Surface mount quartz crystal resonators and methods for making same

Abstract

A surface mount quartz crystal resonator includes a quartz crystal-based plate including a central portion adapted to resonate at a desired frequency, and a border substantially surrounding a peripheral region of the central portion. The border includes a first region physically separated from the central portion, and a second region joined to the central portion. A base plate is provided which is secured to the plate so that the central portion of the plate is free to resonate relative to the base plate. A cover plate is provided and is secured to the plate so that the plate is located between the base plate and the cover plate. At least one, and preferably both, of the base plate and the cover plate are made of quartz.

What is claimed is:  
     
         1 . A resonator plate comprising: 
 a quartz crystal-based plate, including 
 a central portion having a top surface and a bottom surface and adapted to resonate at a desired frequency, and  
 a border substantially surrounding the central portion, the border including a first region physically separated from the central portion, a second region joined to the central portion, and an outer edge surface;  
   a first electrode disposed on the top surface of the central portion and including conductive plating on the outer edge surface of the border; and    a second electrode disposed on the bottom surface of the central portion.    
     
     
         2 . The resonator plate of  claim 1  wherein the quartz crystal-based plate has a length and a width defining a substantially rectangular outer periphery, and the length of the quartz crystal-based plate is aligned along the X-crystallographic axis.  
     
     
         3 . The resonator plate of  claim 1  further comprising a planar area sized to accommodate the first electrode, the planar area comprising a substantially ridgeless plane extending continuously across at least a portion of the top surface of the central portion to the outer edge surface.  
     
     
         4 . The resonator plate of  claim 3  wherein the planar area is a recessed planar area with respect to at least one surface area adjacent the planar area.  
     
     
         5 . The resonator plate of  claim 4  wherein the planar area defines a groove transversing the second region of the border.  
     
     
         6 . The resonator plate of  claim 3  wherein the planar area is an elevated planar area with respect to at least one surface area adjacent the planar area.  
     
     
         7 . The resonator plate of  claim 3  wherein the planar area defines an elevation across the second region of the border.  
     
     
         8 . The resonator plate of  claim 1  which is adapted to resonate at a frequency in a range of between about 3.5 MHz and about 100 MHz.  
     
     
         9 . The resonator plate of  claim 1  which is adapted to resonate at a frequency of about 50 MHz.  
     
     
         10 . A resonator assembly comprising: 
 a quartz crystal-based resonator plate, including 
 a central portion having a top surface and a bottom surface and adapted to resonate at a desired frequency, and  
 a border substantially surrounding the central portion, the border including a first region physically separated from the central portion, a second region joined to the central portion, and an outer edge surface;  
   a first electrode disposed on the top surface of the central portion and including conductive plating on the outer edge surface of the border;    a second electrode disposed on the bottom surface of the central portion;    a base plate secured to the resonator plate; and    a cover plate secured to the resonator plate.    
     
     
         11 . The resonator assembly of  claim 10  wherein the the base plate includes a terminal electrode conductively connected to the first electrode on the resonator plate.  
     
     
         12 . The resonator assembly of  claim 10  wherein the second electrode includes conductive plating on the outer edge surface of the border.  
     
     
         13 . The resonator assembly of  claim 10  wherein the quartz crystal-based resonator plate has a length and a width defining a substantially rectangular outer periphery, and the length of the quartz crystal-based plate is aligned along the X-crystallographic axis.  
     
     
         14 . The resonator assembly of  claim 10  further comprising a planar area sized to accommodate the first electrode, the planar area comprising a substantially ridgeless plane extending continuously across at least a portion of the top surface of the central portion to the outer edge surface.  
     
     
         15 . The resonator assembly of  claim 14  wherein the planar area is a recessed planar area with respect to at least one surface area adjacent the planar area.  
     
     
         16 . The resonator assembly of  claim 15  wherein the planar area defines a groove across the second region of the border.  
     
     
         17 . The resonator assembly of  claim 14  wherein the planar area is an elevated planar area with respect to at least one surface area adjacent the planar area.  
     
     
         18 . The resonator plate of  claim 17  wherein the planar area defines an elevation across the second region of the border.  
     
     
         19 . The resonator assembly of  claim 10  which is adapted to resonate at a frequency in a range of between about 3.5 MHz and about 100 MHz.  
     
     
         20 . The resonator assembly of  claim 10  which is adapted to resonate at a frequency of about 50 MHz.  
     
     
         21 . The assembly of  claim 10  which has a volume of less than about 10 cubic millimeters.  
     
     
         22 . The assembly of  claim 10  which has a volume of about 3.2 cubic millimeters.  
     
     
         23 . The assembly of  claim 10  which has a volume of about 2.0 cubic millimeters.  
     
     
         24 . A resonator plate comprising: 
 a quartz crystal-based resonator plate, including 
 a central portion having a top surface and a bottom surface adapted to resonate at a desired frequency, and  
 a border substantially surrounding the central portion, the border including a first region physically separated from the central portion, a second region joined to the central portion, and an outer edge surface;  
   a first electrode, disposed on the surface of the central portion and extending substantially continuously across the second region of the border to the outer edge surface; and    a second electrode disposed on the bottom surface of the central portion and extending substantially continuously across the second region of the border to the outer edge surface, 
 wherein of the first electrode includes conductive plating on a portion of the outer edge surface of the border and the second electrode includes conductive plating on another portion of the outer edge surface of the border.  
   
     
     
         25 . The resonator plate of  claim 24  wherein the quartz crystal-based plate has a length and a width defining a substantially rectangular outer periphery, and the length of the quartz crystal-based plate is aligned along the X-crystallographic axis.  
     
     
         26 . The resonator plate of  claim 24  further comprising a planar area sized to accommodate the first electrode, the planar area comprising a substantially ridgeless plane extending continuously across at least a portion of the top surface of the central portion to the outer edge surface.  
     
     
         27 . The resonator plate of  claim 26  wherein the planar area is a recessed planar area with respect to at least one surface area adjacent the planar area.  
     
     
         28 . The resonator plate of  claim 27  wherein the planar area defines a groove across the second region of the border.  
     
     
         29 . The resonator plate of  claim 26  wherein the planar area is an elevated planar area with respect to at least one surface area adjacent the planar area.  
     
     
         30 . The resonator plate of  claim 29  wherein the planar area defines an elevation across the second region of the border.  
     
     
         31 . A method of manufacturing a quartz crystal-based resonator plate comprising the steps of: 
 providing a solid quartz crystal based plate having a top surface, an opposing bottom surface, an outer edge, and an outer edge surface;    removing a portion of the plate to form the quartz crystal-based plate having a slot physically separating a central portion of the plate from a border of the plate;    forming a planar area on the top surface of plate wherein the planar area extends along a common plane from the central portion across a portion of the border and to the outer edge of the plate, and wherein the planar area comprises one of an elevated planar area and a recessed planar area, with respect to an adjacent surface area of the plate;    applying an electrode material to at least a portion of the planar area, and    repeating the forming and applying steps on the opposing bottom surface of the plate.    
     
     
         32 . The method of  claim 31  wherein the step of applying comprises applying conductive plating to the outer edge surface of the plate.  
     
     
         33 . The method of  claim 31  further comprising the step of stacking a plurality of quartz crystal-based plates and plating an edge of each of the plates by applying conductive plating to the stack of plates.