Elecromigration Calculation of Interconnect

How can calculate the EM of particular interconnect??
could u please explain with example.

This is a problem with many layers to it.

You need physics-of-failure, reality-based electromigration
coefficients from some reliability test that can let you
figure interconnect life based on current density and
local temperature (I have seen many tests conducted
(heh) poorly, failing to figure in self-heating let alone
measure the worst case at point of failure, leading to
bogus low current density ratings, a joy for any power
IC designer to live with).

Then you need to find your worst case current density
point and value, bearing in mind the Z dimension may
be compromised by step coverage at contacts or
underlying topography and that local heating may
come from interconnect I*R or from location above
"heaters" (or both). You may also apply some guess
at defect-based (not "killer", but still) notching,
voiding, thinning as observed in production. Whether
you want the pain depends on your regime - "HiRel"
where one life test fail bombs the lot, will look real
close but a throwaway talking Christmas card will
not.

Usually somebody will give you a rule, and somebody
else will bless simple compliance to that current density
limit and you're clean (personally - fab may still toss
garbage your way and badness ensue).

J=I/(t*w)
J<Jmax "or else".
t, w might embed the above-discussed detractors.
Use temperature matters hugely, check vs rules-basis
temp including local heating vs gross junction temp
vs application case temp & Pdiss.