Ceramic Package Penetrating Electrodes for Laser Heat Dissipation
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Solution Overview
Problem
The existing light emitting apparatuses using surface emitting lasers face issues with heat dissipation, leading to increased temperature, reduced emission efficiency, and potential damage due to thermal expansion differences between ceramic packages and printed boards, along with misalignment of light emission direction.
Innovation Solution
The solution involves a ceramic package design with a back-surface heat-dissipating electrode and penetrating electrodes that enhance heat dissipation and prevent thermal expansion-induced damage, while maintaining the alignment of light emission by spacing penetrating electrodes to minimize surface irregularities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If surface emitting laser elements are arrayed 2-dimensionally to achieve high-density integration, then light output capability is improved, but heat generation increases and heat dissipation becomes insufficient
Solution Approach 1:
The patent introduces a third dimension by forming penetrating electrodes that extend vertically through the ceramic package substrate, creating a three-dimensional heat dissipation pathway. This allows heat to be conducted from the mount portion through the substrate thickness to the back surface, adding a vertical heat escape route that complements the traditional planar heat dissipation path.
Solution Approach 2:
The penetrating electrodes act as thermal intermediaries, bridging the heat transfer path between the mount portion where lasers are mounted and the back surface of the ceramic package. These electrodes serve as dedicated thermal conduits that facilitate efficient heat flow from the heat-generating laser elements to the external environment.
2Temperature
If ceramic package is used for mounting surface emitting laser elements to improve heat dissipation, then heat-dissipating characteristics are improved, but thermal expansion difference causes damage to soldered portions
Solution Approach 1:
The patent modifies the thermal management parameters by introducing penetrating electrodes with optimized thermal conductivity and cross-sectional area. This changes the heat flow distribution parameters, reducing thermal gradients and associated thermal stresses that cause solder joint failure during thermal cycling.
Solution Approach 2:
The patent addresses thermal expansion issues by designing the penetrating electrode structure and mounting configuration to accommodate differential thermal expansion between the ceramic package and printed board. The robust electrode-mount portion connection and distributed heat dissipation reduce expansion-induced stresses on soldered portions.
3Temperature
If penetrating electrodes are formed close to mount portion to improve heat dissipation, then heat dissipation is improved, but light emission direction becomes misaligned
Solution Approach 1:
The patent applies local quality by creating an asymmetric arrangement where penetrating electrodes are positioned preferentially on one side of the mount portion rather than uniformly distributed. This localized configuration optimizes heat dissipation from the laser elements while maintaining sufficient distance from the light emission path to prevent misalignment.
Solution Approach 2:
The patent segments the heat dissipation function by separating the roles of different electrode arrangements: penetrating electrodes handle vertical heat conduction through the substrate, while ground terminals and ground wiring on the back surface handle lateral heat distribution and external connection, preventing interference with light emission direction.
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 design effectively manages heat dissipation, prevents thermal expansion-related damage, and ensures accurate light emission direction, improving the longevity and performance of surface emitting laser arrays in light emitting apparatuses.
Implementation Method 1
a plurality of penetrating electrodes 36 are formed in the package substrate 21 between the bottom surface 26 in the opening portion 22 and the back surface 29 of the ceramic package 20
Implementation Method 2
a back-surface heat-dissipating electrode 33 extending substantially throughout the back surface of the ceramic package 20
Implementation Method 3
heat dissipation is solely dependent on the ceramic material with the superior heat-dissipating characteristics
Implementation Method 4
a repetitive stress is produced by the difference in the coefficients of thermal expansion between the ceramic package and the printed board
Data Source
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AI summary
A light emitting apparatus (50) includes a surface emitting laser and a ceramic package (20). The surface emitting laser has a common electrode on the back surface thereof and is mounted on the ceramic package via the common electrode. The common electrode of the surface emitting laser is electrically connected to a mount portion (31) of the ceramic package. The mount portion is electrically connected to a back-surface electrode (32) on the back surface of the ceramic package. The mount portion is also thermally connected to a back-surface heat-dissipating electrode (33) on the back surface of the ceramic package via a penetrating electrode (36) that penetrates the ceramic package. The surface emitting laser is spaced apart from the penetrating electrode in order to prevent inclination in light-emitted direction. The back-surface heat-dissipating electrode prevents destruction of a soldered portion when the light emitting apparatus is mounted on a substrate by soldering.