Diode Laser Assembly with Deformable Metallic Layer
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Solution Overview
Problem
Existing methods for producing diode lasers face challenges with mechanical stresses, unevenness, and material migration, which can lead to overheating and failure, particularly at the p-side contact surface, and are not tolerant of deviations in the flatness of the laser bar and heat-conducting bodies.
Innovation Solution
A method involving a laser bar with p- and n-contact areas, a heat-conducting body, and a cover with a second metallic layer having a nub structure, where the laser bar is arranged between the heat-conducting body and the cover, with the metallic layers forming a mechanical connection that compensates for unevenness and allows for plastic deformation, ensuring a stable and stress-free assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a soldering process is used to join the laser bar to heat-conducting bodies, then current-carrying capacity is improved, but mechanical stresses are introduced that impair electro-optical properties
Solution Approach 1:
The patent replaces the soldering process (thermal/chemical joining) with a mechanical clamping system using a cover and screw connection. This eliminates the thermal stresses and material migration associated with soldering while maintaining electrical contact through the metallic layers and bonding wires.
Solution Approach 2:
The patent introduces metallic layers (first and second metallic layers) as intermediary elements between the laser bar contact surfaces and the heat-conducting bodies. These layers provide both electrical conductivity and mechanical compliance, allowing for stress-free electrical connection while maintaining good thermal contact.
2Quantity of substance
If uniform metallic layers are used between contact surfaces, then electrical connection is improved, but manufacturing precision requirements become excessively high
Solution Approach 1:
The patent employs metallic layers with locally varied thickness rather than uniform thickness throughout. The layers are thicker in certain regions to compensate for surface unevenness and provide adequate material for reliable electrical contact, while being thinner in other regions. This local variation in quality allows tolerance of μm-range deviations in surface flatness.
Solution Approach 2:
The patent changes the thickness parameter of the metallic layers to accommodate variations in contact surface flatness. By adjusting the layer thickness locally, the system maintains reliable electrical connection even when surface deviations reach the micrometer range, thereby reducing manufacturing precision requirements.
3Ease of manufacture
If indium layers are used to create material bonds, then assembly without soldering is achieved, but material migration occurs leading to laser failure
Solution Approach 1:
The patent divides the metallic layer into multiple segments or regions with different thicknesses rather than using a continuous uniform layer. This segmentation prevents excessive material flow and migration while still providing adequate material for electrical contact and bonding, thereby eliminating the reliability issues associated with continuous indium layers.
Solution Approach 2:
The patent uses the metallic layers as intermediary elements that mediate between the laser bar and heat-conducting bodies without requiring the layers to migrate or flow excessively. The layers provide a stable, non-migrating interface that maintains reliable electrical and thermal contact throughout operation.
4Ease of manufacture
If bonding wires are used for n-side contact, then assembly simplicity is maintained, but current-carrying capacity is limited
Solution Approach 1:
The patent merges the functions of electrical contact and current conduction by using a solid cover structure with metallic layers that provide both the bonding interface and the current-carrying path. This combines the simplicity of bonding-wire assembly with the high current capacity of solid electrical connections.
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 method enables the production of diode lasers with improved flatness, reduced smile value, and enhanced electro-optical properties, including high polarization and uniform near-field distribution of laser radiation, while avoiding material migration and mechanical stress, thus increasing yield and performance.
Implementation Method 1
the second metallic layer at least in sections in the area of the raised points having a plastic undergoes deformation
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a method for the production of a diode laser having a laser bar (3), wherein a metal layer (17) having raised areas (19) is used which is located between the n-side (9) of the laser bar and the cover (14). The metal layer can be plastically deformed during installation without volume compression in the solid physical state. As a result the laser module can be reliably installed and a slight deviation (smile value) of the emitters from a centre line is achieved.