LED Lead Frame Reflection Layer Coverage for Higher Luminous Efficiency
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Solution Overview
Problem
The luminous efficiency of semiconductor light-emitting devices is reduced due to partial absorption of light by the lead frame, as the reflection layer on the lead frame's trench-defining sidewall does not cover the entire surface effectively.
Innovation Solution
A semiconductor light-emitting device design that includes a lead frame with a side body having an inner surface covered by a reflection layer, where the reflection layer's height is not smaller than 90% of the side body's height, ensuring effective light reflection and minimizing absorption by the lead frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a reflection layer is formed on the trench-defining sidewall of the lead frame, then light absorption by the lead frame is reduced, but the reflection layer only covers a part of the sidewall (height not greater than 60% of sidewall height), so light absorption is not sufficiently prevented
Solution Approach 1:
The patent changes the height parameter of the reflection layer from the conventional not greater than 60% of sidewall height to not smaller than 90% of sidewall height. This parameter change ensures that the reflection layer covers substantially the entire trench-defining sidewall, effectively preventing light absorption by the lead frame while maintaining manufacturing feasibility.
2Loss of energy
If the reflection layer covers the entire sidewall (height >= 90% of sidewall height), then light absorption is significantly reduced, but the manufacturing precision and uniformity of the reflection layer formation become more challenging
Solution Approach 1:
The patent introduces a curved portion in the trench-defining sidewall with a specific slope range (tan 40° to tan 60° at 50% height of curved portion). This curvature design optimizes the surface for reflection layer formation, ensuring uniform coverage up to 90% or more of the sidewall height while facilitating the manufacturing process through controlled geometric features.
3Ease of manufacture
If the trench-defining sidewall has a large and uniform slope, then the structure is simple to manufacture, but the reflection layer can only cover a part of the sidewall and has insufficient height coverage
Solution Approach 1:
The patent replaces the large and uniform slope with a curved portion that has a gradually increasing slope from bottom to top, with the slope at 50% height ranging from tan 40° to tan 60°. This curved design maintains manufacturing simplicity while enabling the reflection layer to achieve comprehensive coverage of at least 90% of the sidewall height, resolving the contradiction between ease of manufacture and coverage precision.
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 enhanced reflection layer coverage significantly reduces light absorption by the lead frame, thereby improving the luminous efficiency of the semiconductor light-emitting device.
Implementation Method 1
a reflection layer is generally formed on a trench-defining sidewall of the lead frame... light emitted from the light-emitting element is partially absorbed by the lead frame, thereby lowering the luminous efficiency
Data Source
AI summary
A semiconductor light-emitting device includes a lead frame, a light-emitting element, and a reflection layer. The lead frame includes a main body and a side body extending upwardly from the main body. The main body and the side body cooperatively define a receiving space. The side body has an inner surface facing the receiving space, and a first height measured from a surface of the main body. The light-emitting element is disposed on the surface of the main body and in the receiving space. The reflection layer covers at least a part of the inner surface, and has a second height measured from the surface of the main body. The second height is not smaller than 90% of the first height.