Common PCB Failures: Causes, Symptoms, and Solutions

PCB failures are rarely random.
In most cases, failures are the result of design decisions, material choices, or manufacturing process limitations.

Understanding common PCB failure modes helps engineers:

• Identify root causes faster
• Improve design-for-manufacturability (DFM)
• Reduce field failures and warranty costs

This article provides a practical overview of the most common PCB failures, their symptoms, and how they are prevented in modern PCB manufacturing.

What Is a PCB Failure?

A PCB failure occurs when a board no longer meets its electrical, mechanical, or reliability requirements.

Failures can appear:

• During electrical testing
• During PCB assembly
• After thermal cycling
• In real-world operation

Many failures originate long before the PCB is powered on.

Open Circuits and Short Circuits

Typical Symptoms

• Electrical test failure
• No signal continuity
• Unexpected current paths

Common Causes

• Incomplete copper plating
• Over-etching or under-etching
• Inner layer misregistration

Prevention Methods

• Controlled etching processes
• Electrical testing (E-test)
• AOI inspection during fabrication

Related: PCB Electrical Testing Explained

Delamination

Delamination refers to the separation between PCB layers or between copper and dielectric material.

Symptoms

• Blistering during soldering
• Internal voids visible by X-ray
• Reduced mechanical strength

Root Causes

• Excessive moisture absorption
• Improper lamination parameters
• Incompatible material selection

In-depth guide:
PCB Delamination Causes and Prevention

Delamination

Delamination refers to the separation between PCB layers or between copper and dielectric material.

Symptoms

• Blistering during soldering
• Internal voids visible by X-ray
• Reduced mechanical strength

Root Causes

• Excessive moisture absorption
• Improper lamination parameters
• Incompatible material selection

In-depth guide:
PCB Delamination Causes and Prevention

Conductive Anodic Filament (CAF) Failures

CAF is a latent failure mode that develops over time.

Characteristics

• Progressive insulation breakdown
• Often appears after months or years
• Triggered by moisture and voltage bias

Contributing Factors

• Glass fibre exposure
• Resin-rich areas
• High-humidity environments

Technical breakdown:
CAF Failure in PCB Explained

Solder Mask and Surface-Related Failures

Although often overlooked, surface-related defects can cause real functional problems.

Examples

• Solder mask cracking
• Poor adhesion
• Corrosion exposure

Prevention

• Proper surface preparation
• Controlled curing processes
• Material compatibility checks

How PCB Failure Analysis Is Performed

When failures occur, manufacturers use structured analysis methods.

Common tools include:

• Cross-section analysis
• X-ray inspection
• Thermal stress testing
• Electrical re-testing

Methods overview:
PCB Failure Analysis Methods Explained

Role of Manufacturing Process Control

Most PCB failures are preventable.

Key control areas include:

• Lamination profiles
• Copper plating thickness
• Material storage and handling
• Inspection and testing coverage

Manufacturers like TOPFAST integrate failure feedback into continuous process improvement rather than treating failures as isolated events.

Design Decisions That Increase Failure Risk

Design choices strongly influence failure probability.

High-risk design practices include:

• Extremely thin dielectrics
• Minimal annular rings
• High aspect ratio vias
• Tight spacing in humid environments

Design perspective:
PCB Quality and Reliability Design Guidelines

Conclusion

PCB failures are rarely caused by a single factor.
They are usually the result of interactions between design, materials, and manufacturing processes.

Understanding common failure modes allows engineers to:

• Design more robust PCBs
• Select appropriate materials
• Apply the right inspection and testing strategies

This article serves as the foundation of the PCB Failure Analysis content cluster.

Common PCB Failures FAQ