Motor Vehicle PCB Housing Deformation for Gas-Tight Contact

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Solution Overview

Problem

Existing electrical circuit arrangements for motor vehicle control units have limited holding force and ohmic contact stability due to non-positive connections and gas-tight issues, leading to high impedance and fretting corrosion, which affects the reliability of the contact over the service life.

Innovation Solution

The solution involves creating a printed circuit board with indentations, such as grooves or plated-through holes, that are metallized or filled with conductive material, allowing the housing to be deformed into these areas to form a positive fit and gas-tight ohmic contact, enhancing lateral fixation and maintaining low-impedance contact resistance despite environmental stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the housing is embossed onto a metallized surface of the printed circuit board to create thermal and ohmic contact, then thermal contact and ohmic contact are achieved, but the holding force is limited and the contact is not gas-tight

Engineering Contradiction:
Improvecontact stabilityVSAvoidholding force
Core Design Contradiction:
ReliabilityVSForce

Solution Approach 1:

The contact area is segmented into multiple discrete contact points formed by embossing the housing onto the metallized surface. This segmentation creates multiple independent contact zones that collectively provide both thermal conduction and electrical contact while maintaining gas-tight sealing through the deformation geometry

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The solution transitions from a two-dimensional surface contact to a three-dimensional deformation contact. The housing is embossed to create protrusions that deform the metallized surface, forming dimples or cavities that provide mechanical interlocking in the lateral direction while maintaining contact pressure for thermal and electrical conduction

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

2Reliability

If the housing is embossed onto the printed circuit board surface, then ohmic contact is created, but oxide layer formation occurs and contact resistance increases over time

Engineering Contradiction:
Improvecontact resistance stabilityVSAvoidservice life
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The housing is pre-formed with embossing features before assembly, and the metallized surface is prepared in advance. During assembly, the embossing action creates immediate gas-tight contact that prevents oxide layer formation from the outset, rather than relying on post-assembly protection

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The deformation process creates a gas-tight seal between the housing and the metallized surface, effectively creating an inert or oxygen-excluded environment at the contact interface. This prevents oxidation of the contact surfaces during operation, maintaining low contact resistance throughout the service life

Inventive Principle:
Principle #39Inert atmosphere (Inert environment)

3Ease of manufacture

If a non-positive connection is used to fix the printed circuit board, then assembly is simple, but the holding force is limited and lateral fixation is insufficient

Engineering Contradiction:
Improveassembly simplicityVSAvoidlateral holding force
Core Design Contradiction:
Ease of manufactureVSForce

Solution Approach 1:

The fixation system is segmented into multiple discrete embossing locations distributed across the contact area. Each location provides independent mechanical interlocking through the deformation geometry, collectively delivering strong lateral holding force while maintaining assembly simplicity through a single embossing operation

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The embossing process creates curved or rounded deformation features in the metallized surface, such as dimples or cavities. These curved geometries provide mechanical interlocking by engaging with the corresponding protrusions on the housing, preventing lateral displacement while maintaining assembly simplicity

Inventive Principle:
Principle #14Spheroidality (Curvature)

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 significantly increases the holding force and maintains low-impedance contact over the service life, preventing oxidation and fretting corrosion, enabling the contact to be used as a reliable ground connection for electrical components.

Implementation Method 1

this is intended to create thermal contact between the printed circuit board and the housing

Methodology Applied
Scientific EffectThermal contact: Conduction (thermal)

Implementation Method 2

an ohmic contact to the preferably grounded housing is also to be created if the surface of the printed circuit board on which the housing is embossed in some areas is metallized

Methodology Applied
Scientific EffectOhmic contact: Conduction (electrical)

Implementation Method 3

Since the deformation area is molded into the depression at least in some areas, a positive fit is achieved. This leads to a significantly improved holding force in the lateral direction

Methodology Applied
Scientific EffectPositive fit: Mechanical Fastener

Implementation Method 4

the ohmic contact created as a result of the molded-in deformation area is gas-tight. The gas-tight connection of the contact surfaces impedes, preferably prevents, their oxidation

Methodology Applied
Scientific EffectOxidation prevention: Oxidation

Data Source

PatentEP2649870B1Electrical circuit arrangement and method for producing an electrical circuit arrangement
Publication Date: 2015.01.07 ROBERT BOSCH GMBH
  • EP2649870B1 patent drawingFigure 1
  • EP2649870B1 patent drawingFigure 2

AI summary

The invention relates to an electrical circuit arrangement (1), more particularly for a control unit of a motor vehicle, comprising at least one printed circuit board (2) and a housing (3), wherein the housing (3) has at least one guide region (4) for guiding the at least one printed circuit board (2). In this case, provision is made for the at least one printed circuit board (2) to have at least one depression, and for the housing (3) to be mechanically deformed in at least one deformation region (10) of the at least one guide region (4) in such a way that the at least one deformation region (10) is shaped into the at least one depression at least regionally.