Flip Chip LED Package Alignment Tolerance via Segmented Bonding
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Solution Overview
Problem
Conventional flip chip package structures face reduced structural strength and increased failure risk due to increased alignment tolerance requirements, which compromise the bonding region between the light emitting diode chip and the package base.
Innovation Solution
The implementation of a flip chip package structure with a bonding layer on the package base and metal bonding pillars on the light emitting diode chip, where the distances between these elements are greater than the width of the pillars, ensuring proper alignment tolerance and maintaining a bonding region, thus preventing electrical shorts and enhancing structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the interval between the first electrode and the second electrode is increased to increase alignment tolerance, then the alignment error tolerance is improved, but the bonding region becomes smaller and the structural strength is reduced
Solution Approach 1:
The patent introduces bonding pillars as separate discrete elements distributed across the bonding region. These pillars segment the bonding function, allowing the electrodes to be spaced farther apart for alignment tolerance while the multiple distributed pillars collectively maintain structural strength through distributed bonding points.
2Manufacturing precision
If the interval between the first electrode and the second electrode is increased to increase alignment tolerance, then the alignment error tolerance is improved, but the bonding region becomes smaller making package failure more likely
Solution Approach 1:
The bonding pillars are strategically positioned in specific locations within the bonding region, creating local bonding strength at critical points. This local quality approach ensures reliability at key interfaces while allowing the overall electrode spacing to be increased for alignment tolerance.
3Manufacturing precision
If the bonding region is reduced due to increased electrode spacing, then the alignment tolerance is improved, but the structural strength is reduced
Solution Approach 1:
The bonding structure combines multiple materials including the bonding layer, bonding pillars, and insulating layers to create a composite bonding system. This composite approach allows the structure to maintain strength through material properties and configuration even when the overall bonding region is reduced due to increased electrode spacing.
Data Source
AI summary
A flip chip package structure includes a package base and a LED chip. The package base includes a first substrate, a first and a second electrodes disposed on the first substrate and a bonding layer disposed on the first substrate. The LED chip is flipped on the package base and includes an epitaxy layer, a third and a fourth electrodes disposed on the epitaxy layer and contacting the first and the second electrodes, a second insulating layer disposed between the third and the fourth electrodes, and a plurality of bonding pillars disposed on the second insulating layer and contacting the bonding layer. A minimum interval between the bonding layer, the first and the second electrodes and a minimum interval between the bonding pillars, the second and the third electrodes are larger than a width of each bonding pillar.