Mirrored pin assignment for two sided multi-chip layout
AssigneeHewlett-Packard Company
InventorsDaniel L. Schumacher, John Wood
Life of this patent
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Abstract
The invention provides for increased IC density on circuit boards having at least one IC mounted on each side of a two sided PC or SMT board by utilizing one or more IC's having pin assignments arranged as a mirror image of each other along a centerline through the IC package in the X or Y axis, such that one or more IC's having the same set of mirror image pin assignments mounted on each side of a circuit board and rotated 180 degrees in relationship to each other will ensure that the pin assignments of the same type will be directly opposite each other and separated by the circuit board.
Claims13
An integrated circuit package for mounting to a circuit board having a top side and a bottom side, comprising:
- a plurality of pin assignments, arranged as a mirror image around the periphery of said package and positioned as a mirror image of each other along an arbitrary axis drawn through the center of said IC package;
- a plurality of non-mirror image pin assignments, wherein, said integrated circuit package provides for enhanced lead routing on said circuit board when mounting a first integrated circuit package on the top side and said second integrated circuit package is mounted on said bottom side, and wherein said integrated circuit packages are rotated 180 degrees with respect to each other such that said mirror pin assignments are directly opposite each other on opposite sides of said circuit board.
A circuit board having a top side and a bottom side, said circuit board comprising;
- a first mirror image integrated circuit mounted on said top side and a second mirror image integrated circuit mounted on said bottom side, said first and second mirror image integrated circuits being rotated 180 degrees with respect to each other and positioned directly opposite each other on either side of said circuit board, wherein, said first and second integrated circuits further comprising a package having a plurality of pin assignments arranged as a mirror image around the periphery of said package and positioned as a mirror image of each other along an arbitrary axis drawn through the center of said IC package and a plurality of non-mirror image pin assignments, wherein, said plurality of mirror image pin assignments will be directly opposite each other on either side of said circuit board.
A method for reducing problems associated with lead routing on a circuit board having a top side and a bottom side, comprising the method steps of:
- fabricating a mirror image integrated circuit having pin assignments positioned as a mirror image of each other along an arbitrary axis drawn through the center of said circuit,
- mounting a first mirror image integrated circuit on the top side,
- mounting a second mirror image integrated circuit on the bottom side, wherein said first and second mirror image integrated circuits are rotated 180 degrees in relationship with each other,
- mounting at least one additional integrated circuit of a different type on the top side of said PC board, said additional integrated circuit having some pin assignments which are identical to those on said first and second mirror image integrated circuit,
- coupling a first set of leads between said first mirror image integrated circuit pin assignments and said pin assignments on said integrated circuit of a different type,
- coupling a second set of leads between said second mirror image integrated circuit pin assignments and said pin assignments on said integrated circuit of a different type, wherein, said first and second set of leads follow the same direction because of said mirror image pin assignment and minimizes the potential for lead crossover.
Dependencies are inferred from the claim text.