Optical Semiconductor Bonding Structure for Solder-Free Heat Dissipation
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Solution Overview
Problem
Bottom emission type semiconductor laser elements face issues with solder creep leading to short circuits and reduced laser light oscillation due to contamination and increased thermal resistance, affecting heat dissipation and output power.
Innovation Solution
The optical semiconductor device employs diffusion bonding between a mounting member and an optical semiconductor element using Au layers, eliminating the need for solder and positioning the light emitting part closer to the mounting member for enhanced heat dissipation, while forming an insulating film to control optical reflectivity and reduce thermal and electric resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder is used to bond the semiconductor laser element to the mounting member, then bonding is achieved, but the solder creeps up on the end face causing short circuits and contamination in the light emitting part
Solution Approach 1:
The patent extracts and eliminates the solder material from the bonding process. Instead of using solder to bond the semiconductor laser element to the mounting member, the invention uses a eutectic alloy layer formed by diffusion bonding between Au layers. This removes the harmful solder creep phenomenon entirely while maintaining effective bonding.
Solution Approach 2:
The patent introduces a eutectic alloy layer as an intermediary bonding interface between the semiconductor laser element and mounting member. This eutectic layer, formed through diffusion bonding of Au layers at controlled temperatures, serves as a mediator that provides reliable bonding without the harmful effects of traditional solder, preventing both short circuits and contamination.
2Temperature
If the light emitting part is positioned nearer to the bottom for better heat dissipation, then heat dissipation capability is improved, but the risk of solder contamination increases
Solution Approach 1:
The patent removes solder from the bonding process entirely, replacing it with a eutectic alloy bonding system. This elimination allows the light emitting part to be positioned closer to the mounting member for optimal heat dissipation without any risk of solder contamination, as the eutectic alloy does not exhibit harmful creep behavior.
3Reliability
If multiple bonding layers are used to prevent contamination, then reliability improves, but manufacturing complexity increases
Solution Approach 1:
The patent employs composite material structure with multiple functional layers: Au layers on the semiconductor element and mounting member, a eutectic alloy layer formed through diffusion bonding, and an insulating film. This composite structure provides both contamination prevention and reliable bonding while maintaining manufacturing feasibility through a integrated diffusion bonding process.
4Object-generated harmful factors
If diffusion bonding is used instead of solder, then solder creep is eliminated, but bonding process complexity increases
Solution Approach 1:
The patent controls the bonding process by adjusting parameters including heating temperature (maintained at or above the eutectic point), heating time, and atmospheric conditions (inert gas or vacuum). These parameter controls enable diffusion bonding to proceed reliably without solder creep, achieving both elimination of harmful effects and manufacturing feasibility.
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 approach prevents contamination, improves heat dissipation, reduces power consumption, and enhances the reliability and quality of the semiconductor device by minimizing thermal and electric resistance fluctuations, thus ensuring stable laser light oscillation and reduced manufacturing costs.
Implementation Method 1
heating under vacuum, the multiple sets of the mounting members and the optical semiconductor elements clamped using the jig, thereby to bond together the mounting member and the optical semiconductor element in each of the multiple sets, by diffusion bonding between the first bonding member or bonding layer and the second bonding member or bonding layer
Data Source
AI summary
Provided here are: a mounting member having a front surface on which a diffusion bonding layer is formed; an optical semiconductor element provided with a light emitting part therein, and having a rear surface on which a diffusion bonding layer is formed; and an electrode layer formed from the diffusion bonding layer and the diffusion bonding layer by diffusion bonding therebetween; wherein, in the optical semiconductor element, the light emitting part is provided near a side of the optical semiconductor element so as to be displaced toward the mounting member. This configuration not only makes unnecessary the use of a solder, an Ag paste and the like to thereby prevent the light emitting part in the optical semiconductor element from being contaminated by the solder, but also allows the light emitting part to be closer to the mounting member-side to thereby achieve improvement in heat-dissipation capability.