由於高功率電子產品持續增加的需求，功率模組具有高功率密度與高散熱結構已成為開發主流。現今，多數功率模組使用接合導線作為電性傳遞，這將導致其散熱能力有限。功率晶片產生的熱會直接影響導線之可靠度，故接合導線的失效模式必須被探討。隨著功率負載持續地增加，晶片溫度也逐漸升高。因此，雙面功率模組進一步提出來解決散熱問題。然而，過高的晶片溫度導致常見的銲錫無法維持其功能。因此，當晶片溫度持續地上升，功率模組接合材料之耐高溫特性被高度地要求。本研究目的是預測高功率模組之電、熱與力的耦合行為，並判斷接合導線之破壞行為。且提出具有耐高溫能力之接合材料作為高功率模組之接點，其機械特性透過剪力與張力測試在預定的應用溫度下進行檢驗。
根據實際功率模組建構三維有限元素模型，且透過數值分析預測其電熱偶合效應與熱應力行為。最大電流密度和對應的電流聚集效應產生在IGBT晶片與接合導線之界面；同時，電流負載在功率晶片引起最大的溫度梯度，進一步影響結構的熱應力。分析結果與IGBT晶片的量測溫度進行驗證，以確認本研究所用的數值方法是可信的。探討接合導線之熱應力行為與失效模式，且進行接合導線的參數化設計分析，預測其耦合行為和評估其散熱能力。
本研究選擇具有高熔點的Au-20Sn共晶銲料作為接合材料，並檢驗其機械特性。實驗說明Au-20Sn銲料轉變形成具更高熔點的介金屬化合物 (AuSn與Au5Sn)，其材料特性符合功率模組之高溫應用需求。利用剪力測試分析在各種熱處理條件下，銲點微結構改變對於其材料強度的影響，亦檢驗在不同應用溫度下銲點材料之機械強度且評估其耐溫能力。解析銲點破壞模式並觀察其初始破壞界面與破壞路徑，這意味著在先進封裝結構可能造成銲點毀損的位置。透過張力測試在各種應變率與溫度負載下量測Au-20Sn銲料的非線性材料參數，檢驗應變率與溫度效應對於材料機械強度的影響，並完成Au-20Sn銲料之應力應變曲線。實驗結果說明當熱處理周期增加、溫度上升或應變率下降，會導致材料強度衰退。最後，建立Au-20Sn銲料溫度相依的材料參數，可以應用在有限元素模型作為非線性材料參數，並可以準確地評估高功率模組的可靠度。

Power module with high power density and high heat dissipation structure has been developed because of increasing requirement for high-power electric products. Nowadays, most power modules use metal wire as interconnection, which results in the limited heat dissipation capability. The heat generated by the power chip directly affects the reliability of the wire; thus, the failure mode of bonding wire is essential investigated. Along with continuously increasing power load, chip temperatures have gradually increased. Therefore, the double-sided power module was further proposed to solve the thermal issue. However, the exceeding high chip temperature bring about that the common solder unable sustain its function. Thus, the bonding materials with high-temperature resistant characteristics are highly demanded when chip temperatures are continuously increasing. The study aims to predict the electro-thermo-mechanical coupling behavior of high-power module and determine the failure behavior of bonding wire. A joint material with high-temperature resistance capability is also proposed. Its mechanical characteristics at the intended application temperatures were examined by shear test and tensile test.
A three-dimensional (3D) finite element (FE) model based on an actual power module was established to predict the electro-thermal coupling effect and thermal mechanical behavior by numerical analysis. The maximum current density and the corresponding current crowding effect were generated at the interface between the insulated gate bipolar transistor (IGBT) chip and bonding wire. Meanwhile, the current load induces the maximum temperature gradient at the power chip and affects the structure thermal stress. The analysis result was validated with the measurement temperatures of IGBT chip to confirm that the numerical methodology is reliable. The thermal-mechanical behavior and failure mode of the bonding wire were also investigated. The parametric design of bonding wire was analyzed to predict the coupling behavior as well as further estimate their heat dissipation capabilities.
An Au-20Sn eutectic solder with a high melting point was used as the bonding material, which further determines its mechanical characteristics. Experiments showed that the Au-20Sn solder transforms into intermetallic compound (IMC) materials with higher melting points (AuSn and Au5Sn), which meet the high temperature requirements. A shear test was used to analyze joint microstructure variations with regard to the influence of corresponding material strength at various thermal treatment conditions. Mechanical strength of joint at different application temperatures was also examined to assess the temperature resistant capabilities. The joint failure mode was analyzed to observe the initial break location and failure path, which means likely to cause the joint damage in advanced package structure. Nonlinear material properties of Au-20Sn solder were measured at various strain rates and temperature loads by tensile test. The strain rate and temperature effects on the influence of material strength were examined to accomplish the stress-strain curve for the Au-20Sn solder. The experimental results showed that the material strength declined when the treatment duration increased, when the temperature increased, and when the strain rate decreased. Finally, the temperature dependent material properties for Au-20Sn was established, which can be applied in FE model as nonlinear parameters and can accurately assess the reliability of high-power module.

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