Transmission-line spring structure

Abstract

A curved transmission-line spring structure formed by self-bending materials (e.g., stress-engineered materials, intermetallic compounds and/or bimorphs) that are layered to form a stripline or microstrip transmission line. A dielectric layer is sandwiched between two conductive layers, which form the signal and ground lines of the structure. The various layers are etched to form an elongated spring structure, and then one end of the spring structure is released from the underlying substrate, causing the tip of the released end to bend away from the substrate for contact with a second device. One or both of the conductive layers is fabricated using self-bending spring metals to facilitate the bending process, and plated metal is utilized for conductivity. Alternatively, or in addition, the dielectric layer is formed using a stress-engineered dielectric material. Two-tip and three-tip structures are used to facilitate connection of both the ground and signal lines.

1 . An assembly comprising: 
 a substrate including first and second contact pads;    an elongated transmission-line spring structure having an anchor region attached to the substrate, a curved cantilever region extending from the anchor region away from the substrate, and at least one tip located at a distal end of the cantilever region,    wherein said transmission-line spring structure includes:    a first elongated conductive layer having a first end connected to the first contact pad and a second end located adjacent to the at least one tip;    a second elongated conductive layer having a first end connected to the second contact pad and a second end located adjacent to the at least one tip; and    a dielectric layer formed between the first and second conductive layers such that the first and second conductive layers are separated by the dielectric layer.    
   
   
       2 . The assembly according to  claim 1 , 
 wherein the first elongated conductive layer is formed between the dielectric layer and the substrate, and    wherein the first elongated conductive layer comprises spring metal.    
   
   
       3 . The assembly according to  claim 2 , 
 wherein the second conductive layer is formed on a surface of the dielectric layer opposite to the first elongated conductive layer, and    wherein at least one of the first elongated conductive layer and the second elongated conductive layer comprises plated metal.    
   
   
       4 . The assembly according to  claim 1 , 
 wherein the dielectric layer is formed between the second elongated conductive layer and the substrate, and    wherein the second elongated conductive layer comprises spring metal.    
   
   
       5 . The assembly according to  claim 4 , 
 wherein the first conductive layer is formed between the dielectric layer and the substrate, and    wherein at least one of the first elongated conductive layer and the second elongated conductive layer comprises plated metal.    
   
   
       6 . The assembly according to  claim 1 , wherein both the first elongated conductive layer and the second elongated conductive layer comprise spring metal.  
   
   
       7 . The assembly according to  claim 6 , wherein at least one of the first elongated conductive layer and the second elongated conductive layer further comprises plated metal.  
   
   
       8 . The assembly according to  claim 1 , wherein the dielectric layer comprises a stress-engineered dielectric material.  
   
   
       9 . The assembly according to  claim 8 , wherein at least one of the first elongated conductive layer and the second elongated conductive layer comprise spring metal.  
   
   
       10 . The assembly according to  claim 8 , wherein at least one of the first elongated conductive layer and the second elongated conductive layer comprises plated metal.  
   
   
       11 . The assembly according to  claim 1 , 
 wherein the first elongated conductive layer includes a first layer portion defining a first tip and a second layer portion defining a second tip,    wherein the dielectric layer extends along the first layer portion to the first tip, and    wherein the second elongated conductive layer extends along the dielectric layer over the first layer portion, and includes a tip portion located over the first tip.    
   
   
       12 . The assembly according to  claim 1 , 
 wherein the first elongated conductive layer includes a first layer portion defining a first tip and a second layer portion defining a second tip,    wherein the dielectric layer includes a first dielectric portion extending along the first layer portion and a second dielectric portion extending along the second layer portion,    wherein the second elongated conductive layer extends along the dielectric layer over the first layer portion, and includes an upper tip portion located over the first tip, and    wherein the second dielectric portion terminates adjacent to the second tip such that the second tip extends from an end of the second dielectric portion.    
   
   
       13 . The assembly according to  claim 1 , 
 wherein the first elongated conductive layer includes a first layer portion defining a first tip, a second layer portion defining a second tip, and a third layer portion defining a third tip, the first layer portion being located between the second and third layer portions,    wherein the dielectric layer extends along the first layer portion to the first tip, and    wherein the second elongated conductive layer extends along the dielectric layer over the first layer portion, and includes an upper tip portion located over the first tip.    
   
   
       14 . The assembly according to  claim 1 , 
 wherein the first elongated conductive layer includes a first layer portion defining a first tip, a second layer portion defining a second tip, and a third layer portion defining a third tip, the first layer portion being located between the second and third layer portions,    wherein the dielectric layer includes a first dielectric portion extending along the first layer portion, a second dielectric portion extending along the second layer portion, and a third dielectric portion extending along the third layer portion,    wherein the second elongated conductive layer extends along the dielectric layer over the first layer portion, and includes an upper tip portion located over the first tip, and    wherein the second dielectric portion and the third dielectric portion terminate adjacent to the second tip and the third tip, respectively, such that the second tip and the third tip extend from ends of the second and third dielectric portions, respectively.    
   
   
       15 . The assembly according to  claim 1 , 
 wherein the first elongated conductive layer includes a first layer portion defining a first tip, a second layer portion defining a second tip, and a third layer portion defining a third tip, the first layer portion being located between the second and third layer portions,    wherein the dielectric layer includes a first dielectric portion extending along the first layer portion, a second dielectric portion extending along the second layer portion, and a third dielectric portion extending along the third layer portion,    wherein the second elongated conductive layer extends along the dielectric layer over the first layer portion, and includes an upper tip portion located over the first tip, and    wherein the spring structure further comprises:    a third elongated conductive layer formed on the second dielectric portion and having a second tip portion located over the second tip; and    a fourth elongated conductive layer formed on the third dielectric portion and having a third tip portion located over the third tip.    
   
   
       16 . The assembly according to  claim 15 , wherein the spring structure further comprises: 
 a first metal via extending between the second layer portion and the third elongated conductive layer through the second dielectric portion; and    a second metal via extending between the third layer portion and the fourth elongated conductive layer through the third dielectric portion.    
   
   
       17 . The assembly according to  claim 15 , wherein the spring structure further comprises: 
 a first metal side structure extending between the second layer portion and the third elongated conductive layer along a side of the second dielectric portion; and    a second metal side structure extending between the third layer portion and the fourth elongated conductive layer along a side of the third dielectric portion.    
   
   
       18 . A transmission-line spring structure having an anchor region, a curved cantilever region extending from the anchor region, and at least one tip located at a distal end of the cantilever region, wherein said transmission-line spring structure comprises: 
 a first elongated conductive layer extending between the anchor region and the at least one tip;    a dielectric layer formed on the first elongated conductive layer; and    a second elongated conductive layer formed on the dielectric layer and extending between the anchor region and the at least one tip,    wherein the dielectric layer extends along the first and second elongated conductive layers such that the first and second conductive layers are separated by the dielectric layer.    
   
   
       19 . A transmission-line spring structure comprises: 
 a first elongated conductive layer including an anchor region, a first layer portion extending from the anchor region to a first tip, and a second layer portion extending from the anchor region to a second tip,    a dielectric layer formed on the first elongated conductive layer and extending along the first layer portion between the anchor region and the first tip, and    a second elongated conductive layer formed on the dielectric layer and extending over the first layer portion, wherein the second elongated conductive layer includes a tip portion located over the first tip.    
   
   
       20 . The transmission-line spring structure of  claim 19 , 
 wherein the first elongated conductive layer further comprises a third layer portion extending from the anchor region to a third tip, and    wherein the first layer portion is located between the second layer portion and the third layer portion.