Semiconductor Laser Submount Bonding for Low Thermal Resistance
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Solution Overview
Problem
Existing semiconductor laser packaging structures face challenges in achieving high heat dissipation performance and robustness against temperature cycles, leading to increased thermal resistance and decreased optical output power.
Innovation Solution
The proposed semiconductor light-emitting apparatus includes a substrate, a submount with a spacer region, and a semiconductor laser bonded with AuSn solder. The submount is bonded to the substrate using a thicker second bonding material, which is controlled to maintain a thickness that suppresses crack occurrence and thermal resistance increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a packaging structure with AuSn solder and submount is used to connect semiconductor laser to heat dissipation block, then heat dissipation performance is improved, but thermal strain resistance during temperature cycles deteriorates
Solution Approach 1:
The patent changes the physical state of the bonding material from solid (conventional AuSn solder) to liquid (low-melting-point alloy), which fundamentally alters the mechanism of thermal strain resistance while maintaining heat dissipation performance. The liquid state allows continuous adjustment and flow to accommodate thermal expansion differences.
Solution Approach 2:
The patent uses a composite structure combining the semiconductor laser chip, submount, liquid bonding material, and heat dissipation block. The liquid bonding material acts as a composite interface that simultaneously provides thermal conduction and mechanical compliance to handle thermal strain.
2Reliability
If bonding material thickness is increased to suppress crack occurrence, then thermal strain resistance is improved, but thermal resistance increases
Solution Approach 1:
The patent changes the bonding material from solid to liquid state, which allows achieving crack suppression through viscosity and flow properties rather than thickness. The liquid bonding material can accommodate thermal strain through its fluid nature without requiring increased thickness, thus avoiding thermal resistance increase.
3Strength
If conventional solid bonding material is used to bond submount to substrate, then bonding strength is achieved, but thermal strain accommodation deteriorates
Solution Approach 1:
The patent fundamentally changes the bonding material from solid to liquid state, transforming the mechanism of strength provision from rigid mechanical bonding to fluid adhesion and capillary forces. This liquid state enables simultaneous achievement of bonding strength and thermal strain accommodation through its flow and deformation capabilities.
Solution Approach 2:
The liquid bonding material serves as an intermediary between the submount and substrate, providing a compliant interface that mediates thermal strain while maintaining bonding. Its liquid nature allows it to act as a shock absorber and stress distributor across the bonding interface.
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 the semiconductor light-emitting apparatus' ability to withstand thermal strain from temperature cycles while maintaining low thermal resistance, ensuring stable optical output power even after repeated temperature cycle tests.
Implementation Method 1
optical semiconductor device chip 1010 disclosed in PTL 1 is connected to submount 1020 with AuSn solder 1041 interposed therebetween. Submount 1020 is connected to metal heat dissipation block 1030 with AuSn solder 1042 interposed therebetween.
Implementation Method 2
to efficiently transfer heat generated in the semiconductor laser to the outside, a packaging structure including the semiconductor laser should have high heat dissipation performance.
Data Source
AI summary
Semiconductor light-emitting apparatus includes substrate, submount above substrate, and semiconductor laser above submount. Semiconductor laser and submount are bonded to each other with first bonding material. Substrate and submount are bonded to each other with second bonding material. Submount has first region and second region near substrate, first region being a region on which spacer is disposed, and second region being a region without spacer. Submount is bonded to substrate by covering at least a portion of second region with second bonding material.