How to perform printed circuit board analysis?

A printed circuit board sits at the heart of almost every electronic product, from a car window lifter to a medical monitor. When a board stops working, or when a new design needs to be checked before mass production, the fastest way to find answers is to analyse the board itself. Printed circuit board analysis is a structured process of inspecting, testing, and examining a PCB to find out why it failed, whether it meets its specification, or how it was built. This article walks through the practical steps you can follow to perform PCB analysis, whether you are troubleshooting a returned unit or verifying a prototype.

Step 1: Define what you want the analysis to answer

Before touching the board, decide what kind of analysis you need. The three most common goals are:

• Failure analysis - locating the specific component, solder joint, trace, or design flaw that stopped the board from working.
• Quality verification - checking that a board or assembly meets the agreed standard before it ships.
• Reverse engineering - understanding the circuit and layout of an existing board.

Most PCB analysis work falls into the first category. Start by collecting whatever information you already have: the schematic, the bill of materials, the failure report, and any environmental conditions the board was exposed to. This background data often points you straight to the likely cause and saves hours of blind searching.

Step 2: Start with visual inspection

Visual inspection is non-destructive, fast, and should always come first. Under a magnifying glass or an optical microscope, look for the obvious signs of trouble: cracked solder joints, lifted pads, burnt or charred components, discoloured traces, corrosion, and foreign material on the surface. In production, this step is often automated with AOI (automated optical inspection), which scans every board against the expected pattern and flags deviations. Many manufacturers also use SPI (solder paste inspection) right after printing to catch paste defects before components are placed.

If you are checking a board against an industry standard, IPC-A-610 is the reference most electronics manufacturers use for judging the acceptability of solder joints and assemblies. A trained eye following this standard can classify most visible defects without any further testing.

Step 3: Test the board electrically

Visual inspection only shows the surface. To understand how the board actually behaves, you need to test it electrically. Two tests dominate PCB analysis:

• ICT (in-circuit test) - a bed-of-nails fixture checks individual components and connections to catch shorts, opens, and wrong-value parts.
• FCT (functional test) - the board is powered up and run through its intended functions to confirm it works as designed.

For intermittent or heat-related faults, a thermal imaging camera is a powerful tool. When a board is powered, a short circuit or a high-resistance joint heats up, and the camera shows exactly where the hot spot is. This single test can localise a fault that would otherwise take hours to find. Oscilloscope measurements are equally useful for checking signal integrity and timing on communication and control boards.

Step 4: Look inside with X-ray and other non-destructive methods

Some defects are hidden under components. Ball-grid-array (BGA) packages, QFN parts, and multi-layer boards hide their solder joints and internal layers completely. X-ray inspection is the standard way to see inside: it reveals voids in solder balls, shorts between pins, and opens in connections that no optical tool can reach. X-ray is especially valuable on dense boards with 01005 components and fine-pitch BGAs, where a single bad joint can stop the whole assembly from working.

For laminate-level problems such as internal delamination, scanning acoustic microscopy (C-SAM) uses ultrasound to detect air gaps between layers. It is the go-to method when you suspect the board material itself, not the components, is the problem.

Step 5: Go deeper with destructive physical analysis

When non-destructive testing has narrowed the fault to a specific area but cannot show the root cause, the next step is destructive physical analysis. The most common technique is micro-sectioning: a small coupon is cut from the board around the defect, mounted in epoxy, and ground and polished until the exact cross-section is exposed. Under a microscope you can then measure plating thickness, inspect the intermetallic layer of a solder joint, and see cracks that were invisible from the surface.

For contamination and material questions, a scanning electron microscope with energy-dispersive X-ray spectroscopy (SEM/EDS) identifies the elemental composition of residues and foreign particles. This is how labs confirm whether a corrosive deposit contains chlorine or bromine, or whether a whisker-like growth is actually a metal dendrite. These techniques require specialist equipment, which is why most companies send this stage of analysis to a laboratory or to their EMS partner rather than building the capability in-house.

Step 6: Record findings and act on them

An analysis is only useful if the results are documented and turned into action. A good analysis report should state the failure mode, the root cause, and a clear corrective action. The corrective action should be specific enough to verify: for example, increasing plating thickness in a microvia, changing the reflow profile, or adding pre-bake time for moisture-sensitive components. Without this final step, the same fault will simply come back in the next batch.

When to hand analysis to an EMS partner

Performing PCB analysis in-house makes sense for simple visual checks and routine testing. But a full analysis - especially one that combines ICT, FCT, X-ray, thermal imaging, and micro-sectioning - requires equipment and expertise that most product companies do not have on site. This is where an experienced electronics manufacturing services (EMS) provider earns its keep. A one-stop partner can run the complete pcba testing process on your boards, from first-article inspection and AOI through ICT, FCT, X-ray, and reliability testing, and can tell you exactly what the results mean for your design.

Farway Electronic, an EMS manufacturer based in Shenzhen, runs exactly this kind of testing capability alongside its production lines. Its inspection equipment includes SPI, AOI, X-ray, ICT, FCT, plug-in visual inspection, thermal imaging, and high- and low-temperature reliability testing, all managed under IPC-A-610 assembly standards and ISO 9001, ISO 13485, and IATF 16949 quality systems. When a board fails in the field or a new design needs validation, the same team that builds the board can analyse it - which shortens the loop between finding a problem and fixing it.

Beyond testing, the analysis often points back to how the board was made. Issues like CAF, delamination, and solder-joint fatigue are frequently traced to the pcb board making process or to how the assembly was handled. Working with a manufacturer that controls both the board fabrication and the pcb smt assembly gives you a single point of accountability when something goes wrong, and makes it far easier to turn an analysis finding into a permanent fix.

Conclusion

Printed circuit board analysis does not have to be a mystery. Start with a clear goal, inspect visually, test electrically, look inside with X-ray, go deeper with cross-sectioning when needed, and finish by documenting the root cause and the corrective action. For boards that need the full range of tests, an EMS partner with in-house testing equipment can do the work faster and more reliably than trying to assemble the capability yourself. The result is the same in every case: you learn exactly what happened to the board, and you know precisely what to change so it does not happen again.