Mini LED Circuit Substrate Layout for Solder Joint Detection
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Solution Overview
Problem
Large light-emitting substrates with numerous Mini LEDs face challenges in precise soldering detection, leading to defects due to poor soldering of individual Mini LEDs, which affects the stability and quality of the substrate.
Innovation Solution
A circuit substrate design with conductive patterns that include a body portion and extension portions, where the extension portions protrude from the body portions, allowing for accurate detection of soldering quality by exposing a limited area for solder wetting, and a manufacturing method involving a solder flux layer for improved precision and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the conductive pattern area is increased to ensure complete coverage by the chip, then the soldering coverage is improved, but the detection capability is lost because no portion remains exposed for observation
Solution Approach 1:
The conductive pattern is divided into two functional segments: a first portion covered by the chip for soldering and a second portion extending beyond the chip for detection. This segmentation allows both soldering coverage and detection capability to coexist by assigning different functions to different parts of the same conductive pattern structure.
Solution Approach 2:
Different portions of the conductive pattern have different functional qualities: the first portion (under the chip) provides soldering surface, while the second portion (extending outward) provides detection surface. This local differentiation of function resolves the contradiction by optimizing each portion for its specific purpose rather than requiring the entire pattern to serve both functions equally.
2Manufacturing precision
If the total area of conductive patterns is increased to ensure complete soldering coverage, then the soldering quality is improved, but the chip area is exceeded causing misalignment and affecting detection precision
Solution Approach 1:
The conductive pattern area is segmented into a first portion (area S1) that is covered by the chip for soldering and a second portion (area S2) that extends beyond the chip for detection. This segmentation ensures that the total area can be sufficiently large for complete soldering coverage while maintaining a controlled extension for precise detection, preventing misalignment issues.
Solution Approach 2:
The conductive pattern extends slightly beyond the chip boundary (excessive action) but only to the extent necessary for detection (partial action). The extension area is carefully controlled to provide sufficient detection capability without excessive overlap that would cause misalignment, achieving the optimal balance between coverage and precision.
3Reliability
If the conductive pattern is completely covered by the chip, then the soldering connection is ensured, but the soldering quality cannot be detected as no exposed portion remains
Solution Approach 1:
The conductive pattern is segmented into a first portion covered by the chip that ensures soldering connection reliability, and a second portion extending beyond the chip that enables soldering quality detection. This segmentation simultaneously achieves both complete connection coverage and detectable exposure.
Solution Approach 2:
The second portion of the conductive pattern acts as an intermediary element that transfers the soldering quality information from the hidden first portion to the observable external region. By detecting the soldering state of the exposed second portion, the quality of the soldered first portion can be inferred without direct observation of the solder joint itself.
4Measurement precision
If the conductive pattern area is reduced to fit within the chip area, then the alignment precision is improved, but the soldering coverage becomes insufficient leading to poor soldering quality
Solution Approach 1:
The conductive pattern is segmented into a first portion within the chip area that ensures precise alignment and a second portion extending beyond the chip area that provides additional soldering coverage. This segmentation allows the pattern to benefit from both the alignment precision of being chip-bound and the coverage advantage of extended area.
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 design enables effective soldering and detection of each Mini LED, enhancing the stability and quality of the light-emitting substrate by ensuring proper soldering and reducing defects, while the manufacturing method improves precision and extends stencil life.
Implementation Method 1
The conductive pattern is connected to at least one of the bumps on the chip through the solder flux layer
Implementation Method 2
allowing for accurate detection of soldering quality by exposing a limited area for solder wetting
Data Source
AI summary
A circuit substrate includes a base substrate, traces, a protective layer, and an electronic device. The traces are provided on the base substrate. The protective layer is provided on the traces, and has openings each exposing a portion of a trace, the portion serving as a conductive pattern. The electronic device includes a chip and multiple bumps provided on the chip. The conductive pattern is connected to at least one of the bumps on the chip. The conductive pattern includes a first portion and a second portion connected to each other. An orthographic projection of the chip on the base substrate covers an orthographic projection of the first portion on the base substrate, and is non-overlapping with an orthographic projection of the second portion on the base substrate. The total area of conductive patterns connected to the chip is less than an area of the chip.