Flexible Circuit Board Ridge Flexion Zone LED Mounting

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Solution Overview

Problem

The use of stiff circuit substrates for LED packages can lead to design limitations and electrical connection failures due to flexion, and the cost of packaging LED chips is high, necessitating improved methods for securing LED packages to flexible substrates and simplifying their placement.

Innovation Solution

A flexible circuit board with a ridge defining a flexion zone around the component mounting area, which insulates the area from forces applied to the substrate, and a method involving mechanical deformation of the substrate without heat to form the ridge, allowing for roll-to-roll manufacturing and direct mounting of LED chips or packages.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a flexible substrate is used for LED packages, then design flexibility and adaptability are improved, but the adhesive may crack during flexion compromising electrical connection

Engineering Contradiction:

Improvedesign flexibilityVSAvoidelectrical connection reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The substrate is segmented into distinct functional zones: a flexion zone that can bend and a protected mounting area that remains stable. The ridge structure divides the substrate to create this segmentation, allowing the LED package to be mounted on a stable area while the substrate can still flex overall, preventing adhesive cracking while maintaining design flexibility

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the substrate are given different mechanical properties through the ridge structure. The protected mounting area has restricted flexion to maintain stability for electrical connections, while other areas can flex. This local differentiation of mechanical behavior resolves the contradiction between overall flexibility and local connection stability

Inventive Principle:

Principle #3Local quality

2Reliability

If LED chips are packaged into LED packages, then protection and electrical connection are improved, but manufacturing cost increases significantly

Engineering Contradiction:

Improveprotection and electrical connectionVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The substrate structure merges the protective function traditionally provided by separate LED packages into the substrate itself. The protected mounting area and ridge structure provide mechanical protection and stable electrical connections directly, eliminating the need for separate LED package components and reducing manufacturing complexity and cost

Inventive Principle:

Principle #5Merging (Combining)

3Ease of operation

If conventional adhesive methods are used to attach LED packages, then ease of assembly is improved, but the adhesive cracks under flexion stress

Engineering Contradiction:

Improveease of assemblyVSAvoidbond strength under flexion

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

By segmenting the substrate into flexion and protected zones, the adhesive bond is placed only in the stable protected mounting area, away from flexion stresses. This maintains the simplicity of adhesive assembly while preventing adhesive cracking, as the adhesive is never subjected to bending forces

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS9335034B2Flexible circuit board for electronic applications, light source containing same, and method of making

Publication Date: 2016.05.10 OSRAM SYLVANIA INC

AI summary

A flexible circuit board is described that includes a flexible substrate, at least one ridge defining a flexion zone and a component mounting area. The flexion zone acting to dissipate at least a portion of a force applied to the substrate, so as to insulate the component mounting area from the force. Light sources using such flexible circuit boards and methods for making such circuit boards are also described.