在第一態樣中，本發明係關於線材，其包含具有表面之線芯(在下文中亦簡稱為「芯」)，該線芯具有疊合於其表面上之塗層，其中線芯本身由以下組成： (a) 0.1 wt.-%至0.3 wt.-% (重量-%、以重量計之%)、較佳0.2 wt.-%之量之銀， (b) 在99.64 wt.-%至99.9 wt.-%、較佳99.7 wt.-%至99.9 wt.-%或甚至更佳99.75 wt.-%至99.85 wt.-%範圍內之量之銅， (c) 在0 wt.-ppm至100 wt.-ppm (重量-ppm、以重量計之ppm)、較佳50 wt.-ppm至100 wt.-ppm、更佳70 wt.-ppm至80 wt.-ppm、尤其75 wt.-ppm範圍內之量之磷及 (d) 在0 wt.-ppm至500 wt.-ppm、較佳0 wt.-ppm至100 wt.-ppm範圍內之量之其他組份(除銀、銅及磷之外之組份)， 其中任何其他組份之個別量均小於30 wt.-ppm， 其中以wt.-%及wt.-ppm計之所有量均基於芯之總重量，且 其中塗層係包含內鈀層(基底層)及毗鄰外金層(頂層)之雙層， 其中內鈀層之重量相對於線芯之重量在1.5 wt.-%至2.5 wt.-% 範圍內且 其中外金層之重量相對於線芯之重量在0.09 wt.-%至0.18 wt.-%範圍內。 下表編譯線芯組成之一些較佳實施例：
本發明線材較佳係用於微電子裝置中接合之接合線材。其較佳係一體式物體。已知且出現眾多可用於本發明之線材之形狀。在剖面圖中，較佳形狀係圓形、橢圓形及矩形形狀。對於本發明，術語「接合線材」包含所有形狀之橫剖面及所有常用線材直徑，但具有圓形橫剖面及細直徑之接合線材較佳。平均橫剖面在(例如) 50µm2
至5024 µm2
或較佳113µm2
至2375 µm2
範圍內；相應地在較佳圓形橫剖面情形中，平均直徑在(例如) 8µm至80 µm或較佳12 µm至55 µm範圍內。 線材或線芯之平均直徑或簡言之直徑可藉由「篩分方法」獲得。根據此方法可測定經界定長度之線材之物理重量。基於此重量，使用線材材料之密度來計算線材或線芯之直徑。將直徑作為在五次切割具體線材時之五個測量值之算術平均值來計算。 與上文所提及者一致，線芯以上文所揭示之比率包含(a)銀、(b)銅及(c)磷。然而，本發明經塗覆線材之銀合金化銅芯可以總量之0 wt.-ppm至500 wt.-ppm、較佳0 wt.-ppm至100 wt.-ppm包含(d)其他組份。在本發明上下文中，通常亦稱為「不可避免的雜質」之其他組份係少量之化學元素及/或化合物，其源自所用原料中存在之雜質或線材製造製程，即(d)型其他組份之存在可(例如)源自銀及/或銅中存在之雜質。此等其他組份之實例係：Au、Ni、Pd、Pt、Fe、Si、Mn、Cr、Ce、Mg、La、Al、B、Zr、Ti、S等。其他組份(d)之0 wt.-ppm至500 wt.-ppm或甚至0 wt.-ppm至100 wt.-ppm之較低總量確保線材性質之良好再現性。芯中存在之其他組分(d)通常並非單獨地添加。每一個別其他組份係以基於線芯總重量之小於30 wt.-ppm之量包含在內。 線芯係體材料之同質區域。由於任一體材料始終具有可能在一定程度上展現不同性質之表面區域，故線芯之性質應理解為體材料之同質區域之性質。體材料區域之表面可在形態、組成(例如硫、氯及/或氧含量)及其他特徵方面有所不同。表面係線芯與疊合於線芯上之塗層之間之界面區域。通常，塗層完全疊合於線芯之表面上。在線芯與疊合於其上之塗層之間之線材區域中，可存在芯及塗層二者之材料組合。 疊合於線材表面上之塗層係包含內鈀層及毗鄰外金層之雙層。內鈀層之重量相對於線芯之重量在1.5 wt.-%至2.5 wt.-%範圍內且外金層之重量相對於線芯之重量在0.09 wt.-%至0.18 wt.-%範圍內。內鈀層以及外金層二者皆為薄層。在此上下文中，術語「薄」、「厚」或「塗層厚度」意指塗層在垂直方向上對芯縱軸之大小。對於平均橫剖面在50 µm2
至5024 µm2
