在電子組裝行業中，我們常常使用銅作為主要金屬材料。本研究通過向銅中添加微量的鎳、矽和鎂元素，形成了Cu-3.0 wt%Ni-0.65 wt%Si-0.15 wt%Mg（C7025）銅鎳矽鎂合金。此合金具有較高的強度、良好的折彎特性、耐熱性以及優異的耐應力和腐蝕特性，廣泛應用於電器端子、汽車端子、導線架和IC插拔元件等領域。然而，C7025在導線架領域被廣泛應用，但尚未有學者探討添加微量鎳、矽和鎂元素形成的C7025銅鎳矽鎂合金與無鉛銲料之間的界面反應。因此，本研究旨在研究其液固界面反應，並探討其作為導線架材料的適用性。
目前，最常用的無鉛銲料是以純錫為基礎，並添加微量的銅、銀、鋅等元素的合金銲料。本研究選擇了三種無鉛銲料：Sn、Sn-3.0wt.%Ag-0.5wt.%Cu和Sn-0.7wt.%Cu，並以液態/固態反應偶的形式，在240、255和270oC的反應溫度下，對反應時間為0.5至20小時的界面反應進行研究，並利用掃描電子顯微鏡結合掃描電子顯微鏡/能量分散光譜儀深入研究其界面反應。
研究結果顯示，在240oC的反應溫度下，反應時間為0.5-5小時時，Sn/C7025反應偶界面僅生成扇貝狀（Cu,Ni6Sn5相，而Cu3Sn相僅會在240oC反應10小時、255oC反應10小時和270oC反應5小時後使用掃描電子顯微鏡觀察到。值得注意的是，在SAC/C7025和SC/C7025反應偶中，Cu3Sn相在270oC反應2小時後就會使用掃描電子顯微鏡觀察到。隨著時間和溫度的增加，介金屬相的厚度也會逐漸增加。其中，在反應20小時時，Cu3Sn相仍不明顯，這是因為C7025中的Ni原子促進了Cu6Sn5的成核，而抑制了Cu3Sn相的生長。銲點推球測試結果顯示，隨著溫度的升高，脆性逐漸增加。較高的溫度有助於形成規則的晶粒分佈和IMC層，但過高的溫度可能導致脆性增加降低剪切強度。在本研究中，這三個系統的介金屬相厚度與反應時間的平方根呈線性關係，反應機制主要受擴散控制。本研究所使用之C7025反應偶所抑制空孔的生成以及其機械性質強度並不明顯，因此在導線架之應用較無特別突出。

In the electronic assembly industry, copper is commonly used as the primary metal material. In this study, a Cu-3.0 wt%Ni-0.65 wt%Si-0.15 wt%Mg (C7025, copper-nickel-silicon-magnesium alloy) was developed by adding trace amounts of nickel, silicon, and magnesium to copper. This alloy exhibits high strength, good bending characteristics, heat resistance, as well as excellent stress and corrosion resistance, making it widely used in areas such as electrical terminals, automotive terminals, wire frames, and IC interconnect components. However, while C7025 is extensively utilized in the wire frame field, there has been no investigation on the interface reactions between the C7025 copper-nickel-silicon-magnesium alloy and lead-free solders. Therefore, this study aims to explore the liquid-solid interface reactions and assess the suitability of this alloy as a wire frame material.
Currently, the most commonly used lead-free solder is tin-based with the addition of trace amounts of copper, silver, zinc, and other elements. Three types of lead-free solders were selected for this study: Sn, Sn-3.0 wt%Ag-0.5 wt%Cu, and Sn-0.7 wt%Cu. The interface reactions were studied using liquid/solid reaction couples at reaction temperatures of 240°C, 255°C, and 270°C, with reaction times ranging from 0.5 to 20 hours. Scanning electron microscopy combined with energy-dispersive X-ray spectroscopy was employed to investigate the interface reactions in depth.
The results revealed that at a reaction temperature of 240°C and a reaction time of 0.5-5 hours, only a scallop-shaped (Cu,Ni)6Sn5 phase was formed at the Sn/C7025 reaction couple interface. The Cu3Sn phase was observed using scanning electron microscopy only after reaction times of 10 hours at 240°C, 10 hours at 255°C, and 5 hours at 270°C. It is noteworthy that the Cu3Sn phase could be observed after 2 hours of reaction at 270°C in the SAC/C7025 and SC/C7025 reaction couples. The thickness of the intermetallic compound (IMC) layer gradually increased with time and temperature. However, even after 20 hours of reaction, the Cu3Sn phase was not prominent, attributed to the Ni atoms in C7025 promoting the nucleation of Cu6Sn5 and inhibiting the growth of Cu3Sn. The ball shear test results showed that with increasing temperature, brittleness gradually increased. Higher temperatures facilitated the formation of a regular grain distribution and IMC layer, but excessively high temperatures could lead to increased brittleness and decreased shear strength. In this study, the thickness of the intermetallic phases in all three systems showed a linear relationship with the square root of reaction time, suggesting a diffusion-controlled reaction mechanism. The C7025 reaction couple used in this study did not show significant suppression of void formation or notable enhancement in mechanical properties, suggesting a limited advantage in wire harness applications.

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