Xray Inspection Test Conditions AN

Xray Inspection Test Conditions AN
X-ray Inspection Test Condition
Recommendations
Application Note
1. Introduction
It has been well established that semiconductor ICs can suffer damage caused by X-ray inspection. While
this phenomenon does not always result in a system level failure, customers might have no means to recover
from the effects of the X-ray exposure if data corruption or other failure mode occurs. Spansion® studies have
shown that programmed cells within a flash array may experience a change in threshold voltage (Vt) as a
result of certain X-ray inspection conditions. Any significant negative perturbation in the Vt of a programmed
cell will result in incorrect sensing of the programmed bit logic state during a read operation, resulting in such
bits incorrectly reading in the unprogrammed logic state.
2. Spansion X-ray Qualification Test Conditions
Below are the test conditions and equipment parameters that Spansion employs when conducting X-ray
inspection as part of the product qualification process. Spansion can guarantee that its products will suffer no
damage when these conditions are applied:
 X-ray Inspection Test Equipment
– Shimadzu (Model SMX-160GT) (See Note)
– Dosimeter: High Dose LiF TLD
– 300-µm thick Zn Filter
 X-ray Inspection System Conditions
– Tube Voltage:
110 kV
– Tube Current:
40 µA
– Center Distance to Source:
40 mm
– Exposure Time:
240s
 X-ray Inspection Test Procedure
– Products are functionally tested and programmed to a known data pattern containing both programmed
‘0’ and unprogrammed ‘1’ logic states prior to X-ray inspection.
– Products are arranged in a circular pattern around the center of the X-ray system stage to insure
uniform exposure.
– The Zn filter is placed between the X-ray source and the products being inspected.
– A dosimeter is included in each batch of units to record the X-ray dose absorbed during inspection.
– Products are exposed to the X-ray beam for 240s (4 minutes), which corresponds to the worst case
inspection time of most circuit board inspection systems and has been determined to be adequate to
assess any board assembly issues.
– After exposure, products are retested to insure there is no loss of functionality or change in preprogrammed data pattern has occurred.
– With this test procedure, X-ray dose received by the products will not exceed 10 rads, while still
enabling adequate imaging and resolution required for circuit board inspection.
Note: Equipment is mentioned as a point of information and not as a product endorsement.
Publication Number Xray_Inspection_Test_Conditions_AN
Revision 01
Issue Date July 11, 2012
A pplication
Note
3. X-ray Inspection Recommendations
There are many commercially available circuit board inspection systems and each employs different X-ray set
up conditions and exposure doses. It is not possible to provide a single set of recommendations that will apply
to all inspection systems. However, in order of effectiveness, the following are the mitigation techniques
Spansion recommends to minimize the effects of any potential damage resulting from X-ray inspection:
1. If X-ray inspection is performed after the flash has been programmed, consider erasing and
reprogramming the flash data.
2. Use a 300-µm thick Zn filter; 1-mm thick Al or Brass filters are also effective.
3. Use the smallest X-ray tube kV-peak possible that still produces adequate images during board
inspection.
4. Use the smallest X-ray tube current possible that produces adequate images.
5. Use the largest X-ray tube to sample distance (i.e. lowest magnification) possible.
6. Use the shortest inspection time possible, preferably on a sampling basis rather than 100% board
inspection.
4. X-ray Inspection References
These Spansion documents provide additional information on X-ray effects on flash:
Impact of X-Ray Inspection on Spansion Flash Memory (Application Note)
Spansion X-ray Physics.pptx (Tutorial Presentation)
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5. Revision History
Section
Description
Revision 01 (July 11, 2012)
Initial release
July 11, 2012
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Note
Colophon
The products described in this document are designed, developed and manufactured as contemplated for general use, including without
limitation, ordinary industrial use, general office use, personal use, and household use, but are not designed, developed and manufactured as
contemplated (1) for any use that includes fatal risks or dangers that, unless extremely high safety is secured, could have a serious effect to the
public, and could lead directly to death, personal injury, severe physical damage or other loss (i.e., nuclear reaction control in nuclear facility,
aircraft flight control, air traffic control, mass transport control, medical life support system, missile launch control in weapon system), or (2) for
any use where chance of failure is intolerable (i.e., submersible repeater and artificial satellite). Please note that Spansion will not be liable to
you and/or any third party for any claims or damages arising in connection with above-mentioned uses of the products. Any semiconductor
devices have an inherent chance of failure. You must protect against injury, damage or loss from such failures by incorporating safety design
measures into your facility and equipment such as redundancy, fire protection, and prevention of over-current levels and other abnormal
operating conditions. If any products described in this document represent goods or technologies subject to certain restrictions on export under
the Foreign Exchange and Foreign Trade Law of Japan, the US Export Administration Regulations or the applicable laws of any other country,
the prior authorization by the respective government entity will be required for export of those products.
Trademarks and Notice
The contents of this document are subject to change without notice. This document may contain information on a Spansion product under
development by Spansion. Spansion reserves the right to change or discontinue work on any product without notice. The information in this
document is provided as is without warranty or guarantee of any kind as to its accuracy, completeness, operability, fitness for particular purpose,
merchantability, non-infringement of third-party rights, or any other warranty, express, implied, or statutory. Spansion assumes no liability for any
damages of any kind arising out of the use of the information in this document.
Copyright © 2012 Spansion Inc. All rights reserved. Spansion®, the Spansion logo, MirrorBit®, MirrorBit® Eclipse™, ORNAND™ and combinations
thereof, are trademarks and registered trademarks of Spansion LLC in the United States and other countries. Other names used are for
informational purposes only and may be trademarks of their respective owners.
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