Segmented Conducting Layer on Flexible Wiring Board

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Solution Overview

Problem

Conventional printed wiring boards face issues with conducting layers separating from the base film due to stress during the formation of protrusions in the terminals, leading to electrical disconnection in devices like inkjet printheads.

Innovation Solution

A printed wiring board design featuring an electrically insulating flexible layer with protrusions on one side and conducting layers on the other, connected by wires extending in a direction, which prevents separation of the conducting layers from the flexible layer during protrusion formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If protrusions are formed in the terminals of the conducting layers on the FPC by pressing, then electrical connection is achieved, but the conducting layers separate from the base film due to stress on the bonding surface

Engineering Contradiction:

Improveelectrical connectionVSAvoidbonding between conducting layer and base film

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The conducting layer is divided into multiple segments along the wire extension direction. Each segment is independently bonded to the base film, distributing the stress from protrusion formation across multiple bonding zones rather than concentrating it at a single location, thereby preventing separation while maintaining electrical connectivity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The conducting layer is designed with locally enhanced bonding characteristics at critical stress points. The segmented structure provides localized bonding zones that can withstand the stress of protrusion formation, while other portions maintain their electrical conduction function

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS7703889B2Printed wiring board and electric device using the same

Publication Date: 2010.04.27 BROTHER KOGYO KK

AI summary

There is disclosed a printed wiring board comprising: an electrically insulating flexible layer which has on one of its opposite sides a protrusion which forms a corresponding recess on the other side of the flexible layer; an electrically conducting layer formed on the protrusion; and a wire formed on the flexible layer, connected to the conducting layer, and extending in a direction. The conducting layer has a shape long in the direction of extension of the wire.