Semiconductor Laser Package Layout for Low-Inductance Signal Paths
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Solution Overview
Problem
In semiconductor devices, increased distance between signal lines and lead pins leads to thicker metal bonding materials, resulting in higher inductance components, which can cause transmission loss and deterioration of frequency characteristics, particularly when mounting semiconductor lasers.
Innovation Solution
A semiconductor device design featuring a base body with through holes, sealing bodies filling the space between leads and the base body, a dielectric substrate with erected main surfaces, and a rear surface conductor with the sealing body positioned directly below it, reducing the distance between leads and signal lines and thus minimizing the inductance component of the connecting members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the distance between the signal line and lead pin increases, then the space for mounting electronic components is improved, but the metal bonding material becomes thicker and inductance increases causing signal quality deterioration
Solution Approach 1:
The patent introduces a rear surface conductor on the back side of the dielectric substrate to connect with the lead pin, creating a new dimensional path for electrical connection. This allows the signal line on the front surface to be connected to the lead pin through a shorter vertical path via the rear surface conductor, effectively reducing the inductance without compromising front surface mounting space.
Solution Approach 2:
The rear surface conductor acts as an intermediary element between the signal line and lead pin. By introducing this intermediate conductive layer on the rear surface of the dielectric substrate, the patent creates a more efficient electrical connection path that reduces inductance while maintaining adequate spacing between components on the front surface.
2Length of stationary object
If the metal bonding material thickness increases, then the distance between signal line and lead pin is accommodated, but the inductance component increases causing transmission loss
Solution Approach 1:
The patent utilizes the vertical dimension by placing a rear surface conductor on the back side of the dielectric substrate. This allows the electrical connection to proceed vertically through the rear surface conductor rather than horizontally through thick bonding material, significantly reducing the effective current path length and associated inductance and transmission losses.
Solution Approach 2:
The patent replaces the conventional horizontal metal bonding material connection with a vertical connection path through the rear surface conductor. This substitution changes the connection geometry from a planar mechanical bonding approach to a three-dimensional conductive path that minimizes inductance and energy loss.
3Device complexity
If the inductance component of connecting members increases, then the package structure is simplified, but the frequency characteristics deteriorate
Solution Approach 1:
The patent segments the electrical connection path into multiple sections: the signal line on the front surface, the rear surface conductor on the back surface, and the connection through the dielectric substrate. This segmentation allows each portion to be optimized independently, with the rear surface conductor specifically designed to minimize inductance while maintaining overall package simplicity.
Solution Approach 2:
By introducing the rear surface conductor dimension, the patent creates a three-dimensional connection architecture that reduces inductance without increasing planar complexity. The vertical connection path through the rear surface conductor provides a compact solution that maintains simple package external dimensions while improving internal electrical characteristics.
Data Source
AI summary
A semiconductor device according to the present disclosure includes a base body having a first face and a second face, a lead passing through a through hole penetrating the base body and extending to a side of the first face, a sealing body filling the through hole, a dielectric substrate having a first main surface and a second main surface erected with respect to the first face, a semiconductor laser provided on a side of the first main surface of the dielectric substrate, a signal line provided on the first main surface and electrically connected to the semiconductor laser, a connecting member electrically connecting the signal line and the lead to each other, and a rear surface conductor provided on the second main surface, wherein the sealing body is provided directly below the rear surface conductor as viewed from a direction perpendicular to the first face.