Elevated PCB Bridging Bars for Thermal Dissipation

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Solution Overview

Problem

Existing circuit board designs for high-power applications, such as electric motors in motor vehicles, face challenges in cost-effectively dissipating thermal energy from power components, as conventional solutions like metal core PCBs and heat sinks increase manufacturing costs and board size.

Innovation Solution

The use of bridging bars made of tinned copper, which are rigid and lack electrical isolation, allowing for effective heat dissipation by exposing a larger surface area to the air and reducing the overall board size, while maintaining the ability to conduct large currents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If metal core PCBs or heat sinks are used to dissipate heat from power components, then heat dissipation effectiveness is improved, but manufacturing costs increase

Engineering Contradiction:
Improveheat dissipation effectivenessVSAvoidmanufacturing costs
Core Design Contradiction:
TemperatureVSEase of manufacture

Solution Approach 1:

The circuit board itself serves as the heat dissipation structure through elevated copper traces that act as self-supported heat sinks, eliminating the need for separate metal core PCBs or attached heat sinks. The copper traces on the PCB directly dissipate heat from power components without requiring additional thermal management components.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The copper traces are elevated above the PCB surface to create a three-dimensional heat dissipation structure. This vertical dimension increases the surface area exposed to air for convection and radiation, improving heat dissipation effectiveness while using standard PCB manufacturing processes.

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

2Temperature

If large-dimensioned plate-shaped copper conductors are used on the circuit board surface for high current conduction and heat dissipation, then heat dissipation and current conduction are improved, but the overall area of the circuit board must be enlarged

Engineering Contradiction:
Improveheat dissipationVSAvoidcircuit board area
Core Design Contradiction:
TemperatureVSArea of stationary object

Solution Approach 1:

Instead of expanding copper conductors horizontally across the PCB surface, the invention elevates them vertically to create bridge-like structures. This vertical dimension provides additional heat dissipation surface area without increasing the horizontal footprint of the circuit board.

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

Solution Approach 2:

The elevated copper traces serve multiple functions simultaneously: they conduct high currents, dissipate heat through increased surface area exposure to air, and maintain compact board dimensions. This multi-functionality eliminates the need for separate heat dissipation components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Temperature

If large-dimensioned plate-shaped copper conductors with non-standard thickness are used, then heat dissipation and current conduction are improved, but multilayer manufacturing technique is required which increases costs

Engineering Contradiction:
Improveheat dissipationVSAvoidmanufacturing complexity
Core Design Contradiction:
TemperatureVSEase of manufacture

Solution Approach 1:

The PCB manufacturing process itself creates the elevated copper trace structures through standard lamination and etching techniques. The copper-clad laminate layers are processed to form the bridge-like structures, eliminating the need for specialized multilayer manufacturing or post-assembly heat sink attachment.

Inventive Principle:
Principle #25Self-service

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 solution enables efficient heat dissipation with a smaller board footprint, reducing manufacturing costs and improving thermal management for high-power components without the need for external isolation, thus enhancing the performance and reliability of circuit boards in applications like reversible seatbelt pretensioners.

Implementation Method 1

the bar surface facing the circuit board in the middle portion is exposed to the surrounding air. The bar surface exposed to the surrounding air is almost doubled in this way, which contributes to effective heat dissipation

Methodology Applied
Scientific EffectHeat dissipation: Convection

Implementation Method 2

the bar surface facing the circuit board in the middle portion is exposed to the surrounding air. The bar surface exposed to the surrounding air is almost doubled in this way, which contributes to effective heat dissipation

Methodology Applied
Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 3

Metal core PC boards can be used which contain an inner core of aluminium or copper, for instance, through which the heat losses are distributed and can be dissipated

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 4

The bridging bars according to the invention are essentially rigid or form-stable... made of tinned copper... can easily be dimensioned to conduct relatively large currents, for example 1 A or more

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP2200408B1Circuit board device, in particular for an electric power consuming device in a motor vehicle
Publication Date: 2013.05.08 AUTOLIV DEV AB
  • EP2200408B1 patent drawingFigure 1
  • EP2200408B1 patent drawingFigure 2~3
  • EP2200408B1 patent drawingFigure 4~5

AI summary

A circuit board device (10), in particular for an electric power consuming device in a motor vehicle, comprising a circuit board (11) with a substrate (18) and at least one layer (17) of electrically conductive pattern, and at least one electronic component (12-16) mounted on said circuit board (11) and electrically connected via said electrically conductive pattern (17), characterised in that said circuit board device (10) comprises at least one electrically conducting bridging bar (27, 28) connected to the surface of said circuit board (11) with end sections (31, 32, 35, 36), and spaced from the surface of said circuit board (11) in a middle section (39, 40).