PCB Planar Transformer Assembly for Stable Spacing and Heat Dissipation

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Solution Overview

Problem

Traditional transformers are large, bulky, and difficult to manufacture precisely, leading to inefficiencies and reliability issues, especially in harsh environments like those found in vehicles, where mechanical stress and temperature variations cause property changes and potential electrical failure.

Innovation Solution

A planar transformer design featuring a stacked coil assembly with elastically compressible elements between PCBs, surrounded by a magnetic core, allowing accurate spacing and thermal contact for efficient heat dissipation, and incorporating split core portions for enhanced reliability and compactness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If traditional transformers are used, then they can provide galvanic isolation and voltage conversion, but they are large and bulky with low power density

Engineering Contradiction:
Improvetransformer volumeVSAvoidpower density
Core Design Contradiction:
Volume of moving objectVSPower

Solution Approach 1:

The patent transitions from traditional three-dimensional wound coil structures to a planar two-dimensional winding configuration integrated into PCBs. This dimensional change allows the transformer to achieve compact form factor while maintaining or improving power density through optimized current paths and reduced magnetic path length.

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

Solution Approach 2:

The patent combines the transformer windings with the PCB structure itself, integrating the copper traces directly into the board layers. This merging eliminates separate winding components and reduces overall transformer volume while improving power density through closer coupling between windings and core.

Inventive Principle:
Principle #5Merging (Combining)

2Volume of moving object

If planar transformers with integrated PCB windings are used, then they become more compact with higher power density, but they are difficult to manufacture precisely

Engineering Contradiction:
Improvetransformer volumeVSAvoidspacing precision
Core Design Contradiction:
Volume of moving objectVSManufacturing precision

Solution Approach 1:

The patent divides the transformer into modular components: separate PCB assemblies with pre-defined coil patterns, discrete magnetic core pieces, and individual spacing elements. This segmentation allows each component to be manufactured and tuned independently with high precision before final assembly, overcoming the manufacturing precision challenges of integrated planar designs.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces removable spacing elements as intermediary components between the PCB windings and magnetic core. These spacing elements serve as adjustable mediators that enable precise control of the air gap distance, allowing fine-tuning of electrical properties such as leakage inductance without requiring ultra-precise manufacturing tolerances on the PCB or core themselves.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Manufacturing precision

If external components are added to tune electrical characteristics, then the desired electrical properties can be achieved, but the cost, space, and weight increase

Engineering Contradiction:
Improveelectrical property toleranceVSAvoidsystem complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent designs the transformer to be self-tuning through adjustable spacing elements that allow the leakage inductance to be precisely controlled during assembly. This self-service approach eliminates the need for external tuning components by making the transformer's own structure adjustable, thereby achieving desired electrical properties without adding external components that would increase complexity.

Inventive Principle:
Principle #25Self-service

4Adaptability or versatility

If transformers are subjected to mechanical stress and temperature variations, then they can operate in harsh environments, but their properties change over time leading to reliability issues

Engineering Contradiction:
Improveenvironmental toleranceVSAvoidproperty stability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent employs elastically compressible spacing elements that can dynamically adapt to thermal expansion and mechanical stress. These elements maintain constant pressure on the PCB assemblies against the magnetic core, ensuring stable electrical contact and consistent electrical properties despite temperature variations and vibrations in harsh automotive environments.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent pre-compresses elastic elements during assembly to create a cushioning effect that compensates for future thermal expansion and mechanical stress. This beforehand cushioning ensures that the transformer maintains its electrical characteristics and structural integrity over time, preventing property drift that would lead to reliability issues in harsh environments.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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 design achieves high efficiency and reliability with precise electrical properties, reduced size, and improved durability against mechanical stress and temperature variations, minimizing the need for external components and enhancing thermal conductivity.

Implementation Method 1

at least one elastically compressible element sandwiched between the first and second PCB. Additionally, the at least one elastically compressible element is compressed by the first and second PCB so as to push the first and second PCB away from each other

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

a magnetic core assembly comprising a top core portion and a bottom core portion, wherein the first and second PCB are arranged between the top and bottom core portions and wherein the top and bottom core portions are configured to form a casing around the first and second PCB

Methodology Applied
Scientific EffectFerromagnetism: Ferromagnetism

Implementation Method 3

At least one of the top and bottom core portions comprises a protrusion protruding out from the inner surface so as to contact the other core portion through the central openings of the first and second PCB

Methodology Applied
Scientific EffectMagnetic coupling: Magnetic Field

Data Source

PatentEP4712118A1Planar transformer
Publication Date: 2026.03.18 AROS ELECTRONICS
  • EP4712118A1 patent drawingFigure 1
  • EP4712118A1 patent drawingFigure 2a~2c
  • EP4712118A1 patent drawingFigure 3a~3b

AI summary

The present disclosure relates to planar transformer (10)comprising a first PCB (1) comprising a first coil pattern surrounding a first opening (11), a second PCB (2) comprising a second coil pattern surrounding a second opening (21), and at least one elastically compressible element (5) sandwiched between the first and second PCB (1, 2). The planar transformer (10) further comprises a top core portion (3) and a bottom core portion (4), wherein the first and second PCB (1, 2) are arranged between the top and bottom core portions (3, 4) and, wherein the at least one elastically compressible element (5) is compressed by the first and second PCB (1, 2) so as to push the first and second PCB (1, 2) away from each other, towards the inner surfaces of the top and bottom core portions (3, 4) of the magnetic core assembly, respectively.