We have talked before about the importance of components such as the core and wire, but in this document, we will focus on the coil former. A coil former plays a big role in a magnetic component, it is where the wire is winded; hence the bobbin determines the working space, how will the connections go and the heat flow. Standard bobbins not always have the desired characteristic for a specific design, so we optimize them for each case.

Customized coil former:

In SPC we adjust the coil former to our needs with fast prototypes that can be later manufactured. We make small changes in standard coil formers and 3D-print them to make tests as fast as our customers' needs:

  • Longer bobbins for many stacks
  • Special coil formers for a specific magnetic component
  • Better heat evacuation
  • Thinner bobbins mean a bigger winding window
  • Easier to wind designs


Experimental results:

We test all the coil formers, including the customized, to know their temperature behavior, parasitics, and mechanical parameters.

Example: The temperature of the wire of the inductor of Figure 3 is measured with 22 A of DC.


The red line shows the temperature evolution in a standard coil former, while the blue shows the evolution in a special coil former designed to reduce heat.

The temperature difference between the outside layer of the two coil formers grows over time, reaching a difference of 10ºC after 390 seconds.