Multilayer wiring board

Abstract

A multilayer wiring board includes a first dielectric layer, a high-frequency signal line formed on a first surface of the first dielectric layer, a ground layer formed on a second surface of the first dielectric layer, and a second dielectric layer covering part of the ground layer. The high-frequency signal line is electrically connectable to a center conductor of a coaxial structure. The second dielectric layer is spaced from an edge of the first dielectric layer to which the coaxial structure is to be connected, so that a ground exposure portion of the ground layer is exposed on the edge of the first dielectric layer. The ground layer is electrically connectable directly to an outer conductor of the coaxial structure at the ground exposure portion.

What is claimed is: 
     
       1. A multilayer wiring board to which a coaxial structure for transmitting an electric signal with a center conductor and an outer conductor is connected, the multilayer wiring board comprising:
 a first dielectric layer; 
 a high-frequency signal line formed on a first surface of the first dielectric layer, the high-frequency signal line having a connecting portion that is electrically connectable to the center conductor of the coaxial structure; 
 a ground layer formed on a second surface of the first dielectric layer; and 
 a second dielectric layer covering part of the ground layer, the second dielectric layer having an edge spaced from an edge of the first dielectric layer that faces with the coaxial structure when the coaxial structure is connected to the multilayer wiring board, the edge of the second dielectric layer being located at an inner side of the multilaver wiring board than the edge of the first dielectric layer, thereby exposing a ground exposure portion of the ground layer-en between the edge of the first dielectric layer and the edge of the second dielectric layer, 
 the ground layer being electrically connectable directly to the outer conductor of the coaxial structure at the ground exposure portion, 
 wherein the high-frequency signal line is exposed to an outside of the multilayer wiring board near the connecting portion thereof when the coaxial structure is connected to the multilayer wiring board. 
 
     
     
       2. The multilayer wiring board as recited in  claim 1 , wherein the ground exposure portion of the ground layer is electrically connected directly to the outer conductor of the coaxial structure by at least one of a solder material, silver paste, and a conductive adhesive material applied to the ground exposure portion. 
     
     
       3. The multilayer wiring board as recited in  claim 1 , wherein the ground exposure portion of the ground layer is electrically connected directly to the outer conductor of the coaxial structure by a contact protrusion extending from the outer conductor of the coaxial structure. 
     
     
       4. The multilayer wiring board as recited in  claim 1 , wherein the ground exposure portion is located right below the center conductor of the coaxial structure when the coaxial structure is connected to the multilayer wiring board. 
     
     
       5. The multilayer wiring board as recited in  claim 1 , further comprising a control signal layer formed on a surface of the second dielectric layer for forming a control signal circuit. 
     
     
       6. The multilayer wiring board as recited in  claim 1 , wherein the coaxial structure comprises a connector to be mounted on the multilayer wiring board. 
     
     
       7. The multilayer wiring board as recited in  claim 1 , wherein the edge of the first dielectric layer is brought into contact with the coaxial structure when the coaxial structure is connected to the multilayer wiring board. 
     
     
       8. The multilayer wiring board as recited in  claim 1 , wherein the high-frequency signal line is electrically connectable to the center conductor of the coaxial structure at the shortest distance.