Not every PCB assembly project requires every available manufacturing process.

Many buyers ask:

"Do we really need X-Ray inspection?"

"Is Functional Testing necessary?"

"Should we add conformal coating?"

The answer depends on your product design, operating environment, reliability requirements, and production goals.

Choosing the right processes can improve product reliability while avoiding unnecessary manufacturing costs.

When Do You Need X-Ray Inspection?

X-Ray inspection is mainly used to inspect areas that cannot be seen through traditional optical inspection.

Unlike AOI, which checks visible solder joints, X-Ray can examine hidden connections inside components.

X-Ray Is Recommended When Your PCB Includes:

• BGA Components
• BGA packages have solder balls underneath the chip.

Because these solder joints are hidden, AOI cannot verify them.
X-Ray can detect:

• Solder voids
• Missing solder balls
• Solder bridging
• Poor connections
• QFN Components

QFN packages often contain hidden bottom pads.
X-Ray helps verify solder quality and prevent reliability issues.
High-Reliability Products
Industries such as:

• Medical electronics
• Automotive electronics
• Aerospace
• Industrial control

often require additional inspection to reduce failure risks.

When Do You Need Functional Testing (FCT)?

Functional Testing verifies whether the assembled PCB actually works.

It is especially important when the PCB includes:

• Microcontrollers
• Firmware
• Sensors
• Communication modules
• Displays
• Motors
• Wireless functions

FCT can detect problems such as:

• Software configuration errors
• Communication failures
• Incorrect operation
• Sensor issues
• FCT Is Highly Recommended For:
• Electronic Products With Embedded Software

A PCB may be assembled correctly but still fail because firmware is incorrect.

Customer-Facing Products

Products shipped directly to end users benefit from final functional verification.

Complex Industrial Equipment

Downtime caused by PCB failure can be expensive, making FCT valuable.

When Do You Need Conformal Coating?

Conformal coating is a protective layer applied to the PCB surface.

Its purpose is to protect electronic components from environmental damage.

Conformal Coating Is Recommended When Products Face:

Moisture
Examples:

• Outdoor equipment
• Marine electronics
• Smart devices
• Dust and Contamination

Examples:

• Industrial equipment
• Factory automation systems
• Temperature Changes

Frequent temperature cycles can create condensation and corrosion risks.
Chemicals
Certain environments expose electronics to oils, gases, or corrosive substances.
Common Applications Using Conformal Coating
Conformal coating is often used in:
Automotive electronics

• LED lighting
• Medical devices
• Industrial controllers
• Aerospace electronics
• Outdoor IoT devices

Do You Need All Three?

Not necessarily.

Different processes solve different problems.

Process Main Purpose Typical Applications

X-Ray Inspect hidden solder joints BGA, QFN, high-density PCB

FCT Verify product operation Embedded systems, IoT, industrial products

Conformal Coating Environmental protection Outdoor, moisture, harsh environments

A product may require one, two, or all three depending on its application.

How PCBAMake Helps Customers Select the Right Process

At PCBAMake, our engineering team evaluates each project based on:

• PCB design complexity
• Component packages
• Product environment
• Reliability requirements
• Production volume

We help customers select appropriate inspection and protection methods instead of adding unnecessary processes.
The goal is simple:

Build reliable PCB assemblies while keeping manufacturing costs reasonable.

X-Ray inspection, Functional Testing, and conformal coating are valuable tools in PCB assembly, but they are not required for every project.

The right choice depends on your product requirements.

Understanding when each process is necessary helps buyers make better decisions, improve product reliability, and avoid unnecessary manufacturing expenses.

FAQ

Is X-Ray inspection required for all PCB assemblies?

No. It is mainly needed for boards with hidden solder joints such as BGA or QFN components.

Does every PCBA need Functional Testing?

No. Simple boards may not require FCT, but complex electronic products usually benefit from it.

Can conformal coating improve PCB reliability?

Yes. It helps protect PCBs from moisture, dust, chemicals, and environmental stress.