Can anyone explain me why there is no electromigration in bidirectional nets...and how to know which net is bidirectional either P/G nets or Signal nets or wt?
Signal nets are always bi directional only. in signal there will no electro migration instead there will be metal migration due to thermal and joule heating effect.
Normally, when electromigration occurs, electrons will migrate in the direction of current.
So , in unidirectional nets , they migrate continuously in one direction and hence the metal will etch away.
Norrmally, power and ground nets carry unidirectinal signal .i.e. constant VDD & VSS.
where as in signal nets , they carry signal which might propagate in two directions. So , the net effect of electron migration will get nullified.