在半導體封裝的接合技術上，因銲線接合技術發展時間較久，在相關設備及技術上也較為成熟，故目前在封裝製程上銲線接合技術仍為主流。在銲線製程材料上，銅線相對於金線的主要優勢有節省線材成本高達30~50%、高導電性、導熱率佳、較高的線弧穩定度及較慢的介金屬化合物(IMC)生成速度。IMC的生成某種程度上能強化接合強度，但IMC 層的電阻較高。而伴隨IMC 的成長，IMC 層與線材的界面上會有Kirkendall 孔洞[31]的出現，且孔洞亦隨熱處理時間遞增而擴大成長為裂縫(Crack)，將導致接點電性的劣化並降低鍵結的可靠度。

本實驗以市面上尚未正式推出的0.7mil 金鈀銅線及既有的鍍鈀銅線來當作這次實驗的線材。實驗結果顯示，金鈀銅線在拉斷力(Breaking load)及伸長率(Elongation)指標都優於鍍鈀銅線；再經由微硬度試驗得知，線材表面及結球部分金鈀銅線在硬度上比鍍鈀銅線軟，且在相同流量的保護氣體下，FAB (Free Air Ball)成型金鈀銅線比鍍鈀銅線有較佳的真圓度。

本次實驗更進一步探討放電燒球後其鍍層對於銅球的包覆性，在鍍鈀線上取七點去做元素分析，表面均有鈀層包覆，無漏銅之現象，而在金鈀銅線上亦均有金及鈀的元素分布在表面；在IMCs(Intermetallic compounds, 介金屬化合物)生成試驗上發現，這兩種線材的生成速度亦非常接近。但在作業性上，因為鍍鈀線在二銲點的魚尾(Stitch)成型較不穩定，且尾線(Tail)截斷速度過快，導致銲接過程機台容易鳴叫斷線(Short tail)，而實驗結果得知，在鍍鈀層再鍍上一層金，不僅對於鍍層上的微細孔洞有改善，在機台上的作業性也有提升。

In semiconductor packaging industry, the wire bonding technology has been developed for a long time. Since the equipment and technology are more mature than the others, wire bonding technology is still the mainstream for packaging technology. For the material used in the process, copper wires have numerous advantages over gold wires. Copper wires can save the cost up to 30~50% compared with gold wires, and the high electrical conductivity, good thermal conductivity, high stability of wire and slower growth speed in intermetallic compound (IMC) are all the advantages making copper wires more favorable. The formation of the IMC can strengthen the bond, but the IMC layer has higher electric resistance. During the growth of the IMC, Kirkendall voids[31] will appear at the interface between the IMC layer and the wire, and the voids will enlarge to form cracks through heat treatment, thus leading to the deterioration of electrical contacts and the reduction of reliability of bondability.

The materials used in this experiment are the 0.7mil Au-Pd-plated copper wires which are not yet on the market and the existing Pd-plated copper wires. The experimental results show that Au-Pd-plated copper wire has a better breaking load and better elongation than these of the Pd-plated copper wire. The micro-hardness test shows that Au-Pd-plated copper wire is softer than the Pd-plated copper wire. With the same forming gas flow rate, Au-Pd-plated copper wire has better FAB (Free Air Ball) formation roundness than the Pd-plated copper wire.

This experiment also examines the coverage of the coating on the copper ball after the EFO (Electrical Flame-Off). By choosing seven different spots on Pd-plated copper wire for element analysis, it is observed that the surfaces are all covered with a layer of palladium, and there is no exposed Cu. Gold and palladium are also found on the surface of the Au-Pd-plated copper wire. The growth of IMCs (Intermetallic Compounds) test shows that the growth rate on Au-Pd-plated copper wire is the same as the Pd-plated copper wire. During the wire bonding process, the Pd-plated copper wire is found unstable in the formation of second bond stitch and on the joint with the finger. Moreover, the tails are cut-off too fast causing alarm of the equipment with short tail defect. However, the experiment result shows that with an extra layer of gold coated on the palladium layer, voids on the plating layer can be reduced and the work efficiency can be improved.

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