2011-08-012024-05-18https://scholars.lib.ntu.edu.tw/handle/123456789/700513摘要：目前SnAgCu 系列無鉛銲料已是國際間各大電子公司所採用之主要電子銲料，SnAgCu系列銲料之組成相當廣泛，一般Ag 在銲料中的濃度在0-4wt.%間，而Cu 則在0-2wt.%間不等。其中以美國工業聯盟NEMI 所推薦的Sn(3.9±0.2)Ag(0.6±0.2)Cu、日本Senju 之Sn3Ag0.5Cu、以及AIM CASTIN 之Sn2.5Ag0.8Cu0.5Sb 最為多數人接受。近年來許多研究學者，嘗試以這些銲料為基礎，在其中添加微量的合金元素，以改善其性能。本計畫申請人所帶領之研究團隊首先於2002 年發現在SnAg 及SnAgCu 中，添加微量Ni 元素對銲料與Cu 基材 (substrate) 之反應有極大之影響，添加這些元素後會使得生成於界面之Cu3Sn 層變薄。本研究團隊最近亦發現添加微量 Fe 或Co 元素也有相同之效果、並首次証實元素添加量即使小到100 ppm (0.01 wt.%) 仍有效果。 使Cu3Sn層變薄最大的優點是減少伴隨Cu3Sn 生成之微孔的數量。這些微孔一般被認為是Kirkendall voids，但是亦有學者認為這些微孔之起源仍有爭論，宜暫時先以micro voids 稱之為宜。這些微孔不但可能會在SnAgCu 與Cu 反應時出現，亦可能會在共晶PbSn 與Cu 反應時出現，這顯示這類微孔之生成與Sn/Cu 二元反應有密切關係。德州儀器的研究人員並在2004 年首度證實此類微孔的確會造成電子產品之可靠度下降。由於這些微孔只會出現在Cu3Sn/Cu 界面處、或在Cu3Sn 內部，這兩種情形都與Cu3Sn 的生長有關。因此瞭解Cu3Sn 的生長行為就顯得格外重要。能夠抑制此一介金屬生長的因素，理論上應會對提升銲點可靠度有所幫助。 本計畫之總目標是去深入了解微量元素的添加對無鉛銲料與 Cu 反應所產生之影響。本研究除了將對現象作一完整觀察與描述外，並將對其機制作深入探討，此外並將初步評估微量元素的添加對銲點機械性質的影響。微量元素添加的種類限定在Fe、Co、Ni、Cu (本研究暫將SnAgCu 銲料中之Cu 元素視為添加元素) 。上述目標預計於三年內完成。在第一年我們計畫探討不同元素添加量下，對迴銲及固態熱處理時界面反應之影響，並將對其機制作深入探討。在第二年我們預計將探討在不同銲點體積下，前一年觀察到的效應是否仍然存在?亦或有所改變? 也就是說我們將探討對實際銲點很重要的所謂的體積效應 (solder volume effect)。本計畫的第三年則預計將評估微量元素的添加對實際銲點機械性質的影響。本計畫總目標完成後，將可建立不同溫度下、不同添加元素種類及添加量下，介金屬生長的動力學資料、擴散動力學與消耗動力學資料，並深入了解外部添加元素作用之本質。也將對微量元素的添加對實際銲點機械性質的影響有初步之瞭解。<br> Abstract: In the past few years, the SnAgCu family of solders has obtained a wide acceptance as a replacement for the PbSn eutectic solder for electronic applications. There are several popular SnAgCu compositions, including Sn(3.9±0.2)Ag(0.6±0.2)Cu, recommended by NEMI, Sn3Ag0.5Cu, recommended by Senju, and the AIM CASTIN 之Sn2.5Ag0.8Cu0.5Sb. At present, relatively fewer activities are undertaken by researchers worldwide to develop another solder family to replace the PbSn eutectic solder. Instead, the current main research thrust in lead-free solder alloy development is on enhancing or fine-tuning the various properties of SnAgCu through adding minor alloying elements. In 2002, our research group first showed that Ni could substantially hinder the Cu3Sn growth during soldering as well as during the following solid-state aging. We later also showed that Fe and Co additions had similar effects. More importantly, additions as minute as 100 ppm (0.01 wt. %) was proven to be effective. As the Cu3Sn growth had been linked to the formation of micro voids, which in turn increased the potential for brittle interfacial fracture. Recently, it was indeed shown by research group from TI that drop test performance decreased with thickening of the Cu3Sn layer. The formation of the micro voids with the growth of Cu3Sn had been identified in both the reaction of SnAgCu and Cu and eutectic PbSn with Cu. This suggested that the root cause for the formation of these micro voids is the binary reaction between Sn and Cu. Accordingly, the Ni addition to solders offers the potential benefit of raising solder joint reliability through decreasing the amount of the micro voids. The key objectives of this study are to examine the effects of micro alloy additions on the interfacial reactions between the solders and the Cu substrate, and to understand the fundamental mechanism for such effects. The effects of alloy additions on the mechanical properties of the solder joints will also be assessed. The alloy elements to be investigated include Fe, Co, Ni and Cu. (Here we view Cu in SnAgCu as an alloying element.) These objectives are to be achieved in three years. In the first year, the objective is to establish an understanding on the effects of different levels of alloy additions on the interfacial reactions during the reflow as well as during the aging stage. The underlying mechanism will be explored. In the second year, the solder volume effect on the reactions studied during the first year will be investigated. We would like to know whether different solder volumes will change the results we obtained in the first year. In the third year, the effect of micro alloy additions on the mechanical response of the solder joints will be evaluated. The accomplishment of the stated objectives of this study will provide the community the detailed fundamental kinetic data that are critical in designing more reliable electronic products.銲料合金添加柯氏孔洞界面反應solderalloy additionKirkendall voidsinterfacial reaction