Semiconductor Laser Package with Recessed Substrate
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Solution Overview
Problem
Semiconductor edge emitting lasers face challenges in surface mount technology due to beam widening issues, vulnerability to contamination, and limited flexibility in board design, as well as difficulties in thermal dissipation when mounted on printed circuit boards.
Innovation Solution
A laminate leadless carrier package with a semiconductor laser chip mounted adjacent to an edge recess region on a substrate, featuring conductive and dielectric layers, wire bonds, and an optically transparent molding compound encapsulation, allowing for side-looker or top-looker configurations on printed circuit boards, and providing thermal conduits for heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the semiconductor laser chip is mounted at the edge of the substrate to allow beam widening beyond the board, then the beam can widen without intersecting the surface, but the laser facet becomes more vulnerable to contamination and humidity
Solution Approach 1:
The patent introduces an encapsulation material as an intermediary substance that fills the recess region and covers the laser chip facet. This encapsulation material acts as a protective barrier between the laser facet and the external environment (contamination and humidity), while still allowing the laser beam to pass through effectively. The encapsulation material mediates between the need for edge mounting (for beam widening) and the need for facet protection.
2Illumination intensity
If the semiconductor laser chip is mounted at the edge of the substrate, then the beam can widen in an area beyond the board, but this limits the flexibility of board design and makes certain packaging options impractical
Solution Approach 1:
The patent utilizes the vertical dimension by creating a recess region that extends downward from the surface of the substrate. This allows the laser chip to be mounted in a position where the beam can widen horizontally beyond the board edges, while the recess provides vertical clearance. This dimensional approach enables the laser to be positioned away from the board edge in the vertical direction, thereby increasing design flexibility and compatibility with various packaging options like laminate leadless carriers.
3Ease of manufacture
If surface mount technology is used to mount the laser on the main driver board, then manufacturing is simplified, but thermal dissipation from the laser chip becomes difficult
Solution Approach 1:
The patent extracts the thermal management function from the standard surface mount configuration by creating a dedicated recess region that can accommodate thermal dissipation structures. The recess allows for the integration of heat sinks or thermal conduction paths directly at the laser chip location, separating the thermal management consideration from the electrical mounting considerations. This enables effective thermal dissipation while maintaining the ease of surface mount manufacturing.
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 protects the laser facet from contamination, enhances board design flexibility, and improves thermal dissipation, ensuring reliable and efficient operation of semiconductor laser chips in surface mount technology.
Implementation Method 1
providing thermal conduits for heat dissipation
Implementation Method 2
an optically transparent molding compound encapsulation
Data Source
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Figure 5
AI summary
A laminate leadless carrier package having a semiconductor chip mounted at the edge of a recess region in a substrate supporting the chip, the substrate having a plurality of conductive and dielectric layers, a wire bond coupled to the optoelectronic chip and a wire bond pad positioned on the top surface of the substrate. An encapsulation covers the laser chip, the wire bond, and at least a portion of the top surface of the substrate including the recess region. The encapsulation is an optically transparent molding compound. The package is arranged to be mounted as a side-looker and/or a top-looker.