之上文所提及實例性範圍內之線材或對於平均直徑在8 µm至80 µm之上文所提及實例性範圍內之圓形線材，內鈀層之厚度可在(例如) 20 nm至350 nm、較佳30 nm至340 nm範圍內且外金層之厚度可在(例如) 1 nm至25 nm、較佳2 nm至20 nm範圍內。在直徑為18 µm之圓形線材之實例性實施例中，內鈀層之厚度可在(例如) 60 nm至90 nm範圍內且外金層之厚度可在(例如) 1 nm至10 nm、較佳2 nm至6 nm範圍內。 關於該雙層之組成，其內層之鈀含量係基於內塗層總重量之(例如)至少50 wt.-%、較佳至少95 wt.-%。尤佳地，內塗層由純鈀組成。純鈀通常具有基於內塗層總重量之小於1 wt.-%之其他組份(除鈀之外之組份)。毗鄰外金層之金含量基於外塗層之總重量係(例如)至少50 wt.-%、較佳至少95 wt.-%。尤佳地，外塗層由純金組成。純金通常具有基於外塗層總重量之小於1 wt.-%之其他組份(除金之外之組份)。 在實施例中，本發明線芯之特徵至少在於以下固有性質(i)至(iii)中之一者(參見如下文所述「測試方法A」)： (i)在縱向(線芯之縱向)上量測之平均線材粒度(平均粒度)在3 µm至6 µm範圍內， (ii)在縱向上量測之平均粒度與線芯直徑之比率在0.05至0.25、較佳0.1至0.20範圍內， (iii)在縱向上量測之平均粒度對芯平均粒度之標準偏差比率(RSD)在0.1至0.4範圍內。 本文關於線芯使用術語「固有性質」。固有性質意指線芯本身具有之性質(獨立於其他因素)。相對於固有性質之外來性質取決於線芯與其他因素(如所用量測方法及/或量測條件)之關係。 在另一態樣中，本發明亦係關於上文所揭示本發明實施例中之任一者中用於製造本發明經塗覆線材之方法。該方法包含至少步驟(1)至(5)： (1)提供期望組成之前驅物項，即提供由以下組成之前驅物項： (a) 0.1 wt.-%至0.3 wt.-%、較佳0.2 wt.-%之量之銀， (b)在99.64 wt.-%至99.9 wt.-%、較佳99.7 wt.-%至99.9 wt.-%或甚至更佳99.75 wt.-%至99.85 wt.-%範圍內之量之銅， (c)在0 wt.-ppm至100 wt.-ppm、較佳50 wt.-ppm至100 wt.-ppm、更佳70 wt.-ppm至80 wt.-ppm、尤其75 wt.-ppm範圍內之量之磷及 (d)在0 wt.-ppm至500 wt.-ppm、較佳0 wt.-ppm至100 wt.-ppm範圍內之量之其他組份(除銀、銅及磷之外之組份)， 其中任何其他組份之個別量係小於30 wt.-ppm， 其中以wt.-%及wt.-ppm計之所有量均係基於前驅物項之總重量， (2)使前驅物項伸長以形成經伸長之前驅物項，直至獲得在5024 µm2
至70650 µm2
範圍內之中間橫剖面或在80 µm至300 µm、較佳130 µm至230 µm範圍內之中間直徑為止， (3)在完成製程步驟(2)後所獲得之經伸長前驅物項表面上沈積內鈀層(基底層)及毗鄰外金層(頂層)之雙層塗層， (4)進一步使在完成製程步驟(3)後所獲得之經塗覆前驅物項伸長直至獲得期望最終橫剖面或直徑為止，且 (5)最終在450℃至650℃範圍內之爐設定溫度下使完成製程步驟(4)後所獲得之經塗覆前驅物分股退火達0.1秒至3秒範圍內之暴露時間以形成經塗覆線材。 本文使用術語「分股退火」。相對於「分批退火」，其係容許快速產生具有高再現性之線材之連續製程。在本發明上下文中，分股退火意指在將欲退火之經塗覆前驅物牽拉或移動穿過習用退火爐且在已離開退火爐後纏繞於捲上的同時動態地完成退火。此處，退火爐通常呈既定長度之圓柱形管之形式。使用其經界定溫度輪廓，在可在(例如) 10米/分鐘至60米/分鐘範圍內選擇之既定退火速度下，可界定並設定退火時間/爐溫參數。 本文使用術語「爐設定溫度」。其意指在退火爐之溫度控制器中固定之溫度。 退火爐可係室式爐型爐(在分批退火情形中)或管式退火爐(在分股退火情形中)。 此揭示內容區別前驅物項、經伸長之前驅物項、經塗覆前驅物項、經塗覆前驅物與經塗覆線材。