PCBA Vibration Reliability Assessment for Downhole Drilling

Solution Overview

Problem

Downhole drilling operations face challenges in assessing the reliability of printed circuit board assemblies (PCBAs) under vibration conditions, as existing methods struggle to accurately pinpoint failure sites and modes due to reversible electrical resistance changes and complex failure mechanisms.

Innovation Solution

A method involving a test vehicle with electronic components subjected to step stress profiling, where natural vibration frequency and overstress limits are determined, and the components are tested until failure, followed by detailed failure analysis using electrical resistance measurement and cross-sectioning for mode identification.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If vibration tests are conducted to understand damages caused by vibrations, then reliability assessment information is obtained, but it is difficult to pinpoint the failure site and the failure mode

Engineering Contradiction:

Improvereliability assessmentVSAvoidfailure site identification

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent applies preliminary action by pre-coating the PCB assembly with a fracture visualization material before vibration testing. This allows failure sites to be visually identified after testing, as the coating cracks at the same locations where solder joint failures occur, making failure detection straightforward without complex post-test analysis

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent utilizes color changes through the application of a fracture visualization coating that changes appearance when cracked. The coating contains pigments or dyes that reveal crack patterns visually, allowing operators to easily locate and analyze failure sites by observing color changes or pattern disruptions on the PCB surface after vibration exposure

Inventive Principle:

Principle #32Color changes

2Measurement precision

If electrical resistance monitoring is used during vibration loading, then real-time failure detection is achieved, but the resistance immediately returns to normal when vibration loading is off due to crack healing

Engineering Contradiction:

Improvereal-time failure detectionVSAvoidfailure state stability

Core Design Contradiction:

Measurement precisionVSStability of the object's composition

Solution Approach 1:

The patent applies preliminary action by pre-coating the PCB assembly with a fracture visualization material before vibration testing. This allows failure sites to be visually identified after testing, as the coating cracks at the same locations where solder joint failures occur, making failure detection straightforward without complex post-test analysis

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The fracture visualization coating acts as an intermediary that provides permanent visual evidence of failure locations. While electrical resistance monitoring detects functional failures, the coating provides a stable, permanent record of where failures occurred, complementing the electrical measurements with visual confirmation that persists after vibration loading ends

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If detailed failure analysis including cross-sectioning is performed, then failure modes are accurately identified, but the analysis process becomes more complex and time-consuming

Engineering Contradiction:

Improvefailure mode identificationVSAvoidanalysis time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies preliminary action by pre-coating the PCB assembly with a fracture visualization material before vibration testing. This allows failure sites to be visually identified after testing, as the coating cracks at the same locations where solder joint failures occur, making failure detection straightforward without complex post-test analysis

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies segmentation by using the fracture visualization coating to divide and highlight specific failure locations on the PCB assembly. The coating cracks selectively at failure sites, effectively segmenting the analysis focus from the entire assembly to only the relevant failure points, thereby reducing the time and effort needed for comprehensive inspection

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS11029677B2Method of assessing reliability of electronics assemblies under drilling vibration conditions

Publication Date: 2021.06.08 CHINA PETROLEUM & CHEMICAL CORP

AI summary

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.