Not to mention that the .050" core makes a good shield when x-rayed with the BGA on the top side, which is why we were turning the Kv up anyway. Now, if its on the bottom side during x-ray and nearly flush to the x-ray source.....
Mike Sewell
Franklin Asbell <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
09/28/2005 09:16 AM
Please respond to TechNet E-Mail Forum <[log in to unmask]>; Please respond to Franklin Asbell <[log in to unmask]>
To: [log in to unmask]@SMTP@Exchange
cc: (bcc: Michael Sewell/LABARGE)
Subject: Re: [TN] X-ray inspection damaging components...
My first question at such a technical meeting would be
How much exposure will damage the part?
I'm sure if you place the part in the chamber, turn on the xray and go to
lunch you might have some problems. But would seconds, cause damage?
What might be happening is component vendors want to protect their product
and obviously so, so they place tighter than required standards on them,
what is the time to failure under 90kv at 20mA, and at 50mA, and at 90mA?
What is time to failure under 40kv at 90mA for 5 seconds? Or 30 seconds?
Just some things I would try to answer during such an IPC technical
activity.
Franklin
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard
Sent: Wednesday, September 28, 2005 9:01 AM
To: [log in to unmask]
Subject: Re: [TN] X-ray inspection damaging components...
Good Morning, Stephen!
This is good information. So now we have component vendors telling us
some of their components should not be overexposed to X-rays. Was there
any type of notation on the part print?
The industry needs a standard. We need to have some type of rating
system for components that can be damaged by X-rays.
Jack, is there any activity going on with this within IPC?
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Wednesday, September 28, 2005 8:50 AM
To: [log in to unmask]
Subject: [TN] X-ray inspection damaging components...
Morning All!
I submitted a question to Altera via their email support center about
x-ray inspection possibly damaging a EPM7256EEFI100-7 device. The device
is a EEPROM made using an advanced CMOS process.
Here is our exchange so far:
>Request No: 10515187 Status: Close-Pending Date Opened (PDT): 9/26/2005
>07:24 AM Date Closed (PDT):
>Inquiry Type: Product Question
>Device Family: Device:
>Title: X-ray inspection of devices
>
>Description: I am doing x-ray inspection of a EPM7256AEFI100-7 device
after board assembly.
>The PCB has a 1.27mm thick copper core in the center of it, so it
>requires
that a high kv x-ray must
>be done in order to see the solder connections of the device. The x-ray
source power is around
>120-130kv. Will this x-ray power level damage the device?
>
>Thank-you,
>
>-Stephen Gregory-
>Process Engineer
>LaBarge Inc.
>
>
------------------------------------------------------------------------
--------------------
>
>Updates 1 - 2 of 2 Add an Update / Previous / Next
>
>Date Created (PDT) 9/27/2005 07:44 PM
>
>To Customer:
>
>Hi Stephen,
>
>Typically assembly uses 90KV using 10 to 20mA with a few second for
inspection of IC package. Our
>recommendation will be a pro-rated 130KV with 7mA to 13mA for a few
second. Note that Prolong exposure
>under X-ray will definitely damage the device. I hope it's helpful to
you.
>
>Best Regards,
>Daniel Cao
My question is; doesn't the figure of 90KV at 10-20mA seem pretty low?
My current Glenbrook RTX-113 operates at 35-52KV at 20-50mA, and
higher-end Glenbrook systems will pump 70-90KV at 90-100mA. Right now,
I'm using a Fein Focus Tiger 160 for x-ray inspection of some copper
cored assemblies that we're building because I have to, that's the only
way we can inspect the BGA's. The copper core in the PCB won't allow
x-ray of the BGA's unless you use a system that can penetrate the core.
But if these devices can be damaged at such a low voltage (if indeed
Daniel's figures are correct), shouldn't Altera issue some sort of
warning to their customers about x-ray damaging the devices? After all,
there will be a lot of customers using x-ray for inspection.
Kind regards,
-Steve Gregory-
Senior Process Engineer
LaBarge Incorporated
Tulsa, Oklahoma
(918) 459-2285
(918) 459-2350 FAX
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