Everything You Need to Know About Custom Magnetics

Custom Magnetics

Custom magnetics are created for a customer’s particular needs. They’re often individual inductors, chokes, or transformers made using copper wires wound on soft magnetic materials. Custom magnetics can also be assemblies of numerous components like connectors, capacitors, inductors, and capacitors to build complete filters. Assemblies can include unique termination configurations, mounting features, or properties that promote cooling.

Not all custom magnetics have magnetic cores. They’re known as air core tools and are utilized in high-frequency apps in flux antennae for wireless charging or telemetry transfer devices. Other custom magnetics may be electro-mechanical and even produce motion. This article discusses everything you need to know about custom magnetics.

1. When do designers need custom magnetics?

Normally, design engineers are tasked with creating circuits with the best-possible performances for the least possible costs. They usually try using off-the-shelf devices provided on manufacturers’ websites or catalogs with datasheets detailing electrical dimensions and performances. If design engineers can’t find products suitable for their electrical or mechanical needs, they can engage with reliable custom magnetics manufacturers, such this company that has made its name in Contract Manufacturing in Mexico. They offer various electromagnetic services and products you can trust.

2. How much do custom magnetics cost?

Generally, custom magnetics are costlier than standard options. Unless when in high volumes, these devices are created with a manual labor level and won’t be completely automated, raising costs. Designers might compromise on performance, size, or efficiency to use low-cost standard solutions.

3. NRE (non-recurring engineering) fees

For a manufacturer or supplier to provide custom magnetics, they might incur custom magnetic core tooling, assembly tooling, and product development costs. The costs are usually passed on to clients as NRE fees, one-off payments made upfront by customers to suppliers. Nonetheless, other suppliers give the alternative to amortize the fees into the custom magnetics’ cost. A device’s design mostly stays confidential between the customer and the manufacturer/ supplier. A signed mutual NDA (non-disclosure agreement) between the client and the supplier is wise because it protects confidential information.

4. How to choose a custom magnetics manufacturer

You want to partner with the right manufacturer when looking for custom magnetics. The best custom magnetics supplier should specialize in your market segment. Regardless of whether you’re in industrial, mechanical, automotive, or aerospace, selecting a manufacturer experienced in your field makes your work easier because they’re likely to have the materials, design experience, test equipment, and processes in place to help attain your needs. To find the right custom magnetics manufacturer consider the following:

  • Quality and manufacturing certifications:  The best custom magnetics manufacturer should have all the appropriate certifications. So, ensure they’re accredited depending on your specific industry. For instance, if you’re looking for automotive-grade devices, check their TS-16949 certification plus their testing ability to AEC-Q200 requirements
  • Manufacturing and design location: Custom magnetics usually require a comprehensive interchange between manufacturing and design engineers. It would be more convenient if the design and manufacturing locations were in the same area. This promotes productive in-person meetings while ensuring online meetings happen in the same time zone
  • Technology: Choosing a manufacturer who can use the latest technology is essential because it ensures the most cost-effective and efficient custom magnetics

5. The design information your custom magnetics manufacturer may require

Once you find a suitable manufacturer, they might require specific information to design custom magnetics that matches your needs. They may need:

  • Black box requirements: Your design engineer can have black box specifications with output and input currents and voltages for a transformer or rated current and inductance requirements for an inductor
  • Build-to-print specifications: A design engineer experienced in transformers and inductors can help you provide in-depth specifications containing tolerances and values for inductance, rated current, DC resistance, and more. They also state the precise magnetic core materials and shapes and can give comprehensive dimension specifications. A design engineer can also provide the manufacturer with test requirements and 3D or 2D drawings

Alternatively, the custom magnetics manufacturer can give you design guidance to help create a cost-effective and best-performing solution. Excellent communication between the manufacturer’s engineer and your (customer) design engineer is essential for great results.


Several variables go into designing top-quality custom magnetics, including technical specifications, considerations for picking a manufacturer/ supplier, and other requirements. Familiarizing yourself with everything you need to know about custom magnetics can help ensure you get the best quality devices designed to meet your requirements while lowering production time and cost.