Hi Phil,

In a previous existence I have had to look at this, it was a while back but we were asked to estimate total dose that the part was likely to receive.

As I remember it, it boiled down to a relatively simple calculation (albeit this was only an estimate).

Your x-ray should tell you the Volts and Amps it is using for any given inspection (i.e. power) - the dosage is then proportional to the square of the distance between the source and the object.


For the IC set we were looking at even with multiple inspections through assembly life we were well below 10% of allowable total dose, but I know that on other areas of the hardware there were chips with closer gates and less redundant paths (and so, as I understand it - higher chance of a radiation event causing a latch up)

I seem to remember that in order to back up our estimate we did spend a little time with a total dose meter sat next to an assembly in the x-ray as well.

The stuff I did was quite a few years ago so it's probably worth talking to you x-ray supplier as not only has the technology become far more refined, but I suspect the knowledge will have done too.


Sue Knight
Project Engineer

Web: www.sti-limited.com
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Phil Bavaro
Sent: 20 November 2012 23:30
To: [log in to unmask]
Subject: [TN] Xray Inspection of Flight Hardware for Space Applications

Ok, here is one that is news to me.......

We have an effort going on that involves measuring the radiation that an x-ray inspection system exposes to space application hardware.

I was surprised to find that there are a few papers online speaking relatively to this issue and one dated as early as 2007.

The issue seems to be that components without a lot of Radiation Design Margin (RDM) may get their margin used up during assembly inspection operations if the exposure exceeds a certain number of kRad(Si).

I know I have been out of the loop for Class 3A Space hardware for a while, but I find it hard to believe that x-ray inspection has the potential to damage any hardware.

What kind of controls do the rest of you have in place to account for this potential assembly nightmare?  I know many of us are building Space hardware with BGAs, QFNs, etc but now I am wondering how do you know that a given part is ok to put through the x-ray inspection machine.

I guess I should be happy.....it isn't everyday that I learn something new.
________________________________
 This message and any attachments are solely for the use of the addressee and may contain L-3 proprietary information that may also be defined as USG export controlled technical data. If you are not the intended recipient, any disclosure, use or distribution of its content is prohibited. Please notify the sender by reply e-mail and immediately delete this message and any attachments.

______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________

The information contained in this communication, and any attachments, may be confidential and/or privileged. It is intended only for the use of the named recipient.

If you are not the intended recipient please contact us.
Tel: +44 (0)1256 768070
Fax: +44 (0)1256 760718
Email: [log in to unmask]

In such an event you should not access any attachments, nor should you disclose the contents of this communication or any attachments to any other person, nor copy, print, store or use the same in any manner whatsoever.

Thank you for your co-operation.

______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________