Improving quality of keyboard by analyzing the migration of Ag ions (日本信頼性学会第14回信頼性シンポジウム報文集) -- (セッション3 ハードウェア面〔英文〕)

概要

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The major failure in the field was that several keys were operated simultaneously on the keyboard of a personal computer. Based upon detail failure analyses, we found that the malfunction was result from an Ag ion migration in a membrane since the pattern of the membrane on the keyboard was composed of Ag paste. From the simulated tests, we noticed that the Ag ion migration was happened by moisture penetration into the membrane when the board is exposed to high temperature and high humidity for a long time. In this study, we developed a semi-waterproof membrane not only can prevent happening of a migration but also does not increase a manufacturing cost. It was verified that the mean lifetime of the newly-designed membrane can be assured minimum 5 years at the condition of (40℃, 90%RH). In addition, an accelerated test was developed to induct an ion migration and to validate reliability in a relatively short time. We found that the value of the acceleration factor was 17 at the stress (85℃, 85%RH) compared to the condition of (40℃, 90%RH)
日本信頼性学会の論文
2001-11-30