NanocrystallineMatched choke cores for an EMI filter series
A filter manufacturer needed consistent permeability between cores to hold insertion loss within specification across production lots.
The customer supplied the target impedance curve and the mechanical envelope of the existing housing. We selected a nanocrystalline grade with the permeability band required by the curve, wound matched pairs from the same ribbon lot and measured each pair before shipment. Cores were supplied in plastic cases to avoid handling stress, which had previously shifted inductance during assembly. Samples were approved after the first round, and the pilot batch confirmed that pair-to-pair variation stayed inside the customer's incoming inspection limits. Series delivery follows a fixed schedule with inspection reports attached to each carton label.
