At 02:53 PM 5/30/00 -0600, you wrote:

>Help,
>
>My company is asking for information leading to the possible purchase of an X-ray machine for BGA s.
>
>We are placing some with metal tops such as the ALTERA.  ANY info on who, what, where, etc. etc. etc.
>
>Would be kindly appreciated.

I have an opinion here, and it's just an opinion...

Buying an X-Ray machine "for BGA's" is pretty common, as of course you can't "see" the joints much otherwise.

But you wouldn't buy an X-Ray machine just to check your lungs every 6 months, would you? Not even if you were doing it for every employee, you wouldn't.

My brother is a radiologist. He can look at images which look like clouds, and pick out the "Roentgen signs" that indicate disease and abnormalities. When I look at them, they look like clouds. It took him years of internship and residency to develop the skill analyze the images, plus a photographic knowledge of human anatomy achieved along the way. He needs to know what every section of a body SHOULD look like, and indicators for many abnormalities in males, females, adults, juveniles.

If you do buy one, you should plan to dedicate a technician who will learn how to operate the equipment, process the images, and interpret what is found - and the time and cost of this manpower is probably greater than the cost of the equipment. You can expect it to be a long process to get much useful information. There are many types of packages, and they are mounted on different boards with different pads. This will change every six months or so with some regularity.

Some  people think the process of interpreting the image ought to be simple, like looking at the x-ray of a broken arm, and seeing the crack, and saying, "yes, it's broken". The reality is that you see cloudy images and have to adjust the contrast and use a lot of your training and experience to determine what the image means.

Having an X-Ray machine just to find shorts on BGA's after soldering is overkill. What you may want is the ability to make judgements about the amount of solder, the voids, and the wetting. This requires laminography, sophisticated image processing, a trained technician, and then you have indications which can be used to make logical inferences, not necessarily clear cut process measurements. (I've seen my brother arguing with other radiologists about the meaning of images, and he wrote a chapter in one of the medical texts...)Your mileage may vary, etc.


cheers,


Jerry Cupples
Interphase Corporation