Method of machining glass substrate and method of fabricating high-frequency circuit

Abstract

A method of machining a glass substrate by using a laser, in which a low-permittivity, low-dielectric-loss glass substrate capable of coping with mass production processes is made applicable as the substrate of a high-frequency circuit intended for microwave and millimeter-wave bands in particular. For that purpose, a glass substrate is provided in which the amount of air bubbles in glass is arbitrarily controlled to improve the workability of the substrate itself. Then, the glass substrate is machined while being irradiated with a pulsed laser for a plurality of times, thereby improving the machining shape of the glass substrate. Since glass substrates which are typically difficult to machine can be easily applied to the fabrication of high-frequency circuits, it becomes possible to supply high-performance circuits and apparatuses widely to the public.

What is claimed is:  
     
         1 . A glass substrate machining method comprising the steps of: 
 machining a glass substrate by using a CO 2  laser of variable pulse width as machining means;    a first step of executing a single laser irradiation; and    a second step of executing a plurality of laser irradiations.    
     
     
         2 . The glass substrate machining method according to  claim 1 , wherein the pulse width of said laser in the second step is greater than that in the first step.  
     
     
         3 . A high-frequency circuit fabricating method comprising 
 machining a glass substrate by using a CO 2  laser;    controlling an amount of air bubbles in said glass substrate to improve the workability of said glass substrate.    
     
     
         4 . A high-frequency circuit fabricating method according to  claim 3 , comprising forming a thin insulator on a glass surface.  
     
     
         5 . A high-frequency circuit fabricating method according to  claim 3 , wherein an internal cavity is formed within said glass substrate.  
     
     
         6 . A high-frequency circuit fabricating method according to  claim 3 , wherein said glass substrate, after said laser machining, has a large surface area in the machined surface due to bubble traces in glass; and 
 forming a metal film through simple electroless plating, to improve heat radiation property of the metal film-formed portion.    
     
     
         7 . A radio terminal apparatus comprising a high-frequency circuit fabricated by the machining method according to  claim 3 .  
     
     
         8 . A radio terminal apparatus comprising a high-frequency circuit fabricated by the glass substrate machining method according to  claim 4 .  
     
     
         9 . A radio terminal apparatus comprising a high-frequency circuit fabricated by the glass substrate machining method according to  claim 5 .  
     
     
         10 . A radio terminal apparatus comprising a high-frequency circuit fabricated by the glass substrate machining method according to  claim 6 .  
     
     
         11 . A radio base station apparatus comprising a high-frequency circuit fabricated by the glass substrate machining method according to  claim 3 .  
     
     
         12 . A radio base station apparatus comprising a high-frequency circuit fabricated by the glass substrate machining method according to  claim 4 .  
     
     
         13 . A radio base station apparatus comprising a high-frequency circuit fabricated by the glass substrate machining method according to  claim 5 .  
     
     
         14 . A radio base station apparatus comprising a high-frequency circuit fabricated by the glass substrate machining method according to  claim 6 .  
     
     
         15 . A radar apparatus comprising a high-frequency circuit fabricated by the glass substrate machining method according to  claim 3 .  
     
     
         16 . A radar apparatus comprising a high-frequency circuit fabricated by the glass substrate machining method according to  claim 4 .  
     
     
         17 . A radar apparatus comprising a high-frequency circuit fabricated by the glass substrate machining method according to  claim 5 .  
     
     
         18 . A radar apparatus comprising a high-frequency circuit fabricated by the glass substrate machining method according to  claim 6.