Placement
This phase is for defining the locations of the design elements with respect to the package. While there may be only a few elements to place, this can be difficult because of geometric restrictions of the substrate, such as cavities or geometric centering between all of the component I/Os.
If the component has multiple die, some latitude may be given to the designer for placement. In this situation, the designer is responsible for optimizing for die-to-die interconnect while at the same time optimizing for die-to-component fanout routing.
Die-to-Die Placement
For die-to-die placement optimization, the designer should attempt to minimize crossing of signals between die and the number of signals that pass through another die to reach its destination. To accomplish this, you should attempt to rotate dies, align dies that interconnect with each other, and place dies relatively close to each other to optimize the routing real estate. In most cases, however, component designers do not have much freedom in die rotation and placement. Therefore, if you cannot achieve optimized routing with imposed placement, it is best to consult with the logic and manufacturing engineers before making changes.
Die-to-Component Placement
For die-to-component placement optimization, die should be placed as close to the geometric center of the component as possible. If multiple dies are used, each die that connects to the component should be placed so that the die’s I/O is on the outside edges, close to the component edge, and no obstructions exist between the die and the component I/O.
You should carefully place signals that require performance constraints, such as delay or crosstalk, or require special routing. Acknowledging these requirements allows for optimized real estate to handle discrete components.
Related Topics
Die-to-Component I/O Net Assignment
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