Inductance Measurements

What is Inductance?

The property of a trace that opposes the change of current flowing through it and even a straight trace will have some inductance.

Inductors do this by generating self-induced electromagnetic fields (EMF) within themselves as a result of their changing the magnetic field. In an electrical circuit, when the emf is induced in the same circuit in which the current is changing this effect is called Self-induction, ( L ) but it is sometimes commonly called back-EMF as its polarity is in the opposite direction to the applied voltage.

When the EMF is induced into an adjacent component situated within the same magnetic field, the emf is said to be induced by Mutual-induction, ( M ) and mutual induction is the basic operating principal of MEMS (micro-electromechanical system), used in airbag deployment, insulin pumps, and building ventilation systems. Self-inductance is a special case of mutual inductance, and because it is produced within a single isolated circuit we generally call self-inductance simply, Inductance.

The basic unit of measurement for inductance is called the Henry, ( H ) after Joseph Henry, but it also has the units of Webers per Ampere ( 1 H = 1 Wb/A ).

Coils

PCB’s can have several different types of inductance patterns; the most common patter is a coil. Coils can have different trace widths and spacing in combination with different sized inner diameters (see figure 1) to create a wide range of inductance. The coils could also be arranged in a pattern to create different types of MEMS.

The sample PCB shown in figure 3 has three coils. Figure 4 shows one coil as a generator and two sensor coils.

Why Gardien’s Solution?

Gardien has implemented a simplified, and flexible solution into our G-Serries Flying Probe machines and fixture-based machines. Gardien designed the process for ease of use on our service floors, allowing accuracy and reduced training (virtually push-button technology).

Parameters that can be adjusted to meet the PCB build requirements:

Resistance within fixed tolerance
Inductance within fixed tolerance
Frequency

All information from the PCB fabrication drawing is transferred in the Tooling process via UCAMCO software to the job specific files. The information is then output into the file that is used to perform the measurement.

Interested?

We offer our services under 2 distinct frameworks: the OnDemand Solution and the Integrate Solution.
Depending on your needs, you can either outsource specific testing requirements or we can completely run your test area or test department on your behalf. Contact us now and we’ll find the best solution for your business.