Preventing misshaped solder balls

Abstract

“Thick line dies” that, during manufacture, avoid locating an upstanding edge of a photoresist layer (for example, the edge of a dry film photoresist layer) on top of a “discontinuity.” In this way solder does not flow into the mechanical interface between the photoresist layer and the layer under the photoresist layer in the vicinity of an upstanding edge of the photoresist layer.

1 - 11 . (canceled) 
     
     
         12 . A semiconductor die contact assembly comprising:
 a ball limiting metallurgy layer defining a top surface having a first region;   a first thick pad being located under the first region forming a footprint within the first region;   a photoresist layer located on top of the top surface of the ball limiting metallurgy layer;   a first pocket located over the first thick pad;   a first stage upstanding wall defining the first pocket; and   a first pre-reflow solder structure located within the first pocket and over a portion of the footprint of the first thick pad; the first upstanding wall extending upwards from the first region of the top surface;   wherein:   no portion of the first region of the top surface is located on any downward-inclined discontinuity; and   a thickness of the first thick pad is substantially greater than  1  micrometer.   
     
     
         13 . The semiconductor die contact assembly of  claim 12  wherein:
 the top surface of the ball limiting metallurgy layer includes: (i) a first elevated region located over at least a portion of the footprint of the first thick pad, (ii) a first non-elevated region located away from a vicinity of the footprint of the first thick pad, and (iii) a downward-inclined discontinuity region located between the elevated region and the non-elevated region. 
 
     
     
         14 . The semiconductor die contact assembly of  claim 13 , wherein:
 the first region of the top surface of the ball limiting metallurgy layer is entirely located within the elevated region.   
     
     
         15 . The semiconductor die contact assembly of  claim 12  wherein:
 the thickness of the first thick pad is at least approximately 4 micrometers. 
 
     
     
         16 . The semiconductor die contact assembly of  claim 12  further comprising:
 a passivation layer located between the thick metal pad and the ball limiting metallurgy layer, the passivation layer covering an outer boundary portion of the first thick pad. 
 
     
     
         17 . The semiconductor die contact assembly of  claim 16  wherein:
 an entirety of the first stage upstanding wall extends upwards from the passivation layer.