術語「前驅物項」用於尚未達到線芯之期望最終橫剖面或最終直徑之彼等預備階段線材，而術語「前驅物」用於具有期望最終橫剖面或期望最終直徑之預備階段線材。在完成製程步驟(5)後，即在期望最終橫剖面或期望最終直徑下之經塗覆前驅物之最終分股退火後，獲得在本發明意義上之經塗覆線材。 如製程步驟(1)中所提供之前驅物項可藉由使銅與期望量之銀且(視情況但較佳)亦與適當量之磷合金化/摻雜而獲得。可藉由熟習金屬合金技術者已知的習用製程來製備銅合金本身，例如，藉由將銅、銀及視情況磷以期望比率熔融在一起。在該製程中，可利用母合金。舉例而言，可利用感應火爐來實施熔融製程，且在真空下或在惰性氣體氛圍下工作係有利的。所用材料可具有(例如) 99.99 wt.-%及以上之純度級。可冷卻如此產生之熔體以形成基於銅之前驅物項之均質片。通常，此前驅物項係呈直徑為(例如) 2 mm至25 mm且長度為(例如) 2 m至100 m之棒之形式。此棒可藉由鑄造熔融於適當模具中之該銅合金，隨後冷卻且固化而製得。 在製程步驟(2)中，使前驅物項伸長以形成經伸長前驅物項，直至獲得在5024 µm2
至70650 µm2
範圍內之中間橫剖面或在80 µm至300 µm、較佳130 µm至230 µm範圍內之中間直徑為止。伸長前驅物項之技術係已知的且在本發明上下文中似乎可用。較佳技術係軋延、型鍛、模拉伸或諸如此類，其中模拉尤佳。 在後一情形中，以若干製程步驟拉製前驅物項，直至達到期望中間橫剖面或期望中間直徑為止。此線材模拉伸方法為熟習此項技術者所熟知。可採用習用碳化鎢及金剛石拉伸模且可採用習用拉伸潤滑劑以輔助拉伸。 本發明方法之步驟(2)可包括經伸長前驅物項之中間退火之一或多個子步驟。此中間退火可在(例如) 200℃至650℃範圍內之爐設定溫度下實施(例如) 0.5秒至1秒之暴露時間。此中間退火通常藉由分股退火方法實施。 在製程步驟(3)中，將包含內鈀層及毗鄰外金層之雙層塗層沈積於在完成製程步驟(2)後所獲得之經伸長前驅物項之表面上，以便將塗層疊合於該表面上。熟習此項技術者將理解，沈積內鈀層及外金層，使得內鈀層之重量相對於經伸長前驅物項之重量在1.5 wt.-%至2.5 wt.-%範圍內且外金層之重量相對於經伸長前驅物項之重量在0.09 wt.-%至0.18 wt.-%範圍內。 熟習此項技術者已知如何計算經伸長前驅物項上之此塗層之厚度以最終(即在最終伸長經塗覆前驅物項後)獲得以針對線材實施例所揭示之層厚度之塗層。熟習此項技術者已知多種用於根據實施例於銅合金表面上形成材料之塗層之技術。較佳技術係鍍覆(例如電鍍及無電鍍覆)、自氣相沈積材料(例如濺鍍、離子鍍覆、真空蒸發及物理氣相沈積)及自熔體沈積材料。在本發明之上下文中，電鍍係較佳技術。 在製程步驟(4)中，將完成製程步驟(3)後所獲得之經塗覆前驅物項進一步伸長直至獲得線材之期望最終橫剖面或直徑為止。伸長經塗覆前驅物項之技術係如上文在製程步驟(2)之揭示內容中所提及之彼等之相同伸長技術。 在製程步驟(5)中，在完成製程步驟(4)後所獲得之經塗覆前驅物最終在(例如) 450℃至650℃範圍內之爐設定溫度下分股退火0.1秒至3秒之暴露時間，或在較佳實施例中，500℃至600℃持續0.3秒至1秒。在實例性實施例中，尤其在直徑為約18 µm之線材之實例性實施例中，最終分股退火可在530℃之爐設定溫度下實施0.8秒之暴露時間。 在較佳實施例中，將最終分股退火之經塗覆前驅物(即仍熱的經塗覆線材)在水中淬火，其中在實施例中，可含有一或多種添加劑，例如0 wt.-ppm至1000 wt.-ppm之添加劑。在水中淬火意指立即地或迅速地，即在0.2秒至0.6秒內(例如)藉由浸漬或滴落使最終分股退火之經塗覆前驅物自其在製程步驟(5)中所經歷之溫度冷卻降至室溫。 製程步驟(2)之可選子步驟中間退火以及製程步驟(5)之最終分股退火可在惰性或還原氛圍下實施。多種類型之惰性氛圍以及還原氛圍為業內所已知且用於吹掃退火爐。已知惰性氛圍之氮或氬係較佳的。已知還原氛圍之氫係較佳的。另一較佳還原氛圍係氫及氮之混合物。較佳氫及氮之混合物係90 vol.-%至98 vol.-%氮及相應地2 vol.-%至10 vol.-%氫，其中vol.-%總量係100 vol.-%。較佳氮/氫混合物等於93/7、95/5及97/3 vol.-%/vol.-%，其各自基於混合物之總體積。 使用該等類型之惰性或還原氣體之吹掃較佳以10 min-1
