PCB Planar Transformer Insulation Layout for High-Voltage Isolation

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Solution Overview

Problem

Traditional planar transformers used in aeronautical applications fail to adequately segregate high-voltage and low-voltage networks due to insufficient insulation between conductive layers, posing a risk of electric arcs at high voltages, especially in unpressurized environments.

Innovation Solution

The planar transformer design incorporates internal conductive layers separated by multiple layers of insulating material, including substrate plates and prepreg layers, enhancing insulation and preventing electric arcs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional planar transformer design with single insulating layer is used, then manufacturing simplicity is maintained, but insulation reliability deteriorates under high voltage conditions

Engineering Contradiction:
Improveinsulation reliabilityVSAvoidinsulation structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The insulation structure is segmented into multiple discrete layers: a first insulating layer between primary winding turns, a second insulating layer between secondary winding turns, and a third insulating layer between primary and secondary windings. This segmentation provides distributed insulation barriers that collectively enhance reliability under high voltage conditions while maintaining manufacturing feasibility through standardized layer integration.

Inventive Principle:
Principle #1Segmentation

2Volume of moving object

If conductive layers are placed close together for compactness, then device size is reduced, but risk of electric arcs increases under high voltage

Engineering Contradiction:
Improvetransformer volumeVSAvoidelectric arc risk
Core Design Contradiction:
Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

Multiple insulating layers act as intermediary barriers between conductive layers carrying different voltages. The first insulating layer mediates between adjacent primary winding turns, the second insulating layer mediates between secondary winding turns, and the third insulating layer mediates between primary and secondary windings. These intermediaries prevent direct electrical breakdown and electric arc formation while allowing compact layer stacking.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If high voltage and low voltage networks are isolated using traditional insulation, then galvanic isolation is achieved, but insulation integrity becomes difficult to guarantee under environmental stress

Engineering Contradiction:
Improvegalvanic isolation integrityVSAvoidinsulation verification complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

Different insulating layers are strategically positioned at specific locations where voltage stress and environmental exposure are most severe. The third insulating layer between primary and secondary windings provides enhanced local protection at the critical isolation interface. This localized quality enhancement ensures galvanic isolation integrity without requiring complete redesign of the entire insulation system.

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

The enhanced insulation design ensures reliable operation across high-voltage and low-voltage networks, reducing the risk of electric arcs and improving safety in aeronautical applications.

Implementation Method 1

the internal conductive layer of the first winding and the internal conductive layer of the second winding, facing each other, are separated only by a thickness of insulating material

Methodology Applied
Scientific EffectElectrical insulation: Dielectric

Implementation Method 2

a magnetic core (102) having several legs, for example three legs (104, 106, 108)

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP4685825A1Planar transformer
Publication Date: 2026.01.28 SAFRAN ELECTRICAL & POWER CHATOU SAS
  • EP4685825A1 patent drawingFigure 1
  • EP4685825A1 patent drawingFigure 2
  • EP4685825A1 patent drawingFigure 3

AI summary

The planar transformer (100) comprises: - a first printed circuit board (110); - a second printed circuit board (112); - a primary winding (114) consisting of at least one turn; - a secondary winding (116) consisting of at least one turn; and - a magnetic core (102) for coupling the primary (114) and secondary (116) windings. Each turn of the primary winding (114) is formed in an internal conductive layer (110INT1-4) of at least one of the first printed circuit board (110) and the second printed circuit board (112), this internal conductive layer being covered on each side with insulating material.