Composite Module Ground Electrode Segmentation for Stray Capacitance Reduction
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Solution Overview
Problem
In compact composite modules, close proximity of wiring electrodes and ground electrodes leads to undesired stray capacitance and interference from external signals, deteriorating frequency characteristics and impedance.
Innovation Solution
A composite module design featuring an outer ground electrode and a first ground electrode on the same surface as the wiring electrode, with cutouts to reduce stray capacitance and adjust impedance, while ensuring shielding from external interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the wiring electrodes and ground electrodes are disposed close to one another to reduce the size and thickness of the composite module, then the size and profile of the composite module are reduced, but undesired stray capacitance is produced between the electrodes, deteriorating frequency characteristics and impedance
Solution Approach 1:
The ground electrode is divided into multiple separate ground electrodes positioned at different locations. This segmentation reduces the overlapping area between the wiring electrode and any single ground electrode, thereby reducing stray capacitance while maintaining overall shielding effectiveness through the distributed ground electrode arrangement.
Solution Approach 2:
The ground electrodes are positioned to provide localized shielding at specific regions where wiring electrodes are located, rather than using a continuous ground plane. This allows for reduced stray capacitance in critical areas while maintaining shielding where needed, optimizing the balance between size reduction and electrical performance.
2Reliability
If a cutout is provided in the ground electrode at a portion overlapping with an inductor element to reduce stray capacitance, then frequency characteristics are improved, but the ground electrode area is reduced causing increased parasitic inductance in connecting wiring
Solution Approach 1:
Instead of creating a large cutout in a single ground electrode, the ground electrode is segmented into multiple smaller ground electrodes distributed around the wiring electrode. This segmentation reduces stray capacitance without significantly reducing the total ground electrode area, thereby avoiding increased parasitic inductance while still improving frequency characteristics.
3Object-generated harmful factors
If a cutout is provided in the ground electrode to reduce stray capacitance, then stray capacitance is reduced, but the ground electrode area is considerably reduced, and shielding effect is weakened allowing external signals to interfere with the wiring electrode
Solution Approach 1:
The ground electrode is segmented into multiple distributed ground electrodes that collectively provide both stray capacitance reduction and shielding. The segmented structure reduces overlapping area with the wiring electrode to minimize stray capacitance, while the distributed arrangement maintains shielding effectiveness against external signals.
Solution Approach 2:
The shielding function is achieved not only through the planar ground electrode structure but also through the three-dimensional arrangement of multiple ground electrodes at different positions and potentially different layers. This multi-dimensional approach maintains shielding effectiveness while reducing stray capacitance through optimized spatial distribution.
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
Significantly reduces stray capacitance and prevents external signal interference, maintaining stable frequency characteristics and impedance, while allowing for miniaturization of the module.
Implementation Method 1
the wiring electrode is shielded by the outer ground electrode and the first ground electrode on the one main surface side of the wiring substrate. Accordingly, for example, in the case where the one main surface side of the wiring substrate is connected with a mother board, signals leaked from other elements, modules, and so on located on the mother board are prevented from interfering with the wiring electrode
Implementation Method 2
providing the first cutout makes it possible to reduce an area where an electrode section of the first ground electrode and the wiring electrode overlap with each other, so that stray capacitance produced between the two electrodes is significantly reduced or prevented
Data Source
AI summary
A composite module includes outer ground electrodes on one main surface of a wiring substrate, a wiring electrode inside the wiring substrate, and a first ground electrode between the wiring electrode and the outer ground electrode. A cutout is provided in the first ground electrode at least at a portion of a region overlapping with the wiring electrode and the outer ground electrode when viewed from above, and the wiring electrode overlaps with at least one of the first ground electrode and the outer ground electrode when viewed from above to reduce stray capacitance produced on the wiring electrode and to adjust impedance of the wiring electrode while preventing signals leaked from the exterior from interfering with the wiring electrode.