Coaxial Through-Package Via Shielding for Low-Loss RF Signals
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Solution Overview
Problem
Semiconductor device packages face challenges in accommodating sophisticated features that impact reliability, performance, and cost, particularly in minimizing electromagnetic interference (EMI) and signal loss while maintaining low product costs.
Innovation Solution
The implementation of a coaxial through package via (TPV) in semiconductor devices, utilizing a laser direct structuring process to form conductive traces and shield conductors within an encapsulant, which are connected to a ground voltage supply, thereby creating a coaxial structure that minimizes signal loss and EMI interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional packaging configurations are used to accommodate sophisticated semiconductor device features, then the devices can be manufactured with standard processes, but the reliability decreases and product costs increase
Solution Approach 1:
The packaging structure is segmented into distinct functional layers: the package substrate with circuit traces, the encapsulant material providing protection and isolation, and the coaxial TPV structure with signal and shield conductors. This segmentation allows each component to be optimized independently while maintaining overall reliability.
Solution Approach 2:
The coaxial TPV structure employs nesting by placing the signal conductor inside the shield conductor, with both conductors embedded within the encapsulant material. This nested configuration provides electromagnetic shielding while maintaining a compact structure that reduces complexity.
2Adaptability or versatility
If sophisticated features are included in semiconductor devices, then device functionality is enhanced, but manufacturing costs increase
Solution Approach 1:
The encapsulant material serves multiple functions simultaneously: it provides mechanical protection for the semiconductor die, acts as an insulator between conductors, supports the coaxial TPV structure, and enables laser direct structuring for cost-effective manufacturing. This multi-functionality reduces the need for additional components and processing steps.
Solution Approach 2:
The patent replaces traditional mechanical drilling and plating processes with laser direct structuring to form the coaxial TPV openings and deposit conductive materials. This substitution reduces manufacturing complexity and costs while enabling sophisticated RF features.
3Loss of energy
If traditional via structures are used in package substrates, then manufacturing is simpler, but RF signal loss increases
Solution Approach 1:
The coaxial TPV structure uses composite construction with conductive materials (signal and shield conductors) embedded in the encapsulant material. This composite structure provides both mechanical support and electromagnetic shielding, reducing RF signal loss while maintaining manufacturability.
Solution Approach 2:
The patent transitions from planar 2D circuit traces to three-dimensional coaxial structures by forming vertical openings through the encapsulant and depositing conductive materials in a cylindrical configuration. This dimensional change enables controlled impedance and reduced signal loss for RF applications.
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 coaxial TPV structure achieves low-loss RF signal propagation and reduces EMI interference, enhancing device reliability and performance while maintaining cost-effectiveness.
Implementation Method 1
Openings are formed using laser ablation thus activating the encapsulant at the sidewalls of the openings
Data Source
AI summary
A method of forming a semiconductor device is provided. The method includes encapsulating with an encapsulant at least a portion of a semiconductor die and a package substrate, the encapsulant including an additive selectively activated by way of a laser. A first opening is formed in the encapsulant, the first opening exposing a predetermined first portion of the package substrate. The additive is activated at the sidewalls of the first opening. A second opening is formed in the encapsulant, the second opening encircling the first opening and exposing a predetermined second portion of the package substrate. The additive is activated at the sidewalls the second opening. A conductive material is plated on the additive activated portions of the encapsulant.