| 摘要: | 焊錫接合技術對於現代電子工業是非常重要，由於鉛(Pb)具有毒性本質與考 慮對環境和人體健康的危害，所以無鉛焊錫必須取代有鉛焊錫，然而高強度機械 性質和優良潛變阻抗與熱老化性質對焊錫接合的可靠度是一個重要問題，但在另 一方面銀的價格在現在與未來會越來越貴，低價格錫銅合金對未來無鉛焊錫使用 是有利。然而鎳(Ni)和銅(Cu)的墊層常常被使用在晶片接合端奌與電路載板上接 奌金屬結構焊接，從機械破壞測試的破裂SEM 圖得知，靠近Ni 端的微結構(Sn 相與eutectic 結構)比靠近Cu 端的微結構的機械強度弱，但是我們還是不了解在 焊料微接奌在鎳(Ni)端和銅(Cu)端之間相對應硬度的相關性，所以本論文最主要 目的是研究Sn(Cu)合金微結構與硬之關聯性。 隨著不同固化冷卻速率與老化時間來研究Sn(Cu)合金中亞共晶與過共晶的 微結構，對於Sn(Cu)合金中亞共晶合金(Sn0.4Cu and Sn0.7Cu )，它的微結構主要 包含錫晶粒相與Sn(Cu)共晶結構，而Sn(Cu)共晶結構是由錫相與Cu6Sn5 化合物 相所組成，錫晶粒相主要出現在Sn0.7Cu 亞共晶結構，其原因應該是由於在非平 衡冷卻過程中所產生。此外可發現粗Cu6Sn5 化合物均勻存在Sn1.0Cu 微結構中， 而包含粗胖Cu6Sn5 化合物與Sn(Cu)共晶結構(由錫相與Cu6Sn5 化合物相所組成) 則存在Sn1.4Cu 和Sn2.1Cu 合金。隨著微量銅的添加，錫(銅)合金硬度會隨著增 加，當微量銅的添加到1.0 wt%時可使硬度達到最高值，但此時硬度易開始隨銅 含量增加而下降。 根據硬度測試結果，硬度與Cu6Sn5 化合物的粒徑大小和間距成反比，此時硬 度可由-經驗化公式表示為Ln H = k3 1 或Rn H = k4 1 ，從先前Sn1.0Cu 的實驗結果 顯示，可進一步公式化經驗方程式為 或 ，總結論我 們對錫銅合金找出一個經驗通式 和H = H = H = 5.6 , n 1 (hyper - eutectic) 0.3 0.8 = R E 3.64 , n 1 (hypo- eutectic) 0.3 0.8 < R Solder jointing technology is very important for the modern electronic industry. Due to Pb has a toxic nature and the environmental and health hazard concerns. So, Pb-free solders are developed to replace SnPb. Yet, high strength mechanical property, the superior creep resistance and thermal fatigue are the important issues for the solder joint reliability. On the other hand, silver would be very costy in the future. The low-cost Sn(Cu) alloys offer good advantages for the future Pb-free solders. However, Cu and Ni are often used in the bond pads on the chip and broad side for the current flip-chip interconnect structure. It has been reported that the solder microstructure (Sn phase and eutectic structure) near the Ni side is weaker than that near the Cu. But, we do not clearly understand the relation between solder joint microstructure with hardness along Ni and Cu bond pad. So, the main objective of this thesis is to study the correlation between the hardness and the microstructure of Sn(Cu) alloys. The microstructure of hyper-eutectic and hypo- eutectic of Sn(Cu) alloys are investigated under different cooling rates and aging times. For the hypo-eutectic Sn(Cu) alloys (Sn0.4Cu and Sn0.7Cu ), their microstructure mainly contain the primary Sn grains and the eutectic structure. The eutectic structure is composed of Sn phase and Cu6Sn5 compound phase. The major reason for the appearance of Sn grains in the eutectic Sn0.7Cu should be due to the non-equilibrium cooling during the solidification process of Sn0.7Cu alloy. Furthermore, for the Sn1.0Cu alloy, round primary Cu6Sn5 particles was uniformly exhibited in Sn1.0Cu. For Sn1.4Cu and Sn2.1Cu alloys, contain chunky Cu6Sn5 particles and eutectic structure of Sn and Cu6Sn5 compound phase. It found that the hardness initially would increase with Cuadditives in Sn(Cu) alloys. As the Cu concentration reaches 1.0 wt%, the hardness has a maximum value. Then, hardness started decreasing with Cu concentration. According to our hardness testing results, the hardness is inversely proportional to the Cu6Sn5 compound particle size and space. Thus, the hardness can be further formulated as Rn H = k4 1 and Ln H = k3 1 , respectively. From Sn1.0Cu results shown previously, it was further formula as empirical equation can be expressed as : or , In conclusion, we formulate an the empirical equation for regulating the hardness of Sn(Cu) solder alloys ; and or and . |
