Hermetic Electronic Package Layout to Reduce Implant Charging Eddy Currents

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Solution Overview

Problem

Implantable medical devices face challenges with environmental factors such as electromagnetic fields used for charging, which can cause eddy currents and reduce charging efficiency, and the need for a hermetic seal to maintain device integrity.

Innovation Solution

An electronic package design featuring a nonconductive substrate with a conductive layer hermetically sealed over an opening, a conductor block electrically connected to the conductive layer, and an electronic device connected to the conductive layer, all encapsulated within a nonconductive cover to reduce eddy currents and enhance hermeticity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conductive layer is hermetically sealed to provide electrical connections, then electrical connectivity is improved, but eddy currents are generated when exposed to electromagnetic fields

Engineering Contradiction:
Improveelectrical connectivityVSAvoideddy currents
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The conductive layer is segmented into multiple discrete conductive traces rather than a continuous layer. These traces are arranged in a pattern that interrupts eddy current paths while maintaining electrical connectivity to the conductor block and electronic device. The segmentation breaks up large conductive areas into smaller isolated sections, reducing eddy current formation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The conductive layer has different properties in different locations: it provides continuous connectivity where needed (at contact points with the conductor block and electronic device) but is interrupted or patterned in areas where eddy currents would form. This local variation in conductive quality allows simultaneous achievement of electrical connectivity and eddy current reduction.

Inventive Principle:
Principle #3Local quality

2Reliability

If a hermetic seal is implemented to maintain device integrity, then device reliability is improved, but electromagnetic field penetration for charging is reduced

Engineering Contradiction:
Improvedevice integrityVSAvoidcharging efficiency
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The housing material properties are optimized to balance hermeticity and electromagnetic transparency. The design adjusts material selection, thickness, and composition parameters to achieve sufficient sealing while maintaining adequate electromagnetic field penetration for efficient wireless charging.

Inventive Principle:
Principle #35Parameter changes

3Object-generated harmful factors

If a nonconductive cover is used to reduce eddy currents, then eddy current formation is reduced, but hermetic sealing complexity increases

Engineering Contradiction:
Improveeddy currentsVSAvoidsealing structure
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The nonconductive cover is nested within the overall housing structure, with the conductive layer and conductor block integrated into the same assembly. This nested arrangement allows the nonconductive cover to reduce eddy currents while the integrated design minimizes additional sealing complexity by combining multiple functions in a unified structure.

Inventive Principle:
Principle #7Nested doll (Nesting)

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 electronic package provides low resistance for large electrical currents, reduces eddy-current formation when exposed to electromagnetic fields, and maintains hermeticity, enhancing the efficiency and reliability of implantable medical devices.

Implementation Method 1

a conductive layer hermetically sealed to a first major surface of the substrate over an opening disposed through the substrate

Methodology Applied
Scientific EffectHermetic sealing:

Implementation Method 2

A nonconductive cover can be disposed over the electronic device and the nonconductive substrate such that the electronic device is disposed within a cavity of the cover. The cover can be sealed to the substrate.

Methodology Applied
Scientific EffectHermetic sealing:

Implementation Method 3

Implantable medical devices face challenges with environmental factors such as electromagnetic fields used for charging, which can cause eddy currents and reduce charging efficiency

Methodology Applied
Scientific EffectEddy currents: Eddy Currents

Implementation Method 4

An electromagnetic field generated by a transmitting coil outside the body can transmit power across a cutaneous (skin) barrier to a magnetic receiving coil implanted within the body

Methodology Applied
Scientific EffectElectromagnetic field: Electromagnetic Induction

Implementation Method 5

The electronic package provides low resistance for large electrical currents

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP4284498B1Electronic package and device including same
Publication Date: 2025.04.23 MEDTRONIC INC
  • EP4284498B1 patent drawingFigure 1~2
  • EP4284498B1 patent drawingFigure 3~4
  • EP4284498B1 patent drawingFigure 5

AI summary

Various embodiments of an electronic package and implantable medical device are disclosed. The electronic package includes a nonconductive substrate having a first major surface, a second major surface, and an opening disposed through the substrate between the first major surface and the second major surface. The package also includes a conductive layer hermetically sealed to the first major surface of the substrate and over the opening; a conductor block disposed in the opening and extending beyond the second major surface of the substrate, where the conductor block is electrically connected to the conductive layer; and an electronic device disposed adjacent to the first major surface of the substrate and electrically connected to the conductive layer. The package also includes a nonconductive cover disposed over the electronic device and the nonconductive substrate and hermetically sealed to the substrate, where the electronic device is disposed within a cavity of the cover.