Reflective Bump Layer for Semiconductor Light Emitting Devices
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Solution Overview
Problem
Semiconductor light emitting devices face issues with light extraction efficiency due to light absorption by metallic bumps and complex, costly manufacturing processes in existing wafer level coating methods.
Innovation Solution
A method involving the formation of a reflective bump layer around a conductive bump core on semiconductor light emitting devices, using inkjet technology with light reflective materials like silver or aluminum, to reflect light without absorption, while simplifying the bump formation process by eliminating the need for additional photo processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a metallic bump is used to make electrical connection, then electrical connection is achieved, but light extraction efficiency is reduced due to light absorption
Solution Approach 1:
The patent applies a reflective layer on the metallic bump to convert the harmful light absorption effect into a beneficial light reflection effect. The reflective layer causes light that would have been absorbed by the metallic bump to be reflected back into the semiconductor device, thereby improving light extraction efficiency while maintaining the electrical connection function.
Solution Approach 2:
The patent creates a composite structure by combining a metallic bump material with a reflective coating material. This composite bump structure integrates both the electrical conductivity of the metal and the light reflection properties of the coating, resolving the contradiction between electrical connection and light extraction efficiency.
2Productivity
If a wafer level coating method is used to apply phosphor, then manufacturing efficiency is improved, but the manufacturing process becomes more complex and costly due to bump formation requirements
Solution Approach 1:
The patent merges the bump formation process with the phosphor application process by applying the reflective coating during the phosphor coating step. This integration eliminates the need for separate bump formation steps, reducing process complexity while maintaining wafer-level manufacturing efficiency.
Solution Approach 2:
The phosphor coating process is given multiple functions: it not only applies the phosphor material but also forms the reflective layer on the bumps. This multi-functionality reduces the overall process complexity while maintaining high manufacturing efficiency.
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
Improves light extraction efficiency by reflecting emitted light and simplifies the manufacturing process by eliminating the need for additional photo processes in forming the conductive bump.
Implementation Method 1
forming a reflective bump layer enclosing the bump core... allowing light emitted from the light emitting device to be reflected without being absorbed by a bump
Implementation Method 2
The reflective bump layer may be formed by dotting a light reflective material on the bump core in an inkjet scheme and firing the light reflective material dotted on the bump core
Implementation Method 3
dotting a light reflective material on the bump core in an inkjet scheme and firing the light reflective material dotted on the bump core
Data Source
AI summary
A method of manufacturing a semiconductor light emitting device includes forming a plurality of semiconductor light emitting devices on a substrate, the semiconductor light emitting devices having at least one electrode pad formed on upper surfaces thereof; forming a conductive bump by forming a bump core on the electrode pad of each of the semiconductor light emitting devices and forming a reflective bump layer enclosing the bump core; forming a resin encapsulating part containing a phosphor on the plurality of semiconductor light emitting devices to encompass the conductive bump; polishing the resin encapsulating part to expose the bump core of the conductive bump to an upper surface of the resin encapsulating part; and forming individual semiconductor light emitting devices by cutting the resin encapsulating part between the semiconductor light emitting devices.