Piezoelectric Base Structure Using Intermetallic-Bonded Glass Substrates

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Solution Overview

Problem

Existing piezoelectric device containers, particularly ceramic bases, face limitations in structure, accuracy, and cost as they struggle to meet the demands of thinning and downsizing.

Innovation Solution

A base for a piezoelectric device comprising a first substrate made of glass or crystal, with a mounting pad, contact holes and wirings, metal films for intermetallic bonding, a second substrate, routing wirings, castellations, and external mounting terminals, which are bonded using intermetallic bonding to enhance structural integrity and reduce thickness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a ceramic base is used for the piezoelectric device, then structural integrity and reliability are improved, but device thickness and cost increase

Engineering Contradiction:

Improvestructural integrityVSAvoiddevice thickness

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The base is divided into two separate substrates (first substrate and second substrate) that are bonded together through intermetallic bonding. This segmentation allows each substrate to be optimized independently - the first substrate can be made thinner while the second substrate provides structural support, resolving the contradiction between thickness reduction and structural integrity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The base uses a composite structure combining glass or crystal substrates with metal films (such as Cu, Al, or their alloys). This composite material approach enables the glass/crystal substrates to provide thinness and light weight while the metal films provide structural strength and bonding capability, achieving both thickness reduction and reliability maintenance

Inventive Principle:

Principle #40Composite materials

2Reliability

If a ceramic base is used for the piezoelectric device, then reliability is improved, but manufacturing cost increases

Engineering Contradiction:

Improvestructural integrityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention changes the material parameters from traditional ceramic to glass or crystal substrates with metal films. This parameter change enables the use of more cost-effective materials and manufacturing processes while maintaining or improving structural integrity through the intermetallic bonding mechanism

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention replaces the traditional ceramic firing process with a bonding process using intermetallic bonding between metal films. This substitution eliminates the need for high-temperature ceramic sintering, reducing manufacturing complexity and cost while achieving reliable structural integration

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Length of moving object

If glass or crystal substrate is used instead of ceramic, then cost and thickness are reduced, but bonding strength and structural integrity worsen

Engineering Contradiction:

Improvedevice thicknessVSAvoidbonding strength

Core Design Contradiction:

Length of moving objectVSStrength

Solution Approach 1:

Metal films (such as Cu, Al, or their alloys) are introduced as intermediary layers between the glass/crystal substrates. These metal films serve as bonding mediators that form strong intermetallic bonds with both substrates, enabling reliable bonding of thin glass/crystal structures that would otherwise be difficult to join

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

Inventive Principle:

Principle #40Composite materials

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 provides a cost-effective and structurally superior alternative to ceramic bases, enabling thinner and more accurate piezoelectric devices with improved manufacturing throughput and reduced device thickness.

Implementation Method 1

The second substrate is bonded to the first substrate by an intermetallic bonding. The second metal film constitutes the intermetallic bonding together with the first metal film.

Methodology Applied

Scientific EffectIntermetallic bonding: Welding

Data Source

PatentUS12567851B2Base for piezoelectric device and piezoelectric device

Publication Date: 2026.03.03 NIHON DEMPA KOGYO CO LTD

AI summary

A base for a piezoelectric device includes: a first substrate, mounting pads, a contact hole and a contact hole wiring, a first metal film, a second substrate, a second metal film, a routing wiring, a castellation, and an external mounting terminal. The second substrate is made of a material identical to the material of the first substrate. The second substrate is bonded to the first substrate by intermetallic bonding. The second metal film is disposed on a third surface. The third surface is a surface on the first substrate side of the second substrate. The second metal film constitutes the intermetallic bonding together with the first metal film. The routing wiring reaches a fourth surface that is an opposite surface of the third surface of the second substrate via the third surface and a side surface of the second substrate from the contact hole wiring.