Reliability Investigation Procedures

Reliability has become one of the most critical performance indicators in modern electronics. Whether deployed in industrial automation systems, automotive control units, telecommunications infrastructure, medical devices, aerospace equipment, or data center hardware, semiconductor components are expected to maintain stable operation over extended service lives and under increasingly demanding environmental conditions. When unexpected failures occur, organizations must determine not only what failed, but why the failure occurred, how widespread the risk may be, and what actions are necessary to prevent recurrence.

Reliability investigation procedures provide the structured methodology required to evaluate product performance, identify degradation mechanisms, quantify operational risks, and support corrective actions. In many cases, the reliability investigation process becomes the bridge between isolated field failures and long-term product improvement initiatives.

Reliability Failures Versus Functional Defects

A distinction must be made between a functional defect and a reliability failure.

A functional defect is generally present when the product leaves the factory and can often be detected during manufacturing or incoming inspection. Reliability failures, by contrast, emerge after a period of operation and are typically associated with aging, environmental stress, material degradation, or cumulative operating conditions.

Typical Reliability Failure Categories

These mechanisms often develop gradually and may not be detectable through conventional production testing.

Why Reliability Investigations Matter

Industry reliability studies indicate that field failures can cost 50 to 500 times more than defects identified during manufacturing.

The objective of reliability investigation is therefore not merely failure diagnosis but risk mitigation across the entire product lifecycle.

Establishing the Investigation Scope

Effective reliability investigations begin with clearly defined objectives.

Investigators must determine:

• What failure occurred?

• Under what conditions did it occur?

• How frequently is it occurring?

• Which populations may be affected?

• What level of risk exists?

Initial Data Collection

Before laboratory testing begins, relevant information should be gathered.

Typical data includes:

• Part number

• Date code

• Manufacturing lot

• Environmental conditions

• Operating history

• Failure symptoms

• System configuration

• Application details

Incomplete information frequently leads to extended investigation timelines and inconclusive results.

Traceability Requirements

Traceability data allows investigators to determine whether failures are:

• Isolated incidents

• Lot-specific issues

• Supplier-related concerns

• Design-related problems

Without traceability, identifying systemic patterns becomes significantly more difficult.

Failure Reproduction and Verification

One of the most important stages in any reliability investigation is reproducing the reported failure.

A failure that cannot be reproduced may still be real, but establishing causality becomes far more challenging.

Verification Activities

Typical procedures include:

• Functional testing

• Electrical characterization

• Environmental simulation

• Stress testing

• Comparative analysis

Reproducibility Metrics

The ability to reproduce failures often determines whether root causes can be conclusively identified.

Electrical Characterization Procedures

Electrical analysis provides the first detailed assessment of device behavior.

Investigators compare measured performance against specification limits and known-good reference samples.

Common Electrical Evaluations

Depending on device type, testing may include:

• Leakage current measurement

• Supply current analysis

• Functional verification

• Timing characterization

• Memory retention testing

• Signal integrity evaluation

Electrical Failure Indicators

Electrical signatures often provide the first clues regarding underlying failure mechanisms.

Visual Inspection and Microscopic Analysis

Although advanced analytical equipment receives significant attention, visual inspection remains one of the most effective diagnostic tools.

Common Findings

Microscopic examination frequently reveals:

• Corrosion products

• Surface contamination

• Package cracking

• Lead oxidation

• Mechanical damage

• Rework evidence

Magnification levels between 50× and 500× can expose subtle indicators that are impossible to detect with the naked eye.

Reliability-Relevant Observations

Examples include:

• Moisture ingress pathways

• Thermal stress indicators

• Material discoloration

• Early-stage delamination

Visual evidence often guides subsequent analytical activities.

X-Ray Inspection for Internal Structure Assessment

Many reliability failures originate within structures that cannot be evaluated externally.

X-ray technology enables non-destructive examination of internal package features.

Typical Inspection Targets

• Wire bonds

• Die attach integrity

• BGA solder joints

• Internal voids

• Delamination zones

Common Reliability Findings

X-ray analysis is particularly valuable when investigating intermittent field failures.

Environmental Stress Evaluation

Reliability failures frequently emerge only under specific environmental conditions.

Environmental testing attempts to recreate these conditions under controlled laboratory settings.

Common Reliability Tests

Thermal Cycling

Repeated temperature changes induce mechanical stress.

Typical range:

-40°C to +125°C

Temperature-Humidity Bias (THB)

Evaluates moisture resistance under electrical bias.

