LED Resin Sealing Structure for Light Reflection and Wire Bonding
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Solution Overview
Problem
Conventional semiconductor light-emitting devices face challenges in achieving high emission efficiency and miniaturization due to inefficient use of light emitted laterally and downwards from the LED element, particularly with gold plating affecting reflectance and wire bondability.
Innovation Solution
A semiconductor light-emitting device design featuring a printed-wiring board with an LED element sealed by a first resin body positioned slightly lower than the PN-junction and a second resin body, where the first resin body has a higher light reflectance and diffuse reflection effect, enhancing the reflection of laterally and downwards emitted light without increasing device width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If reflective films are provided on the entire surfaces of substrate electrodes to improve emission efficiency, then light reflectance increases, but wire bondability deteriorates
Solution Approach 1:
The patent applies local quality by providing reflective films only in specific regions where light reflection is needed, rather than covering the entire substrate electrode surface. The first resin body is positioned to cover the wire bonding areas, preventing reflective films from being deposited on these critical regions, thus maintaining wire bondability while still achieving light reflection in other areas to improve emission efficiency.
Solution Approach 2:
The patent segments the substrate electrode surface into different functional zones: areas covered by the first resin body where no reflective film is provided (for wire bonding), and exposed areas where reflective films are provided (for light reflection). This segmentation allows simultaneous optimization of both wire bondability and emission efficiency in different regions.
2Loss of energy
If device width is increased to widen reflective film area, then emission efficiency improves, but miniaturization is counteracted
Solution Approach 1:
The patent transitions from a two-dimensional approach (expanding reflective film area horizontally by increasing device width) to a three-dimensional approach by introducing the first resin body that vertically covers the wire bonding areas. This allows the reflective films to be effectively widened in the horizontal direction without increasing the overall device width, as the resin body protects the underlying electrode regions.
Solution Approach 2:
The first resin body is positioned within the device structure, nesting the wire bonding protection function within the overall device footprint. This allows the reflective films to extend further horizontally under the resin body's protective coverage, improving light reflection efficiency without proportionally increasing the device's external dimensions.
3Reliability
If gold plating is applied to substrate electrodes for wire bondability, then wire bonding reliability improves, but light reflectance decreases
Solution Approach 1:
The patent applies local quality by using gold plating only in the regions covered by the first resin body where wire bonding occurs, rather than plating the entire substrate electrode. This localized gold plating maintains excellent wire bondability in the bonding areas while allowing other regions to use reflective materials with higher light reflectance properties.
Solution Approach 2:
The substrate electrode is segmented into gold-plated regions (under the first resin body for wire bonding) and non-gold-plated regions (exposed areas for light reflection). This segmentation allows optimization of wire bondability in bonding areas and light reflectance in optical areas simultaneously.
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 configuration increases light reflectance, enabling a semiconductor light-emitting device with high emission efficiency and small size, allowing for reduced number of LED elements and cost savings in miniaturization.
Implementation Method 1
the first resin body has a higher light reflectance and diffuse reflection effect, enhancing the reflection of laterally and downwards emitted light
Data Source
AI summary
A semiconductor light-emitting device includes: a printed-wiring board; a light-emitting diode element mounted on the printed-wiring board; and a resin body for sealing the light-emitting diode element. The resin body is composed of a first resin body arranged around the light-emitting diode element, and a second resin body, which seals the light-emitting diode and the first resin body. An upper edge of the first resin body disposed at a lower position of the PN-junction is configured to be at least on or beyond an imaginary line that connects the PN-junction and a lower edge of the second resin body.