Laser Diode Package With Internal Fluid Cooling Channels
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Solution Overview
Problem
Semiconductor laser diodes face thermal dissipation challenges due to high heat generation per unit area, leading to elevated junction temperatures and reduced efficiency and service life, especially when densely packed in arrays, where existing cooling mechanisms are inadequate and can cause corrosion and are costly.
Innovation Solution
A laser diode assembly with macrochannel cooling channels on both sides of the diode, utilizing electrically-insulating heat sinks with solder bonds and a substrate flow channel system for coolant passage, allowing for efficient heat transfer from both sides while keeping electrical and coolant paths separate to prevent corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If laser diodes are densely packed into arrays to generate required input power, then power output is improved, but heat extraction capability deteriorates due to decreased space for heat extraction
Solution Approach 1:
The patent transitions from single-sided cooling to dual-sided cooling by adding cooling channels on both the top and bottom surfaces of the heat sink. This dimensional expansion allows heat to be extracted from both sides of the laser diode array simultaneously, effectively doubling the heat extraction surface area and capability while maintaining the same array packing density.
2Loss of energy
If traditional pin fin heat exchangers are used with water cooling, then heat dissipation is achieved, but the distance between heat source and coolant causes elevated temperatures and poor performance
Solution Approach 1:
The patent extracts the water channels from the traditional distant pin fin heat exchanger and relocates them directly into the heat sink structure itself. This extraction and repositioning places the coolant channels in immediate proximity to the heat source, eliminating the thermal distance barrier and enabling efficient heat transfer from the laser diode junction to the coolant.
3Temperature
If macrochannel coolers are used with small water channels close to the heat source, then thermal transfer efficiency is improved, but electrical current and coolant reside in the same physical space causing corrosion
Solution Approach 1:
The patent segments the heat sink structure into distinct functional zones: an electrically conductive upper portion that contacts the laser diode for electrical current flow, and an electrically insulating lower portion containing the water channels. This segmentation creates a physical and electrical barrier that separates the electrical current path from the coolant, preventing corrosion while maintaining close thermal coupling through the conductive heat sink material.
4Reliability
If deionized water is used as coolant in macrochannel coolers, then corrosion is reduced, but all exposed parts must be made of glass, plastic, stainless steel, or gold-plated materials increasing cost
Solution Approach 1:
The heat sink structure performs multiple functions simultaneously: it provides electrical conduction for current flow to the laser diode, thermal conduction for heat transfer to the coolant, and electrical insulation to protect the coolant from corrosion. This multi-functionality allows the use of standard, cost-effective materials like copper or aluminum that would normally corrode in water, eliminating the need for expensive specialized materials.
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 solution provides superior thermal performance by maintaining lower junction temperatures, enhancing efficiency, and extending the service life of laser diodes while maintaining a compact design and avoiding corrosion issues.
Implementation Method 1
the coolant water flows and absorbs the heat
Implementation Method 2
efficient thermal transfer
Data Source
AI summary
A laser diode assembly has a laser diode. The laser diode has an emitting surface and a reflective surface opposing the emitting surface. The laser diode has first and second side surfaces between the emitting and reflective surfaces. A first electrically-insulating heat sink is attached to the first side surface of the laser diode via a first solder bond, and the first heat sink has a first cooling channel. A second electrically-insulating heat sink is attached to the second side surface of the laser diode via a second solder bond, and the second electrically-insulating heat sink has a second cooling channel. A substrate has a top side and a bottom side, and the top side being in communication with a first bottom side of the first electrically-insulating heat sink and a second bottom side of the second electrically-insulating heat sink. The substrate has a flow channel system for passing a coolant to the first cooling channel and the second cooling channel. A metallization layer is attached to the first electrically-insulating heat sink and the second electrically-insulating heat sink. The metallization layer is electrically coupled to the laser diode and conducts electrical current to the laser diode. The metallization layer is isolated from the coolant.