Common conditions:

85°C / 85% RH

Highly Accelerated Stress Testing (HAST)

Accelerates moisture-related degradation mechanisms.

Power Cycling

Evaluates long-term electrical loading effects.

Why Environmental Testing Is Critical

A component that passes all room-temperature evaluations may still fail under operational conditions.

Environmental testing often reveals latent weaknesses that remain hidden during standard inspection procedures.

Destructive Physical Analysis

When non-destructive methods fail to establish root cause, physical analysis becomes necessary.

Decapsulation

Decapsulation removes package material to expose the semiconductor die.

Investigators examine:

• Die markings

• Bond pads

• Metallization layers

• ESD damage

• EOS damage

Cross-Section Analysis

Cross-sectioning provides detailed information regarding:

• Solder joint integrity

• Material interfaces

• Internal cracking

• Delamination

Scanning Electron Microscopy

SEM enables high-resolution examination of:

• Crack propagation

• Corrosion mechanisms

• Material degradation

• Failure sites

These techniques are widely used in high-reliability industries where definitive conclusions are required.

Reliability Modeling and Statistical Analysis

Modern reliability investigations increasingly rely on statistical tools.

Individual failures provide valuable information, but broader trends often reveal systemic risks.

Common Reliability Metrics

Weibull Analysis

Weibull modeling helps investigators determine:

• Early-life failures

• Random failures

• Wear-out failures

This methodology is widely used for lifetime prediction and reliability assessment.

Root Cause Determination

Reliability investigations ultimately seek to identify causal mechanisms rather than merely document symptoms.

Structured Analytical Methods

Common approaches include:

• Five Whys Analysis

• Fishbone Diagrams

• Fault Tree Analysis

• Failure Mode and Effects Analysis (FMEA)

• 8D Problem Solving

Example

Observed Failure:
Industrial controller resets unexpectedly.

Immediate Cause:
Communication processor loses connectivity.

Failure Mechanism:
Solder fatigue beneath BGA package.

Root Cause:
Thermal expansion mismatch between PCB and package materials.

Corrective Action:
PCB redesign and thermal management optimization.

This structured progression ensures that corrective actions address underlying causes.

Case Study: Reliability Investigation of an FPGA-Based Control System

An industrial automation manufacturer experienced increasing field failures involving FPGA-based motion-control modules.

Reported Symptoms

Failures included:

• Intermittent communication loss

• Random system resets

• Reduced operational reliability

Field failure rates reached approximately 3.4%.

Investigation Activities

The reliability investigation incorporated:

• Traceability analysis

• Electrical characterization

• Thermal imaging

• X-ray inspection

• Thermal cycling

• Cross-sectional analysis

Findings

Electrical testing showed intermittent behavior.

Thermal cycling successfully reproduced failures.

Cross-sectional analysis identified micro-cracks within BGA solder joints beneath the FPGA package.

Root Cause

Repeated thermal expansion generated mechanical stress exceeding solder fatigue limits.

The FPGA itself remained electrically functional.

Corrective Measures

Implemented actions included:

• PCB layout optimization

• Assembly profile improvements

• Enhanced thermal management

Results

The investigation demonstrated how reliability failures often originate at the system level rather than within the semiconductor die itself.

Digital Reliability Investigation Systems

Advanced organizations increasingly manage reliability investigations through integrated quality platforms.

Capabilities include:

• Traceability management

• Failure databases

• Reliability analytics

• Corrective action tracking

• Supplier quality integration

Performance Improvements

Organizations adopting digital systems often report:

Digitalization supports continuous reliability improvement by connecting individual investigations with long-term quality trends.

Quality Assurance Capabilities and Reliability Support Services

Effective reliability investigations require more than laboratory testing. Successful programs combine engineering expertise, advanced analytical tools, traceability systems, supplier quality management, and structured corrective-action processes capable of identifying and eliminating long-term reliability risks.

Professional semiconductor reliability services may include:

• Reliability failure investigations

• Electrical characterization and functional testing

• X-ray inspection and internal structure verification

• Environmental stress and accelerated life testing

• Decapsulation and die analysis

• Root cause investigation support

• Corrective and preventive action (CAPA) management

• Supplier quality assessments

• Traceability and lot-control services

• Counterfeit risk mitigation programs

At semi, reliability investigations are supported through comprehensive quality-management systems, supplier qualification procedures, advanced traceability controls, multi-stage inspection programs, and engineering-driven analytical methodologies. These capabilities help customers improve product reliability, reduce field failures, strengthen operational stability, and support long-term performance across industrial, communications, automotive, medical, and embedded electronic applications.

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