Characterization of dielectric materials

Patent metadata

Field	Value
Publication number	US-9689822-B2
Application number	US-201514602370-A
Country	US
Kind code	B2
Filing date	Jan 22, 2015
Priority date	Jan 22, 2015
Publication date	Jun 27, 2017
Grant date	Jun 27, 2017

Abstract

A system and a method for characterizing a dielectric material are provided. The system and method generally include applying an excitation signal to electrodes on opposing sides of the dielectric material to evaluate a property of the dielectric material. The method can further include measuring the capacitive impedance across the dielectric material, and determining a variation in the capacitive impedance with respect to either or both of a time domain and a frequency domain. The measured property can include pore size and surface imperfections. The method can still further include modifying a processing parameter as the dielectric material is formed in response to the detected variations in the capacitive impedance, which can correspond to a non-uniformity in the dielectric material.

First claim

The invention claimed is:

1. A method for evaluating a dielectric material comprising:
providing a dielectric material including a first major surface, a second major surface, and a thickness therebetween;
providing a first electrode adjacent the first major surface and a second electrode adjacent the second major surface, wherein the first and second electrodes and the dielectric material are moveable relative to each other in a lengthwise direction of the dielectric material;
applying an excitation signal to at least one of the first and second electrodes to generate an electric field across the dielectric material, wherein the excitation signal includes an alternating current waveform having a plurality of component frequencies;
measuring the electrical signature of the dielectric material by sampling the current or voltage from at least one of the first and second electrodes; and
comparing the measured electrical signature against an expected electrical signature to evaluate, based on the comparison, a property of the dielectric material over at least a portion of the length of the dielectric material, wherein the property of the dielectric material includes pore size.

2. The method according to claim 1 wherein the electrical signature includes the amplitude of the sampled current or voltage over time.

3. The method according to claim 1 wherein the electrical signature includes the frequency of the sampled current or voltage over time.

4. The method according to claim 1 wherein the electrical signature includes the dominant frequencies of the sampled current or voltage.

5. The method according to claim 1 wherein measuring the electrical signature is performed at the plurality of component frequencies.

6. The method according to claim 1 wherein providing the dielectric material includes manufacturing the dielectric material in accordance with a processing parameter, the method further including adjusting the processing parameter for the manufacture of a further dielectric material in view of the comparison of the measured electrical signature against the expected electrical signature.

7. A system for characterizing a dielectric material comprising:
a first electrode on a first side of the dielectric material and a second electrode on a second side of the dielectric material, wherein the dielectric material and at least one of the first and second electrodes are moveable relative to each other in a lengthwise direction of the dielectric material, the first electrode being capacitively coupled to the second electrode through the dielectric material to define a capacitive coupling;
a waveform generator adapted to provide an excitation signal to at least one of the first electrode and the second electrode of the capacitive coupling, wherein the excitation signal includes an alternating current waveform having a plurality of component frequencies and wherein the excitation signal causes a current or a voltage at the capacitive coupling; and
a measurement circuit electrically coupled to at least one of the first electrode and the second electrode, the measurement circuit being adapted to measure the current or the voltage at the capacitive coupling for evaluating a property of the dielectric material over at least a portion of the length of the dielectric material, wherein the property of the dielectric material includes pore size.

8. The system of claim 7 wherein the dielectric material is a continuous roll-formed substrate.

9. The system of claim 8 wherein the first electrode is a roller having a cylindrical outer surface in engagement with the first side of the roll-formed substrate.

10. The system of claim 9 wherein the second electrode is a roller having a cylindrical outer surface in engagement with the second side of the roll-formed substrate.

11. The system of claim 9 wherein the second electrode is a conductive plate having a major surface in engagement with the second side of the roll-formed substrate.

12. A method for evaluating a dielectric substrate comprising:
providing a dielectric substrate including a first major surface, a second major surface, a thickness therebetween, and a length;
providing a first electrode adjacent the first major surface and a second electrode adjacent the second major surface, the dielectric material and at least one of the first and second electrodes being moveable relative to each other in a lengthwise direction of the dielectric material;
generating an electric field across the thickness of the dielectric substrate at a plurality of locations along the length of the dielectric substrate by applying an excitation signal to at least one of the first and second electrodes, wherein the excitation signal includes an alternating current waveform having a plurality of component frequencies;
measuring the capacitive impedance across the dielectric substrate at the plurality of locations along the length of the dielectric substrate; and
determining a variation in the capacitive impedance of the dielectric substrate along the length of the dielectric substrate to evaluate, based on the determined variation, a property of the dielectric material over at least a portion of the length of the dielectric material, wherein the property of the dielectric material includes pore size.

13. The method according to claim 12 wherein measuring the capacitive impedance is performed with respect to a time domain.

14. The method according to claim 12 wherein measuring the capacitive impedance is performed with respect to a frequency domain.

15. The method according to claim 12 wherein determining a variation in the capacitive impedance is based on a change in capacitive impedance over time.

Assignees

• Ut Battelle Llc
• Ut Battelle Llc

Inventors

• King Danny J
• Babinec Susan
• Hagans Patrick L
• Maxey Lonnie C
• Payzant Edward A
• Daniel Claus
• Sabau Adrian S
• Dinwiddie Ralph B
• Armstrong Beth L
• Howe Jane Y
• Wood Iii David L
• Nembhard Nicole S

Classifications

• G01N27/221 Primary

  by investigating the dielectric properties (using microwaves G01N22/00; measuring loss factors or dielectric constants per se G01R27/26) · CPC title

• G01N27/24 Primary

  Investigating the presence of flaws · CPC title