Placement of sacrificial solder balls underneath the PBGA substrate

摘要

The present invention discloses techniques that improve the reliability of a flip packages that uses underfill encapsulation. One embodiment of the present invention describes a method and apparatus of packaging a flip chip by relocating the neutral plane of the package substrate away from its mid-plane. Another embodiment of the present invention describes a method and apparatus of arranging the layers of a laminate for use in PBGA packaging that arranges the layers of the laminate according to the stiffness of each layer. Another embodiment of the present invention describes a method and apparatus of packaging a flip chip that uses one or more redundant interconnections at the bottom of the package substrate where the redundant interconnections are within the shadow of the IC chip.