Magnetoelectric macro fiber composite fabricated using low temperature transient liquid phase bonding

• US 10,312,429 B2
• Filed: 07/28/2016
• Issued: 06/04/2019
• Est. Priority Date: 07/28/2016
• Status: Active Grant

• Current Assignee: Eyob, LLC
• Original Assignee: Eyob, LLC
• Inventors: Varghese, Ron
• Primary Examiner(s): Stoner, Kiley S
• Application Number:
  US15/222,070
• Publication Number:
  US 20180033947A1
• Time in Patent Office: 1,041 Days
• Field of Search: 2281791-18022, 228245-262, 228175-176
• CPC Class Codes: B23K 1/0016 Brazing of electronic components
• CPC Class Codes: B23K 2101/36 Electric or electronic devices
• CPC Class Codes: G01R 33/18 Measuring magnetostrictive properties
• CPC Class Codes: H10N 30/00 Piezoelectric or electrostrictive devices integrated devices or assemblies of multiple devices H10N39/00
• CPC Class Codes: H10N 30/073 by fusion of metals or by adhesives
• CPC Class Codes: H10N 30/85 Piezoelectric or electrostrictive active materials
• CPC Class Codes: H10N 35/85 Magnetostrictive active materials

Abstract

A composite material fabricated using a novel process and materials. The piezoelectric and magnetostrictive layers of the composite material are coated, layered, and bonded using a process known as LTTLP bonding. The resulting magnetoelectric composite fibers are bonded to a polyimide film based copper flexible circuit using a room temperature curing epoxy. The sensor that results is an MEMFC that outperforms conventionally fabricated MEMFCs.

Claims

1. A magnetoelectric composite material comprised of:

a layer of piezoelectric (PE) material;

a layer of magnetostrictive (MS) material;

the layer of piezoelectric material bonded to the layer of magnetostrictive material using low temperature transient liquid phase (LTTLP) bonding, forming a composite material;

the LTTLP bond comprised of;

titanium, gold, and a solder alloy;

 

the titanium used to form an adhesion layer on the PE material and the MS material;

 

the gold used to form a bonding layer on the PE material and the MS material; and

 

the solder alloy used to bond the PE material and MS material together by diffusing into the bonding layers;

the composite material divided into multiple fibers;

a flexible circuit;

the flexible circuit applied to the composite material;

an epoxy spin coating applied to the combination of the flexible circuit and composite material;

wherein the solder alloy has a melting point at or below a Curie temperature of the PE material and at or below a Curie temperature of the MS material.

2. The composite material of claim 1, further comprising:

an interdigitated electrode having a first electrode pattern and a second electrode pattern, the interdigitated electrode bonded to either the PE material or the MS material;

whereby deformation of the composite material causes a voltage difference between the first electrode pattern and the second electrode pattern.

3. The composite material of claim 1, wherein the solder alloy the solder alloy is 52% Indium (In) and 48% Tin (Sn), with a eutectic point of 118°

C.

4. A method of fabricating a composite material with piezoelectric (PE) and magnetostrictive (MS) layers, the method comprising:

creating a PE adhesion layer by coating one side of a piezoelectric material with a layer of a first metal;

creating an MS adhesion layer by coating one side of a magnetostrictive material with a layer of the first metal;

creating a PE bonding layer by coating the PE adhesion layer with a layer of a second metal;

creating a MS bonding layer by coating the MS adhesion layer with a layer of the second metal;

creating an PE solder layer by depositing solder alloy on the PE bonding layer;

creating a MS solder layer by depositing solder alloy on the MS bonding layer;

pressing the PE solder layer and MS solder layer against one-another while heating to a temperature;

the temperature no greater than a Curie temperature of the magnetostrictive material;

thereby bonding the PE and MS materials to each other, resulting in the composite materials;

slicing the composite material into fibers;

applying a flexible circuit to the composite material;

spin coating the composite material and flexible circuit with epoxy; and

vacuum bonding the composite material and flexible circuit.

5. The method of claim 4, further comprising the step of:

bonding an interdigitated electrode on the piezoelectric material, the interdigitated electrode having a first electrode pattern and a second electrode pattern.

6. The method of claim 4, wherein:

the first metal is titanium; and

the second metal is gold.

7. The method of claim 4, wherein:

the solder alloy is composed of 52% Indium (In) and 48% Tin (Sn), with eutectic point of 118°

C.

8. A composite material fabricated by the process of:

coating a piezoelectric (PE) material with one or more layers of metal;

coating a magnetostrictive (MS) material with one more layers of metal;

creating a first solder layer by depositing solder alloy on the one or more layers of metal of the PE material;

creating a second solder layer by depositing solder alloy on the one or more layers of metal of the MS material;

pressing the first solder layer and second solder layer together while applying heat, thereby bonding the PE and ME materials to each other, resulting in a magnetoelectric composite materials;

slicing the magnetoelectric composite material into fibers;

applying a flexible circuit to the magnetoelectric composite material;

spin coating the magnetoelectric composite fibers and flexible circuit with epoxy; and

vacuum bonding the magnetoelectric composite material and flexible circuit;

thereby creating an MEMFC.

9. The composite material fabricated by the process of claim 8, wherein:

the one or more layers of metal applied to the PE material is titanium.

10. The composite material fabricated by the process of claim 8, wherein:

the one or more layers of metal applied to the PE material is a layer of titanium followed by a layer of gold.

11. The composite material fabricated by the process of claim 8, wherein:

the solder alloy has a melting point at or below a Curie temperature of the PE material and at or below a Curie temperature of the MS material.

12. The composite material fabricated by the process of claim 8, further comprising the step of:

bonding an interdigitated electrode on the piezoelectric material, the interdigitated electrode having a first electrode pattern and a second electrode pattern.