Piezoelectric Actuator Bonding Structure to Prevent Electrode Shorting

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Solution Overview

Problem

Existing piezoelectric elements face issues with reduced driving efficiency, accuracy of oscillation angle detection, and unreliable electrical connections due to the presence of conductive adhesives and insulating underfill materials between the substrate and piezoelectric elements, leading to potential short circuits.

Innovation Solution

A piezoelectric unit design where a bonding member with conductivity is used to connect the metal substrate and piezoelectric element, with specific portions of the bonding member avoiding contact with the electrodes, ensuring electrical connection while preventing short circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If insulating underfill material is disposed to reach the side surface of the piezoelectric element to prevent short circuit, then electrical insulation is improved, but driving efficiency and measurement precision deteriorate due to interface interference

Engineering Contradiction:

Improveelectrical insulationVSAvoidoscillation angle detection accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent removes the insulating underfill material from the region between the substrate and piezoelectric element, extracting the harmful interface that interferes with vibration propagation and detection accuracy. The conductive adhesive is disposed to extend to the side surface of the piezoelectric element, eliminating the need for insulating underfill in this region while maintaining electrical insulation through the conductive adhesive's controlled extension.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The conductive adhesive serves as an intermediary material that simultaneously provides electrical connection and prevents short circuit by extending to the side surface of the piezoelectric element. This eliminates the need for a separate insulating underfill material in the critical region, removing the interface that causes vibration interference and detection errors.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If insulating underfill material is disposed between substrate and piezoelectric element to prevent short circuit, then electrical insulation is improved, but driving efficiency deteriorates due to vibration propagation interference

Engineering Contradiction:

Improveelectrical insulationVSAvoiddriving efficiency

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent extracts the insulating underfill material from the region between the substrate and piezoelectric element, removing the interface that interferes with vibration propagation. The conductive adhesive is extended to the side surface to provide electrical insulation without creating an interface that would impede mechanical coupling and vibration transmission.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If both conductive adhesive and insulating underfill material are disposed between substrate and piezoelectric element to prevent short circuit, then electrical insulation is improved, but device complexity increases

Engineering Contradiction:

Improveelectrical insulationVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the functions of electrical connection and electrical insulation into a single material - the conductive adhesive. By extending the conductive adhesive to the side surface of the piezoelectric element, it simultaneously provides electrical connection between substrate and element while preventing short circuit, eliminating the need for separate insulating underfill material and simplifying the overall structure.

Inventive Principle:

Principle #5Merging (Combining)

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

This design enhances driving efficiency and reliability of electrical connections, preventing short circuits and maintaining accurate oscillation angle detection in piezoelectric elements.

Implementation Method 1

a bonding member having conductivity and bonding the metal substrate and the piezoelectric element

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

a piezoelectric element disposed on a placement surface of the metal substrate... a piezoelectric body having a first main surface opposite the placement surface

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS12529888B2Piezoelectric unit and actuator device

Publication Date: 2026.01.20 HAMAMATSU PHOTONICS KK

AI summary

A piezoelectric drive element disposed on a placement surface of a metal substrate includes a piezoelectric drive body having a first main surface opposite the placement surface, a second main surface on a placement surface side, and a side surface, and a first electrode disposed on the first main surface. The piezoelectric drive element is disposed on the placement surface such that a part of the placement surface is located outside the side surface. A second bonding member having conductivity includes a first portion disposed between the placement surface and the piezoelectric drive element, and a second portion being continuous from the first portion and disposed in a corner formed by the part of the placement surface and the side surface. The second portion does not reach the first electrode.