PCB inspection: Taking it to the next level with X-ray

No one thinks it’s OK for a diagnostic device to just stop working. Or for flight instruments to conk out. Dependent on complex PCBs for their smarts, these devices have to be 100%, 24/7 reliable. Is it any wonder that PCB inspection is a critical part of PCB manufacturing and assembly? These things have to be right when they leave the factory floor.

To ensure quality, an inspection of every board is par for the course in PCB manufacturing. Inline automated optical inspection (AOI) is common. But denser board layouts and new chip designs like Ball Grid Arrays (BGAs) can foil AOI because solder connections are hidden by the chip packaging. X-ray inspection to the rescue.

How PCB manufacturing uses X-ray inspection equipment

Just like a doctor uses an X-ray image to see what’s going on inside your body, a PCB manufacturer uses X-ray inspection equipment to see what’s going on “inside” a circuit card. Items, like solder, that are made of heavier elements absorb more X-rays and are easily imaged, while lighter elements, like chip bodies, are more transparent to X-rays.

X-rays pass through the body of a chip to see underlying solder connections. This is the only way to inspect BGAs, Quad Flat No-leads packages (QFNs) and the like since the solder connections are under the chip and hidden from AOI equipment.

Advantages of PCB X-ray inspection
X-rays let you see what can’t be seen optically. Like Superman seeing through walls, the PCB manufacturer with x-ray inspection equipment can:

• See-through BGAs and other chip packaging with “hidden” connections to inspect the quality of solder connections and identify problems.

• See-through solder joints to see voiding caused by bubbles as well as instances of insufficient solder.

• Inspect parts under a shield cover.

PCB inspection at Caltronics

Caltronics is committed to delivering top-quality PCBs and electronic assemblies. One way we do this is by continuing investment in our PCB inspection program.

If you’d like to know more about PCB inspection: