以高自由度加速模型評估電子元件之可靠度

Abstract

要在短時間內瞭解如電子連接器等電子元件之可靠度特性，常需以加速試驗取得產品之失效壽命，而後再進行可靠度分析與評估。本研究為瞭解某廠商所設計之2-mm Hard Metric Connector連接器端子之可靠度，特別針對同型但不同鍍層厚度之端子連接器實施不同複合應力加速壽命試驗，而後透過迴歸分析求取連接器端子在加速環境下之壽命，接著藉由加速模型，將端子於加速環境下之壽命反推至正常環境下之壽命，最後搭配可靠度相關理論評估此型連接器端子之可靠度指標。有別於許多加速試驗僅探討兩種加速應力因子對試驗產品的影響，本研究考慮三種以上的加速應力因子，並將加速模型改寫成為高自由度的一種Generalized Log-Linear (GLL)模型，做為分析的依據。分析結果顯示，所探討的連接器端子對於插拔有很高的耐久度，但無法承受高溫造成的影響。透過加速模型，本論文發現在溫度45℃、使用插拔次數50次、MFG倍率為0.5的使用環境下，鍍層50微英吋之端子平均失效時間為595,760小時，相當於68.01年；鍍層40微英吋之端子平均失效時間為600,584小時，相當於68.56年；鍍層30微英吋之端子平均失效時間為490,151小時，相當於55.95年；鍍層20微英吋之端子平均失效時間為415,537小時，相當於47.46年。以上結果顯示，本研究所探討之連接器端子無論在何種鍍層下，均具有相當高的可靠度。

In order to understand the reliability characteristics of electronic device, such as electronic connector, researchers often use accelerated life test to obtain the life of products, and then analyze and assess the reliability of products. In this study, to understand the reliability properties of 2-mm Hard Metric Connector, the accelerate life tests with multiple stress factors were conducted for different types of plating thickness of connector pins. After the test, life of connector pins in accelerated life test is analyzed with regression analysis, and the results are used to extrapolate the life in normal environment by acceleration model. Finally, the reliability index of connector pins with reliability theory is evaluated. Unlike many accelerated tests that only cover the impact of products by two acceleration factors, three and more types of acceleration factor are included in this study. For this reason, the common acceleration model is transformed to Generalized Log-Linear (GLL) model with high degree of freedom which this study is based. According to the analysis results, it is found that these types of connector pins have a high durability for plugging and unplugging, but cannot endure the impact of high temperature. The prediction for connector pins life in normal operated condition with temperature of 45 ℃, durability cycles of 50, and MFG rate of 0.5, the life of 50 μ' plating thickness is 595,760 hours, the 40 μ' plating thickness is 600,584 hours, the 30 μ' plating thickness is 490,151 hours, and the life of 20 μ' plating thickness is 415,537 hours. As a result, no matter what the plating thickness of connector pins is, all of them have very high reliability in this study.