# US 11,029,677 B2 · Method of assessing reliability of electronics assemblies under drilling vibration conditions

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- Number: US 11,029,677 B2
- Document ID: US11029677B2
- Status: Granted
- Kind: B2
- Application number: 15/858,978
- Filed: 2017-12-29
- Published: 2019-07-04
- Granted: 2021-06-08
- Earliest claimed: 2017-12-29
- Assignees: China Petroleum & Chemical Corporation
- Applicants: China Petroleum & Chemical Corporation; Sinopec Tech Houston, LLC.
- Inventors: Sheng Zhan; Jinhai Zhao; Fengtao Hu; Herong Zheng
- Web page: https://patentgrep.com/patent/US11029677B2

## CPC

- G05B 23/0243: {model based detection method, e.g. first-principles knowledge model}
- E21B 7/04: Directional drilling
- E21B 17/16: Drill collars
- E21B 44/005: {Below-ground automatic control systems}
- E21B 47/007: Measuring stresses in a pipe string or casing (for locating blocked portions of pipes E21B47/09)
- G05B 13/04: involving the use of models or simulators
- G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G)
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS

## Abstract

A method for assessing reliability of an electronic component under downhole vibration conditions include designing a set of vibration test conditions and conduct failure analysis. The vibration test conditions include the natural vibration frequency, the overstress limit of the test vehicle, and the step stress profile for testing the test vehicle. The failure analysis of the failed electronic component includes the step of measuring an electrical resistance of the failed electronic component without a vibration load. When the electrical resistance of the failed electronic component remains large, the failed electronic component is cross-sectioned. Finally, the cross-sectioned electronic component is examined to identify a failure mode.

## Claims

### Claim 1

A method for assessing reliability of an electronic component under downhole vibration conditions, comprising:
mounting one or more electronic components on a printed circuit board to form a test vehicle;
measuring a natural vibration frequency of the test vehicle;
choosing a test vibration frequency range that includes the natural vibration frequency of the test vehicle;
determining an overstress limit of the test vehicle, wherein the overstress limit has a power spectral density (PSD) value of 0.6 G2/Hz;
determining a step stress profile for testing the test vehicle, wherein the step stress has a maximum value lower than the overstress limit of the test vehicle;
testing the test vehicle according to the step stress profile until one or more of the plurality of electronic components on the test vehicle fails;
measuring an electrical resistance of the failed electronic component without a vibration load;
when the electrical resistance of the failed electronic component remains large, cross-sectioning the failed electronic component; and
examining the cross-sectioned electronic component to identify a failure mode,
wherein testing the test vehicle according to the step stress profile comprises applying to the test vehicle a stress of PSD value ranging from 0.1 G2/Hz to 0.3 G2/Hz.

### Claim 2 (depends on 1)

The method of claim 1, wherein the electronic component is a plastic dual in-line package (PDIP) insertion mounted on the test vehicle.

### Claim 3 (depends on 2)

The method of claim 2, wherein the PDIP has a plurality of lead terminals, and a metallurgy finish of the lead terminals is SnPd or Matte Sn.

### Claim 4 (depends on 2)

The method of claim 2, wherein the failure mode is one or more selected from the group consisting of lead wire fracture, intermetallic solder-to-board pad separation, pad-to-board separation, and board trace.

### Claim 5 (depends on 1)

The method of claim 1, wherein the electronic component is soldered to the printed circuit board.

### Claim 6 (depends on 5)

The method of claim 5, wherein the solder is Sn37Pb (SnPb) or Sn3.0Ag0.5C (SAC).

### Claim 7 (depends on 5)

The method of claim 5, wherein the printed circuit board comprises one or more pads, wherein a pad finish is selected from the group consisting of Hot Air Solder Leveled (HASL), immersion Sn (ImSn), immersion Ag (ImAg), electroless nickel immersion gold (ENIG), and organic solubility preservative (OSP).

### Claim 8 (depends on 1)

The method of claim 1, wherein the electronic component has been aged at an elevated temperature for a period of time.

### Claim 9 (depends on 8)

The method of claim 8, wherein the aging is conducted at 125° C. for 100 hours.

### Claim 10 (depends on 1)

The method of claim 1, wherein the electronic component has been aged at a subzero temperature for a period of time.

### Claim 11 (depends on 10)

The method of claim 10, wherein the aging is conducted at −50° C. for 1000 hours.

### Claim 12 (depends on 1)

The method of claim 1, wherein the cross-sectioned electronic component is examined using an optical microscope or X-ray.

### Claim 13 (depends on 1)

The method of claim 1, wherein the test vibration frequency ranges from 40 Hz to 500 Hz.

### Claim 14 (depends on 1)

The method of claim 1, wherein the step stress profile comprises applying PSD of 0.1 G2/Hz for 6 hours, 0.2 G2/Hz for 6 hours, and 0.3 G2/Hz for 6 hours in succession.