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X-ray inspection of PCBs

As the complexity and miniturisation of printed circuit board assemblies (PCBA) has increased, so too has the demand for X-ray inspection of PCBAs. That’s why Circuitwise has invested in X-ray machines and it is one of the few companies in Australia to have this capability.

Example of a Ball Grid Array

Because components are becoming smaller and more densely packed together, it is harder to visually inspect for defects. Some components such as Ball Grid Arrays (BGA) place solder connections underneath the component, out of sight altogether. Other components that have similar visibility challenges include Land Grid Array (LGA), Dual Flat No-Lead (DFN), QFN (Quad Flat No-lead) and power devices such as DPAK body type.

Sometimes defects are inside the components themselves or even between the board layers. With increasing costs of critical components and the trend toward higher value boards, the cost of disposing or remediating faulty PCBAs makes the extra step of x-ray inspection worthwhile.

X-ray inspection has the ability to penetrate layers and packaging making it an increasingly popular tool for detailed inspection. X-ray machines work by generating X-ray photons and passing them through the object to a detector. Heavy elements such as metals, absorb more photons compared to the plastics of packaging and other elements in a PCB. The machine can then generate an image or even a video.

Because metallic components stand out in X-rays, solder bridges are easy to identify, even when covered by components, such as BGAs. Another use is the detection of solder voids, created with gas or flux is entrapped during soldering. Similarly, X-rays are good at analysing the quality of pin-hole fills around through-hole components. A final benefit of X-ray inspection is the ability to detect any unwanted metallic debris that has found its way to parts of the board that are meant to be free of metal.

Despite these benefits, X-ray inspection is still seen as an optional element in the PCB assembly process. This partly arises from a lack of understanding of how to best make use of the technology. Depending on the complexity of the assembly, Circuitwise will use X-ray inspection during prototyping and for inspection of First Articles coming off the production line and Golden Boards. This ensures that any defects in components or issues that might be repeated are detected early and dealt with prior to the main production run.

A key application of X-ray inspection is the detection of counterfeit products. The use of counterfeit products arises when manufacturers are forced to go outside official distribution channels to obtain components that are scarce. Components become scarce when there is a shortage of supply, as is currently the case, or when semiconductor companies cease production (and end-of-life event).

In these circumstances, grey market operators will offer products not endorsed by the manufacturer. These components come from a huge variety of sources, ranging from innocent sources such as surplus stock through to a range of dodgy sources such as recycled components, rebadged inferior products or reject piles from the original manufacturers that somehow find their way to the grey market.

X-ray machines can be used to scan a golden sample of a component, which is known to be good, and compare the image to scans of grey market components to determine if they are genuine components and not a counterfeit copy. This is just one part of our service to deal with counterfeit components and you can read more on our other counterfeit detection services.

An unusual application of our X-ray machines is the analysis of what is inside new releases consumer technology from leading vendors. For example, whenever a new phone is released, there is always a big rush to determine what new components are inside a phone and who supplied them. In what is known as a teardown, companies and enthusiasts alike will dismantle the phone (or any other electronic product) and analyse the components and how they work.

On a number of occasions, Circuitwise has hosted a teardown of leading consumer products, such as the iPhone 7 when it was released. Companies specializing in analysing consumer technology fly from the US to Sydney to use our machine and publish their Teardown in real-time. A highlight of that particular visit was an X-ray video of the phone’s haptic motors in action (see below).

The reason Circuitwise is often chosen to host these teardowns is that we are close to the International Dateline. So when phones are released, Australia is one of the first countries in the world where they go on sale. Phones are rushed from the store to the Circuitwise site to be dismantled. It is quite a sight to behold our boardroom table completely covered with hundreds of minute components.

If you have a need to use an X-ray machine for any of the reasons outlined above, don’t hesitate to contact us (link above).

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