Printed-Core Integrated Transformer With Void-Free Closed Magnetic Loop

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Solution Overview

Problem

Existing integrated transformers face challenges with AC winding loss due to fringing effects and air bubbles or voids that inhibit achieving high isolation performance ratings, particularly in compact designs.

Innovation Solution

A method involving a printing process to deposit and cure magnetic paste onto a laminate structure, forming transformer core pieces that encircle openings, and joining them to create a closed magnetic loop structure, thereby eliminating air gaps and voids.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If magnetic films are added on the top and bottom of a lamination with conductive windings separated by an isolation barrier to improve performance of an integrated air core transformer with a small footprint, then the transformer performance is improved, but AC winding loss increases due to fringing effects caused by the airgap between two magnetic plates

Engineering Contradiction:

Improvetransformer performanceVSAvoidAC winding loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent merges the magnetic core pieces directly with the laminate structure by forming them from the same laminated layers, eliminating the airgap between separate magnetic plates and windings. This integration combines the magnetic path and winding support into a single unified structure, removing the source of fringing effects while maintaining small footprint and performance benefits.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If a lamination is assembled within magnetic core structures to provide an isolated closed magnetic loop transformer, then isolation performance is improved, but air bubbles or other voids are introduced and trapped which inhibit achievement of the desired isolation performance rating

Engineering Contradiction:

Improveisolation performanceVSAvoidisolation performance rating

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The magnetic core pieces are formed as integral parts of the laminate structure through a unified lamination and curing process, eliminating separate assembly steps that would introduce air bubbles and voids. The magnetic material and structural laminate are combined in a single manufacturing sequence, ensuring void-free construction while achieving the closed magnetic loop necessary for high isolation performance.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The magnetic paste is applied to the laminate layers before final curing, allowing the magnetic material to be positioned and bonded simultaneously with the laminate structure formation. This preliminary positioning ensures that magnetic core pieces are firmly attached without voids before the structure is finalized, preventing isolation performance degradation from air bubbles.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If wire wound transformers are used to provide electrical isolation with good performance, then isolation performance is improved, but the devices are large and expensive

Engineering Contradiction:

Improveelectrical isolationVSAvoiddevice size

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent replaces traditional wire-wound transformer construction with a printed circuit board-based laminate structure where conductive traces form the windings and laminated magnetic material forms the core. This substitution of mechanical wire-winding with planar printed conductors dramatically reduces device size while maintaining electrical isolation performance through the same magnetic coupling principles.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

This approach enhances the transformer's power delivery capability and isolation performance by reducing leakage flux and increasing quality factor and inductance density, while also reducing manufacturing costs and ensuring reliable isolation.

Implementation Method 1

performing a printing process that deposits a magnetic paste onto a first side of a laminate structure using a stencil

Methodology Applied

Scientific EffectPrinting process: 3D Printing

Implementation Method 2

curing the magnetic paste to form a first transformer core piece

Methodology Applied

Scientific EffectCuring: Photopolymerisation

Implementation Method 3

forming a closed magnetic loop structure... increasing quality factor and inductance density

Methodology Applied

Scientific EffectMagnetic flux: Magnetic Field

Data Source

PatentUS11887776B2Method for manufacturing an integrated transformer with printed core piece

Publication Date: 2024.01.30 TEXAS INSTRUMENTS INC

AI summary

A method includes performing a printing process that deposits a magnetic paste onto a first side and into an opening of a laminate; curing the magnetic paste to form a first transformer core piece having a first portion along the first side and a second portion filling the opening of the laminate; joining a second transformer core piece to a side of the second portion of the first transformer core piece to form a transformer. A transformer includes a laminate; a first core piece; and a second core piece, the first core piece comprising: a cured magnetic paste, a first portion along a side of the laminate, and a second portion filling an opening of the laminate, the second core piece extending along a side of the second portion of the first transformer core piece, and the laminate having windings that encircle the opening.