Microsemi completes impressive FPGA reliability testing

7/15/2012 12:00 AM EDT

The phrase "commercial-grade" is a bit confusing. Generally "commercial-grade" and "industrial-grade" for the FPGAs denote the operating temperature range of 0 to 60degC and (-40) to (+85) degC respectively, for which FPGA specs are specified. Hope that is not what is meant here?

7/15/2012 8:08 PM EDT

This is very interesting. However, it is nice if it it list all tests conducted and its conditions. Also, how does this FITS compare with FGPA from other vendors?

7/17/2012 10:18 PM EDT

Thanks for the comments. Hopefully I can address the questions raised.

Firstly, regarding the tests conducted and their conditions. The parts being tested were divided into three groups. The first group (277 parts) was operated in a high temperature operating life test (case temp ~ 85degC), the second group (272 parts) was operated in a low temperature operating life test (ambient temp ~ -55degC), and the third group (182 parts) was exposed to a temperature cycle test in which parts operated alternately at 85degC and -55degC. In each case, prior to testing, the parts were programmed with a complex design which has very high sensitivity to small timing changes which could indicate changes to the impedance of the programmable interconnect elements over time. The fact that no timing changes were observed over the extremely long duration and harsh conditions of the testing indicates that the programmable interconnect elements are extremely robust and suitable for the most demanding of high-reliability applications.

This set of tests exposed parts to test conditions for over 4 years. For comparison, the high temperature operating life test required for qualification to Mil Std 883 class B is 1,000 hours (6 weeks) at 125 degC. Mil Std 883 class B is often used for qualification of microcircuits intended for terrestrial or airborne military applications. For flight-critical space applications, qualification to QML class V is often required. The life-test requirement for QML class V qualification is up to 6,000 hours (almost 35 weeks). The tests referred to in this news article lasted almost 6 times as long as the most stringent QML class V qualification. This is an unprecedented amount of reliability testing for an FPGA, and probably for any highly-integrated microcircuit.

7/17/2012 10:19 PM EDT

To answer the question about “commercial-grade” parts – yes this can be a confusing point and should be clarified. The term “commercial” is ambiguous – sometimes it is used in its strictest sense, meaning parts that are guaranteed to operate over the commercial temperature range of 0 to 70 degC. However, sometimes engineers working on defense and space systems use the term “commercial” simply to differentiate devices built for non-space applications from devices built for space applications. That is the case in this news article. In these tests, the devices tested were industrial temperature parts – guaranteed to operate over the industrial temperature range of -40 to 85 degC. They were plastic-packaged devices, not built to the same standard as FPGAs intended for space applications – for example they had no radiation mitigation built in, no hermetic packaging, and they were not subjected to Mil Std 883 class B screening, which would have included a dynamic burn-in, temperature cycling, temperature testing at -55degC and 125degC as well as room temp, etc. Microsemi is not suggesting that industrial parts can substitute for space-grade parts in space applications – they cannot because they don’t have radiation mitigation, burn-in, full temperature screening, hermetically-sealed packaging, etc. The point is that since the industrial parts use identical programmable interconnect elements as the space parts, they served very well as a cost-effective alternative to the space version for the purpose of these reliability tests.