Flexible Printed Circuit Connection Structure for Busbar

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Solution Overview

Problem

Existing connection methods between flexible printed circuits (FPCs) and flat-plate-shaped conductive bodies, such as busbars, face challenges in maintaining consistent contact area and conductivity due to positional deviations and the nature of conductive adhesives used, which can lead to variations in contact resistance and potential connection failures.

Innovation Solution

A connection structure featuring a flexible printed circuit with wiring patterns that include connection target portions extending in a specific direction to cross the flat-plate-shaped connection portions of a conductive body, utilizing a conductive adhesive to ensure electrical connection, with the connection portions and target portions being designed to maintain a consistent contact area even with positional deviations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conductive adhesive is used to connect the wiring pattern and the busbar, then the wiring pattern and the busbar can be electrically connected, but the contact area varies due to positional deviations leading to inconsistent contact resistance

Engineering Contradiction:
Improveelectrical connection stabilityVSAvoidcontact area consistency
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent changes the geometric parameters of the connection structure by making the connection target portions longer than the width of the connection portions in the preset direction. This parameter change ensures that even when positional deviations occur during assembly, the overlapping area between connection portions and target portions remains substantially constant, thereby maintaining consistent contact resistance and reliable electrical connection.

Inventive Principle:
Principle #35Parameter changes

2Strength

If the wiring pattern and busbar are pressed together with adhesive, then they are joined mechanically and electrically, but excess adhesive and fillers are pushed out causing potential connection issues

Engineering Contradiction:
Improvejoint strengthVSAvoidadhesive overflow and filler displacement
Core Design Contradiction:
StrengthVSObject-generated harmful factors

Solution Approach 1:

The patent designs the connection target portions to extend beyond the connection portions in the preset direction, creating a pre-configured overlapping region. This preliminary geometric arrangement ensures that when adhesive is applied and pressed, the excess adhesive and fillers are contained within the extended target portions rather than being pushed out to harmful locations, thus maintaining joint strength while preventing connection issues.

Inventive Principle:
Principle #10Preliminary action

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 configuration ensures a stable and consistent electrical connection between the FPC and the conductive body, reducing the likelihood of connection failures due to positional deviations and maintaining optimal contact resistance, thereby enhancing the quality of signal transmission.

Implementation Method 1

the connection portion and the connection target portions are electrically connected using a conductive adhesive to connect the wiring pattern and the conductive body

Methodology Applied
Scientific EffectConductive adhesive: Conduction (electrical)

Implementation Method 2

This portion is heated from outside, whereby the base material is set in a state that the wiring pattern and the busbar are electrically connected to each other by the fillers

Methodology Applied
Scientific EffectThermal heating: Heating

Data Source

PatentEP3819935B1Connecting structure including circuit body and conductive body
Publication Date: 2022.01.26 YAZAKI CORP
  • EP3819935B1 patent drawingFigure 1
  • EP3819935B1 patent drawingFigure 2
  • EP3819935B1 patent drawingFigure 3

AI summary

A connection structure includes: a circuit body including a flexible printed circuit having a wiring pattern; and a conductive body including a connection portion. The connection portion has a flat-plate shape and is connected to a mounting surface of the circuit body. The wiring pattern has a number of connection target portions each extending in a preset direction to cross the connection portion and is longer than a width of the connection portion in the preset direction. The connection portion and the connection target portions are electrically connected using a conductive adhesive to connect the wiring pattern and the conductive body.