至125 min-1
、更佳15 min-1
至90 min-1
、最佳20 min-1
至50 min-1
範圍內之氣體交換速率(=氣體流率[公升/分鐘]:內爐體積[公升])來實施。 在完成製程步驟(5)及可選淬火後，製成本發明之經塗覆線材。為充分地自其性質獲益，將其立即用於線材接合應用(即無延遲地，例如，在完成製程步驟(5)後不超過60天停機時間內)係有利的。另一選擇為，為保持線材之寬線材接合製程窗性質且為防止其受氧化或其他化學侵蝕，通常在完成製程步驟(5)後立即(即無延遲地，例如，在完成製程步驟(5)後＜1小時至5小時內)將成品線纏繞且真空密封且然後儲存以供進一步用作接合線材。以真空密封條件之儲存不應超過6個月。在打開真空密封後，線材應在不超過60天內用於線材接合。 較佳地，所有製程步驟(1)至(5)以及纏繞及真空密封均在潔淨室條件(US FED STD 209E潔淨室標準，1k標準)下實施。 本發明之第三態樣係可藉由上文所揭示製程根據其任一實施例獲得之經塗覆線材。已發現，本發明之經塗覆線材非常適宜用作線材接合應用中之接合線材。線材接合技術為熟習此項技術者所熟知。在線材接合過程中，通常形成球接合(第一接合)及針腳式接合(第二接合，楔接合)。在接合形成期間，施加一定力(通常以克來量測)，該力係藉由施加擦洗幅度(通常以µm來量測)來支持或藉由施加超音波能量(通常以mA來量測)來支持。在線材接合製程中，所施加力之上限與下限間之差與所施加擦洗幅度之上限與下限間之差的數學乘積或所施加力之上限與下限間之差與所施加超音波能量之上限與下限間之差的數學乘積界定線材接合製程窗：( 所施加力之上限 - 所施加力之下限 ) · ( 所施加擦洗幅度之上限 - 所施加擦洗幅度之下限 )= 線材接合製程窗。
或( 所施加力之上限 - 所施加力之下限 ) · ( 所施加超音波能量之上限 - 所施加
超音波能量之下限 )= 線材接合製程窗。
線材接合製程窗界定力/擦洗幅度組合或力/超音波能量組合之區域，其容許形成滿足規範之線材接合，即其通過習用測試，僅舉幾例，如習用拉力測試、球剪切測試及球拉力測試。 換言之，第一接合(球接合)製程窗區域係接合中所用力之上限與下限間之差及所施加擦洗幅度之上限與下限間之差之乘積或接合中所用力之上限與下限間之差及所施加超音波能量之上限與下限間之差之乘積，其中所得接合須滿足某些球剪切測試規範，例如0.0085克/µm2
之球剪切，接合墊上不會不黏等；而第二結合(針腳式接合)製程窗區域係接合中所用力之上限與下限間之差及所施加擦洗幅度之上限與下限間之差之乘積或接合中所用力之上限與下限間之差及所施加超音波能量之上限與下限間之差之乘積，其中所得接合須滿足某些拉力測試規範，例如2.5克之拉力，導線上不會不黏等。 對於工業應用，出於線材接合製程穩健性之原因，期望具有寬線材接合製程窗(以g計之力對以µm計之擦洗幅度或以g計之力對以mA計之超音波能量)。本發明線材展現相當寬之線材接合製程窗。 以下非限制性實例說明本發明。該等實例用於實例性闡明本發明且不意欲以任一方式限制本發明或申請專利範圍之範圍。實例
自由空氣球(FAB)之製備： 根據FAB之KNS Process User Guide (Kulicke & Soffa Industries Inc, Fort Washington, PA, USA，2002，2009年5月31日)中所述之程序來進行。藉由經標準點火(單一步驟，17.8 µm線材，EFO電流50 mA，EFO時間200 µs，95 vol.-%氮/5 vol.-%氫氛圍下)實施習用電火炬(EFO)點火來製備FAB。測試方法 A. 至 F .
