IEC 63093-5:2025

Overview

IEC 63093-5:2025 - "Ferrite cores - Guidelines on dimensions and the limits of surface irregularities - Part 5: EP‑cores and associated parts for use in inductors and transformers" defines mechanical and visual requirements for a preferred range of EP‑cores (sizes EP5 to EP30) made of ferrite. The standard specifies the principal dimensions that ensure mechanical interchangeability, essential coil‑former dimensions, terminal‑pin locations on a 2.50 mm printed wiring grid, and the effective magnetic parameters to be used in calculations. It also gives illustrated guidance and numerical limits for allowable surface irregularities (chips, cracks, flash, pull‑outs, crystallites, pores) useful in supplier–user negotiations.

Key topics and technical requirements

• Mechanical interchangeability: Principal dimensions and tolerances for EP‑core sizes (EP5…EP30) to ensure assemblies and wound coil formers fit across suppliers.
• Coil former dimensions: Essential limits for formers that mate with EP‑cores (see main dimensions and tables for e, f, d, s, etc.).
• Pin locations and base outlines: Terminal pin coordinates referenced to a 2.50 mm PCB grid for both SMD and PTH versions, with base outlines relative to mounting direction.
• Effective parameters: Effective magnetic parameters and A‑values are tabulated (Table 2) and calculated per IEC 60205; the standard instructs use of K(nom.) for those calculations.
• Surface irregularities: Definitions, examples (figures), and numerical acceptance criteria:
  • Minimum visually distinguishable area: 0.5 mm²
  • For chips on mating surfaces, cumulative chip area must be < 4% of the relevant mating surface (ring and centre pole considered separately)
  • Detailed limits for cracks, flash, pull‑outs, crystallites and pores with inspection reference areas and visual limits are provided.

Applications and users

This part of IEC 63093 is intended for:

• Ferrite core manufacturers and suppliers - to dimension products and set acceptable surface quality.
• Designers of inductors, transformers and magnetic assemblies - to select cores and coil formers that guarantee mechanical interchangeability.
• PCB and component layout engineers - for correct pin‑grid placement (2.50 mm grid) and footprint design.
• Procurement and quality engineers - for supplier agreements, inspection criteria and acceptance testing of ferrite EP‑cores.

Practical benefits include reduced redesign risk, consistent assembly fit, reliable electromagnetic parameter use in calculations, and clearer supplier–user quality agreements.

Related standards

• IEC 60205 - Calculation of the effective parameters of magnetic piece parts (referenced for parameter computations).
• IEC 60401‑1 - Terms and nomenclature for ferrite cores (physical irregularities and dimensions).
• IEC 63093‑1 - General specification for ferrite cores (definitions and general limits of surface irregularities).

Keywords: IEC 63093-5:2025, ferrite cores, EP‑cores, surface irregularities, coil formers, inductors, transformers, mechanical interchangeability, effective parameters, 2.50 mm PCB grid.