SAW Transducer Passivation for Corrosion-Free Electroplating

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Solution Overview

Problem

Existing SAW devices face issues with corrosion and size increase due to protective walls and top covers used to isolate the IDT during electroplating processes, which adversely affect circuit miniaturization and increase costs.

Innovation Solution

A manufacturing method for SAW devices that includes forming a passivation layer on the transducer to protect it from chemical solutions, followed by a photoresist layer patterning and stripping process, allowing for electroplating without protective walls, thus maintaining the transducer's integrity and reducing device size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If protective walls and top covers are used to isolate the IDT during electroplating, then the IDT is protected from corrosion and damage, but the device size increases and manufacturing cost increases

Engineering Contradiction:

ImproveIDT protection from corrosionVSAvoiddevice size

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The patent divides the protective function into two segments: a passivation layer that provides chemical protection against electroplating solutions, and a photoresist layer that provides physical protection during processing. This segmentation eliminates the need for bulky protective walls and top covers, reducing device size while maintaining IDT protection.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a passivation layer as an intermediary substance between the IDT and the electroplating environment. This thin film layer acts as a chemical barrier that protects the IDT from corrosion without requiring mechanical protective structures, thereby reducing device volume.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If protective walls and top covers are used to isolate the IDT, then the IDT is protected from chemical solutions, but the device complexity and cost increase

Engineering Contradiction:

ImproveIDT protection from chemical solutionsVSAvoiddevice structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the essential protective function from the complex mechanical structure (protective walls and top covers) and implements it through simple thin film deposition processes. The passivation and photoresist layers provide the necessary protection without adding structural complexity.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses disposable photoresist layers that are applied temporarily during manufacturing and then removed. These low-cost, temporary protective layers replace expensive, permanent mechanical protective structures, reducing both device complexity and manufacturing cost.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Ease of manufacture

If traditional electroplating processes are used without protective measures, then manufacturing is simpler, but the IDT suffers from corrosion and damage

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidIDT integrity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies protective layers (passivation and photoresist) before the electroplating process begins. This preliminary protective action ensures IDT integrity throughout manufacturing while maintaining process simplicity, as the protection is built-in rather than requiring complex protective structures.

Inventive Principle:

Principle #10Preliminary action

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 method results in a compact, cost-effective SAW device with improved performance and precise operating frequency, eliminating the need for protective walls and enhancing manufacturing yield.

Implementation Method 1

A transducer and a solder layer are provided on the piezoelectric substrate, and the transducer is covered with a passivation layer

Methodology Applied

Scientific EffectPassivation:

Implementation Method 2

forming a first photoresist layer on the piezoelectric substrate, and patterning the first photoresist layer to form a first patterned photoresist layer

Methodology Applied

Scientific EffectPhotolithography:

Implementation Method 3

Electroplating or chemical plating processes may be used to form the connections (e.g., copper pillars) of the SAW device

Methodology Applied

Scientific EffectElectroplating: Electroplating

Data Source

PatentUS12512803B2Acoustic wave device and manufacturing method thereof

Publication Date: 2025.12.30 RICHWAVE TECH CORP

AI summary

A manufacturing method of an acoustic wave device and an acoustic wave device are provided. The manufacturing method includes providing a piezoelectric substrate. A transducer and a solder layer are provided on the piezoelectric substrate, and the transducer is covered with a passivation layer. The method further includes forming a first photoresist layer on the piezoelectric substrate, and patterning the first photoresist layer to form a first patterned photoresist layer. The first patterned photoresist layer covers an upper surface of the passivation layer and exposes an upper surface of the solder layer. The method further includes forming a metal layer on the upper surface of the solder layer and the first patterned photoresist layer, and stripping the first patterned photoresist layer.