所有測試及量測均在T = 20℃及相對濕度RH = 50%下實施。 A. 線性截距方法 首先將線材使用冷鑲嵌環氧樹脂封裝(potted)且然後藉由標準金相技術拋光(橫切)。使用多製備半自動拋光器使用較低力及最佳速度研磨並拋光試樣，在試樣表面上使用最小變形應力。最終，將經拋光試樣使用三氯化鐵化學蝕刻以外露晶粒邊界。使用線性截距方法在光學顯微鏡下使用1000之放大率根據ASTM E112-12標準來量測平均粒度。 B. FAB形態 藉由掃描電子顯微鏡(SEM)使用1000之放大率來檢查所形成之FAB。 評估： ++，極佳(圓球) +，良好(圓球)； 0，可接受 (不完全圓，但FAB表面上無明顯高臺)； -，桃形球 --，嚴重桃形球 本文所用術語「桃形球」應意指在FAB尖端形成兩個具有分離半球之高臺。 C. 經接合球形 所形成FAB自預定之高度(203.2 µm之尖端)及速度(6.4 µm/秒之接觸速度)下降至Al-0.5wt.-%Cu接合墊。在觸及接合墊後，一組經定義接合參數(接合力為100 g，超音波能量為95 mA且接合時間為15 ms)開始生效以使FAB變形並形成經接合球。在形成球後，毛細管上升至預定之高度(線頸高度為152.4 µm且環高度為254 µm)以形成環。在形成環後，毛細管下降至導線以形成針腳。在形成針腳後，毛細管上升且線材夾具閉合以切割線材以獲得預定之尾長(尾長延伸254 µm)。對於各試樣，使用放大率為1000之顯微鏡將5個經接合線材進行光學檢查。 評估： +，圓形； 0，可接受； -，花形。 D. 偏心球(OCB) 應用如方法C所述之相同方法，但測定球之中心性，而非檢查球之圓度。對於各試樣，光學檢查5個經接合線材。 評估： ++，完全中心化 +，中心化； 0，可接受偏離中心； -，偏離中心； --，極偏離中心。 E. FAB上之Pd分佈 首先將FAB使用冷鑲嵌環氧樹脂封裝，藉由標準金相技術橫切。使用多製備半自動拋光器使用較低力及最佳速度研磨並拋光試樣，在試樣表面上使用最小變形應力。最終在放大率為1000之高倍顯微術下檢查經拋光試樣。對於各試樣，光學檢查5個FAB。 目視評估： ++，Pd極均勻覆蓋FAB殼，且Pd覆蓋度≥ FAB高度之80%； +，Pd均勻覆蓋FAB殼，且Pd覆蓋度≥ FAB高度之70%； 0，Pd部分地覆蓋FAB殼且部分地擴散至球中，且FAB高度之Pd覆蓋度介於50%與70%之間； -，Pd大部分擴散至球中，且形成Cu-Pd合金，且FAB高度之Pd覆蓋度為≤50%； --，Pd大部分擴散至球中，且形成Cu-Pd合金，且FAB高度之Pd覆蓋度為≤30%。 F. 抗腐蝕性： 將線材球接合至Al-0.5wt.-%Cu接合墊。將具有如此接合之線材之測試裝置在130℃溫度、85%相對濕度(RH)下在高度加速之應力測試(HAST)室中儲存96小時，且稍後在低倍顯微鏡鏡(Nikon MM-40)下以100X放大率檢查經提升球之數目。觀察到較多數目之經提升球指示若干界面流電腐蝕。進行分級意義上之評估： ++，最少經提升球 +，較少經提升球； 0，中間經提升球； -，較多經提升球； --，最多經提升球實例 1 ： 線材試樣 1 至 8
將一定量之至少99.99%純度(「4N」)之銅、銀及磷在約1200℃下在真空烘箱中各自熔融於坩堝中。然後呈8 mm棒之形式之線芯前驅物項自熔體連續澆鑄。然後在若干拉伸步驟中將棒拉伸以形成具有直徑為200 µm之圓形橫剖面之線芯前驅物。將線芯前驅物使用由840 nm厚內鈀層及45 nm厚外金層組成之雙層塗層電鍍且其後進一步拉伸至17.8 µm之最終直徑，其中最終鈀塗層厚度為75 nm且最終金塗層厚度為4 nm，隨後在530℃之爐設定溫度下最終分股退火0.8秒之暴露時間，隨後立即在含有500 wt.-ppm之表面活性劑之水中將如此獲得之經塗覆線材淬火。 藉助此程序製造若干不同本發明以及比較試樣1至9之鈀及金塗覆之基於銅之線材。表1顯示線芯組成。 實例 2 ： 線材試樣 9 至 10
類似於實例1，試樣5來進行；然而，內鈀及外金塗層之層厚度不同，如表2中所記錄。
下表3顯示某些測試結果. In a first aspect, the present invention relates to a wire comprising a core having a surface (hereinafter also simply referred to as "core") having a coating laminated on a surface thereof, wherein the core itself is composed of The following composition: (a) 0.1 wt.-% to 0.3 wt.-% (% by weight, % by weight), preferably 0.2 wt.-% of silver, (b) at 99.64 wt.-% Copper in an amount ranging from 99.9 wt.-%, preferably 99.7 wt.-% to 99.9 wt.-% or even better 99.75 wt.-% to 99.85 wt.-%, (c) at 0 wt.- Ppm to 100 wt.-ppm (weight-ppm, ppm by weight), preferably 50 wt.-ppm to 100 wt.-ppm, more preferably 70 wt.-ppm to 80 wt.-ppm, especially 75 wt Phosphorus in the range of -ppm and (d) other components in the range of 0 wt.-ppm to 500 wt.-ppm, preferably 0 wt.-ppm to 100 wt.-ppm (except silver) And components other than copper and phosphorus, wherein any of the other components are less than 30 wt.-ppm, wherein all amounts in wt.-% and wt.-ppm are based on the total weight of the core, and Wherein the coating comprises an inner palladium layer (base layer) and a double layer adjacent to the outer gold layer (top layer), wherein the weight of the inner palladium layer is between 1.5 wt.-% and 2.5 wt. Within the range of % and wherein the weight of the outer gold layer is in the range of 0.09 wt.-% to 0.18 wt.-% with respect to the weight of the core. The following table compiles some of the preferred embodiments of the core composition: The wire of the present invention is preferably used in a bonded wire for bonding in a microelectronic device. It is preferably an integral object. A wide variety of shapes of wires that can be used in the present invention are known and appear. In the cross-sectional view, the preferred shape is a circular shape, an elliptical shape, and a rectangular shape. For the purposes of the present invention, the term "bonding wire" encompasses cross-sections of all shapes and all common wire diameters, but bonded wires having a circular cross-section and a fine diameter are preferred. The average cross section is in the range of, for example, 50 μm 2 to 5024 μm 2 or preferably 113 μm 2 to 2375 