Integrated Backlight Wiring Structure Without PCB Mounting

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Solution Overview

Problem

Existing backlight units fail to provide a cost-effective and efficient solution for reducing manufacturing costs in the production of display devices.

Innovation Solution

A backlight unit is designed with a substrate having a wiring layer formed on a separate base substrate instead of a printed circuit board, incorporating a lower and upper conductive layer, a light emitting element, and a connection member to reduce material costs and simplify the structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a printed circuit board is used as the substrate for mounting light emitting elements, then the structural stability and electrical connection reliability are improved, but the manufacturing cost and device complexity increase

Engineering Contradiction:
Improveelectrical connection reliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the substrate and wiring layer into a single integrated structure. The base substrate itself serves as the mounting platform for light emitting elements, while conductive layers (first and second conductive layers) are formed directly on the base substrate to provide electrical connections. This eliminates the need for a separate printed circuit board, reducing device complexity while maintaining electrical connection reliability through the integrated wiring layer design.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The base substrate performs multiple functions simultaneously: it serves as the mechanical support structure for mounting light emitting elements, as the foundation for forming conductive wiring layers, and as part of the overall electrical connection system. This multi-functionality reduces the need for separate dedicated components, thereby simplifying the overall device structure while maintaining reliability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If a printed circuit board is used as the substrate, then the electrical connection and structural support are improved, but the manufacturing cost increases

Engineering Contradiction:
Improveelectrical connectionVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

By combining the substrate and wiring layer functions into a single integrated component, the patent reduces the total number of parts that need to be manufactured and assembled. The conductive layers are formed directly on the base substrate through deposition processes, eliminating the need for separate PCB manufacturing and assembly steps, thereby reducing manufacturing cost while maintaining electrical connection reliability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent employs composite material structures where conductive materials (such as aluminum, copper, or their alloys) are deposited on the base substrate to form the wiring layer. This composite approach allows optimization of each layer for its specific function while achieving overall cost-effectiveness through reduced material usage and simplified manufacturing processes compared to traditional PCB-based solutions.

Inventive Principle:
Principle #40Composite materials

3Ease of manufacture

If the upper conductive layer is disposed only in the non-light emitting area, then the manufacturing cost is reduced, but the electrical connection efficiency may be affected

Engineering Contradiction:
Improvemanufacturing costVSAvoidelectrical connection efficiency
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The patent applies local quality by positioning the upper conductive layer specifically in the non-light emitting area where it is needed for electrical connections and signal routing. In the light emitting area, only the lower conductive layer is present to minimize light interference and maintain display quality. This localized arrangement reduces manufacturing cost by limiting material usage to where it is functionally necessary, while maintaining electrical connection efficiency through proper design of the connection paths in the non-light emitting area.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The conductive wiring structure is segmented into different layers and areas: the lower conductive layer spans the entire base substrate including light emitting areas, while the upper conductive layer is segmented to exist only in non-light emitting areas. This segmentation allows each layer to perform its specific function optimally, reducing overall material cost while maintaining necessary electrical connections through the coordinated design of both segments.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP4425545B1Backlight unit
Publication Date: 2025.12.10 SAMSUNG DISPLAY CO LTD
  • EP4425545B1 patent drawingFigure 1
  • EP4425545B1 patent drawingFigure 2
  • EP4425545B1 patent drawingFigure 3~4

AI summary

A backlight unit includes: a base substrate in which a light emitting area and a non-light emitting area are defined; a wiring layer including: a lower conductive layer disposed on the base substrate; an intermediate conductive layer disposed on the lower conductive layer; and an upper conductive layer disposed on the intermediate conductive layer; a light emitting element disposed on the wiring layer in the light emitting area; a connection member electrically connecting the light emitting element and the wiring layer, the connection member contacting the intermediate conductive layer of the wiring layer and the light emitting element; a backlight flexible substrate electrically connected to the wiring layer in the non-light emitting area; and a pad connection member electrically connecting the wiring layer and the backlight flexible substrate in the non-light emitting area, the pad connection member contacting the upper conductive layer of the wiring layer.