The Effect Of Stress On Initial Permeability In Ferrite Cores

By Datatronic

Many of today's modern electronic circuits are built around magnetic components. A principal player in the design of these magnetic components is the ferrite core. Ferrite cores come in many different shapes and sizes and are made from many different raw materials. The magnetic properties of ferrite materials depend on many things. Such characteristics as the size of the grains created, typically between 5 and 40 um, and the sintering (firing) processes strongly determine the properties of the final product.

Once a ferrite core is completed there are other outside conditions that can also determine the performance of the magnetic component in which it is used. The purpose of this paper is to discuss in particular the effects on Initial Permeability (µi), thus inductance, which are a result of the various construction techniques and environmental conditions encountered. Permeability is generally defined as the ratio between the induced magnetic flux in the material and the magnetic force which causes it. In many applications the change in initial permeability is not as critical as the resulting minimum value. A simple review is in order.