Company HTV in Bensheim, Germany, researches meanwhile already more than a decade in the field of „sustainment“ of electronic components and assemblies and, thus, can retrospect to nearly 8 years of experience in active conservation of electronic components.
In the high security building, specifically designed for conservation and storage, more than 100 millions of components and assemblies are currently stored and wait in “deep sleep” for delivery on call on the part of the customer. At the time of conversion to „lead-free“ in 2003 the company had already a conclusive and comprehensive concept for the suitable long-term storage of components and therefore possesses a lead in this complex topic which hardly can be caught up. Challenge in this type of storage are the manifold aging processes, which can already after 1–2 years be responsible, that a processing of components is no longer possible respectively that their functionality is affected or no longer existent. Basis for the development of an appropriate conservation procedure was therefore the detailed identification and analysis of all aging processes involved as well as their impacts to the diverse electronic and electromechanical components. In the past the erroneous assumption was that the storage in nitrogen stops aging processes. Today it is known that this method prevents from oxidation only for 1–2 years! A sustainable reduction of aging processes is only possible on the basis of complex adaption and control of ambient conditions during storage.
The storage periods of 30 to 50 years, prognosticated by the company, are achieved by performing comprehensive analyses and process controls in a preliminary stage and also concomitantly to storage. Hence, the present component condition is documented and, thus, an appropriate adaption of storage parameters is enabled.
Specially developed systems for absorption of corrosive harmful substances as well as novel functional films and adapted temperature profiles are here the key factors of the TAB-storage method during storage. In the event of component discontinuation by manufacturers production of complete assemblies is possibly threatened. Particularly in case of externally, extensively certified products as well as high-value and long-living goods a considerable risk exists in this respect. Expensive, time-consuming redesigns and resulting new releases are often the consequence. Due to this pressure a „Last time buy“ is executed in many cases, where the estimated demand for the next years is ordered and stored under standard conditions. Based on this approach it is problematic that most of these components available in the market are only imperfectly suitable for a conventional long-term storage or not at all due to their internal structure. As, for example, the layer thickness of pure tin surfaces of contact pins amounts only to a few micrometers it is very susceptible to ever-present diffusion processes. Hence, already after 1–2 years the copper diffuses out from the inside to the surface – soldering processes are, thus, impossible.
Therefore, the conventional nitrogen storage is considered an inappropriate method, since it only prevents from oxidation at metal surfaces for a short period of time. The method for long-term conservation TAB, developed by the company, provides, in contrast, a genuine solution for storage periods up to several decades. Thereby, proven products become sustainable at competitive prices. The high non-material value of discontinued components, which should keep customer products still alive for decades, is, moreover, taken account by an ingenious safety philosophy at the company: Due to multiple measures the specifically designed high security storage building considers, in particular, risks such as natural catastrophes or theft. In addition, formation of fire in all storage areas is impossible due to the innovative method of oxygen reduction. The demand to the unique storage concept of the company requires at present an extension of the existing storage area of its high security storage building by almost 8000 m2 through two new buildings.
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