waleed,

It all started, basically, with MIL, now IPC 279, or is it 2221 (I get so
confused) and improving, STD-275 design guidelines. Aside from all that,
most major corporations (HP, Nortel, etc.) took the guidelines, as they
should, and converted them into design standards or rules no longer guidelines.

Nortel, as but one example, requires a minimum chip device spacing to be
.015". HP and Nortel both have devised requirements for other device spacing
according to their in house reliability testing and in concert with IPC leaders.

Earl Moon

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