μm 2 ; correspondingly, in the case of a preferred circular cross section, the average diameter is, for example, 8 μm to 80 μm or preferably In the range of 12 μm to 55 μm. The average diameter or, in short, the diameter of the wire or core can be obtained by a "screening method". According to this method, the physical weight of the wire of defined length can be determined. Based on this weight, the density of the wire material is used to calculate the diameter of the wire or core. The diameter is calculated as the arithmetic mean of the five measurements at five cuts of a particular wire. Consistent with those mentioned above, the core disclosed above includes ratios (a) silver, (b) copper, and (c) phosphorus. However, the silver alloyed copper core of the coated wire of the present invention may comprise (d) other components in a total amount of from 0 wt.-ppm to 500 wt.-ppm, preferably from 0 wt.-ppm to 100 wt.-ppm. . In the context of the present invention, other components commonly referred to as "inevitable impurities" are small amounts of chemical elements and/or compounds derived from the impurities or wire manufacturing processes present in the materials used, ie (d) other The presence of the component can, for example, be derived from impurities present in the silver and/or copper. Examples of such other components are: Au, Ni, Pd, Pt, Fe, Si, Mn, Cr, Ce, Mg, La, Al, B, Zr, Ti, S, and the like. The lower total amount of 0 wt.-ppm to 500 wt.-ppm or even 0 wt.-ppm to 100 wt.-ppm of the other component (d) ensures good reproducibility of the properties of the wire. The other components (d) present in the core are usually not added separately. Each individual other component is included in an amount of less than 30 wt.-ppm based on the total weight of the core. The homogenous region of the core material. Since any bulk material always has a surface area that may exhibit different properties to some extent, the nature of the core is understood to be the nature of the homogeneous region of the bulk material. The surface of the body material region may vary in morphology, composition (e.g., sulfur, chlorine, and/or oxygen content) and other characteristics. The interface is the interface area between the core and the coating superimposed on the core. Typically, the coating is completely superposed on the surface of the core. In the region of the wire between the wire core and the coating superposed thereon, there may be a combination of materials of both the core and the coating. The coating superposed on the surface of the wire comprises an inner palladium layer and a double layer adjacent to the outer gold layer. The weight of the inner palladium layer is in the range of 1.5 wt.-% to 2.5 wt.-% with respect to the weight of the core, and the weight of the outer gold layer is in the range of 0.09 wt.-% to 0.18 wt.-% with respect to the weight of the core. Inside. Both the inner palladium layer and the outer gold layer are thin layers. In this context, the terms "thin", "thick" or "coating thickness" mean the size of the coating in the vertical direction against the longitudinal axis of the core. For a wire having an average cross-section in the above-mentioned exemplary range of 50 μm 2 to 5024 μm 2 or a circular wire having an average diameter of 8 μm to 80 μm in the above-mentioned exemplary range, The thickness of the palladium layer can be, for example, in the range of 20 nm to 350 nm, preferably 30 nm to 340 nm, and the thickness of the outer gold layer can be, for example, in the range of 1 nm to 25 nm, preferably 2 nm to 20 nm. . In an exemplary embodiment of a circular wire having a diameter of 18 μm, the thickness of the inner palladium layer may be, for example, in the range of 60 nm to 90 nm and the thickness of the outer gold layer may be, for example, 1 nm to 10 nm, It is preferably in the range of 2 nm to 6 nm. With respect to the composition of the bilayer, the palladium content of the inner layer is, for example, at least 50 wt.