Hermetic Package Grounded Metal Ring for RF Stability
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Solution Overview
Problem
Conventional hermetic packages with ungrounded floating metallic rings suffer from unwanted radio frequency (RF) coupling, leading to instability of semiconductor dies and limited operational frequency, necessitating improved designs that suppress RF coupling and enhance stability while maintaining cost and size effectiveness.
Innovation Solution
The hermetic package design incorporates a carrier with a bottom ring structure featuring a grounded metal layer, top ring structure with vias for electrical coupling, and exterior plated layers to prevent RF coupling, using conductive materials like Nickle/Gold or Nickel/Palladium/Gold for enhanced electrical connectivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an ungrounded floating metallic ring is used for hermetic sealing, then the eutectic Gold/Tin solder hermetic seal is achieved, but unwanted RF coupling occurs between input and output
Solution Approach 1:
The patent introduces an intermediary grounding structure consisting of a ground ring and multiple ground connections that mediate between the floating metallic ring and the package ground. This intermediary grounding path eliminates the harmful RF coupling effect while preserving the hermetic sealing function, as the ground ring is electrically connected to the package ground through multiple vias and conductive paths.
Solution Approach 2:
The patent creates equipotential surfaces by connecting the metallic ring to the package ground through the ground ring and multiple ground connections. This equipotentialization eliminates potential differences that cause RF coupling, ensuring that the entire grounding structure remains at the same electrical potential, thereby suppressing unwanted RF signals.
2Reliability
If an ungrounded floating metallic ring is used, then hermetic sealing is maintained, but instability of the semiconductor die occurs
Solution Approach 1:
The ground ring serves as an intermediary grounding structure that provides a stable reference potential to the semiconductor die. By mediating the electrical connection between the package ground and the die, it stabilizes the operating conditions of the semiconductor device while maintaining the hermetic seal integrity.
Solution Approach 2:
The patent establishes equipotential conditions across the semiconductor package by grounding the metallic ring through the ground ring structure. This eliminates potential fluctuations that could cause die instability, providing a stable electrical reference that enhances semiconductor device reliability.
3Device complexity
If the metallic ring is left floating, then the hermetic package structure is simplified, but the package becomes useless beyond a certain frequency of operation
Solution Approach 1:
The patent applies equipotentiality by grounding the metallic ring through the ground ring and multiple connection points. This eliminates the frequency limitation caused by RF coupling, allowing the package to operate effectively across a broader frequency range while adding only moderate structural complexity.
Solution Approach 2:
The patent transitions from a two-dimensional floating ring structure to a three-dimensional grounded structure with vertical vias and multiple grounding layers. This dimensional expansion provides additional grounding paths and reduces RF coupling effects, thereby extending the operational frequency range.
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 effectively suppresses unwanted RF coupling, increases the stability of semiconductor dies, and maintains the cost and size effectiveness of the hermetic package by ensuring the carrier is electrically grounded, thereby preventing RF instability and extending operational frequency.
Implementation Method 1
a number of top vias that extend through the top dielectric ring and electrically couple the top metal layer to the at least one ground section
Implementation Method 2
the first exterior plated layer covers at least a portion of a first exterior sidewall of the bottom ring structure and electrically couples the carrier to the at least one ground section
Implementation Method 3
The conductive material is Nickle/Gold (Ni/Au) or Nickel/Palladium/Gold (Ni/Pd/Au)
Data Source
AI summary
The present disclosure relates to a hermetic package with improved RF stability and performance. The package includes a carrier, a bottom dielectric ring over the carrier, a bottom metal layer over the bottom dielectric ring, a top dielectric ring over the bottom metal layer, a top metal layer over the top dielectric ring, an exterior plated layer, and multiple top vias. Herein, the bottom metal layer includes signal sections and at least one ground section, which is electrically isolated from the signal sections. The exterior plated layer covers at least a portion of a first exterior sidewall of the bottom ring structure and electrically couples the carrier to the at least one ground section. The multiple top vias extend through the top dielectric ring and electrically couple the top metal layer to the at least one ground section.