Backlight PCB Copper Layout for Uniform Display Panel Bending
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Display devices experience non-uniform image quality and mura due to PCB distortion caused by thermal expansion during the reflow process, leading to uneven bending and assembly issues.
Innovation Solution
The PCB is designed with a first conductive layer on the lower surface occupying 90% of the area and a second conductive layer on the upper surface occupying a smaller area, typically 70-90%, to ensure uniform bending in one direction during thermal expansion, preventing distortion and improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the PCB is subjected to thermal expansion during the reflow process, then the light sources can be mounted on the PCB, but the PCB becomes distorted causing non-uniform image quality and mura at the plate boundary
Solution Approach 1:
The patent applies local quality by creating an asymmetric conductive layer structure where the first conductive layer on the lower surface has a different area than the second conductive layer on the upper surface. This local asymmetry in the conductive layer configuration creates controlled differential thermal expansion that compensates for the distortion caused by the reflow process, thereby maintaining PCB flatness while enabling light source mounting.
Solution Approach 2:
The patent utilizes parameter changes by modifying the area parameters of the conductive layers on the PCB. By adjusting the relative areas of the first and second conductive layers, the thermal expansion characteristics of the PCB are changed to achieve uniform bending behavior during the reflow process, preventing distortion and maintaining manufacturing precision.
2Manufacturing precision
If the PCB is allowed to bend uniformly in one direction due to thermal expansion, then distortion is prevented and image quality is improved, but the PCB structure becomes more complex with asymmetric conductive layers
Solution Approach 1:
The patent deliberately introduces asymmetry in the PCB structure by making the first conductive layer have a different area than the second conductive layer. This asymmetric design is not arbitrary but is specifically configured to create controlled uniform bending in one direction during thermal expansion, which prevents distortion and ensures uniform image quality across the display panel.
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 ensures uniform image quality by guiding the PCB to bend consistently, reducing mura at the plate boundaries and enhancing assembly stability.
Implementation Method 1
the PCB is convexly bent in a direction facing the display panel due to thermal expansion after a reflow process
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A display device according to one or more embodiments includes a display panel, a light source module disposed on a rear side of the display panel to generate light supplied to the display panel, and including a plurality of light sources emitting light, and a printed circuit board (PCB) on which the plurality of light sources is mounted, and a bottom chassis disposed on a rear side of the light source module and on which the light source module is assembled, wherein the PCB includes an insulating layer having a non-conductive, a first conductive layer formed on a lower surface of the insulating layer and having a conductive, and a second conductive layer formed on an upper surface of the insulating layer and having a conductive, and wherein the second conductive layer is formed to have a smaller area than the first conductive layer such that the PCB is convexly bent in a direction facing the display panel due to thermal expansion after a reflow process.