PCB Testing Methods That Actually Matter in Production

When a circuit board fails in the field, it’s not just a technical issue—it’s a reputation problem, a return, and a real cost. That’s why PCB testing isn’t something to tack on at the end. It’s something to design for.

Plenty of articles list all the possible testing methods, but here’s the truth: only a few really matter once you’re manufacturing at scale. At Titoma, we build electronics from design to mass production in Asia. Here’s how testing works when quality and deadlines are non-negotiable.

Start with Design, or Start with Problems

Testing is only as good as your preparation. If your layout engineer didn’t leave space for test points, or if your firmware team never thought about how to trigger a functional test, you’ll hit delays. Worse, you’ll ship blind.

Design for Testability (DFT) is part of our Design for Manufacturing (DFM) approach. That means every board we design is made to be tested easily—because adding a test point after tooling is locked is expensive and slow.

Common PCB Testing Methods and When They Actually Make Sense

Let’s break down the most common circuit board testing methods, not by definition, but by what they actually offer in production.

1. AOI – Automated Optical Inspection

Use it when: You want fast inspection of SMT solder quality, component alignment, or polarity.

• It’s camera-based, quick, and effective for high-speed SMT lines.
• Can’t detect internal faults, but great for catching obvious issues like tombstoning or missing components.
• Standard in almost all production runs.

Titoma Tip: AOI is only as good as your solder mask contrast. We’ve seen clients save a few cents on PCB finish and then struggle with inspection accuracy.

New tech is coming: Researchers are now exploring deep learning techniques to improve defect detection, using models that outperform traditional image-based inspection. Promising, but not yet ready for most production floors.

2. ICT – In-Circuit Test

Use it when: You’re making 10,000+ units and can afford the fixture cost.

• Requires test pads on every net you want to probe.
• Very fast once set up—perfect for high-volume lines.
• Upfront cost of the bed-of-nails fixture can be thousands of dollars.

Titoma Tip: We design boards with ICT in mind, including adding dummy pads just to allow future scalability.

3. Flying Probe Test

Use it when: Volumes are low, or you’re still validating design.

• No fixture needed—just probes that move around the board.
• Slow per board but flexible.
• Doesn’t catch all timing or function-related bugs.

Titoma Tip: For early builds or engineering validation units (EVTs), flying probe is a lifesaver. But don’t rely on it for scale.

4. Functional Test (FCT)

Use it when: You care about what the board does, not just what it looks like.

• Simulates real working conditions—power up, load firmware, and run actual operations.
• Often custom-built for your device.
• Takes time and coordination between hardware, firmware, and mechanical teams.

Titoma Tip: This is where many OEMs skip corners. We build these tests early with you to catch real-world failures before they ship.

5. Boundary Scan (JTAG)

Use it when: You have digital ICs, FPGAs, or need test access to internal nets.

• Excellent for dense boards with inaccessible pins.
• Requires support in chip selection and design phase.
• Powerful for debugging and production testing.

Titoma Tip: We’ve used JTAG not just for testing, but also to recover bricked devices at the factory.

6. Burn-In Test

Use it when: You need high reliability—medical, automotive, aerospace.

• Stresses boards with heat, voltage, or load for hours or days.
• Helps catch early-life failures (infant mortality).
• Expensive and time-consuming, but worth it for critical applications.

Titoma Tip: If you need this, plan early. Burn-in chambers and test loads take time and budget.

What Most Companies Miss: Test Fixtures Are Products Too

No test? No data. But you can’t test reliably without a proper jig.

Most delays happen because the fixture is an afterthought—built too late, or by a team that never talked to the firmware engineers. At Titoma, we design fixtures in parallel with your product. Because rework costs more than doing it right once.

Common Mistakes That Complicate Testing

We’ve seen it all—from skipped test points to poor fixture documentation. These common PCB design mistakes that increase manufacturing costs don’t just hurt your BOM—they slow down your production line and hurt yields.

So, What’s the Best PCB Testing Method?

That depends on your volume, complexity, and risk tolerance.

• Prototype or low volume: Flying probe + visual + basic functional test
• Mid-volume: AOI + functional test, possibly light ICT
• High volume: AOI + ICT + FCT, plus inline yield tracking
• High-reliability: Add burn-in and better diagnostics

If you’re building thousands of units with no plan for testing, you’re just hoping nothing breaks. That’s not a strategy.

Conclusion: Good Testing Starts Before the First PCB

At Titoma, we don’t just test—we design so testing is easier, cheaper, and more reliable. That’s how we build electronics that scale, without surprises.

Need a partner who actually engineers for production, not just prototyping?
Talk to us. We’ll help you build smart, testable, and ready-to-scale products—fast.