# US 2018/0321090 A1 · Lifetime Determining Technique for a Solid Electrolytic Capacitor and System for the Same

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- Number: US 2018/0321090 A1
- Document ID: US20180321090A1
- Status: Published application
- Kind: A1
- Application number: 15/966,065
- Filed: 2018-04-30
- Published: 2018-11-08
- Earliest claimed: 2017-05-08
- Assignees: AVX Corporation
- Applicants: AVX Corporation
- Inventors: Jan Petrzilek; Miloslav Uher
- Web page: https://patentgrep.com/patent/US20180321090A1

## CPC

- G01K 3/04: in respect of time
- G01R 27/2605: {Measuring capacitance (capacitive sensors G01D5/24)}
- G01R 31/003: {Environmental or reliability tests (of individual semiconductors G01R31/2642; of PCB's G01R31/2817; of IC's G01R31/2855; of other circuits G01R31/2849)}
- G01R 31/64: Testing of capacitors
- H01G 9/0003: {Protection against electric or thermal overload; cooling arrangements; means for avoiding the formation of cathode films (H01G9/12 takes precedence)}
- H01G 9/025: Solid electrolytes (H01G11/54 takes precedence)
- H01G 9/15: Solid electrolytic capacitors (H01G11/00 takes precedence)
- H01G 9/012: specially adapted for solid capacitors
- H01G 9/042: characterised by the material (H01G11/22 takes precedence)
- H01G 9/052: Sintered electrodes
- G01K: MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR (radiation pyrometry G01J5/00)
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- H01G: CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE (selection of specified materials as dielectric H01B3/00; capacitors having potential barriers H10D1/62, H10K10/10)

## Abstract

A system and method for determining the lifetime of a capacitor element, specifically a capacitor element comprising a solid electrolyte that undergoes oxidation, is provided. The system and method utilize a capacitor element comprising an anode body, a dielectric, and a solid electrolyte, and may also comprise other stages of the production of a capacitor. The system and method provide an estimation of the life of the capacitor while considering the oxidation of the solid electrolyte.

## Claims

### Claim 1

A capacitor lifetime determining system comprising:
a capacitor element, wherein the capacitor element comprises a sintered porous anode body, a dielectric that overlies the anode body, and a solid electrolyte that overlies the dielectric;
a capacitance measuring device, the measuring device configured to measure the capacitance of the capacitor element;
a control device, the control device configured to apply thermodynamic temperatures to the system; and
a computing device, wherein the computing device is configured to determine constants A/x and −E/k associated with data obtained at the applied thermodynamic temperatures based on technique (1):
A
x

t


e
[
-
E
k
]

1
T
=
1
(
1
)
wherein x is an amount of oxidized solid electrolyte, t is a time in which the capacitance of the capacitor element is decreased by a specified level, T is a thermodynamic temperature, A is a frequency factor, k is Bolzmann constant, e is Euler constant, and E is an activation energy of the reaction;
wherein the computing device is configured to determine a time to degradation to the specified level at a proposed thermodynamic temperature using the activation energy and frequency factor associated with the applied thermodynamic temperatures based on technique (1); and
wherein the solid electrolyte comprises a conductive polymer.

### Claim 2 (depends on 1)

The capacitor lifetime determining circuit of claim 1, wherein the capacitor element is exposed to an oxygen-containing environment.

### Claim 3 (depends on 1)

The capacitor lifetime determining circuit of claim 1, wherein the conductive polymer comprises poly(3,4-ethylenedioxythiophene).

### Claim 4 (depends on 1)

The capacitor lifetime determining circuit of claim 1, wherein the sintered anode body comprises tantalum.

### Claim 5 (depends on 1)

The capacitor lifetime determining circuit of claim 1, wherein the capacitor element comprises a graphite layer disposed along the solid electrolyte.

### Claim 6 (depends on 5)

The capacitor lifetime determining circuit of claim 5, wherein the capacitor element comprises a silver layer disposed along the graphite layer.

### Claim 7 (depends on 1)

The capacitor lifetime determining circuit of claim 1, wherein the applied thermodynamic temperatures range from about 70° C. to about 175° C.

### Claim 8 (depends on 1)

The capacitor lifetime determining circuit of claim 1, wherein the proposed thermodynamic temperature ranges from about 20° C. to about 175° C.

### Claim 9

A method of determining the lifetime of a capacitor comprising:
controlling a first temperature to which a first capacitor element is exposed,
measuring a capacitance of the first capacitor element after exposure to the first temperature,
determining a time in which the capacitance of the first capacitor element during exposure to the first temperature is decreased by a specified level,
controlling a second temperature to which a second capacitor element is exposed,
measuring a capacitance of the second capacitor element after exposure to the second temperature,
determining a time in which the capacitance of the second capacitor element during exposure to the second temperature is decreased by the specified level,
applying technique (1) to determine constants A/x and −E/k associated with the first and second temperatures:
A
x

t


e
[
-
E
k
]

1
T
=
1
,
(
1
)
wherein x is an amount of oxidized solid electrolyte, t is time, T is thermodynamic temperature, A is a frequency factor, k is Bolzmann constant, e is Euler constant, and E is activation energy of the reaction and
applying the constants A/x and −E/k associated with the first and second temperatures to technique (1) to determine a time to degradation at a third temperature,
wherein the first and second capacitor elements comprise a sintered anode body, a dielectric formed along the sintered anode body, and a solid electrolyte formed along the dielectric; and wherein the solid electrolyte comprises a conductive polymer.

### Claim 10 (depends on 9)

The method of claim 9, further comprising controlling a plurality of temperatures to which a plurality of capacitor elements are exposed, measuring the capacitance of each of the plurality of capacitor elements after temperature exposure, and determining the time for degradation of the capacitance of each of the plurality of capacitor elements to the specified level.

### Claim 11 (depends on 9)

The method of claim 9, further comprising plotting the time for degradation of the capacitance of the first and second capacitor elements at the first and second temperatures.

### Claim 12 (depends on 9)

The method of claim 9, wherein each of the first and second capacitor elements comprise a graphite layer disposed along the solid electrolyte.

### Claim 13 (depends on 12)

The method of claim 12, wherein each of the first and second capacitor elements comprise a silver layer disposed along the graphite layer.

### Claim 14 (depends on 10)

The method of claim 10, wherein each of the capacitor elements of the plurality of capacitor elements comprises one or more of an external layer comprising a conductive polymer, a graphite layer, and a silver layer.

### Claim 15 (depends on 9)

The method of claim 9, wherein the first and second temperatures range from about 70° C. to about 175° C.

### Claim 16 (depends on 9)

The method of claim 9, wherein the third temperature ranges from about 20° C. to about 175° C.

### Claim 17 (depends on 9)

The method of claim 9, further comprising contacting the first and second capacitor elements with an atmosphere having a relative humidity of about 40% or more.

### Claim 18 (depends on 9)

The method of claim 9, wherein the conductive polymer comprises poly(3,4-ethylenedioxythiophene).

### Claim 19 (depends on 9)

The method of claim 9, wherein the sintered anode body comprises tantalum.

### Claim 20 (depends on 9)

The method of claim 9, further comprising exposing the first and second capacitor elements to an oxygen-containing environment.