# US 7,216,062 B1 · Characterizing degradation of components during reliability-evaluation studies

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- Number: US 7,216,062 B1
- Document ID: US7216062B1
- Status: Granted
- Kind: B1
- Application number: 11/452,632
- Filed: 2006-06-13
- Granted: 2007-05-08
- Earliest claimed: 2006-06-13
- Assignees: Sun Microsystem, Inc.
- Inventors: Dan Vacar; David K. McElfresh; Kenny C. Gross; Leoncio D. Lopez
- Web page: https://patentgrep.com/patent/US7216062B1

## CPC

- G06F 11/008: {Reliability or availability analysis}
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)

## Abstract

A system that characterizes degradation of a component in a system. During operation, the system monitors inferential variables associated with a specimen of the component. Next, the system determines a time for the onset of degradation for the specimen and determines a time for the completion of degradation for the specimen. The system then computes a time interval between the onset of degradation and the completion of degradation, and uses the time interval to look up an entry in a defect library to obtain information which characterizes the degradation of the specimen of the component.

## Claims

### Claim 1

A method for characterizing degradation of a component in a system, comprising:
monitoring inferential variables associated with a specimen of the component;
determining a time for an onset of degradation for the specimen;
determining a time for a completion of degradation for the specimen;
computing a time interval between the onset of degradation and the completion of degradation for the specimen; and
using the time interval to look up an entry in a defect library to obtain information which characterizes the degradation of the specimen of the component.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
determining the sign of the degradation; and
using the time interval and the sign of the degradation to look up an entry in the defect library to obtain information which characterizes the degradation of the specimen of the component.

### Claim 3 (depends on 1)

The method of claim 1, wherein monitoring the inferential variables involves applying a Sequential Probability Ratio Test (SPRT) to time series of the inferential variables to detect changes in the inferential variables.

### Claim 4 (depends on 3)

The method of claim 3, wherein the inferential variables can include:
a physical parameter for the component; and
a first derivative of the physical parameter for the component.

### Claim 5 (depends on 4)

The method of claim 4, wherein determining the time for the onset of degradation involves:
detecting a change in the physical parameter for the component;
determining whether the change indicates that the specimen of the component is at the onset of degradation; and
if so, noting the time when the specimen of the component was determined to be at the onset of degradation.

### Claim 6 (depends on 4)

The method of claim 4, wherein determining the time for the completion of degradation involves:
detecting a change in the first derivative of the physical parameter;
determining whether the change in the first derivative indicates that degradation of the component has completed; and
if so, noting the time when the degradation of the component completed.

### Claim 7 (depends on 1)

The method of claim 1, wherein prior to monitoring the inferential variables, the method further comprises applying test conditions to the specimen of the component.

### Claim 8 (depends on 7)

The method of claim 7, further comprising:
determining if the test conditions need to be modified; and
if so,
altering the test conditions; and
continuing to monitor the inferential variables associated with specimens of the component.

### Claim 9

A computer-readable storage medium storing instructions that when executed by a computer cause the computer to perform a method for characterizing degradation of a component in a system, wherein the method comprises:
monitoring inferential variables associated with a specimen of the component;
determining a time for an onset of degradation for the specimen;
determining a time for a completion of degradation for the specimen;
computing a time interval between the onset of degradation and the completion of degradation for the specimen; and
using the time interval to look up an entry in a defect library to obtain information which characterizes the degradation of the specimen of the component.

### Claim 10 (depends on 9)

The computer-readable storage medium of claim 9, wherein the method further comprises:
determining the sign of the degradation; and
using the time interval and the sign of the degradation to look up an entry in the defect library to obtain information which characterizes the degradation of the specimen of the component.

### Claim 11 (depends on 9)

The computer-readable storage medium of claim 9, wherein monitoring the inferential variables involves applying a Sequential Probability Ratio Test (SPRT) to time series of the inferential variables to detect changes in the inferential variables.

### Claim 12 (depends on 11)

The computer-readable storage medium of claim 11, wherein the inferential variables can include:
a physical parameter for the component; and
a first derivative of the physical parameter for the component.

### Claim 13 (depends on 12)

The computer-readable storage medium of claim 12, wherein determining the time for the onset of degradation involves:
detecting a change in the physical parameter for the component;
determining whether the change indicates that the specimen of the component is at the onset of degradation; and
if so, noting the time when the specimen of the component was determined to be at the onset of degradation.

### Claim 14 (depends on 12)

The computer-readable storage medium of claim 12, wherein determining the time for the completion of degradation involves:
detecting a change in the first derivative of the physical parameter;
determining whether the change in the first derivative indicates that degradation of the component has completed; and
if so, noting the time when the degradation of the component completed.

### Claim 15 (depends on 9)

The computer-readable storage medium of claim 9, wherein prior to monitoring the inferential variables, the method further comprises applying test conditions to the specimen of the component.

### Claim 16 (depends on 15)

The computer-readable storage medium of claim 15, wherein the method further comprises:
determining if the test conditions need to be modified; and
if so,
altering the test conditions; and
continuing to monitor the inferential variables associated with specimens of the component.

### Claim 17

An apparatus that characterizes degradation of a component in a system, comprising:
a monitoring mechanism configured to monitor inferential variables associated with a specimen of the component;
a degradation-detection mechanism configured to:
determine a time for an onset of degradation for the specimen;
determine a time for a completion of degradation for the specimen; and to
compute a time interval between the onset of degradation and the completion of degradation for the specimen; and
a defect-characterization mechanism configured to use the time interval to look up an entry in a defect library to obtain information which characterizes the degradation of the specimen of the component.

### Claim 18 (depends on 17)

The apparatus of claim 17,
wherein the degradation-detection mechanism is configured to determine the sign of the degradation; and
wherein the defect-characterization mechanism is configured to use the time interval and the sign of the degradation to look up an entry in the defect library to obtain information which characterizes the degradation of the specimen of the component.

### Claim 19 (depends on 17)

The apparatus of claim 17, wherein while monitoring the inferential variables, the degradation-detection mechanism is configured to apply a Sequential Probability Ratio Test (SPRT) to time series of the inferential variables to detect changes in the inferential variables.

### Claim 20 (depends on 19)

The apparatus of claim 19, wherein the inferential variables can include:
a physical parameter for the component; and
a first derivative of the physical parameter for the component.