LED Metal Bulk Wafer Level Package Thermal Stress
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Light emitting diodes (LEDs) face issues with heat dissipation and thermal stress, leading to reduced internal quantum efficiency and reliability due to the separation of semiconductor layers from their growth substrates, which can cause damage.
Innovation Solution
A light emitting device with a metal bulk structure is fabricated using a wafer level package process, featuring metal bulks with coefficients of thermal expansion similar to the semiconductor layers to enhance heat dissipation and reduce stress, thereby preventing damage and improving reliability and luminous efficacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heat dissipation pad is employed to solve heat dissipation issues, then heat dissipation is improved, but thermal stress damage to the light emitting diode worsens
Solution Approach 1:
The patent changes the material parameter of the heat dissipation structure by using a metal bulk with a coefficient of thermal expansion matched to the semiconductor layer. This parameter change allows effective heat dissipation while minimizing thermal stress damage, resolving the contradiction between heat dissipation improvement and reliability maintenance.
Solution Approach 2:
The patent employs a composite structure consisting of a metal bulk integrated with the semiconductor layer. This composite material approach combines the high thermal conductivity of metal with the semiconductor properties, achieving both effective heat dissipation and reduced thermal stress through proper material selection and integration.
2Temperature
If the growth substrate is separated from the semiconductor layers to improve heat dissipation, then heat management is improved, but damage to the thin semiconductor layer worsens
Solution Approach 1:
The patent applies preliminary action by forming a metal bulk structure before separating the growth substrate. This pre-formed metal bulk provides mechanical support and stress relief during the separation process, enabling safe substrate removal while maintaining semiconductor layer integrity and achieving improved heat management.
Solution Approach 2:
The metal bulk acts as an intermediary between the growth substrate and the final device structure. During the separation process, the metal bulk mediates the mechanical stresses, protecting the thin semiconductor layer while enabling the removal of the growth substrate for improved heat management.
3Temperature
If a metal bulk with mismatched thermal expansion coefficient is used, then heat dissipation capability is improved, but thermal stress on the semiconductor layer worsens
Solution Approach 1:
The patent fundamentally changes the thermal expansion parameter by selecting a metal material whose coefficient of thermal expansion is substantially matched to the semiconductor layer. This parameter matching resolves the contradiction by enabling effective heat dissipation through the metal bulk while minimizing differential thermal stress that would otherwise damage the semiconductor structure.
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
The metal bulk structure effectively dissipates heat and reduces thermal stress on the semiconductor layers, enhancing the reliability and luminous efficacy of the light emitting device by maintaining a low difference in thermal expansion coefficients.
Implementation Method 1
The metal bulk structure effectively dissipates heat
Implementation Method 2
a difference in coefficients of thermal expansion represented by the following Equation 1 may be 20% or less
Data Source
AI summary
A light emitting device and method of fabricating the same using a wafer level package process are disclosed. The light emitting device has improved heat dissipation to prevent damage by heat, thereby achieving improvement in reliability and luminous efficacy. In addition, the light emitting device has a small difference in coefficients of thermal expansion and thus can reduce stress applied to a light emitting structure to prevent damage to the light emitting structure, thereby achieving improvement in reliability and luminous efficacy.