# US 11,309,484 B2 · PVDF piezoelectric reliability and electrode adhesion improvement

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- Number: US 11,309,484 B2
- Document ID: US11309484B2
- Status: Granted
- Kind: B2
- Application number: 16/246,521
- Filed: 2019-01-13
- Published: 2020-07-16
- Granted: 2022-04-19
- Earliest claimed: 2019-01-13
- Assignees: Littelfuse, Inc.
- Applicants: Littelfuse, Inc.
- Inventors: Yuriy B. Matus; Martin Pineda; Edward W. Rutter, Jr.
- Web page: https://patentgrep.com/patent/US11309484B2

## CPC

- H10N 30/857: Macromolecular compositions
- H10N 30/883: {Additional insulation means preventing electrical, physical or chemical damage, e.g. protective coatings}
- H10N 30/02: Forming enclosures or casings
- H10N 30/05: Manufacture of multilayered piezoelectric or electrostrictive devices, or parts thereof, e.g. by stacking piezoelectric bodies and electrodes
- H10N 30/50: having a stacked or multilayer structure
- H10N 30/704: {based on piezoelectric or electrostrictive films or coatings}
- H10N 30/872: {Interconnections, e.g. connection electrodes of multilayer piezoelectric or electrostrictive devices}
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR

## Abstract

A device may include an inner layer comprising a polyvinylidene fluoride (PVDF) material. The device may also include a first interface layer, disposed on a first side of the inner layer, and a second interface layer, disposed on a second side of the inner layer. The first interface layer and the second interface layer may comprise a mixture of PVDF material and a scavenger component.

## Claims

### Claim 1

A device, comprising:
an inner layer comprising a polyvinylidene fluoride (PVDF) material;
a first interface layer, disposed on a first side of the inner layer;
a second interface layer, disposed on a second side of the inner layer, wherein the first interface layer and the second interface layer comprise a mixture of PVDF material and a scavenger component; and
a first electrode, adjacent the first interface layer, and a second electrode, adjacent the second interface layer, wherein the first electrode and the first interface layer define a first electrode interface, wherein the second electrode and the second interface layer define a second electrode interface, wherein the first electrode interface and the second electrode interface comprise a first roughness and a second roughness, the first roughness and the second roughness being less than a thickness of the first interface layer and a thickness of the second interface layer, respectively, and being greater than 0.1 μm and less than 25 μm.

### Claim 2 (depends on 1)

The device of claim 1, wherein the inner layer comprises a first thickness, wherein the first interface layer comprises a second thickness, and the second interface layer comprise a third thickness, the second thickness and the third thickness being less than the first thickness.

### Claim 3 (depends on 1)

The device of claim 1, wherein the inner layer comprises a thickness of 10 μm to 50 μm, and wherein the first interface layer and the second interface layer comprise an interface layer thickness of 1 μm to 15 μm.

### Claim 4 (depends on 1)

The device of claim 1, wherein the scavenger component comprises at least one of an oxide, a carbonate, a hydroxide, and an amine, wherein the oxide, the carbonate, the hydroxide, or the amine comprises at least one of calcium, magnesium, and zinc.

### Claim 5 (depends on 1)

The device of claim 1, wherein the first interface layer and the second interface layer further comprise an antioxidant.

### Claim 6 (depends on 5)

The device of claim 5, wherein the antioxidant comprises at least one of Agerite, MA, ZMTI, MTI, a phosphite, a thiodiproprionate ester, a phenolic antioxidant, Irganox 565, and Irganox 1010.

### Claim 7 (depends on 1)

The device of claim 1, wherein the first interface layer and the second interface layer further comprise an adhesion promoter.

### Claim 8 (depends on 7)

The device of claim 7, wherein the adhesion promotor comprises a maleic-acid-containing material or other carboxylic acid or salts thereof.

### Claim 9 (depends on 1)

The device of claim 1, wherein the device comprises an interdigitated electrode arrangement, disposed on a first surface of the inner layer.

### Claim 10

A method of forming a piezo-electric device, comprising:
providing an inner layer comprising a polyvinylidene fluoride (PVDF) material;
depositing a first coating on a first side of the inner layer;
depositing a second coating on a second side of the inner layer, opposite the first layer, the first coating and the second coating comprising a scavenger component
depositing a first electrode adjacent the first coating; and
depositing a second electrode adjacent the second coating;
wherein the first electrode and the first coating define a first electrode interface, wherein the second electrode and the second coating define a second electrode interface, wherein the first electrode interface and the second electrode interface comprise a first roughness and a second roughness, the first roughness and the second roughness being less than a thickness of the first coating and a thickness of the second coating, respectively, and being greater than 0.1 μm and less than 25 μm.

### Claim 11 (depends on 10)

The method of claim 10, wherein the first coating forms a first interface layer on the first side and the second coating forms a second interface layer on the second side, wherein the first interface layer and the second interface layer comprise a mixture of PVDF material and the scavenger component.

### Claim 12 (depends on 10)

The method of claim 10, wherein the scavenger component comprises at least one of an oxide, a carbonate, a hydroxide, and an amine, wherein the amine, the carbonate, the hydroxide, or the amine comprises at least one of calcium, magnesium, and zinc.

### Claim 13 (depends on 11)

The method of claim 11, wherein the first coating the second coating further comprise an antioxidant, and wherein the first interface layer and the second interface layer comprise a mixture of PVDF material, the scavenger component, and the antioxidant.

### Claim 14 (depends on 13)

The method of claim 13, wherein the antioxidant comprises at least one of Agerite, MA, ZMTI, MTI, a phosphite, a thiodiproprionate ester, a phenolic antioxidant, Irganox 565, and Irganox 1010.

### Claim 15 (depends on 13)

The method of claim 13, wherein the first coating and the second coating further comprise, an adhesion-promoter, and wherein the first interface layer and the second interface layer comprise a mixture of PVDF material, the scavenger component, the antioxidant, and the adhesion promoter.

### Claim 16 (depends on 11)

The method of claim 11, wherein the first coating and the second coating comprise an electrode material, wherein after the depositing the first coating and the depositing the second coating, a device structure is formed, comprising:
the inner layer, the first interface layer, the second interface layer, a first electrode, disposed adjacent the first interface layer, and a second interface layer, disposed adjacent the second interface layer.

### Claim 17 (depends on 10)

The method of claim 10, wherein the inner layer comprises a thickness of 10 μm to 50 μm, and wherein the first coating and the second coating form a first interface layer and a second interface layer within the inner layer.

### Claim 18 (depends on 16)

The method of claim 16, wherein the first interface layer and the second interface layer comprise an interface layer thickness of 1 μm to 15 μm.