Apparatus for mounting columns for grid array electronic packages

Abstract

A vacuum controlled fixture is provided for positioning columns on sites of an electronic substrate. The fixture includes an internal chamber having spaced apart first and second surfaces extending beneath its principal face. A regular array of column receiving holes extends from the principal face through the first surface of the chamber, and a plurality of vacuum ducts extend from ports in the second surface of the chamber to a vacuum source to evacuate the internal chamber. The ports in the second face of the chamber are laterally offset from the receiving holes in the first face of the chamber to allow seating of the interior ends of the columns on coplanar portions of the rear surface. The ports are preferably centered, equidistant from the closest adjacent receiving holes, thereby providing centering of the columns by means of a vacuum driven air flow around the latter.

1 . A method of mounting a plurality of columns on an electronic assembly comprising the steps of: 
 providing a fixture having an exterior surface comprising a principal face and an internal chamber having a space bounded by first and second surfaces extending beneath and extending substantially parallel to said principal face and having a plurality of column receiving holes of a given diameter arranged in an array and extending from said principal face to said first surface into said chamber and one or more vacuum ducts located on select exterior portions of said fixture in communication with said internal chamber, said vacuum ducts defining openings in said second surface which are laterally displaced with respect to any of said receiving holes in said first surface;    presenting a plurality of columns to said principal face, said columns having a slightly smaller diameter than that of said receiving holes to provide a clearance between a column in a receiving hole and the diameter of the receiving hole and a length exceeding the distance from said principal face to said second surface of said internal chamber;    applying a vacuum to said chamber through said vacuum ducts to draw a respective column, into each respective receiving hole;    presenting a substrate to said principal face;    securing each of said columns in each respective receiving hole to respective sites on said substrate; and    terminating said vacuum to release each of said columns from each respective receiving hole onto said substrate.    
   
   
       2 . The method of  claim 1  wherein said clearance between the diameters of said columns and said receiving holes is sufficient to permit an air flow to be drawn by said vacuum around each of said columns and said flow being sufficient to center each of said columns in a respective receiving hole.  
   
   
       3 . The method of  claim 1  wherein the vacuum is sufficient to hold said columns securely seated against the second surface of said chamber.  
   
   
       4 . The method of  claim 3  wherein the vacuum is sufficient to hold said columns securely seated against the second surface of said chamber.  
   
   
       5 . The method of  claim 1  wherein there is further provided the step of applying a vacuum to said internal chamber sufficient to seat the interior ends of said columns on portions of said second surface adjacent said openings.  
   
   
       6 . The method of  claim 2  wherein there is further provided the step of applying a vacuum to said internal chamber sufficient to seat the interior ends of said columns on portions of said second surface adjacent said openings.