Heat-assisted hermetic spring seal

Abstract

A hermetic seal includes a spring seal compressed with a limited sealing force between sealing surfaces. The sealing surfaces surround a gas-filled cavity that houses heat sensitive components. The hermetic seal includes a film that joins the spring seal to the sealing surfaces. The film includes a material that is softenable by heat to hermetically seal the spring seal to the sealing surfaces. The hermetic seal includes an externally accessible surface for selectively application of the heat to the film, without overheating the heat sensitive components.

1 . A hermetic seal, comprising: 
 a spring seal compressed with a limited sealing force between sealing surfaces that surround a gas-filled cavity that houses heat sensitive components;    a film contacting the spring seal and the sealing surfaces, the film comprising a material that is softenable by heat to hermetically seal the spring seal to the sealing surfaces; and    an externally accessible surface for selectively application of the heat to the film without overheating the heat sensitive components.    
   
   
       2 . The hermetic seal of  claim 1  wherein the spring seal comprises a C-shaped cross-section.  
   
   
       3 . The hermetic seal of  claim 1  wherein the limited sealing force is less than 75 pounds force per running inch of the spring seal.  
   
   
       4 . The hermetic seal of  claim 1  wherein the cavity is filled with a fill gas that comprises helium.  
   
   
       5 . The hermetic seal of  claim 4  wherein the helium comprises at least 90% of the weight of the fill gas.  
   
   
       6 . The hermetic seal of  claim 1  wherein the hermetic seal has a leak rate of less than 3.2×10 −8  cubic centimeters per second.  
   
   
       7 . The hermetic seal of  claim 1  wherein the film comprises a deposit on the spring seal.  
   
   
       8 . The hermetic seal of  claim 1  wherein the film comprises deposits on the sealing surfaces.  
   
   
       9 . The hermetic seal of  claim 1  wherein the film comprises a soft metal plating.  
   
   
       10 . The hermetic seal of  claim 9  wherein the soft metal plating comprises tin.  
   
   
       11 . The hermetic seal of  claim 1  wherein the film comprises an organic film.  
   
   
       12 . The hermetic seal of  claim 1  wherein the hermetic seal is demateable.  
   
   
       13 . The hermetic seal of  claim 12  wherein the demateable hermetic seal is convertible to a non-demateable hermetic seal by increased selective heating of the film above a melting temperature of the film.  
   
   
       14 . The hermetic seal of  claim 1  where the externally accessible surface is accessible through an access opening.  
   
   
       15 . The hermetic seal of  claim 1  where the externally accessible surface is accessible through an access opening adjacent the spring seal.  
   
   
       16 . The hermetic seal of  claim 1  wherein the film has a deformation temperature that is under an average bulk temperature of 100 degrees Centigrade with the limited sealing force applied.  
   
   
       17 . A method of hermetic sealing, comprising: 
 compressing a spring seal with a limited sealing force between sealing surfaces that surround a gas-filled cavity that houses heat sensitive components;    providing a heat-softenable film between the spring seal and the sealing surfaces; and    applying heat to an externally accessible surface to selectively heat the heat-softenable film without overheating the heat sensitive components, the heat softening the heat-softenable film to hermetically seal the spring seal to the sealing surfaces.    
   
   
       18 . The method of  claim 18  wherein the heat-softenable film has a softening temperature that is under an average bulk temperature of 100 degrees Centigrade with the limited sealing force applied, and applying the heat until the temperature of the film is between 100 and 200 degrees Centigrade.  
   
   
       19 . The method of  claim 18  and further comprising: 
 further applying heat to increase the temperature of the film to a melting temperature of the film; and    allowing the film to cool to below the melting temperature to form a non-demateable hermetic seal.    
   
   
       20 . The method of  claim 18  and further comprising: applying the heat-softenable film to the spring seal.  
   
   
       21 . The method of  claim 18  and further comprising: applying the heat-softenable film to the sealing surfaces.  
   
   
       22 . A hermetic seal, comprising: 
 a spring seal compressed with a limited sealing force between sealing surfaces that surround a gas-filled cavity that houses heat sensitive components;    heat-softenable means, disposed between the spring seal and the sealing surfaces, for hermetically sealing the spring seal to the sealing surfaces; and    an externally accessible surface for selective application of the heat to the film without overheating the heat sensitive components.    
   
   
       23 . The hermetic seal of  claim 23  wherein the spring seal comprises a C-shaped cross-section.  
   
   
       24 . The hermetic seal of  claim 23  wherein the cavity is filled with a fill gas that comprises helium.  
   
   
       25 . The hermetic seal of  claim 23  wherein the film comprises a deposit on the spring seal.  
   
   
       26 . The hermetic seal of  claim 23  wherein the film comprises deposits on the sealing surfaces.  
   
   
       27 . The hermetic seal of  claim 23  wherein the film comprises a soft metal plating.  
   
   
       28 . The hermetic seal of  claim 28  wherein the soft metal plating comprises tin.  
   
   
       29 . The hermetic seal of  claim 23  wherein the film comprises an organic film.