-%, preferably at least 95 wt.-%, based on the total weight of the inner coating. More preferably, the inner coating consists of pure palladium. Pure palladium typically has less than 1 wt.-% of other components (components other than palladium) based on the total weight of the inner coating. The gold content adjacent to the outer gold layer is, for example, at least 50 wt.-%, preferably at least 95 wt.-%, based on the total weight of the outer coating. More preferably, the outer coating consists of pure gold. Pure gold typically has less than 1 wt.-% of other components (components other than gold) based on the total weight of the overcoat. In an embodiment, the wire core of the present invention is characterized by at least one of the following intrinsic properties (i) to (iii) (see "Test Method A" as described below): (i) in the longitudinal direction (the longitudinal direction of the core) The average wire size (average particle size) measured above is in the range of 3 μm to 6 μm, and (ii) the ratio of the average particle size to the core diameter measured in the longitudinal direction is in the range of 0.05 to 0.25, preferably 0.1 to 0.20. (iii) The standard deviation ratio (RSD) of the average particle size to the core average particle size measured in the longitudinal direction is in the range of 0.1 to 0.4. This article uses the term "inherent nature" with respect to the core. Intrinsic properties mean the properties of the core itself (independent of other factors). The nature of the properties relative to the intrinsic properties depends on the relationship of the core to other factors, such as the method of measurement and/or measurement conditions. In another aspect, the invention is also directed to a method of making a coated wire of the present invention in any of the embodiments of the invention disclosed above. The method comprises at least steps (1) to (5): (1) providing a desired composition precursor item, ie providing a precursor item consisting of: (a) 0.1 wt.-% to 0.3 wt.-%, Preferably, the amount of silver is 0.2 wt.-%, (b) at 99.64 wt.-% to 99.9 wt.-%, preferably 99.7 wt.-% to 99.9 wt.-% or even more preferably 99.75 wt.-% to An amount of copper in the range of 99.85 wt.-%, (c) from 0 wt.-ppm to 100 wt.-ppm, preferably 50 wt.-ppm to 100 wt.-ppm, more preferably 70 wt.-ppm to An amount of phosphorus in the range of 80 wt.-ppm, especially 75 wt.-ppm, and (d) in the range of 0 wt.-ppm to 500 wt.-ppm, preferably 0 wt.-ppm to 100 wt.-ppm Other components of the amount (except silver, copper and phosphorus), wherein the individual components of any other components are less than 30 wt.-ppm, wherein all of them are wt.-% and wt.-ppm The amount is based on the total weight of the precursor item, (2) the precursor item is elongated to form the elongated precursor item until an intermediate cross section in the range of 5024 μm 2 to 70650 μm 2 or 80 μm to 300 is obtained. Μm, preferably an intermediate diameter in the range of 130 μm to 230 μm, (3) deposition on the surface of the elongated precursor item obtained after the completion of the process step (2) a palladium layer (base layer) and a double layer coating adjacent to the outer gold layer (top layer), (4) further elongating the coated precursor item obtained after the completion of the process step (3) until a desired final cross section is obtained or Up to the diameter, and (5) finally exposing the coated precursor obtained after the completion of the process step (4) to a range of 0.1 second to 3 seconds at a furnace set temperature in the range of 450 ° C to 650 ° C Time to form a coated wire. The term "fractional annealing" is used herein. Relative to "batch annealing", it allows for the rapid production of a continuous