Hyunseok Oh 1, Seunghyuk Choi 1, Keunsu Kim 1, Byeng D. Youn 1, Michael Pecht 2
1Department of Mechanical Engineering, Seoul National University, Seoul 151–742, Republic of Korea
2CALCE, Center for Advanced Life Cycle Engineering, Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20740, USA
Abstract:
Portable electronics makers have introduced liquid damage indicators (LDIs) into their products to detect
warranty abuse caused by water damage. However, under certain conditions, these indicators can exhibit
inconsistencies in detecting liquid damage. This study is motivated by the fact that the reliability of LDIs
in portable electronics is suspected. In this paper, first, the scheme of life tests is devised for LDIs in
conjunction with a robust color classification rule. Second, a degradation model is proposed by
considering the two physical mechanisms—(1) phase change from vapor to water and (2) water
transport in the porous paper—for LDIs. Finally, the degradation model is validated with additional
tests using actual smartphone sets subjected to the thermal cycling of -15°C to 25°C and the relative
humidity of 95%. By employing the innovative life testing scheme and the novel performance
degradation model, it is expected that the performance of LDIs for a particular application can be
assessed quickly and accurately.