More kimchi, less radiation

Business travel is mostly done by our salespeople, but occasionally also the development guys are let out of the office into the wild. This time I had a chance to visit some of our clients in South Korea, to discuss the more technical aspects of our collaborations. I hadn't been to Korea before, and I would say that arriving to the huge Seoul (metro area population 25 M) from our little Helsinki (metro area population 1 M) was certainly an experience. People, cars, high-rises, more cars, more buildings.

I've a feeling we're not in Helsinki anymore. Late night traffic in Seoul.

Being quite jet-lagged I had plenty of opportunities to sample the night-time life in the Seoul area, and a couple of things were immediately obvious. The Korean culture is very disciplined, order and harmony are emphasized, and therefore even in the wee hours of the night the streets feel completely safe. Also, you never have to walk around with an empty stomach; practically in every corner there's a 24h shop with a microwave and a water boiler.

Food is something the Koreans take very seriously. Based on my (admittedly short) experience it seems that everything on offer in the restaurants is always very tasty. This is good news for us foreigners who cannot understand the menus; just order something, anything, and it's going to be good. And a generous portion of the deliciously sour kimchi is guaranteed to be served on every meal. The only issue is that the amount of food is likely going be much larger than you can actually handle. But remember that finishing everything that's offered is considered very impolite.

Suwon City seen from Paldalsan hill. In the center, the towers of Samsung Electronics HQ are reaching for the skies.

Inspecting microscopic solder joints

Eigenor has clients for computed tomography both in the industrial and in the medical imaging sectors. Both types of clients are present in Korea, and electronics manufacturing constitutes an important subsector of them. The ever-continuing reduction in the size of electronic components is a constant source of new and very difficult challenges to the industry. For Eigenor, the main question is how to perform non-destructive X-ray imaging of these tiny components.

Currently the smallest pixel size in X-ray detector panels is about 50 microns, and therefore, in order to see details down to the micron level, a projection magnification of the order of 100 is required. This means that either the detector must be very far from the object, or the source must be very close to the object. The former option is highly impractical and thus the latter option is the one that is used in real-life measurements.

For the case at hand the objective is to inspect the BGA balls of a chip package, and in particular, the quality of the soldering between the ball and the circuit. In the projection setup the X-ray tube is basically touching the circuit board which means that the typical CT scanning trajectories cannot be used. The challenge that we face is producing high-quality reconstruction volumes from a suboptimal geometrical setup. However, 3D imaging with a limited amount of information is exactly the special field of Eigenor's expertise, and we are confident in finding an excellent solution to this problem.

Medical scans with lower dose

One of our Korean clients is about to release a new medical CT scanner. It's quite obvious that in this case the reduction of the radiation dose is of prime importance, and again, this is the kind of problem that Eigenor's solutions are targeted for. Good old filtered backprojection just doesn't cut it any more.

It goes without saying that when developing this type of device, real humans and their brains cannot be utilised for test measurements. However, it's possible to buy a very elaborate brain phantom which tries to mimic the actual human anatomy in great detail. Over the last year or so I have spend countless hours optimizing our tools for the X-ray projections taken with such a phantom head, and now I finally had a chance to "meet him in person", if you will.

First meeting in real life didn't disappoint! Previously I had only received (X-ray) pictures over the internet. He remained unimpressed, though.

One could very well question the usefulness of flying 7000 km back and forth in the age of ubiquitous internet communications. However, nothing is more efficient for figuring out the core issues and their technical details than sitting down at a joint table and scribbling out diagrams on a whiteboard. This becomes even more important when the barriers in language and culture are high. Also, even though Eigenor is purely a software company, being able to actually see the machines where the software is used is always very rewarding, and can often lead to a better understanding of the problems.

A weary traveller heading back to Seoul Incheon Airport.

Tomi Ruokola
Tomography Software Specialist