LED Package Terminal Orientation for Stress Reduction
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Solution Overview
Problem
Flip chip LED packages face damage due to stress concentration on the substrate caused by differences in thermal expansion coefficients between the bump and the module, leading to potential diode damage from cracks.
Innovation Solution
The LED package design includes a sapphire substrate with a stress concentration area where the major axis of the external connection terminal is perpendicular to the (10-10) plane, reducing the likelihood of crack spreading and minimizing diode damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a flip chip LED package structure is used to improve heat dissipation, then heat emission is enhanced, but stress concentration occurs on the substrate due to thermal expansion coefficient differences
Solution Approach 1:
The patent applies local quality by orienting the external connection terminal at a specific angle (30-60 degrees relative to the crystal direction) to create non-uniform stress distribution. This localized structural arrangement directs stress away from critical diode areas while maintaining overall heat dissipation performance through the bump structure.
Solution Approach 2:
The patent changes the orientation parameter of the external connection terminal relative to the substrate crystal structure. By adjusting this angular parameter to 30-60 degrees, the stress distribution pattern is modified to reduce concentration at critical points, thereby preventing diode damage while preserving thermal conduction pathways.
2Reliability
If the external connection terminal is oriented perpendicular to the (10-10) plane, then crack spreading is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent defines a specific angular range (30-60 degrees) for the external connection terminal orientation rather than a single fixed angle. This parameter range provides manufacturing tolerance while still achieving the goal of directing stress away from diode areas, thus balancing crack resistance with manufacturability.
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
This design effectively reduces the occurrence of diode damage by directing stress away from critical areas, enhancing the durability and manufacturing efficiency of the LED package.
Implementation Method 1
the substrate transmits light, and light generated by the light-emitting structure is emitted in a direction toward the substrate
Implementation Method 2
stress may be concentrated on a substrate of the flip chip LED package due to a difference between respective thermal expansion coefficients of the bump and the module
Implementation Method 3
stress may be concentrated on a substrate of the flip chip LED package due to a difference between respective thermal expansion coefficients of the bump and the module
Implementation Method 4
An LED package is a semiconductor device that is capable of generating variously colored light rays by utilizing a recombination of electrons and holes, when current is applied
Implementation Method 5
heat generated during operation is directly emitted to the module via the bump with excellent heat conductivity
Data Source
AI summary
An LED package includes a substrate, a light-emitting structure provided on the substrate, an electrode structure provided on the light-emitting structure, and an external connection terminal provided on the electrode structure, the external connection terminal comprising a major axis and a minor axis. The major axis of the external connection terminal is perpendicular to a cleaving plane of the substrate.