Printed Circuit Board Rigid-Flex Composite Stiffener Design

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Solution Overview

Problem

Existing printed circuit boards (PCBs) are either too flexible or too rigid, and often too thick, leading to snagging issues and high costs due to material constraints, making them unsuitable for various applications.

Innovation Solution

A printed circuit board design that combines a flexible circuit material with a rigid material, where the rigid material is attached to the flexible material and partially removed to create openings, increasing rigidity and reducing thickness, while also providing mechanical flexure characteristics and cost-effectiveness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a flexible circuit material is used, then the PCB can conform to curved surfaces and reduce snagging, but the PCB becomes too flexible and lacks structural stability

Engineering Contradiction:

Improveability to conform to surfacesVSAvoidstructural stability

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The patent combines flexible circuit material (e.g., polyimide) with rigid material (e.g., FR-4) to create a composite structure. The flexible layer provides adaptability to curved surfaces while the rigid layer contributes structural stability, resolving the contradiction between flexibility and stability.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The PCB is divided into distinct functional layers: a flexible circuit material layer for adaptability and a rigid material layer for structural support. This segmentation allows each layer to perform its specialized function, with the flexible layer conforming to surfaces and the rigid layer maintaining stability.

Inventive Principle:

Principle #1Segmentation

2Stability of the object's composition

If a rigid material is used, then the PCB gains structural stability, but the PCB becomes too rigid and cannot conform to curved surfaces

Engineering Contradiction:

Improvestructural stabilityVSAvoidability to conform to surfaces

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The composite structure combines rigid material for stability with flexible circuit material for adaptability. The rigid material provides the necessary structural support while the flexible layer enables conformation to curved surfaces, resolving the contradiction between rigidity and adaptability.

Inventive Principle:

Principle #40Composite materials

3Strength

If conventional PCB materials are used, then the PCB achieves sufficient rigidity, but the overall thickness increases causing snagging issues

Engineering Contradiction:

ImproverigidityVSAvoidthickness

Core Design Contradiction:

StrengthVSLength of stationary object

Solution Approach 1:

The patent uses thin flexible circuit material layers (such as polyimide) that provide sufficient structural properties without adding significant thickness. This thin-film approach maintains rigidity where needed while minimizing overall thickness to prevent snagging issues.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The composite construction allows for optimized thickness distribution, with thin flexible layers providing adaptability and minimal thickness, while rigid material is strategically placed only where structural support is required, achieving rigidity without excessive overall thickness.

Inventive Principle:

Principle #40Composite materials

4Adaptability or versatility

If rigid material is completely removed to create openings, then the PCB flexibility increases, but the structural support is compromised

Engineering Contradiction:

ImproveflexibilityVSAvoidstructural support

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The rigid material is selectively removed only in specific locations where openings are needed, while retaining rigid material in other areas to maintain overall structural support. This local modification approach allows flexibility in specific regions without compromising global structural integrity.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The rigid material layer is segmented into retained portions for structural support and removed portions creating openings for flexibility. This segmentation allows different regions of the PCB to have different mechanical properties, with rigid areas providing support and opening areas providing flexibility.

Inventive Principle:

Principle #1Segmentation

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

The solution results in a PCB with intermediate flexibility and reduced thickness, minimizing snagging risks and improving manufacturing efficiency, while being cost-effective and adaptable to different surfaces.

Implementation Method 1

an adhesive material on the kapton circuit

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS9198282B2Printed circuit board

Publication Date: 2015.11.24 HONEYWELL INTERNATIONAL INC

AI summary

Apparatuses and methods include a printed circuit board having a flexible circuit material, a rigid material over the flexible circuit material, and a first opening extending from a top surface of the rigid material to a first circuit layer of the flexible circuit material, and wherein the rigid material acts as a stiffener for the flexible circuit material.