Flexible Input Output Device Crack Inhibiting Layer

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Solution Overview

Problem

Flexible input and output devices face issues with cracking during the peeling and dividing processes, leading to defects and reduced reliability, especially when exposed to high temperature and high humidity environments, which affects the performance and productivity of light-emitting elements.

Innovation Solution

The implementation of a flexible input and output device structure that includes a first and second flexible substrate with buffer layers and crack inhibiting layers, where the crack inhibiting layers are made of conductive or resin materials to reduce stress and prevent cracking, and are positioned between the sensor element and the end portion of the substrate, enhancing the device's reliability and productivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If peeling is performed between the separation layer and the layer to be separated to transfer the stack to a flexible substrate, then the flexible device can be manufactured, but high bending stress is applied to the end portion of the substrate causing breaking or cracking in the layer to be separated

Engineering Contradiction:

Improveflexible device manufacturingVSAvoidcrack occurrence in layer to be separated

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

A crack inhibiting layer is formed in advance at the end portion of the substrate before the peeling process. This preliminary protective layer prevents stress concentration and crack initiation during the subsequent peeling operation, allowing the stack to be transferred to the flexible substrate without damage.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The crack inhibiting layer acts as a cushioning element positioned at the vulnerable end portion of the substrate. During peeling, this layer absorbs and distributes the bending stress that would otherwise concentrate at the edge, preventing crack propagation in the layer to be separated.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Productivity

If the substrate is divided with a scriber to manufacture multiple devices simultaneously, then productivity is improved, but stress applied during division causes cracking in the thin film, particularly in the layer to be separated

Engineering Contradiction:

Improvesimultaneous manufacturing of multiple devicesVSAvoidcrack occurrence in thin film during division

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The crack inhibiting layer is formed before the substrate division step. This preliminary protective structure remains intact during the scriber division process, preventing stress-induced cracking in the thin film layers even when the substrate is mechanically divided into multiple devices.

Inventive Principle:

Principle #10Preliminary action

3Ease of manufacture

If cracks occur in the end portion of the layer to be separated, then the device can be manufactured, but the cracks develop in high temperature and high humidity environments reducing reliability and causing light-emitting elements to fail

Engineering Contradiction:

Improvedevice manufacturingVSAvoidperformance in high temperature and high humidity environment

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The crack inhibiting layer is formed in advance to prevent crack initiation at the substrate end portion. By eliminating cracks before device completion, the structure remains intact during subsequent high temperature and high humidity exposure, ensuring reliable operation of light-emitting elements.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The crack inhibiting layer converts the harmful effect of stress concentration at the substrate edge into a beneficial protective function. The layer is specifically positioned and designed to withstand environmental stressors like high temperature and humidity, transforming a vulnerable location into a reinforced zone.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS9960213B2Input and output device having touch sensor element as input device and display device

Publication Date: 2018.05.01 SEMICON ENERGY LAB CO LTD

AI summary

A flexible input and output device in which defects due to a crack is reduced. The input and output device includes a first flexible substrate, a second flexible substrate, a first buffer layer, a first crack inhibiting layer, an input device, and a light-emitting element. A first surface of the first flexible substrate faces a second surface of the second flexible substrate. The first buffer layer, the first crack inhibiting layer, and the input device are provided on the first surface side of the first flexible substrate. The first buffer layer includes a region overlapping with the first crack inhibiting layer. The first buffer layer is between the first crack inhibiting layer and the first surface. The input device includes a transistor and a sensor element. The light-emitting element is provided on the second surface side of the second flexible substrate.