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Novel Approach to Reduce Die Area in Pad Limited SoCs by Optimizing Corner Keep Out Rule for Probe

IP.com Disclosure Number: IPCOM000227400D
Publication Date: 2013-May-06
Document File: 4 page(s) / 869K

Publishing Venue

The IP.com Prior Art Database

Abstract

These days many SoCs are pad limited hence it is difficult to reduce the die area. Most of the i/o ring area is constrained for the placement of any i/o pads with packaging or probing rules. One main constraint is in the form of corner keep-out spacing between the corner pads and the adjacent pad from the corner. Due to the corner probe rule, the design tends to be pad limited. This spacing is required to have multiple dies tested in parallel. This in turn reduces tester time and hence cost. It is required that all pads on EWS in the design are probe-able. This probe rule uses 170um and to be followed for all four corners.

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Novel Approach to Reduce Die Area in Pad Limited SoCs by Optimizing Corner Keep Out Rule for Probe

These days many SoCs are pad limited hence it is difficult to reduce the die area.  Most of the i/o ring area is constrained for the placement of any i/o pads with packaging or probing rules.  One main constraint is in the form of corner keep-out spacing between the corner pads and the adjacent pad from the corner.  Due to the corner probe rule, the design tends to be pad limited.  This spacing is required to have multiple dies tested in parallel.  This in turn reduces tester time and hence cost.  It is required that all pads on EWS in the design are probe-able.  This probe rule uses 170um and to be followed for all four corners.

An i/o pad layout with marked bond and probe areas is shown below:

Often, PGE pad placement on die is manipulated to reduce die area as well as tester time.  Intelligent placement of PGE pads on the pad ring aids in meeting the corner keep out rule inherently by design.

The following diagram explains the corner keep-out clearance for one corner of the die:

In the above diagram, for each corner probe pad there must be 170um keep out distance for which if corner probe pad is PGE then 391um keep out clearance has to be maintained.  This area can be saved.

PROPOSED APPROACH

The proposed approach seeks to reduce die area by removing the need for corner keep out rule of 170um for probing.  This will be helpful in pad limited designs.  For this we propose a new method of placing PGE pads.  This is a one-time activity done during...