have been sold anywhere, therefore, it is believed to be an invention of novelty. Moreover, the unique character and ability of present invention are more advanced, it is then believed that the present invention is an invention with progressiveness, and meets the requirement of patent application according to relevant Patent Law. 
     Although the present invention has been described with a certain degree of particularity, the present disclosure has been made by way of example and changes in details of structure may be made without departing from the spirit thereof.