K. Kim 1, B. D. Youn 1, H. Oh 1, S. Choi 2, and Michael Pecht 3
1Department of Mechanical and Aerospace Engineering, Seoul National University, Seoul, Republic of Korea
2Agency for Defense Development (ADD), Daejeon, Republic of Korea 3Center for Advanced Life Cycle
3CALCE, Center for Advanced Life Cycle Engineering, Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20740, USA
Portable electronics including smartphones and tablet PCs change our lives enormously. As portable electronics have become prevalent, the portable electronics market has become more competitive. To attract the customers, portable electronic makers put continuous efforts to reduce the cost and to improve the performance.
According to a study from SquareTrade, Inc., 31% of iPhone 3G models failed in the first 22 months. Two thirds of those failures were considered to be caused by user abuse or accidental damage, and 25% of the failures caused by the users were due to water damage [1, 2]. To reduce warranty costs by refusing warranty or replacement, portable electronics makers have applied liquid damage indicators (LDIs) into their products for show user’s possible abuse.
However, it is suspected that the policy of refusing customers’ claims based on LDI results can be wrong. Actually, several cases have been reported where the color of an LDI has changed by sweat, rain, or a humid atmosphere [3-5]. For this reason, one of the leading smartphone manufacturer paid indemnities to consumer class-action lawsuit alleging the company relied on faulty indicators . There are very few studies for the reliability of LDIs. It is found that Oh et al.  proposed an empirical model to described performance of LDIs and validated with portable devices