Flip Chip Light Extraction via Direct Substrate Bonding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor light emitting devices using flip chips often experience light intensity loss due to bonding materials and improper bonding states, especially during the SMT process, which affects the efficiency of light extraction and device performance.
Innovation Solution
A semiconductor light emitting device design where the electrodes of the flip chip are directly bonded to an external substrate, eliminating the need for bonding with lead frames, and incorporating features like reflective substances, reflecting layers, and reinforcement members to enhance light extraction and stability, while allowing for direct electrical connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bonding materials are used to bond flip chip to lead frames, then electrical connection is achieved, but light intensity is lost
Solution Approach 1:
The patent removes the bonding material layer from the optical path between the light-emitting chip and the external substrate. By directly bonding the chip to the substrate without intervening bonding materials, light can escape without being absorbed or scattered by bonding materials, thus eliminating light intensity loss while maintaining electrical connection through direct contact.
Solution Approach 2:
The patent introduces a reflective layer as an intermediary between the chip and the substrate. This reflective layer serves dual purposes: it provides a bonding interface for electrical connection and simultaneously reflects light that would otherwise be lost, converting harmful light absorption into beneficial light redirection.
2Reliability
If bonding materials are used for bonding flip chip, then electrical connection is established, but bonding state becomes improper
Solution Approach 1:
The patent eliminates bonding materials from the bonding process, reducing the number of process steps and potential failure points. Direct bonding between the chip and substrate simplifies the manufacturing process and improves bonding state precision by removing variables associated with bonding material selection, application, and curing.
3Reliability
If lead frames are used for bonding flip chip, then electrical connection is achieved, but light extraction efficiency decreases
Solution Approach 1:
The patent removes the lead frame structure from the device architecture, allowing light to escape directly from the chip surface without being blocked or scattered by lead frame structures. This extraction of the lead frame eliminates its harmful effect on light extraction efficiency while electrical connection is maintained through direct chip-to-substrate bonding.
Solution Approach 2:
The patent changes the bonding configuration from a lateral/planar arrangement (chip bonded to lead frames) to a vertical arrangement (chip bonded directly to substrate). This dimensional change allows light to escape in multiple directions including laterally, improving light extraction efficiency while maintaining electrical connection.
4Device complexity
If conventional bonding structure is used, then device assembly is simplified, but light loss occurs
Solution Approach 1:
The patent merges the electrical connection function and the light extraction function into a single integrated structure. The direct bonding interface between chip and substrate simultaneously provides both electrical connection and an optical path for light escape, eliminating the need for separate bonding materials that would compromise light extraction.
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 design improves light extraction efficiency by preventing light loss and ensuring stable bonding, allowing for enhanced performance and efficiency in emitting light from multiple directions, including lateral faces.
Implementation Method 1
an active layer 40 adapted to generate light by electron-hole recombination
Implementation Method 2
Three-layered electrode films 90, 91 and 92 adapted to reflect light towards the growth substrate 10
Data Source
AI summary
Disclosed is a semiconductor light emitting device, including: a body, which has a bottom part with at least one hole formed therein, a side wall, and a cavity defined by the bottom part and the side wall; a semiconductor light emitting chip, which is placed in each hole and includes plural semiconductor layers adapted to generate light by electron-hole recombination and electrodes electrically connected to the plural semiconductor layers; and an encapsulating member provided at least to the cavity to cover the semiconductor light emitting chip, in which the electrodes of the semiconductor light emitting chip are exposed towards the lower face of the bottom part of the body.