X-Ray Application

FYI

We recently investigated a PCB that our client found to have intermittent system failures related to a batch of units. The failure mode was identified to this particular board, and traced further to a group of ICs. The failure seemed to be affected by board temperature.

Using real time x-ray techniques, the claim was validated by identifying a BGA location with open joints (Fig. 1 arrows). The views also showed no evidence of solder paste being deposited on the adjoining PCB pads.

Fig. 1 BGA location with open joints

Pic o' the Week

Can you identify the below x-ray image?

Send your guess to picoweek@inspex-inc.com. Picture identity to be announced in our next issue.

During a recent trip, flying at 39,000 feet, we noticed that the radiation levels were much higher than previously measured. After further investigation into the matter and casual conversation with the passenger sitting next to us, we had found they had undergone a heart stress test the day before and had been injected with a radioactive isotope and was measuring more than 3 times the FDA limit.

  The Nuclear or "Thallium" stress test is used to show how well blood flows to the heart muscle. It's usually done along with an exercise stress test on a treadmill or bicycle. When the patient reaches his or her maximum level of exercise, a small amount of a radioactive substance called thallium is injected into the bloodstream. Then the patient lies down on a special table under a camera, "gamma camera”, which can see the thallium and make pictures (Fig. 2).

Fig 2 "Gamma Camera" images

The thallium mixes with the blood in the bloodstream and heart's arteries and enters heart muscle cells. If a part of the heart muscle doesn't receive a normal blood supply, less than a normal amount of thallium will be in those heart muscle cells.

To receive past copies of The Rad, e-mail us at service@inspex-inc.com