Asymmetric Lead Frame for High-Power Semiconductor Laser Heat Dissipation
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Solution Overview
Problem
High-power semiconductor laser elements with long cavity lengths pose a challenge for heat dissipation in thin optical recording/reproducing apparatuses, leading to increased device size due to the need for larger semiconductor laser apparatuses.
Innovation Solution
A semiconductor device with a lead frame having asymmetric inner leads and a resin molding process that positions the high-temperature region of the semiconductor element on the side with the shorter inner lead, allowing for efficient heat dissipation and reduced device size by wire bonding to the larger region and using a dual-wavelength semiconductor laser element with red and infrared outputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the cavity length of the semiconductor laser element is increased to achieve higher power output, then the power output is improved, but the length of the semiconductor laser element and the overall device size are increased
Solution Approach 1:
The patent employs asymmetric lead frame design where the first lead has a longer inner lead portion extending further than the second lead. This asymmetry allows the semiconductor laser element to be mounted at an optimized position relative to the heat dissipation structure, enabling better thermal management for high-power operation without proportionally increasing the overall device length. The asymmetric configuration permits the active cavity region to be positioned optimally while keeping the rear end compact.
Solution Approach 2:
The patent redirects heat dissipation efforts from the longitudinal dimension to the lateral dimension by providing heat dissipation structures on the rear end surface (width direction) rather than extending the device length. The lead frame's asymmetric design allows heat sinks or other dissipation components to be attached to the width-wise rear end, effectively utilizing the width dimension for thermal management and thereby avoiding length increase despite high-power operation requirements.
2Power
If the cavity length of the semiconductor laser element is increased to achieve higher power output, then the power output is improved, but the heat dissipation becomes more difficult
Solution Approach 1:
The patent incorporates heat dissipation structures on the rear end of the lead frame before the semiconductor laser element is fully operated at high power. This preliminary provision of thermal management infrastructure allows the long-cavity, high-power laser element to dissipate heat effectively from its mounting region, preventing excessive temperature buildup that would otherwise limit power output or damage the element.
Solution Approach 2:
The lead frame serves as an intermediary thermal management component between the semiconductor laser element and the external environment. By designing the lead frame with asymmetric leads and providing heat dissipation structures on its rear end, it acts as a heat transfer mediator that conducts away thermal energy from the laser element's mounting region, enabling sustained high-power operation without direct thermal contact between the element and the device housing.
3Length of stationary object
If the device size is reduced to meet thin equipment requirements, then the portability is improved, but the heat dissipation capability is reduced
Solution Approach 1:
The patent shifts heat dissipation from the length dimension to the width dimension by attaching heat dissipation structures to the rear end surface of the lead frame. This allows the device to maintain a compact length suitable for thin equipment while providing adequate thermal management capacity through the width-wise configuration of the heat dissipation path.
Solution Approach 2:
The patent concentrates heat dissipation resources locally at the rear end of the lead frame where the semiconductor laser element is mounted. By providing heat dissipation structures specifically at this location rather than distributing them uniformly throughout the device, the design achieves effective thermal management in a localized region, enabling compact overall device dimensions while maintaining sufficient heat dissipation capability at the critical mounting point.
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
The solution enables a compact semiconductor device with effective heat dissipation, maintaining high-power performance while minimizing the size increase of the semiconductor laser apparatus, allowing for efficient operation at higher temperatures.
Implementation Method 1
the first lead, the second lead, and the third lead are held by resin
Implementation Method 2
the semiconductor element and the first, second, and third leads are connected via wires
Implementation Method 3
the semiconductor element has an asymmetric temperature distribution during an operation, and the semiconductor element has a high-temperature region side on a third lead side
Data Source
AI summary
In a semiconductor device where a semiconductor element having an asymmetric temperature distribution during an operation is mounted, inner leads on the right and left ends have asymmetric lengths, so that the right and left regions of a semiconductor element mounting part have different sizes. The semiconductor element is mounted so as to have a high-temperature region side in a wide region of the mounting part, and the inner leads are wire bonded at the center to the wide region of the mounting part. It is thus possible to provide a small semiconductor device in which a long semiconductor element is mounted with heat dissipation.