Microelectronics Reliability, Vol. 42, pp. 641-651, 2002

The "Trouble Not Identified" Phenomenon in Automotive Electronics

Dawn A. Thomas
358 Hungerford Drive
Rockville, MD 20850

Ken Ayers
Hancock, Rothert & Bunshoft LLP
4 Embarcadero Center
San Francisco, CA 94111

Michael Pecht
University of Maryland
College Park, MD 20742


In some cases, a failure occurs that cannot be verified, replicated at will, or attributed to a specific failure site, mode, and mechanism. Terms used to describe this phenomenon include trouble not identified (TNI), no trouble found (NTF), cannot duplicate (CND), 're-test ok' (RTOK), no-fault found (NFF), and intermittent malfunctions. This paper discusses the concept, causes, and impact of the "trouble not indented" phenomenon on the automotive electronics industry. A case study is presented to clarify the issues. The key conclusion is that a manufacturer should assume that all field returns are field failures, unless some alternative reason can be verified. In fact, any company that produces a safety or emission regulated product should assume that every complaint or return of that product is a failure, and take on full responsibility for ascertaining the root cause. It must not be assumed that a returned module that passes tests associated with an engineering specification is good.

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