Silica glass member for hermetic sealing of ultraviolet smd led element and method for manufacturing quartz glass member for ultraviolet led

Abstract

Provided is a silica glass member for hermetic sealing of an ultraviolet SMD LED element to be suitably used for hermetic sealing of, and as a transmission window material for, a surface mount-type package (SMD) having an ultraviolet LED mounted thereon and configured to emit ultraviolet light in a wavelength range of from 200 nm to 350 nm. The silica glass member for hermetic sealing includes a silica glass substrate, which is homogeneously and integrally formed without an internal boundary, wherein the silica glass substrate has: a first surface on an inside opposed to an SMD LED element; and a second surface on an outside corresponding to the first surface, wherein an outer peripheral portion of the first surface has formed therein a substrate joining plain surface for joining to the container outer periphery joining plain surface, and wherein the second surface on the outside corresponding to the first surface has formed therein a lens-like convex portion configured to process emitted light from the ultraviolet SMD LED element.

1 . A silica glass member for hermetic sealing of an ultraviolet SMD LED element that is configured to emit light in a wavelength range of from 250 nm to 350 nm and is placed in a hermetic sealing container having a container outer periphery joining plain surface formed in an outer peripheral portion thereof, the silica glass member for hermetic sealing comprising:
 a silica glass substrate, which is homogeneously and integrally formed without an internal boundary, wherein the silica glass substrate has:
 a first surface on an inside opposed to the SMD LED element; and 
 a second surface on an outside corresponding to the first surface, wherein an outer peripheral portion of the first surface has formed therein a substrate joining plain surface for joining to the container outer periphery joining plain surface, and the second surface on the outside corresponding to the first surface has formed therein a lens convex portion configured to process emitted light from the ultraviolet SMD LED element. 
   
     
     
         2 . A silica glass member for hermetic sealing according to  claim 1 , wherein a plurality of the lens convex portions are formed on the second surface. 
     
     
         3 . A silica glass member for hermetic sealing according to  claim 1 , wherein the substrate joining plain surface formed in the first surface has a surface accuracy equal to 1 μm or less and a surface roughness of 0.05 μm to 0.3 μm in terms of Ra value, and the lens convex portion in the second surface has a surface roughness of 0.05 μm to 0.5 μm in terms of Ra value. 
     
     
         4 . A silica glass member for hermetic sealing according to  claim 1 , wherein the silica glass member for hermetic sealing has an internal transmittance at a thickness of 3 mm of 95% to 99% for ultraviolet light having a wavelength of 300 nm to 400 nm and an internal transmittance at a thickness of 3 mm of 92% to 99% for ultraviolet light having a wavelength of 245 nm or more and less than 300 nm. 
     
     
         5 . A silica glass member for hermetic sealing according to  claim 1 , wherein respective differences between internal transmittances of the silica glass member for hermetic sealing at a thickness of 3 mm for ultraviolet light having wavelengths of 350 nm, 300 nm, and 250 nm measured using an integrating sphere and internal transmittances thereof at a thickness of 3 mm for ultraviolet light having wavelengths of 350 nm, 300 nm, and 250 nm in general measurement are each within 0.5%. 
     
     
         6 . A silica glass member for hermetic sealing according to  claim 1 , wherein bubbles contained in the silica glass member for hermetic sealing each has a diameter equal to 50 μm or less, and the bubbles contained have a total cross-sectional area equal to 1×10 −3  mm 2  or less per 0.1 cm 3  of a volume of the silica glass member for hermetic sealing. 
     
     
         7 . A silica glass member for hermetic sealing according to  claim 1 , wherein the silica glass member for hermetic sealing contains OH groups at a concentration of 0.1 ppm to 20 ppm. 
     
     
         8 . A method for manufacturing a quartz glass member for an ultraviolet LED, the method comprising:
 a molding step of mixing silica powder and a binder component to form a resultant mixture, followed by molding the resultant mixture to obtain a molded body having a predetermined shape;   a heat treatment step of subjecting the molded body to heating treatment with various gases; and   a vitrification step of vitrifying the molded body subjected to heat treatment into transparent glass after the heat treatment step, the heat treatment step comprising:
 a degreasing step for organic matter at 1,000° C. or less with an atmosphere containing oxygen; 
 a purification step for a metal impurity at 1,200° C. or less with an atmosphere containing hydrogen chloride after the degreasing step; and 
 a step of promoting repairing of an oxygen-deficient defect at a wavelength of about 250 nm at 1,150° C. or less with an oxidizing atmosphere after the purification step. 
   
     
     
         9 . A method according to  claim 8 , wherein the molding step comprises a molding step with a metal mold. 
     
     
         10 . A method according to  claim 8 , wherein the oxidizing atmosphere comprises an atmosphere containing one or more of oxygen and water vapor. 
     
     
         11 . A method according to  claim 8 , wherein the vitrification step is performed at 1,700° C. or less. 
     
     
         12 . A method according to  claim 8 , wherein the silica powder contains at least one kind of spherical silica, and the silica powder has an Al concentration of 70 ppm or less. 
     
     
         13 . A method according to  claim 8 , further comprising performing heating treatment with a hydrogen atmosphere after the vitrification step. 
     
     
         14 . A method according to  claim 8 , wherein the ultraviolet LED is configured to emit ultraviolet light having a wavelength of from 200 nm to 400 nm.