# US 10,485,109 B2 · Electrical devices with electrodes on softening polymers and methods of manufacturing thereof

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- Number: US 10,485,109 B2
- Document ID: US10485109B2
- Status: Granted
- Kind: B2
- Application number: 15/794,863
- Filed: 2017-10-26
- Published: 2018-05-03
- Granted: 2019-11-19
- Earliest claimed: 2016-10-28
- Assignees: Board of Regents, The University of Texas System
- Applicants: Board of Regents, The University of Texas System
- Inventors: Romil Modi; Jonathan Reeder; Gregory T. Ellson; Walter Voit; Alexandra Joshi Imre
- Web page: https://patentgrep.com/patent/US10485109B2

## CPC

- H05K 3/4007: {Surface contacts, e.g. bumps (H05K3/4092 takes precedence; deposition of finish layers on pads H05K3/24; forming solder bumps H05K3/3465)}
- H05K 1/09: Use of materials for the {conductive, e.g. } metallic pattern
- H05K 1/111: {Pads for surface mounting, e.g. lay-out}
- H05K 3/0041: {by plasma etching}
- H05K 3/048: {using a lift-off resist pattern or a release layer pattern}
- H05K 3/064: {Photoresists}
- H05K 3/067: {Etchants}
- H05K 3/1216: {by screen printing or stencil printing}
- H05K 3/1225: {Screens or stencils; Holders therefor}
- H05K 1/0393: {Flexible materials (H05K1/038 takes precedence; specific organic compositions are classified in H05K1/0313 and subgroups)}
- H05K 3/1283: {After-treatment of the printed patterns, e.g. sintering or curing methods}
- H05K 3/346: Solder materials or compositions specially adapted therefor
- H05K 2203/043: Reflowing of solder coated conductors, not during connection of components, e.g. reflowing solder paste
- H05K 2203/087: Using a reactive gas
- H05K 2203/166: Alignment or registration; Control of registration
- H10P 76/403: {for lift-off processes}
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

Flexible electrical devices comprising electrode layers on softening polymers and methods of manufacturing such devices, including lift-off processes for forming electrodes on softening polymers, processes for forming devices with a patterned double softening polymer layer, and solder reflow processes for forming electrical contacts on softening polymers.

## Claims

### Claim 1

A method of manufacturing an electrical device, comprising:
forming a softening polymer layer with an electrode layer on a surface of the softening polymer layer;
forming a second softening polymer cover layer on the surface of the softening polymer layer, wherein:
a mechanical neutral plane of the electrical device is located at or above the surface of the softening polymer layer, and
an opening in the second softening polymer cover layer exposes a portion of a surface of the electrode layer, wherein the softening polymer layer and second softening polymer cover layer are composed of a softening polymer having a Young's modulus that decreases by more than 1 order of magnitude within an about 30° C. temperature increase.

### Claim 2 (depends on 1)

The method of claim 1, further including:
forming an inorganic hardmask layer on the second softening polymer cover layer;
removing, by a reactive ion etch process, a portion of the inorganic hardmask layer exposed through an opening in a patterned photoresist layer located on the inorganic hardmask layer to form an opening in the inorganic hardmask layer;
removing, by the reactive ion etch process, exposed portions of the cover layer underlying the opening in the inorganic hardmask layer to form the opening in the second softening polymer cover layer; and
removing the patterned photoresist layer and the inorganic hardmask layer.

### Claim 3 (depends on 2)

The method of claim 2, further including:
depositing a second electrode layer on the inorganic liftoff layer and the portion of the surface of the electrode layer.

### Claim 4 (depends on 3)

The method of claim 3, further including removing the inorganic hardmask layer by a horizontal liftoff etch that includes exposing the inorganic hardmask layer to an ester-based photoresist removing solvent or a potassium borate photo developing solution.

### Claim 5 (depends on 1)

The method of claim 1, further including exposing the surface of the softening polymer layer to a reactive ion etch treatment before forming the second softening polymer cover layer on the surface of the softening polymer layer, wherein
the surface of the softening polymer layer after the reactive ion etch treatment has an at least double a root mean squared surface roughness as compared to the surface before the reactive ion etch treatment, and
a thickness of the softening polymer layer after the reactive ion etch treatment is within about ±5 percent of the thickness of the softening polymer layer before the reactive ion etch treatment.

### Claim 6 (depends on 2)

The method of claim 2, wherein the removing, by the reactive ion etch process, of the exposed portions of the cover layer includes forming a plasma formed from a feed gas of oxygen at about 200 W biasing power and a pressure of about 200 mTorr.

### Claim 7 (depends on 1)

The method of claim 1, wherein the within about 30° C. temperature increase is from about 20° C. to about 50° C.

### Claim 8 (depends on 1)

The method of claim 1, wherein the within about 30° C. temperature increase is from about 20° C. to about 37° C.