Wiring Substrate With Stacked Electrodes For Low Impedance
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Solution Overview
Problem
Wiring substrates made of inorganic materials face challenges in achieving low power source impedance and impedance matching due to the microloading effect, which results in high resistance and capacitive characteristics of power and ground lines, making it difficult to secure wide conductor areas and attain impedance matching for high-speed input/output signals.
Innovation Solution
A wiring substrate design featuring a substrate body made of an inorganic material with comb-shaped through-holes for ground and power electrodes and signal electrodes that penetrate through the substrate, allowing for low power source impedance and impedance matching by securing wide conductor areas and optimizing the arrangement of these electrodes to create a strip line structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If very fine wiring patterns and via lines are used to form power and ground lines in inorganic material substrates, then wiring density is improved, but conductor area is reduced resulting in high resistance and high power source impedance
Solution Approach 1:
The patent transitions from planar power/ground planes to three-dimensional stacked electrode structures. Multiple power and ground electrodes are arranged in different layers (first power electrode, first ground electrode, second power electrode, second ground electrode), creating vertical current paths that increase effective conductor area without expanding planar footprint, thereby reducing resistance and power source impedance while maintaining high wiring density
Solution Approach 2:
The patent implements nested electrode structures where signal electrodes are positioned between power and ground electrodes in the vertical stack. The first signal electrode is located between the first power electrode and first ground electrode, while the second signal electrode is between the second power electrode and second ground electrode, creating a compact nested arrangement that maximizes space utilization and reduces impedance
2Manufacturing precision
If very fine wiring patterns are used in inorganic material substrates, then manufacturing precision is improved, but conductor area is reduced making impedance matching difficult
Solution Approach 1:
The patent creates controlled impedance structures by forming signal electrodes that extend between power and ground electrodes in the vertical dimension. This three-dimensional configuration allows precise control of characteristic impedance through electrode spacing, thickness, and positioning, enabling impedance matching for high-speed signals while maintaining fine wiring patterns
Solution Approach 2:
The patent introduces insulating films as intermediary layers between power, ground, and signal electrodes. These insulating films with controlled dielectric properties serve as mediators that enable precise impedance control by adjusting the electrical field distribution between adjacent electrodes, facilitating impedance matching while maintaining fine wiring geometry
3Reliability
If planar power planes and ground planes are formed in organic material substrates, then power source impedance is reduced and impedance matching is achieved, but such structures are difficult to form in inorganic material substrates due to microloading effect
Solution Approach 1:
The patent divides the power and ground connections into multiple discrete electrode segments stacked vertically (first power electrode, first ground electrode, second power electrode, second ground electrode). This segmentation replaces the difficult-to-form planar structures with manageable layered segments that can be fabricated using standard inorganic substrate processing techniques, avoiding microloading issues while achieving low impedance
Solution Approach 2:
The patent resolves the manufacturing difficulty by transitioning from two-dimensional planar planes to three-dimensional stacked electrodes. This dimensional change allows power and ground connections to be formed through vertical layering compatible with inorganic substrate fabrication processes, eliminating the need for large-area planar patterns that cause microloading effects while maintaining low power source impedance
Data Source
AI summary
A wiring substrate includes: a substrate body made of an inorganic material; a first electrode portion, having a flat-plate shape, which penetrates through the substrate body in a thickness direction of the substrate body; a second electrode portion, having a flat-plate shape, which penetrates through the substrate body in the thickness direction and faces the first electrode portion at a prescribed interval; and a first signal electrode, which is provided between the first electrode portion and the second electrode portion and penetrates through the substrate body in the thickness direction, wherein one of the first electrode portion and the second electrode portion is a ground electrode and the other is a power electrode.