LED Chip Electrode Layout and Reflective Layers for Lower Light Loss
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Solution Overview
Problem
Conventional light-emitting devices face issues such as light being blocked or absorbed by electrodes, adverse effects during wire bonding, and light reflection leading to absorption by the substrate or lead frame, which affect efficiency and manufacturing complexity.
Innovation Solution
The design includes a lead frame with a mounting region, wiring bonding regions, and an LED chip with electrodes positioned on the substrate's surface at opposite sides of the semiconductor light-emitting unit, and the use of reflective layers to manage light emission and reflection, ensuring minimal absorption and improved efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If electrodes are disposed on the upper surface of the semiconductor light-emitting unit, then wire bonding can be performed, but light emitted from the LED chip is blocked or absorbed by the electrodes
Solution Approach 1:
The patent moves the electrodes from the upper surface (2D plane) to the lower surface of the semiconductor light-emitting unit, changing their spatial dimension. This allows light to escape from the upper surface without being blocked by electrodes, while wire bonding is performed from the lower surface, effectively separating the light emission path and electrode connection path into different spatial dimensions.
2Illumination intensity
If light is reflected by the surrounding wall or encapsulant, then light distribution is improved, but reflected light enters the substrate and is absorbed
Solution Approach 1:
The patent introduces a reflective layer as an intermediary between the substrate and the encapsulant/surrounding wall. This reflective layer intercepts light that would otherwise enter the substrate and be absorbed, reflecting it back into the light-emitting unit to enhance light distribution while preventing energy loss through substrate absorption.
3Loss of energy
If a flip-chip structure is used, then light is not blocked by electrodes, but specialized equipment and alignment steps are required
Solution Approach 1:
The patent inverts the conventional wire bonding approach by performing wire bonding from the lower surface of the LED chip rather than from the upper surface. This inversion allows the electrodes to be positioned on the lower surface where they cannot block light emission, while still enabling standard wire bonding processes to be used without requiring specialized flip-chip equipment or complex alignment steps.
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 enhances light-emitting efficiency by preventing direct blocking by electrodes and optimizing light reflection, reducing absorption by the substrate or lead frame, and simplifies the manufacturing process by eliminating the need for specialized alignment equipment.
Implementation Method 1
light-reflective layers are used to direct reflected light back into the substrate, enhancing light output
Data Source
AI summary
A light-emitting device includes a lead frame, a light-emitting diode (LED) chip, and an encapsulant. The LED chip is disposed on the lead frame, and includes a substrate, a semiconductor light-emitting unit disposed on a surface of the substrate, and a first electrode and a second electrode, which are disposed on the surface of the substrate, and which are located outwardly of the semiconductor light-emitting unit. The first and second electrodes are electrically connected to a lower surface of the semiconductor light-emitting unit, and are respectively connected to a first wiring bonding region and a second wiring bonding region on the lead frame. The encapsulant encapsulates the LED chip.