Angular Velocity Sensor Multilayer Wiring Crosstalk Reduction
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Solution Overview
Problem
Existing angular velocity measuring devices face issues with crosstalk due to high impedance detection wiring, leading to output deviation and offset temperature drift, and have limited design freedom and mounting area due to symmetrical wiring arrangements, which complicates flip-chip mounting and reduces productivity.
Innovation Solution
A multilayer substrate is used with detection wiring inside and low-impedance wiring facing it, along with element-side and substrate-side low-impedance electrodes to cut off coupling between drive and detection electrodes, allowing for symmetrical wiring and reduced mounting area, thereby preventing crosstalk and improving temperature drift characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If drive wiring and detection wiring are disposed on the surface of the substrate, then wiring layout is simple, but sufficient shielding cannot be provided and coupling capacitance cannot be reduced
Solution Approach 1:
The patent transitions from surface-level wiring to three-dimensional multilayer substrate wiring. Detection wiring is placed in an intermediate layer between drive wiring layers, utilizing the vertical dimension to achieve spatial separation and shielding without increasing surface area or wiring layout complexity.
Solution Approach 2:
The patent introduces a ground wiring layer as an intermediary between the drive wiring and detection wiring. This ground layer acts as a shield that blocks electromagnetic coupling between the high-impedance detection wiring and the drive wiring, reducing coupling capacitance while maintaining simple wiring layout.
2Reliability
If drive wirings and detection wirings are arranged symmetrical to cancel crosstalk, then crosstalk is reduced, but lead-out is limited and mounting surface size is increased
Solution Approach 1:
The patent resolves the symmetry constraint by moving to three-dimensional multilayer wiring. Detection wiring in the intermediate layer can be positioned directly below or adjacent to drive wiring in upper layers, eliminating the need for symmetrical surface arrangement while reducing the mounting surface footprint.
3Device complexity
If wiring lead-out is limited and design freedom is reduced, then symmetrical arrangement is possible, but flip-chip mounting becomes difficult and productivity is reduced
Solution Approach 1:
The patent enables flip-chip mounting by utilizing vertical wiring paths in the multilayer substrate. Electrodes can be accessed from the back surface through intermediate layers, allowing the angular velocity detection element to be mounted face-down without wiring lead-out constraints, thereby enabling high-density flip-chip assembly and improving productivity.
4Device complexity
If coupling capacitance between drive wiring and detection wiring is large, then wiring design is simple, but output deviation and offset temperature drift are greatly affected
Solution Approach 1:
The patent introduces a ground wiring layer as an intermediary shield between drive wiring and detection wiring. This ground layer blocks electromagnetic fields, reducing coupling capacitance to minimal levels (a few fF), thereby eliminating the source of output deviation and temperature drift while maintaining simple wiring design through standardized multilayer construction.
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 solution effectively shields high-impedance detection wiring, reduces output deviation, and enhances design freedom and productivity by allowing flip-chip mounting with improved detection sensitivity and reduced size.
Implementation Method 1
Low-impedance wiring facing the detection wiring is disposed at a location different from the detection wiring in the thickness direction
Implementation Method 2
when an angular velocity is applied around the third axis, a Coriolis force operates on the vibrating body in the second axial direction
Data Source
AI summary
An angular velocity measuring device includes an angular having a mounting surface on which a velocity detection element, element-side drive electrodes and element-side detection electrodes are provided and a ground electrode is disposed between the drive electrodes and the detection electrodes. On the top surface of a multilayer substrate, substrate-side drive electrodes and substrate-side detection electrodes are provided and a ground electrode is disposed between the drive electrodes and the detection electrodes. The electrodes of the angular velocity detection element are connected to the electrodes of the multilayer substrate and the two ground electrodes are arranged to face each other. Furthermore, on the top surface of the multilayer substrate, drive wirings connected to the drive electrodes are provided and, inside the multilayer substrate, detection wirings connected to the detection electrodes are provided. Ground wirings sandwiching the detection wirings in the thickness direction are disposed in the multilayer substrate.