Surface mount RC devices

Abstract

Both discrete and array RC components are described using cofireable resistive material as part of internal electrodes of the device. The devices include a sintered body of multilayer ceramic material in which multiple first and second electrode layers are stacked. Each of the first layers comprises at least one resistive electrode pattern extending across the sintered body between respective pairs of terminations. The second layers comprise an electrode pattern extending transverse to the resistive electrode pattern, such as between end terminations. In some embodiments, opposing side electrodes serve as input and output terminals of a respective feedthrough filter. In a feedthrough arrangement, the third terminal may be provided by one or both of the end terminals. The invention also describes an improved termination structure including a layer made from a metal oxide material.

What is claimed is:  
     
         1 . A method of fabricating a composite RC device, said method comprising steps of: 
 (a) providing a plurality of first ceramic layers having a predetermined dielectric constant;    (b) forming a first selected electrode pattern on said first ceramic layers, said first selected electrode pattern being formed of a substantially nonresistive conductive material;    (c) providing a plurality of second ceramic layers having said predetermined dielectric constant;    (d) forming a second selected electrode pattern on said second ceramic layers, said second predetermined electrode pattern being formed of a cofirable resistive material and configured to yield a desired resistance value; and    (e) said first selected electrode pattern and said second selected electrode pattern being configured to provide a particular electrode overlap to yield a desired capacitance value.    
     
     
         2 . A method of fabricating as in  claim 1 , wherein said particular electrode overlap is relatively limited so as to provide relatively smaller desired capacitance value and relatively lower desired resistance value.  
     
     
         3 . A method of fabricating as in  claim 1 , wherein said conductive material of said first selected electrode pattern is relatively more narrow width so as to provide relatively smaller desired capacitance value without lowering desired resistance value.  
     
     
         4 . A method of fabricating as in  claim 1 , wherein said resistive material of said second predetermined electrode pattern does not engage any device terminations, so as to constitute a series capacitor-resistor-capacitor equivalent circuit.  
     
     
         5 . A composite RC device, said device comprising: 
 a device body having a unitary structure characteristic of a plurality of stacked, pressed and sintered ceramic-electrode layers;    said device body including at least two electrical terminations located on side surfaces thereof;    said ceramic-electrode layers including a plurality of first ceramic layers having thereon a pair of first electrode plates extending to respective of said terminations;    said ceramic-electrode layers further including a plurality of second ceramic layers having thereon a second electrode plate formed of a resistive material; and    said second ceramic layers being interleaved with said first ceramic layers to produce overlaps between each of said second electrode plates and a respective pair of said first electrode plates in an adjacent ceramic-electrode layer.    
     
     
         6 . A composite RC device as in  claim 5 , wherein said overlaps are relatively limited so as to provide relatively smaller resulting capacitance and relatively lower resulting resistance of said device.  
     
     
         7 . A composite RC device as in  claim 5 , wherein said ceramic-electrode layers are relatively thinner so as to provide relatively smaller resulting capacitance without lowering resulting resistance of said device.  
     
     
         8 . A composite RC device as in  claim 5 , wherein said resistive material of said second electrode plate does not engage any device terminations, such that said device constitutes a series capacitor-resistor-capacitor equivalent circuit.