Semiconductor Ball-Pad Void Geometry for Reduced Signal Reflections
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Solution Overview
Problem
Interfaces with discontinuous impedances lead to signal reflections, attenuation, and distortion due to impedance mismatch, affecting power transfer and signal quality in transmission lines.
Innovation Solution
A semiconductor device design featuring conductive layers with grounding nets and signal ball-pads, where the signal ball-pads are positioned within voids with specific diameter ratios and spacing to reduce capacitance and increase impedance, minimizing signal reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If signal ball-pads are positioned close to grounding nets to reduce area, then capacitance decreases and impedance increases, but signal reflections occur due to impedance mismatch
Solution Approach 1:
The patent applies parameter changes by systematically adjusting the ground void diameter ratio (setting it to 1.2 or greater), the spacing distance (set to 0.1 times the ball-pad diameter), and the grounding net configuration. These parameter modifications transform the impedance characteristics of the transmission line, achieving continuous impedance matching that reduces signal reflections while maintaining a practical layout design.
2Reliability
If ground void diameter is increased to reduce capacitance between signal ball-pad and grounding net, then impedance increases, but the spacing between signal ball-pad and grounding net must be precisely controlled
Solution Approach 1:
The patent establishes specific parameter ranges: the ground void diameter ratio should be 1.2 or greater, and the spacing between the signal ball-pad and grounding net lateral wall should be 0.1 times the ball-pad diameter. These quantified parameters provide clear manufacturing guidelines that balance impedance optimization with fabrication feasibility, reducing capacitance while maintaining controllable spacing.
3Ease of manufacture
If conventional transmission line design is used, then manufacturing is simple, but signal reflections and attenuation occur due to impedance mismatch
Solution Approach 1:
The patent applies local quality by introducing ground voids specifically around the signal ball-pads in the conductive layer, rather than uniformly modifying the entire grounding structure. This localized modification creates regions of optimized impedance characteristics at critical signal transmission points, reducing reflections and attenuation while maintaining overall manufacturing simplicity through targeted structural adjustments.
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 design achieves continuous impedance with reduced signal reflections, improving signal quality and power transfer by increasing differential impedance from 50 ohms to 85 ohms, as demonstrated by simulations showing minimized signal reflections and enhanced impedance continuity.
Implementation Method 1
the first signal ball-pad is spaced from a lateral wall of the first void by a first minimum interval, and the first minimum interval is greater than 0.1 times of the first ball-pad diameter
Data Source
Figure 1
Figure 2A~2B
Figure 2C
AI summary
A semiconductor device is provided. The semiconductor device includes a first conductive layer and second conductive layer. The second conductive layer is disposed opposite to the first conductive layer. One of the first conductive layer and the second conductive layer includes a first grounding net and a first signal ball-pad. The first grounding net has a first ground void, and the first signal ball-pad is disposed in the first ground void. The first signal ball-pad has a first ball-pad diameter, the first ground void has a first ground void diameter, and a ratio of the first ground void diameter to the first ball-pad diameter is equal to or greater than 1.2.