August 11, 1998
Dear Valued Customers:
Xilinx has become aware that a number of after-market
companies are offering our customers “up-screening” services
for Xilinx products. These service providers attempt to elevate the
grade level of an IC through the application of post-sale testing and/or
screening. There are high risks associated with this practice
for all but the simplest of components.
For example, a popular approach is to take commercial (C grade)
products and test them at a higher temperature to obtain “I” and “M” grade
components. The difference between the various levels of grading involves
many variables including operating voltage ranges, leakage current, and
speed margins, as well as temperature guardbands. Development of reliable
methodologies and test suites for unique VLSI components, such as FPGAs,
require specialized expertise and large investments. Simply re-testing
our product to some test program that does not test all the operating modes
is not effective or reliable.
Xilinx yields tested product at greater
than six sigma levels of quality. This has been shown repeatedly
by Xilinx data, as well as customers’ data. These levels of quality are
achieved by a continuous improvement process incorporating root cause and
corrective action. Xilinx test methodology is continuously
evolving based on feedback and support
from over 4,000 customers. Very few after-market test houses
have the required hardware implementation and none have Xilinx methodology.
Also, our products are extremely complex,
and can be damaged by the application
of inappropriate configuration fields, voltage or current stresses.
Any third party attempting to test Xilinx devices must have an intimate
knowledge of our architecture, circuit implementation, and design methodology.
Without this expertise it is practically impossible to write safe, efficient
test code.
Another practice is to test and certify commercial product outside the
manufacturer's maximum ratings. This is becoming commonplace
with plastic encapsulated products. This practice is extremely dangerous.
Commercial products must not be used outside their published design ratings
and intended application.
Please be advised that Xilinx can not be responsible for any component
or system failure due to the use of its products outside of Xilinx published
operating parameters and can not warrant any component that has been subjected
to “up-screening.”
To support defense and other high reliability
applications, Xilinx offers a complete line of
extended-temperature products in both ceramic and plastic packages fully
guaranteed by Xilinx. Reaffirming our long-standing
commitment to the Defense and Aerospace markets,
Xilinx has received full QML certification
in November of 1997. Our new QPROTM
line of High-Reliability FPGAs now includes the high density XQ4000XL
3.3V family as well as the XQ4000E 5V family. All of these products
offer the highest cost efficiency, reliability and are available off-the-shelf.
Sincerely
Joseph J. Fabula
Director, Quality Assurance
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