Gold-Silver Alloy Wire Recrystallization for LED Stress Relief
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Solution Overview
Problem
Gold-silver alloy wires used in light emitting devices are prone to breaking due to lower ductility compared to gold wires, which can lead to reliability issues depending on the device size and configuration.
Innovation Solution
A light emitting device design that includes a gold-silver alloy wire with a recrystallized region of 50 μm to 90 μm length and a sealing member with a specific height range to reduce stress on the wire, improving its durability and reducing the likelihood of breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a gold-silver alloy wire is used to increase reflectivity and output, then the reflectivity and light output are improved, but the ductility decreases and the wire becomes more prone to breaking
Solution Approach 1:
The patent changes the physical state and microstructure parameters of the wire by creating a recrystallized region with controlled length (50-90 μm) through thermal processing. This parameter change allows the wire to maintain the high reflectivity of gold-silver alloy while improving ductility and reducing breakage through the recrystallized structure
Solution Approach 2:
The patent creates a composite structure within the wire by forming a recrystallized region with different microstructural properties compared to the base wire material. This composite approach allows different regions of the wire to serve different functions: the recrystallized region provides ductility and stress resistance, while the base alloy provides reflectivity
2Reliability
If the sealing member height is reduced to minimize stress on the wire, then the wire breakage is reduced, but the space for wire routing and bonding is limited
Solution Approach 1:
The patent optimizes the sealing member height parameter to a specific range (90-230 μm from the top of the ball portion) that simultaneously satisfies both requirements: it provides sufficient space for wire routing and bonding operations while minimizing the stress and strain on the wire that would lead to breakage
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 effectively reduces the breakage of gold-silver alloy wires by managing stress through the recrystallized region and sealing member configuration, enhancing the reliability and longevity of the light emitting device.
Implementation Method 1
The wire includes a ball portion and a recrystallized region. The recrystallized region is provided on the ball portion and has a length in a range of 50 μm to 90 μm.
Implementation Method 2
The sealing member has a lower surface and an upper surface opposite to the lower surface and covers the light emitting element and the wire
Data Source
AI summary
A light emitting device includes an electrically conductive member, a light emitting element, a wire, and a sealing member. The wire contains gold and silver and connects the electrically conductive member and the light emitting element. The wire includes a ball portion and a recrystallized region. The ball portion is provided on an electrode of the light emitting element. The recrystallized region is provided on the ball portion and has a length in a range of 50 μm to 90 μm. The sealing member has a lower surface and an upper surface opposite to the lower surface and covers the light emitting element and the wire so that the lower surface faces the electrically conductive member and the light emitting element and so that a distance from a top of the ball portion to the upper surface of the sealing member is 90 μm to 230 μm.