Semiconductor Package Stem Layout for Shorter Leads and Impedance Matching
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Solution Overview
Problem
In semiconductor packages with light emitting elements, the use of thick cooling elements leads to long signal leads, resulting in impaired transmission characteristics due to mismatched characteristic impedance.
Innovation Solution
A stem for semiconductor packages is designed with an eyelet featuring a flat plate, a cavity, and a metal block, where the metal block's volume matches the cavity's volume, allowing for reduced lead lengths and improved impedance matching by integrating the cooling element within the cavity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a thick cooling element is used for temperature adjustment, then the light emitting element can be effectively cooled, but the signal leads become correspondingly long resulting in deteriorated transmission characteristics
Solution Approach 1:
The invention introduces a horizontal metal block component that extends perpendicular to the vertical lead axis, creating a new dimensional space for signal transmission. This allows the signal to bypass the lengthy vertical path through the thick cooling element by traveling horizontally through the metal block, thereby reducing the effective lead length while maintaining cooling functionality.
Solution Approach 2:
The metal block serves as an intermediary structure that connects the lead to the light emitting element without requiring the signal to traverse the entire thickness of the cooling element. The cavity within the metal block provides a pathway that mediates between the need for thermal management and electrical signal transmission, resolving the contradiction between cooling effectiveness and transmission quality.
2Temperature
If long signal leads are used to accommodate the thick cooling element, then the cooling function is maintained, but the characteristic impedance cannot be achieved resulting in impaired transmission
Solution Approach 1:
By extending the metal block horizontally and routing the signal through this new dimensional path, the invention creates a more compact signal transmission route that avoids the impedance issues associated with long vertical leads. The horizontal extension provides a controlled impedance path that is easier to match with standard transmission lines.
Solution Approach 2:
The invention changes the geometric parameters of the lead path by introducing the metal block with specific dimensions (width, height, length) and positioning it at a specific depth within the cooling element. These parameter changes create an optimized transmission path that achieves desired impedance characteristics while maintaining the cooling function.
Data Source
AI summary
A stem for a semiconductor package includes an eyelet including a flat plate having a first surface and a second surface opposite to the first surface, a cavity opening to the first surface of the flat plate, and a metal block protruding from the second surface of the flat plate, and a lead extending through the flat plate from the first surface to the second surface, wherein a volume of the metal block is substantially the same as a volume of the cavity.