電子元件在溫度循環試驗下之熱應力分析

Abstract

電子元件廣泛地運用在汽車各種不同系統中，多數系統的車用電子零件必須在嚴苛的環境下進行運作，其工作環境溫度可能從-40～155°C變化，加上多種材料間的熱膨脹係數（Coefficient of thermal expansion，CTE）不同，容易因較高之熱應力而導致影響電子元件之失效。 本研究使用ABAQUS有限元素軟體，依據實際樣本建立三維數值模型，進行電子元件於溫度循環（Temperature Cycling Test）測試條件下之熱應力分析。結果發現最大應力發生於溫度循環之最高溫150°C，位置則發生於半導體晶片周圍，與實驗中破壞位置相仿，也間接驗證了數值模擬之可信度。 本研究接著提出電子元件幾何設計改良之可能方案，探討不同幾何參數（包含半導體晶片尺寸和厚度、散熱片厚度、封裝體厚度等）對應力所造成之影響，以提供設計改良之參考依據。由數值模擬結果發現改變半導體晶片尺寸和厚度較能有效降低因溫度變化所產生之熱應力。

Nowadays, electronic components are widely used in a variety of systems in automobile. In automobile systems, most electronic components are often working in harsh environments with temperatures ranging from -40 °C to 155 °C. As a consequence, thermal stresses resulted from the difference of coefficients of thermal expansion in different component materials are usually responsible for mechanical failure of the electronic components. In the present study, the finite element software ABAQUS was employed to establish the three-dimensional numerical model for thermal stress analysis of electronic components, based on the experimental conditions of the temperature cycling test. The numerical results revealed that the maximum stress occurred at the temperature 150 °C, located at edge of semiconductor wafer which agrees experimental observations. Such an agreement in turn verifies the validity of the numerical simulations. Parametric studies were subsequently conducted in an effort to offer the improvement strategy on the design of the electronic components. The effect of each of the parameters such as the size and thickness of the semiconductor wafer, the thickness of heat sink and package on the thermal stress was addressed accordingly. It was found that among the foregoing parameters reducing the size and thickness of the semiconductor wafer can effectively diminish the thermal stress induced in the temperature cycling test.