http://www.sandia.gov/media/rhp.htm
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Stadem, Richard
Sent: Monday, September 26, 2005 12:06 PM
To: [log in to unmask]
Subject: Re: [TN] X-ray inspection, can it damage devices?
I have had to address the same concerns for Aerospace programs.
I have not been able to find any formal standards for radiation exposure
limits. All I found was a good paper on the subject from Tom Clifford at
Lockheed Martin ("X-Ray Inspection, Easy Does It" in EP+P magazine)
I also talked to two X-ray vendors and they tell me that even if the
typical X-rays were cranked up to 120kv or about 3-5 watts, a component
would have to be exposed for a full day or longer to accumulate enough
total Rems such that it could hurt the component, and that the only
types of components that could be possibly damaged would be CMOS memory.
I have found some information on protecting components in space systems
from natural X-rays, but nothing on process-generated X-rays. Everybody
tells me it is not a problem. This is not enough for me, so I asked the
folks at IPC but have not heard a response as yet.
Anyone else know of any standards for limitations of X-ray emissions on
electronic components?
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Monday, September 26, 2005 10:17 AM
To: [log in to unmask]
Subject: [TN] X-ray inspection, can it damage devices?
Good Mornin' Everyone!
I hope you all had a good weekend! I worked Saturday, but had Sunday
off. Sat around Sunday and watched the NASCAR race at the "Monster Mile"
in Dover Delaware. 20-year old Kyle Busch gave Jimmie Johnson a run for
his money finishing second at the green/white/checkered ending....but I
digress.....
Anyways, we built an assembly here that has a .050" copper core in the
center of it...not the same assembly as the one I did my "okie
cross-section" on).
It is double-sided SMT, and has BGA's on both sides. I'm doing x-ray
inspection with a Fein Focus Tiger 160, and in order to penetrate the
core and do a proper inspection of the solder joints and spheres of the
BGA's, the x-ray power is up around 120-130kv.
Our customer received a number of the assemblies from us (without test
from us, as they are prototypes and test hasn't been developed yet), and
they are having problems with one of the BGA's.
It's a 100-ball Max-7000 device from Altera, a CMOS EEPROM, and our
customer has been trying to program the device via on-board programming,
but some boards wont program. The x-ray inspection turned out fine. All
BGA's were inspected using oblique angles, so if there was an open
joint, it would have been seen.
They are worried that maybe the x-rays may have damaged the device.
Altera has told our customer that the x-rays shouldn't hurt the device.
I've got
a case number started via email in to Altera (since I can't talk to
anyone on the phone), asking them myself if x-rays will damage the
device. I'm also going to call Fein Focus and talk to them as well.
But have any of you ever heard of x-ray damaging BGA's?
Kind regards,
-Steve Gregory-
Senior Process Engineer
LaBarge Incorporated
Tulsa, Oklahoma
(918) 459-2285
(918) 459-2350 FAX
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847-615-7100 ext.2815
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