CD-R Life Expectancy

CD-R Life Expectancy

Situation You May Encounter:

Questions may arise regarding how long data will be readable on a CD-R Disc. While there is no way one can predict the life of any individual disc, we believe that the best estimate of Imation CD-R life expectancy exceeds 100 years.

Why The Situation Exists:

In the early years of CD manufacture, there was not a very good database upon which to draw in order to determine life expectancy of CDs. Some manufacturers claimed life expectancies of many years or even decades. Some periodicals implied that the life of a CD was unknown. With the conflicting information and no data, people began to wonder just how long CDs would last.

The current situation with Imation CD-Rs is somewhat different. There has been considerable study made on the life expectancy of Imation CD-ROMs. Data and specific reports have been made and ANSI standards (ANSI IT9 Committee) are in progress detailing how lifetime of CD-ROM optical storage media should be assessed.

The construction of a CD-ROM and CD-R are very similar. The CD-R has one additional layer between the polycarbonate substrate and the metal reflector layer. This layer is a photosensitive dye which gives the CD-R the ability to record information.

Accelerated testing data of Imation CD-R media has been compared to that of Imation CD-ROM. The lifetime of a disc may be estimated by measuring changes in the Block Error Rate (BLER). All discs have a low level of errors which can easily be corrected to exactly reproduce the original information. Beginning levels of BLER are usually 5 or less. If they grow to very large numbers then the error correction codes may not be able to function properly. This level varies considerably with a user's system, but according to the ISO/IEC 10149 standard, it should be 220. To be on the safe side, Imation estimates end-of-life to be a very conservative BLER of 50. Accelerated studies have been made and the well known Arrhenius model has been used to estimate the rate of increase in BLER as a function of time at various temperatures. The figure at the bottom of this page is the result of this study.