Flexible Circuit Board Alignment Mark Placement

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Solution Overview

Problem

The existing flexible printed circuit (FPC) boards in display devices face reliability issues due to short circuits caused by bent conductive lines around alignment marks, which reduce the display area and connection reliability.

Innovation Solution

The FPC board design includes alignment marks positioned between conductive fingers, allowing direct connection of conductive lines to circuit pads without bending, maintaining a safe distance and improving connection reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If alignment marks are positioned on lateral sides of circuit pads, then alignment between FPC and display panel is achieved, but conductive lines must bend around alignment marks causing short circuits and reduced reliability

Engineering Contradiction:

Improvealignment precisionVSAvoidconnection reliability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent inverts the conventional placement of alignment marks from the lateral sides of circuit pads to positions between adjacent circuit pads. This inversion eliminates the need for conductive lines to bend around alignment marks, preventing short circuits while maintaining alignment precision through the alternative positioning strategy

Inventive Principle:

Principle #13The other way round (Inversion)

2Measurement precision

If conductive lines are bent around alignment marks, then alignment is achieved, but distance between bend portions is reduced increasing short circuit risk

Engineering Contradiction:

Improvealignment precisionVSAvoidshort circuit risk

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the alignment mark function from its conventional location on lateral sides and relocates it to positions between circuit pads. This extraction removes the harmful interaction between conductive lines and alignment marks, eliminating the bending requirement and associated short circuit risks while preserving alignment functionality

Inventive Principle:

Principle #2Taking out (Extraction)

3Measurement precision

If alignment marks are on lateral sides, then alignment is achieved, but extra area at bottom of display panel is needed reducing display area

Engineering Contradiction:

Improvealignment precisionVSAvoiddisplay area

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

The patent transitions the alignment mark positioning from the lateral dimension (sides of circuit pads) to the vertical dimension (between adjacent circuit pads). This dimensional change repositions alignment marks within the existing bonding area footprint, eliminating the need for additional bottom area while maintaining alignment precision

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS7965366B2Flexible printed circuit board with alignment marks in particular positions

Publication Date: 2011.06.21 INNOLUX CORP

AI summary

An exemplary flexible printed circuit board (2) includes a substrate (221), a plurality of connecting fingers (225, 227) and at least one alignment mark (229). The connecting fingers and the at least one alignment mark are located on a surface of the substrate. The at least one alignment mark is disposed between two of the connecting fingers.