Flex Circuit Power Interconnection for Thermal Stress Reduction

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Solution Overview

Problem

Conventional electrical devices for interconnecting power converters, particularly in harsh environments like aircraft, face challenges with overvoltages, thermomechanical stresses, and limited reliability due to rigid structures and high thermal cycles, which restrict their operating temperature and lifespan.

Innovation Solution

An electrical circuit using a flexible flex circuit with controlled current density and massive metal contact parts, allowing for 3D adaptability and reduced mechanical and thermal stresses, enabling efficient current transmission and mechanical linkage between power components and the flex circuit, thereby enhancing reliability and current handling capacity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If rigid multilayer PCBs or rigid bus bar circuits are used for interconnection, then structural stability is improved, but adaptability to available space and thermal expansion resistance deteriorates

Engineering Contradiction:
Improvestructural stabilityVSAvoidadaptability to available space
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The patent employs flexible circuits (thin films) instead of rigid PCBs or bus bars for electrical interconnection. These flexible circuits can be bent and adapted to fit available three-dimensional spaces while maintaining electrical connectivity, thereby resolving the contradiction between structural stability and spatial adaptability.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The invention transitions from planar rigid interconnections to three-dimensional flexible routing. The flexible circuits enable electrical connections to be made in multiple spatial dimensions, allowing adaptation to complex geometries and confined spaces that rigid flat structures cannot accommodate.

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

2Reliability

If rigid multilayer PCBs or bus bar circuits are used for interconnection, then electrical connectivity is improved, but resistance to thermomechanical stresses from thermal expansion deteriorates

Engineering Contradiction:
Improveelectrical connectivityVSAvoidthermomechanical stresses
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The flexible circuits can accommodate thermal expansion and contraction by deforming elastically, thereby absorbing thermomechanical stresses that would otherwise damage rigid interconnections. This maintains electrical connectivity reliability while resisting harmful thermomechanical effects.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The invention changes the mechanical parameters of the interconnection structure from rigid to flexible, allowing the circuit to dynamically adjust its physical state in response to thermal cycling. This parameter change enables the system to withstand repeated thermal expansion and contraction without compromising electrical connectivity.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If conventional discrete power components mounted on rigid PCBs are used, then ease of manufacture is improved, but current handling capacity and power density deteriorates

Engineering Contradiction:
Improveease of assemblyVSAvoidcurrent handling capacity
Core Design Contradiction:
Ease of manufactureVSPower

Solution Approach 1:

The patent merges the power conversion components and the flexible circuit interconnection into an integrated assembly. The flexible circuits are directly connected to the power components, eliminating the need for separate rigid PCB mounting and external bus bars, thereby achieving both ease of manufacture and high current handling capacity in a single integrated structure.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The flexible circuits enable higher power density by allowing compact three-dimensional arrangement of power components. The flexibility permits closer spacing and more efficient heat dissipation pathways, increasing the current handling capacity beyond what rigid planar structures can achieve while maintaining manufacturing feasibility.

Inventive Principle:
Principle #30Flexible shells and thin films

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 solution effectively reduces current transmission heating and mechanical stresses on contact parts, allowing the flex circuit to manage currents between 1 and 200 A, while improving the assembly's reliability and adaptability in confined, high-temperature environments.

Implementation Method 1

a first conductive layer (3) coming into contact with the component, a second conductive layer (3) coming into contact with the voltage source

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

a dielectric insulator layer (5) insulating the two conductive layers (3) from one another

Methodology Applied
Scientific EffectDielectric insulation: Dielectric

Data Source

PatentEP2856563B1Electrical circuit connecting an electrical component, such as power component
Publication Date: 2016.05.25 SAFRAN ELECTRICAL & POWER
  • EP2856563B1 patent drawingFigure 1~2

AI summary

The invention concerns an electrical circuit comprising at least one electrical component, such as a power component, and an electrical flex circuit (1), characterised in that it comprises at least one electrical conductor part (7) connecting said electrical component to said flex circuit, said electrical conductor part (7) being provided with at least a first contact portion (13) designed to receive in contact a contact element (9) of said electrical power component and a second contact portion (15) designed to receive in contact a conductive layer (3) of said electrical flex circuit, the extent of the width of the second contact portion (15) corresponding to the width of the flex circuit (1), and the extent of the length of same being adjusted to provide a contact surface capable of transmitting a density of electrical current of between 4.5 and 5.5 A/mm² and allowing the electrical circuit to support a current specific to said power component, i.e. between 30 and 80 A.