An electrical substrate useful for semiconductor packages is disclosed. The electrical
substrate includes a core insulative layer. A first surface of the insulative layer
has circuit patterns thereon. Some of the circuit patterns are stepped in their
heights from the first surface, in that a first subportion of the circuit pattern,
including a ball land, extends further from the first surface than a second subportion
of the same circuit pattern, and also extends further from the first surface than
a ball land of other circuit patterns. Accordingly, solder balls fused to the ball
lands of the stepped circuit patterns extend further from the first surface than
same-size solder balls fused to the ball lands of the non-stepped circuit patterns,
thereby circumventing electrical connectivity problems that may arise from warpage
of the electrical substrate.