Flexible PCB Segment Joining for Long Laminated Circuits

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Solution Overview

Problem

Existing methods for connecting flexible PCBs are limited by the dimensions of laminating presses, restricting the length and width of flexible PCBs, and the connection process often renders the joint rigid, losing the flexibility advantages of flexible PCBs.

Innovation Solution

A method involving exposing the cover insulating layer to create contact surfaces, using reinforcing and positioning layers with holes for alignment, and applying a thermally activatable adhesive layer to ensure flexible and low-resistance connections, allowing for larger flexible PCBs with conventional presses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If conventional laminating presses are used, then manufacturing cost is controlled, but the dimensions (length and width) of flexible PCBs are limited

Engineering Contradiction:

Improvelength of flexible PCBVSAvoidmanufacturing capability

Core Design Contradiction:

Length of stationary objectVSEase of manufacture

Solution Approach 1:

The flexible PCB is divided into multiple segments that are manufactured separately using conventional laminating presses and then connected together. This allows each segment to be produced within the size limits of existing equipment while the final assembled PCB can achieve much larger dimensions by combining multiple segments.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The solution transitions from producing a single large PCB in one step to assembling multiple smaller segments in a multi-step process. This dimensional approach to manufacturing enables overcoming the physical limitations of laminating press size while maintaining compatibility with conventional equipment.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If rigid protective elements are used to protect conductive adhesive connections, then connection reliability is improved, but flexibility at the joint is lost

Engineering Contradiction:

Improveconnection reliabilityVSAvoidflexibility at joint

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

Instead of using rigid protective elements, the patent employs flexible cover layers that conform to the bent shape of the PCB. These thin film structures provide protection for the conductive adhesive connections while maintaining the flexibility and bendability of the joint area.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The protective structure changes from rigid to flexible by using materials and designs that adapt to bending. The cover layer parameters (material properties, thickness, structure) are optimized to provide adequate protection while allowing the joint to flex without compromising reliability.

Inventive Principle:

Principle #35Parameter changes

3Strength

If filler materials are used to join flexible PCBs, then mechanical strength is improved, but flexibility at the joining point is reduced

Engineering Contradiction:

Improvemechanical strength of jointVSAvoidflexibility at joining point

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

The patent uses conductive adhesive as a composite bonding material that combines electrical conductivity with flexible mechanical properties. This adhesive creates both electrical and mechanical connections while maintaining flexibility, unlike traditional filler materials that are rigid and compromise bendability.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The solution replaces rigid mechanical filler materials with a flexible conductive adhesive system. This substitution eliminates the need for rigid support structures at the joint, allowing the PCB to maintain its flexibility while achieving adequate mechanical strength through the adhesive bonding.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Enables flexible PCBs with freely selectable dimensions and maintains flexibility in the connection area, facilitating integration into complex structures like multi-pane safety glass.

Implementation Method 1

applying a thermally activatable adhesive layer to ensure flexible and low-resistance connections

Methodology Applied

Scientific EffectThermal activation: Heating

Implementation Method 2

The adhesive layer is then cooled, thereby forming the joint

Methodology Applied

Scientific EffectCooling: Cooling

Data Source

PatentUS20250374440A1Method for forming an electrical and mechanical connection arrangement of at least two flexible printed circuit boards (flexible PCB) or flexible PCB segments as well as subsequently manufactured flexible PCB of any length

Publication Date: 2025.12.04 FEW FAHRZEUGELEKTRIKWERK

AI summary

The invention relates to a method for forming an electrical and mechanical connection arrangement of at least two flexible PCBs or flexible PCB segments, each consisting of a composite of a base insulating layer, an electrically conductive structure, in particular conducting tracks, and a cover insulating layer. The top insulating layer is exposed or removed in a section of the connection area in order to obtain contact surfaces. Using reinforcement and positioning layers and after correct positioning by means of positioning marks, a joining and laminating step is carried out in order to achieve a secure and flexible connection.