Semiconductor Light Emitting Device Wafer Mounting
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Solution Overview
Problem
Conventional semiconductor light emitting devices with flip-chip mount on a circuit substrate face issues such as underfill expansion and contraction during reflow, leading to potential semiconductor layer damage, and are not suitable for mass production due to time-consuming mounting processes. Additionally, light emission from side surfaces is not utilized, and the exposed bottom surface may have pinholes in the protective film, affecting reliability.
Innovation Solution
A method involving an adhesive sheet to array semiconductor light emitting elements with electrodes facing down, filling side surfaces with a resin, creating a wafer, and overlaying it on a large circuit substrate for equal planar sizes, ensuring a gap between the elements and substrate, and using a phosphor layer and reflecting member to direct light emission towards the top surface, while covering the bottom surface with a resin to prevent pinhole issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If one circuit substrate is picked up and one LED die is mounted manually, then precise mounting is achieved, but the process is time-consuming and not suitable for mass production
Solution Approach 1:
The patent combines multiple LED dies into a wafer structure where they are arranged in an array and electrically connected through a single circuit substrate. This allows simultaneous mounting of multiple dies in one operation, achieving both precision and mass production efficiency
Solution Approach 2:
The circuit substrate is designed with multi-functional capability to handle and connect multiple LED dies simultaneously. The substrate serves as a common platform for mounting, electrical connection, and structural support for the entire wafer, enabling scalable production
2Loss of energy
If light is emitted from the side surface of the LED die, then total light output is increased, but the light cannot be utilized and must be redirected
Solution Approach 1:
The patent redirects light emission from the side surface (lateral dimension) to the top surface (vertical dimension) by inverting the LED die during mounting. This dimensional transformation allows the active light-emitting surface to face upward, improving light utilization without requiring complex redirecting structures
3Device complexity
If the bottom surface of the LED die is exposed, then the structure is simplified, but pinholes in the protective film reduce reliability
Solution Approach 1:
The patent applies a resin coating to the side surfaces of the LED die before mounting, creating a protective barrier that prevents pinhole formation and contamination on the bottom surface. This preventive measure ensures reliability while maintaining structural simplicity
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 method prevents underfill-related issues, enables mass production by ensuring equal planar sizes, and improves reliability by directing light emission only towards the top surface and covering the bottom surface to prevent pinhole-related problems, enhancing the semiconductor light emitting device's performance.
Implementation Method 1
a phosphor layer that converts the wavelength of light emitted from the semiconductor light emitting element
Data Source
AI summary
A method for manufacturing a semiconductor light emitting device comprises steps of: arraying semiconductor light emitting elements on an adhesive sheet so that electrodes of the semiconductor light emitting elements face the adhesive sheet; forming a wafer thereof by filling spaces between side surfaces of the semiconductor light emitting elements arrayed on the adhesive sheet with a resin and curing the resin; peeling the adhesive sheet from the wafer; overlaying the wafer on a substrate from which numerous substrates can be obtained by subdivision into individual pieces and the electrodes of the semiconductor light emitting elements and electrodes formed on the large circuit substrate are joined; and subdividing the large circuit substrate, to which the wafer has been joined, into individual semiconductor light emitting devices so that the planar size of the semiconductor light emitting element and that of the circuit substrate are roughly equal.