PCB Power Semiconductor Assembly With Isolated Solder Regions

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Solution Overview

Problem

The challenge in mounting power semiconductor components on printed circuit boards is the difficulty in effectively dissipating heat due to high resistance at the soldered connections, leading to potential short circuits and assembly complexities with multiple output connections, which can result in functional impairment or failure.

Innovation Solution

A printed circuit board arrangement with galvanically isolated soldering areas separated by a web, where the control terminal is connected to one soldering area and output terminals to another, preventing solder flow and allowing for easier assembly and reducing the risk of short circuits by using a dummy output connection that can be decoupled, and a large-area cooling layer for thermal dissipation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If multiple output terminals are used to increase effective cross-sectional area and reduce resistance, then power loss and heat generation are reduced, but mounting precision and assembly complexity increase significantly

Engineering Contradiction:
Improvepower lossVSAvoidmounting precision
Core Design Contradiction:
Loss of energyVSManufacturing precision

Solution Approach 1:

The patent segments the soldering process by providing separate soldering areas for control terminals and output terminals on the circuit board. This segmentation allows each terminal type to be soldered independently with appropriate solder amounts, reducing the risk of solder bridging while maintaining multiple output terminals for lower resistance and power loss.

Inventive Principle:
Principle #1Segmentation

2Loss of energy

If multiple output terminals are used to reduce resistance, then power loss is reduced, but the risk of solder migration and short circuits increases

Engineering Contradiction:
Improvepower lossVSAvoidshort circuit risk
Core Design Contradiction:
Loss of energyVSReliability

Solution Approach 1:

The circuit board features galvanically isolated soldering areas that segment the soldering zones for control and output terminals. This physical segmentation prevents solder migration between different terminal types, eliminating short circuit risks while allowing multiple output terminals to be used for reduced resistance and power loss.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary structure (the separated soldering area design) that mediates between the control terminals and output terminals. This intermediary segmentation acts as a barrier to solder flow while maintaining electrical connectivity where needed, preventing short circuits between control and output terminals.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Area of stationary object

If control terminal and output terminals are located close together to save space, then device compactness is improved, but solder migration risk and short circuit risk increase

Engineering Contradiction:
Improveboard areaVSAvoidshort circuit risk
Core Design Contradiction:
Area of stationary objectVSReliability

Solution Approach 1:

The soldering areas are segmented into distinct zones for control terminals and output terminals, creating physical barriers that prevent solder migration. This segmentation allows terminals to be positioned close together for compact board layout while maintaining reliable isolation to prevent short circuits.

Inventive Principle:
Principle #1Segmentation

4Device complexity

If a single soldering area is used to simplify board design, then device complexity is reduced, but heat dissipation effectiveness and electrical isolation are compromised

Engineering Contradiction:
Improveboard design complexityVSAvoidheat dissipation
Core Design Contradiction:
Device complexityVSTemperature

Solution Approach 1:

The soldering areas are segmented into galvanically isolated zones that can be thermally coupled through the circuit board substrate. This segmentation provides electrical isolation for reliable operation while maintaining thermal pathways for effective heat dissipation from power semiconductor devices, without significantly increasing design complexity.

Inventive Principle:
Principle #1Segmentation

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 simplifies the mounting process, reduces the risk of short circuits, and enhances the thermal management of power semiconductor components, leading to more cost-effective production and reliable operation by preventing solder flow between control and output connections and improving heat dissipation.

Implementation Method 1

The generated thermal energy is usually transferred to a heat sink integrated into the power semiconductor device's housing, which then dissipates the energy to the environment via the housing's exterior.

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

the heat sink must be thermally coupled to the printed circuit board (PCB) or be integrated directly onto the PCB

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 3

This output terminal is electrically and mechanically connected to the contact pad on the circuit board via a single solder joint.

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 4

a relatively high power loss is generated at this point of constriction due to the resulting resistance, which ultimately heats both the output terminal and the solder joint to a greater or lesser extent

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP3031308B1Circuit board assembly, control device for a cooler fan module and method
Publication Date: 2021.10.13 BROSE FAHRZEUGTEILE GMBH & CO KG
  • EP3031308B1 patent drawingFigure 1
  • EP3031308B1 patent drawingFigure 2
  • EP3031308B1 patent drawingFigure 3

AI summary

The present invention relates to a circuit board assembly, comprising a circuit board which has a first and a second solder region, which is galvanically separated from the first, and which furthermore has a separator arranged between the solder regions and rising out from the solder regions, having a power semiconductor component which has a housing having an output connection side, from which at least one control connection and a plurality of output connections protrude, which are arranged substantially adjacent to each other on the output connection side, wherein the control connection is electrically and mechanically connected to the first solder region and the output connections are electrically and mechanically connected to the second solder region and the control connection is separated from the output connections via the raised separator. The present invention furthermore relates to a control device for a cooler fan module of a motor vehicle and to a method for assembling a power semiconductor component on a circuit board.