銀鈀合金及純銅帶材對不同基板之超音波接合

Abstract

隨著綠能產業以及電動車的發展，高功率封模組裝技術必須提供高可靠度以及高散熱性。近年來，銀鈀合金材料被提出作為金線、鋁線及銅線的替代材料，對於高電流密度之功率模組而言，銀鈀合金之低成本、低電阻率、抗電遷移等特性，將提高其可靠度。在聯線技術中，超音波接合可以在室溫中進行，具有高效率，也因此被廣泛應用。 本研究中，將針對Ag-4Pd銀鈀合金帶材以及純銅帶材對於不同富銅陶瓷基板接合後進行可靠度分析，銀鈀合金帶材分別與CuNiAu、CuNiPdAu、CuNi、CuNiPd基板接合，而純銅帶材與CuNiAu、CuNiPdAu、表面有有機鍍層之OSP/Cu基板進行接合。研究中，透過一系列實驗設計後，分析出最適合此兩種帶材之基板種類。在完成超音波接合後，進行拉力強度測試、針對界面進行成分分析、以程式MATLAB對拉力測試後之破壞面進行殘留面積分析，最後經過150、1000小時之高溫儲存試驗分析其可靠度。 研究結果發現，銀鈀合金帶材最佳接合條件為有金鍍層之CuNiPdAu基板，而純銅帶材則為同質接合之OSP/Cu基板。而利用MATLAB分析殘留面積之方法可行，且殘留面積與接合強度呈高度正相關。在可靠度測試方面，無論在銀鈀合金帶材或是純銅帶材，由於界面晶界增加導致固溶擴散提升，具有金鍍層之基板經過150、1000小時之高溫儲存試驗後接合強度皆提升。

With the development of green energy industry and electric car, the electric package technology of high power module must process high reliability and high heat dissipation. In recent years, Silver-Palladium Alloy material has been developed to alternate the Gold, Aluminum, and Copper wires. During the operation of electronic devices, the high current flow might cause failures. The characteristics of Ag-Pd alloy such as low cost, low electrical resistivity, high electromigration durability will enhance the reliability of the device and will solve the problems. Ultrasonic wire bonding has been a predominant interconnection technique in microelectronic packaging industry. In this research, Ag-4Pd Alloy ribbons and Pure Copper ribbons will be bonded on various direct bond copper substrates such as CuNiAu, CuNiPdAu, CuNi, CuNiPd, and OSP/Cu Substrates. The reliability test will be hold after the bonding process. This research includes 5 stages: 1) Ultrasonic Bonding, 2) Pull Strength Test, 3) Interface Analysis, 4) Residual Area Counting with MATLB, 5) Failure mode analysis and 6) 150, 1000HR High Temperature Storage Test. Throughout a series of experiment, the best choice of substrates correspond to theses two ribbons will be found. Throughout the research, the best substrate for Ag-4Pd Alloy ribbons and Pure Copper ribbons are CuNiPdAu substrate and OSP/Cu substrate. In conclusion, MATLAB is a useful way in counting the residual area, and the bonding strength is highly related to the residual area. In the reliability test, the increment of the grain boundary at the interface cause the enhancement of the diffusion rate of solid solution. Under the 150、1000hrs high temperature storage test, the ultrasonic bonding with the substrate which contain Au layer have high reliability no matter in Ag-4Pd Alloy ribbons or Pure Copper ribbons.