Multilayer Ferrite Circulator Assembly for Precise Gyromagnetic Alignment

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Solution Overview

Problem

Existing manufacturing processes for ferrite circulators suffer from issues of electrical discontinuity, misalignment, and mechanical tolerances, leading to reduced performance and inconsistent quality.

Innovation Solution

A precise placement and encapsulation process using pick-and-place machines and laminates with blind holes to ensure electrical continuity and alignment, followed by vacuum pressing to maintain dimensional control and compensate for manufacturing variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If ferrite discs are placed in recesses by force fitting, then assembly is simplified, but manufacturing precision deteriorates due to residual gaps between gyromagnetic cell and ferrite disc

Engineering Contradiction:
Improveassembly processVSAvoidalignment between gyromagnetic cell and ferrite disc
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by pre-forming recesses in the support board at precisely calculated positions and dimensions before inserting the ferrite discs. The recesses are designed with specific depth and diameter to ensure that when ferrite discs are placed therein, their lateral surfaces make direct contact with the gyromagnetic cells, eliminating residual gaps without requiring force fitting. This preliminary preparation of the support board structure ensures both ease of assembly and high manufacturing precision.

Inventive Principle:
Principle #10Preliminary action

2Ease of manufacture

If ferrite discs and magnets are positioned using machining recesses and stacking, then assembly is achieved, but manufacturing precision deteriorates due to XY plane tolerances and off-centering

Engineering Contradiction:
Improveassembly processVSAvoidalignment in XY plane
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent transitions from two-dimensional positioning (XY plane alignment through machining tolerances) to three-dimensional positioning by utilizing the vertical dimension (Z-axis) through precisely controlled recess depths. The recesses are formed at specific depths so that when ferrite discs are inserted, their lateral surfaces automatically align with the gyromagnetic cells in the XY plane, while the vertical positioning ensures proper spacing and contact. This dimensional transformation eliminates the accumulation of XY plane tolerances.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Strength

If pressing and hot bonding is used to bond assembly, then structural integrity is improved, but manufacturing precision deteriorates due to material expansion and decentering

Engineering Contradiction:
Improvebonding strengthVSAvoidalignment during bonding
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by pre-assembling the ferrite discs and magnets onto the support board with precise positioning before the bonding process. The recesses are pre-formed to hold components in their exact final positions, and the support board structure is prepared in advance to maintain dimensional stability during hot bonding. This preliminary preparation ensures that even when materials expand during bonding, the components remain properly aligned and centered.

Inventive Principle:
Principle #10Preliminary action

4Productivity

If conventional manufacturing method is used, then production is achieved, but reliability deteriorates due to residual gaps affecting gyromagnetic effect and isolation between channels

Engineering Contradiction:
Improveproduction capabilityVSAvoidgyromagnetic effect performance
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent applies local quality by creating localized recesses at specific positions where ferrite discs need to be positioned. Each recess is precisely tailored in depth and diameter to ensure that the ferrite disc at that location makes direct contact with its corresponding gyromagnetic cell, eliminating residual gaps locally. This localized precision approach maintains high reliability of the gyromagnetic effect and isolation between channels while preserving overall production capability.

Inventive Principle:
Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Ensures high-performance circulators with consistent electrical continuity and alignment, achieving optimal gyromagnetic effect, low losses, and maximum isolation between channels.

Implementation Method 1

a first magnetic element and a second magnetic element arranged on either side of the ferrite disc, said first magnetic element and said second magnetic element being arranged so as to generate a magnetic field substantially uniform in the ferrite disc

Methodology Applied
Scientific EffectGyromagnetic effect: Magnetic Field

Implementation Method 2

each ferrite disc consisting of a ferrite ceramic whose opposite transverse faces are covered with conductive films

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP4181638B1Improved manufacturing method for ferrite circulator integrated in multilayer board
Publication Date: 2026.05.06 THALES SA
  • EP4181638B1 patent drawingFigure 1
  • EP4181638B1 patent drawingFigure 1
  • EP4181638B1 patent drawingFigure 1

AI summary

This process includes the steps of: preparing (210) magnets (12) and ferrites (10); gluing (220) the ferrites onto a first conductive layer (22); preparing (230) a first laminate (30) having, on one face, blind holes (38) and, on an opposite face, a second conductive layer (34); encapsulating (240) the ferrites in the first laminate, each ferrite being received in a blind hole; etching (250) the first conductive layer to form gyromagnetic cells (52), each cell being opposite a ferrite; gluing the magnets, each magnet being opposite a ferrite; preparing a second laminate having, on one face, blind holes and, on an opposite face, a third conductive layer; encapsulating the magnets in the second laminate; and finalizing the component.