Electromigration Accelerated Life Testing

Black’s Equation for Electromigration Accelerated Life Testing

Black’s equation for estimating the time to failure due to electro migration is a classic. James Black explored and wrote about electromigration in aluminum metallization within semiconductors since 1969.

He and others have explored other materials used as conductor prone to electromigration. Thus, there are a number of models and constants available to match your particular system.

Let’s take a look at the general equation for a microcircuit conductor after a brief description of the failure mechanisms called electromigration.

What is electromigration?

James Black in conference presentation and paper describes electromigration as:

… the transport of ions through a conductor resulting from the passage of direct current. It is caused by a modification of self diffusion from a random process to a directional one by the presence of an electric field and charge carrier flow.

He continues…

This directional effect causes ions to migrate or diffuse downstream in terms of electron wind direction and vacancies move upstream.

The effect is a thinning of the conductor in some areas and thickening in others. Eventually the conductor thins to a point that it is unable to carry the current and fails.