Patterned Piezo Driver Electrode Deposition for Inkjet Printheads

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Solution Overview

Problem

Current methods for manufacturing piezoelectric ink jet printheads face challenges such as stress on metal electrode adhesion and handling of thin piezoelectric material during blanket coating, particularly in achieving high density transducer arrays with tight tolerances.

Innovation Solution

A method involving forming piezoelectric transducers by depositing conductive material in a predetermined pattern on a substrate, either before or after forming individual elements, to minimize blanket coating and prevent shorting, allowing for precise electrode formation on thin slabs and thick-film transducers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If blanket coating of metal electrode material is used over the entire piezoelectric slab, then complete electrode coverage is achieved, but stress on electrode adhesion and risk of shorting increase

Engineering Contradiction:

Improveelectrode adhesionVSAvoidshorting risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by transitioning from blanket coating to patterned deposition of metal electrode material. The conductive material is deposited only in specific predetermined patterns corresponding to individual electrode locations, rather than covering the entire piezoelectric slab. This localized approach reduces stress concentration and eliminates pathways for shorting between adjacent electrodes while maintaining complete electrode coverage where needed.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the continuous blanket electrode coating into discrete patterned electrodes. By dividing the electrode structure into separate, spatially distributed conductive regions, the patent prevents electrical shorting between adjacent piezoelectric elements while ensuring each element receives complete electrode coverage. The segmentation is achieved through controlled deposition patterns that match the underlying piezoelectric element arrangement.

Inventive Principle:

Principle #1Segmentation

2Manufacturing precision

If high density transducer arrays are manufactured with tight tolerances, then printing resolution is improved, but manufacturing difficulty and stress on thin piezoelectric material increase

Engineering Contradiction:

Improvetransducer array densityVSAvoidhandling of thin piezoelectric material

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by forming the metal electrode patterns on the piezoelectric slab before dicing it into individual transducer elements. This sequence allows the electrode material to be deposited while the piezoelectric material is still in a larger, more handleable form, reducing stress and handling difficulty. The predetermined pattern deposition occurs on the intact slab, and only after this is complete is the slab diced into individual high-density transducer elements with tight tolerances.

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If metal film electrode layers are patterned after dicing piezoelectric material, then individual element precision is improved, but electrode formation complexity increases

Engineering Contradiction:

Improveindividual element electrode alignmentVSAvoidelectrode formation process

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent inverts the conventional sequence by depositing patterned metal electrode material before dicing the piezoelectric slab, rather than after. This reversal simplifies the overall process by performing the complex pattern deposition operation on the intact slab where alignment is easier to achieve, and then simply transferring the patterned segments to individual elements during dicing. This eliminates the need for separate, complex electrode formation steps on each diced element.

Inventive Principle:

Principle #13The other way round (Inversion)

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 approach enables the formation of electrical contacts on thin piezoelectric slabs and thick-film transducers, reducing the risk of shorting and improving the manufacturing process for high-density inkjet printheads by providing flexibility in the order of forming individual elements and electrodes.

Implementation Method 1

a voltage is applied to a piezoelectric transducer, typically through electrical connection with a flex circuit electrode electrically coupled to a voltage source, which causes the piezoelectric transducer to bend or deflect, resulting in a flexing of the diaphragm

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

forming at least one electrode pattern by depositing a conductive material on an exposed surface of the at least one piezoelectric layer

Methodology Applied

Scientific EffectPhysical vapor deposition: Physical Vapour Deposition

Data Source

PatentEP3235646B1Method of forming piezo driver electrodes

Publication Date: 2022.03.16 XEROX CORP

Figure 1A
Figure 1B
Figure 2A~2B

AI summary

A method for forming piezoelectric transducers for inkjet printheads includes: forming at least one piezoelectric layer on a substrate; forming at least one electrode pattern by depositing a conductive material on an exposed surface of the at least one piezoelectric layer; and forming a plurality of individual piezoelectric elements from the at least one piezoelectric layer before or after the forming of the at least one electrode pattern.