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September 2005

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Subject:
From:
Steve Gregory <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Date:
Tue, 27 Sep 2005 13:42:39 -0500
Content-Type:
text/plain
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text/plain (182 lines)
Hi Phil!

The BGA in question is a small one, only 100-balls, and a plastic part with
no heat-sink.
It's on the bottomside of the board, and has to go through reflow one more
time when the
topside is built.

As I said, everything looks fine at x-ray...it is inspected pretty closely
too.

Our customer is the one who is worried about x-ray, not us. They can't get
the device to
accept a program on some boards, and they are thinking that possibly x-ray
damaged
the device.

Kind regards,

-Steve Gregory-
Senior Process Engineer
LaBarge Incorporated
Tulsa, Oklahoma
(918) 459-2285
(918) 459-2350 FAX



|---------+---------------------------->
|         |           Phillip Bavaro   |
|         |           <phillipbavaro@YA|
|         |           HOO.COM>         |
|         |           Sent by: TechNet |
|         |           <[log in to unmask]>|
|         |                            |
|         |                            |
|         |           09/27/2005 01:16 |
|         |           PM               |
|         |           Please respond to|
|         |           TechNet E-Mail   |
|         |           Forum            |
|         |           <[log in to unmask]>|
|         |           ; Please respond |
|         |           to Phillip Bavaro|
|         |           <phillipbavaro@YA|
|         |           HOO.COM>         |
|         |                            |
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  |                                                                                                              |
  |       To:       [log in to unmask]@SMTP@Exchange                                                                |
  |       cc:       (bcc: Stephen R Gregory/LABARGE)                                                             |
  |       Subject:  Re: [TN] X-ray inspection, can it damage devices?                                            |
  >--------------------------------------------------------------------------------------------------------------|



Hi Steve,

I haven't ever heard of or experienced any issues with an xray inspection
system causing damage to a chip.    It is hard to believe that xrays
momentarily exposed to a chip could cause damage.

I have seen some Altera BGAs that have difficulty getting good solder joint
reflow due to the heatsinks on top of them, the pwb's 24 layers, and the
sheer number of solderballs (1500+).  With your .050" copper core, I would
look at the thermal reflow and make sure that all the balls on the BGAs
have fully collapsed.

Was this BGA on the second side or first side reflowed?

It is tough sometimes to tell where the problem is if you don't have a
board level test in place.

Phil


Steve Gregory <[log in to unmask]> wrote:
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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__________________________________________________________________
This message may contain information that is privileged and confidential to
LaBarge, Inc.  It is for use only by the individual or entity named above.
If you are not the intended recipient, you may not copy, use or deliver
this message to anyone.  In such event, you should destroy the message and
kindly notify the sender by reply e-mail.

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
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