Coaxial Through-Package Via Structure for Low-Loss RF Packaging
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Solution Overview
Problem
Semiconductor device packaging faces challenges in accommodating sophisticated features while maintaining reliability, performance, and minimizing costs, often resulting in lower reliability and higher costs due to complex configurations.
Innovation Solution
A semiconductor device with a coaxial through package via (TPV) is formed using a semiconductor die and package substrate encapsulated with a laser-activatable additive, where openings are created by laser ablation to expose conductive traces, allowing for electroless plating to form signal and shield conductors connected to ground voltage, achieving low loss RF signal propagation with reduced costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional packaging configurations are used to accommodate sophisticated semiconductor features, then device functionality is achieved, but reliability decreases and costs increase
Solution Approach 1:
The packaging structure is segmented into distinct functional zones: the encapsulant body providing mechanical protection, laser-formed openings creating precise signal pathways, and plated conductive features establishing electrical connections. This segmentation allows each component to optimize its function while maintaining overall reliability.
Solution Approach 2:
The encapsulant is designed with local quality variations through selective laser processing. Specific regions receive laser treatment to form openings and activate additives for plating, while other regions maintain their original protective properties. This localized modification enables sophisticated connectivity features without compromising the overall encapsulant integrity.
2Adaptability or versatility
If conventional packaging configurations are used to accommodate sophisticated semiconductor features, then device functionality is achieved, but manufacturing costs increase
Solution Approach 1:
Traditional mechanical drilling and chemical etching processes are replaced with laser-based formation of openings and activation of encapsulant additives. This substitution eliminates complex tooling requirements, reduces process steps, and enables precise feature creation directly within the encapsulant material, significantly lowering manufacturing costs.
Solution Approach 2:
The encapsulant material is formulated with additives that change state or reactivity in response to laser energy input. By controlling laser parameters (power, pulse duration, wavelength), the same material can be selectively transformed in different regions to create conductive pathways, openings, or adhesive zones, enabling multiple features through a single material system and process.
3Reliability
If through package vias are formed to improve signal propagation, then RF performance improves, but manufacturing complexity increases
Solution Approach 1:
The signal pathway is extracted directly through the encapsulant material by forming openings that traverse the entire encapsulant thickness. This eliminates the need for complex multi-layer substrate routing and intermediate connection structures, creating direct coaxial pathways from top to bottom surfaces while simplifying the overall manufacturing process.
Solution Approach 2:
The encapsulant is formulated as a composite material containing conductive additives (such as metal particles or conductive polymers) dispersed within the dielectric matrix. During laser processing, the additive is selectively activated or concentrated in the opening regions to form conductive pathways, combining the dielectric properties needed for RF insulation with conductive properties for signal transmission in a single material.
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 design enables low loss RF signal propagation while minimizing product costs by using a laser direct structuring process and electroless plating to form conductive paths within the encapsulant, enhancing reliability and performance.
Implementation Method 1
Openings are formed using laser ablation thus activating the encapsulant at the sidewalls of the openings
Implementation Method 2
The semiconductor device is subjected to a plating process which forms a plated signal conductor connected to a first trace in a first opening and a plated concentric shield conductor
Data Source
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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.