在先進封裝製程中，銲接通常透過迴焊製程進行，以連接晶片基板與印刷電路板，確保可靠的電性互連並提升訊號傳輸效率。SAC305為目前常用的無鉛銲料之一，具有良好的機械強度與延展性。然而，其相對較高的熔點會增加迴焊過程中的熱負荷，並提高製造成本。此外，SAC銲料在長時間熱時效後，仍可能產生界面介金屬化合物（IMCs）過度成長與微結構粗化等問題，進而影響接合可靠性。因此，有必要透過合金元素添加，改善其低溫製程適用性與界面穩定性。相關研究顯示，少量Bi的添加可提升銲料機械強度並降低其熔點，而銦（In）的添加則可進一步降低銲料熔點並改善其潤濕性。本研究以含少量Bi之Sn-Ag-Cu-Bi銲料為基礎，探討不同In含量對銲料與Cu基板界面反應之影響。本研究將Sn-Ag-Cu-Bi-xIn（x = 0、6、12）銲料分別與Cu基板進行反應，觀察銲料/Cu界面形成之IMC的微結構與成分變化。隨後於不同溫度下進行高溫儲存（high-temperature storage， HTS）試驗，並計算界面IMC之成長動力學，以評估In含量對界面穩定性的影響。實驗結果顯示，含In銲料與Cu基板反應後，界面形成之IMC由原本的Cu₆Sn₅與Cu₃Sn 轉變為Cu₆(Sn，In)₅與Cu₃(Sn，In)，且其成長速率較慢。隨著 HTS 時間延長與溫度升高，此差異更加明顯。上述結果顯示，In添加可有效抑制界面IMC成長，並提升Sn-Ag-Cu-Bi-xIn銲料/Cu接合界面之穩定性。;In advanced packaging processes， soldering is commonly performed through the reflow process to connect chip substrates and printed circuit boards， ensuring reliable interconnections and enhancing signal transmission efficiency. SAC305 is one of the most commonly used lead-free solder alloys because of its good mechanical strength and ductility. However， its relatively high melting point increases the thermal load during reflow and raises manufacturing costs. In addition， after long-term thermal aging， SAC solder may still suffer from excessive interfacial intermetallic compound (IMC) growth and microstructural coarsening， which can affect joint reliability. Therefore， it is necessary to improve its suitability for low-temperature processing and interfacial stability through the addition of alloying elements. Previous studies have shown that a small amount of Bi can enhance the mechanical strength of solder while lowering its melting point， and indium (In) can further reduce the melting point and improve wettability. Based on Sn-Ag-Cu-Bi solder containing a small amount of Bi， this study investigates the effects of varying In content on the interfacial reaction between the solder and Cu substrates. In this study， Sn-Ag-Cu-Bi-xIn (x = 0， 6， and 12) solder alloys were reacted with Cu substrates to examine the microstructural and compositional changes of the IMCs formed at the solder/Cu interface. High-temperature storage (HTS) tests were then conducted at different temperatures， and the growth kinetics of the interfacial IMCs were calculated to evaluate the effect of In content on interfacial stability. The experimental results indicate that the interfacial IMCs formed at the In-containing solder/Cu interface were identified as Cu₆(Sn， In)₅ and Cu₃(Sn， In)，rather than Cu₆Sn₅ and Cu₃Sn， and exhibited a slower growth rate. This difference became more pronounced with increasing HTS time and temperature. These results indicate that In addition can effectively suppress interfacial IMC growth and improve the stability of the Sn-Ag-Cu-Bi-xIn solder/Cu interface.
