Free tool · PCB inspection planning
PCB Inspection Method Selector: AOI, X-ray, Flying Probe, ICT or FCT
Answer four questions about your board and production volume to get a recommended inspection mix, with the reason for each method.
Methods
What Each Inspection Method Catches
| Method | What it catches | When we use it |
|---|---|---|
| Electrical test | Opens and shorts on every net of the bare board | 100% of bare boards, before shipment or assembly |
| AOI | Inner-layer defects before lamination; on assemblies, missing, shifted or reversed parts and solder fillets (3D AOI) | Every inner layer and every assembled board |
| X-ray | Voids, bridges and opens under BGA, QFN and other hidden joints | Boards with BGA or QFN; 100% for dense BGA or Class 3 |
| Flying probe | Shorts, opens and component values without a fixture | Prototypes, low volumes, or layouts without test points |
| ICT | Shorts, opens and component values through a bed-of-nails fixture | Mid and high volumes with accessible test points |
| Functional test | Whether the powered board works as designed | To your test specification; recommended for Class 3 |
| XRF thickness | Nickel and gold thickness on ENIG | Every lot; readings available on request |
| Impedance (TDR) | Controlled-impedance traces within ±5% | Boards with impedance requirements |
| Solderability | Whether bare-board pads wet properly | In-house test on bare boards |
How the Recommendation Is Made
Production volume
Flying probe needs no fixture, so it is the default for prototypes and runs under about 1,000 boards. Above that, an ICT fixture usually pays for itself through faster test time.
Hidden joints
AOI cannot see under BGA or QFN packages. Boards with a few of them get X-ray on first articles and by sampling; BGA-dense boards and Class 3 builds get 100% X-ray.
Reliability class
IPC-A-610 Class 3 tightens the acceptance limits. We recommend 100% X-ray on hidden joints and functional test for Class 3 products.
Test points
ICT needs accessible test points. Without them, flying probe is used at any volume; adding test points in the layout makes ICT possible later.
For a side-by-side comparison of the three main methods, read AOI vs X-ray vs ICT.
All five methods run in our own factory. See every PCB capability, including assembly limits and certifications.
FAQ
PCB Inspection FAQ
What is the difference between AOI and X-ray inspection?
AOI uses cameras to check what is visible: part presence, position, polarity and solder fillets. X-ray sees through components to check hidden joints under BGA and QFN packages.
Flying probe or ICT: which is better?
Flying probe needs no fixture, so it suits prototypes, low volumes and layouts without test points. ICT uses a bed-of-nails fixture that costs more up front but tests each board much faster, so it pays off at mid and high volumes.
Do I need functional testing?
Functional test powers the board and checks it against your test specification. We recommend it for IPC Class 3 products, and run it for any order where function must be proven before shipment.
Are bare boards tested too?
Yes. Every bare board is 100% electrically tested for opens and shorts before shipment or assembly.
Can I see what the inspection results look like?
Yes. See our sample QC report.
Get Your Inspection Plan Quoted
Send your files and volume; we confirm the inspection coverage in the quote.