銀合金線離子遷移機制研究

由於純金銲線與銅銲線作為打線接合的線材會遭遇許多導致電子元件失效的潛在問題，許多電子封裝廠開始試圖研發純銀銲線和銀合金銲線來替代。然而當通入電流的純銀銲線遇上含有水氣的環境會發生銀離子的電化學遷移現象，造成樹枝狀銀鬚的生成，進而導致電子元件短路，此現象最初是在銀厚膜(Thick Film)電路中發現的。研究證明在純銀銲線中添加一定量鈀或金元素可有效抑制電化學遷移的現象，且在含有一定量鹵素離子的水溶液環境下也可抑制銀鬚的生成，因此本研究主要探討添加鈀和金元素的二元及三元銀合金線材在含鹵素離子的水溶液環境中是否能有效減緩銀離子遷移現象的發生。本研究主要是分別利用二元Ag-4Pd和三元Ag-8Au-3Pd銀合金線材當作陰陽兩電極，在不同濃度的氯化鈉(NaCl)、溴化鈉(NaBr)、碘化鈉(NaI)三種水溶液，採用符合ASTM F-1996標準規範之水滴法進行離子遷移實驗，並透過透過數位光學顯微鏡、SEM、EDS等分析儀器，整理與討論出不同成分及濃度水溶液下分別對二種銀合金材的影響。離子遷移過程中，在含有鹵素離子的水溶液環境下，當銀合金線在高於其臨界離子遷移濃度時，會抑制銀離子遷移形成銀鬚。Ag-8Au-3Pd線和Ag-4Pd線在三種水溶液中當銀鬚碰觸到陽極端時並不會立即發生短路，皆有一段絕緣的時間。隨著鹵素離子含量的增加，提高了銀離子遷移速率，表示鹵素離子的存在對銀離子遷移的影響大過於Au和Pd的抑制作用，但只有Ag-8Au-3Pd線在氯化鈉水溶液中隨著鹵素離子含量越高，銀離子遷移速率反而降低。隨著Pd和Au的添加，銀線材能防止銀鬚形成的臨界離子遷移濃度越高。陽極生成物的成分主要都以AgO及鹵化銀為主，其陽極生成物有多種不同的形貌。

關鍵字

離子遷移；電化學遷移；銀合金銲線；水滴試驗法；樹枝狀晶；鹵素離子

並列摘要

Since pure gold wires and copper wires as bonding wire will encounter many potential problems that cause the failure of electronic devices, many electronic packaging factories have tried to develop pure silver wires and silver alloy wires to replace them. However, when the pure silver wire under the current is exposed to the humid environment, the electrochemical migration of silver will occur, resulting in the formation of dendritic silver whiskers, which will lead to the short circuit of electronic devices. This phenomenon was originally found in the circuit of thick silver film. It’ve shown that a certain amount of palladium or gold adding to the pure silver wires can effectively inhibit the phenomenon of electrochemical migration, and the generation of silver whiskers in an aqueous environment containing a certain amount of halide ions. Therefore, this research mainly discusses whether the binary and ternary silver alloy wires can effectively slow down the occurrence of silver ion migration in the halide aqueous solution. In this study, binary Ag-4Pd and ternary Ag-8Au-3Pd silver alloy wires were used as anode and cathode electrodes, respectively, in different concentrations of sodium chloride (NaCl), sodium bromide (NaBr), and sodium iodide ( NaI) aqueous solutions, and the ion migration experiments were investigated by the water drop test in accordance with ASTM F-1996 standard specifications. Through the analytical instruments of digital optical microscope, SEM and EDS, the influences of two silver alloy wires in the different composition and concentration of the aqueous solution were discussed. When the concentration of the halide aqueous solution is higher than its critical ion migration concentration, it will prevent silver ions migrating to form silver whiskers. The short circuit of Ag-8Au-3Pd wires and Ag-4Pd wires will not happen immediately when the silver whisker touches the anode in the three halide aqueous solutions, and they all have a period of insulation time. As the content of halide ions increases, the ion migration rate of silver ions is increased, indicating that the presence of halide ions has a greater impact on the migration of silver ions than the inhibition of Au and Pd. Only Ag-8Au-3Pd wires in the sodium chloride aqueous solution were found that the higher the halide ion content, the lower the silver ion migration rate. With the addition of Pd and Au, the critical ion migration concentration is higher. The anode products were mainly composed of AgO and silver halide, having different morphologies.

並列關鍵字

ion migration ； electrochemical migration ； silver alloy wire ； water drop test ； dendrites ； halide aqueous solution

參考文獻

[1] G.G. Harman, “Reliability and Yield Problems of Wire Bonding in Microelectronics,” National Inst. Of Standards and Technology, International Society for Hybrid Microelectronics,1991, pp.49-89

Google Scholar

[2] J.-H. CHO, J.-S. CHO, J.-T. MOON, J. LEE, Y.H. CHO, Y.W. KIM, A.D. ROLLETT, and K.H. OH, “Recrystallization and Grain Growth of Cold-Drawn Gold Bonding Wire,” METALLURGICAL AND MATERIALS TRANSACTIONS A, VOLUME 34A, MAY 2003, pp.1113-1125

Google Scholar

[3] Hao-Wen Hsueh, Fei-Yi Hung, Truan-Sheng Lui, Li-Hui Chen, and Kuan-Jen Chen, “Intermetallic Phase on the Interface of Ag-Au-Pd/Al Structure,” Advances in Materials Science and Engineering, 2014

Google Scholar

[4] Tan Chee Wei , Abdul Razak Daud, “Mechanical and Electrical Properties of Au-Al and Cu-Al Intermetallics Layer at Wire Bonding Interface,” J. Electron. Packag. Dec 2003, pp.617-620

Google Scholar

[5] G. Harman, J. Albers, “The Ultrasonic Welding Mechanism as Applied to Aluminum-and Gold-Wire Bonding in Microelectronics,” IEEE Transactions on Parts, Hybrids, and Packaging, 1977, pp.406-412

Google Scholar

國際替代計量

銀合金線離子遷移機制研究

未授權

主題瀏覽