Boat for ball attach manufacturing process

Abstract

A boat onto which solder balls or columns are loaded for an attach process can be used in a universal attach line has a number of attach station to accommodate different types of attach processes. Depending on the process and the desired configuration and form factor of the array of solder balls or columns, a template is selected that covers some of the holes in the universal boat, and exposes other holes. The holes are configured and sized to hold solder balls in the holes such that the solder balls protrude above the top surface of the boat by a predetermined height. This prevents damage to the solder balls while ensuring that the solder balls protrude enough to accommodate imperfectly flat packages that are placed on the array of solder balls held in the boat. Vacuum applied through the holes help to securely hold the balls in place, and a substrate is placed onto the solder balls. Once loaded with balls or columns, the boat is transported to only the appropriate attach stations in the universal attach line, where the different attach operations for a given attach process, such as high temperature ball attach, eutectic ball attach, or column attach, are performed.

What is claimed is:  
     
         1 . A boat for holding solder balls for attach processes, comprising: 
 a substantially planar body with a top surface;    a plurality of holes in the body, each hole being configured to open at a top surface of the body with an opening sized to hold a solder ball in the hole such that the solder ball protrudes above the top surface of the planar body by a predetermined height.    
     
     
         2 . The boat of  claim 1 , wherein each hold is coupled to a vacuum source.  
     
     
         3 . The boat of  claim 2 , wherein each hole includes a vacuum section with a vacuum hole that has a vertical sidewall.  
     
     
         4 . The boat of  claim 3 , wherein each hole has a countershank extending from the top surface to the vertical sidewall of the vacuum hole.  
     
     
         5 . The boat of  claim 4 , wherein the countershank has a countershank angle of between 25° to 60° from vertical.  
     
     
         6 . The boat of  claim 5 , wherein the countershank has a countershank angle of 30°.  
     
     
         7 . The boat of  claim 5 , wherein the countershank has a countershank angle of 45°.  
     
     
         8 . The boat of  claim 5 , wherein the countershank has a countershank angle of 50°.  
     
     
         9 . The boat of  claim 5 , wherein a solder ball is approximately 30 mils in diameter.  
     
     
         10 . The boat of  claim 9 , wherein a 30 mils solder ball protrudes approximately 0.085 mm above the top surface of the planar body.  
     
     
         11 . The boat of  claim 10 , wherein the vacuum holes have a diameter of about 70 mm.  
     
     
         12 . The boat of  claim 11 , wherein the boat is made of graphite.