process of wire with high reproducibility. In the context of the present invention, split annealing means that the annealing is performed dynamically while the coated precursor to be annealed is pulled or moved through a conventional annealing furnace and wound onto a roll after leaving the annealing furnace. Here, the annealing furnace is usually in the form of a cylindrical tube of a predetermined length. Using its defined temperature profile, the annealing time/furnace temperature parameter can be defined and set at a given annealing rate that can be selected, for example, in the range of 10 meters/minute to 60 meters per minute. The term "furnace set temperature" is used herein. It means the temperature fixed in the temperature controller of the annealing furnace. The annealing furnace can be a furnace type furnace (in the case of batch annealing) or a tube annealing furnace (in the case of a strand annealing). This disclosure distinguishes between precursor items, pre-elongation precursor items, coated precursor items, coated precursors, and coated wires. The term "precursor item" is used for the preliminary stage wires that have not yet reached the desired final cross section or final diameter of the core, and the term "precursor" is used for the preliminary stage wire having the desired final cross section or desired final diameter. The coated wire in the sense of the present invention is obtained after the completion of the process step (5), i.e. after the final partial annealing of the coated precursor at the final cross section or the desired final diameter. The precursor item as provided in process step (1) can be obtained by alloying/doping copper with a desired amount of silver and, where appropriate, and with an appropriate amount of phosphorus. The copper alloy itself can be prepared by conventional processes known to those skilled in the art of metal alloys, for example, by melting together copper, silver, and optionally phosphorus in a desired ratio. In this process, a master alloy can be utilized. For example, an induction furnace can be used to carry out the melting process, and it is advantageous to operate under vacuum or under an inert gas atmosphere. The material used may have a purity level of, for example, 99.99 wt.-% or more. The melt thus produced can be cooled to form a homogenous sheet based on the copper precursor item. Typically, the precursor item is in the form of a rod having a diameter of, for example, 2 mm to 25 mm and a length of, for example, 2 m to 100 m. This rod can be produced by casting the copper alloy melted in a suitable mold, followed by cooling and solidification. In the process step (2), the precursor term is elongated to form an elongated precursor item until an intermediate cross section in the range of 5024 μm 2 to 70650 μm 2 or in the range of 80 μm to 300 μm, preferably 130 μm, is obtained. Up to the intermediate diameter in the range of 230 μm. The technique of the elongation precursor item is known and appears to be useful in the context of the present invention. The preferred technique is calendering, swaging, die drawing or the like, with die-drawing being preferred. In the latter case, the precursor item is drawn in a number of process steps until the desired intermediate cross section or desired intermediate diameter is reached. This wire drawing method is well known to those skilled in the art. Conventional tungsten carbide and diamond tensile dies can be used and conventional stretching lubricants can be employed to aid in stretching. Step (2) of the method of the invention may comprise one or more sub-steps of intermediate annealing of the elongated precursor item. This intermediate anneal can be carried out, for example, at a furnace set temperature in the range of 200 ° C to 650 ° C for an exposure time of, for example, 0.5 seconds to 1 second. This intermediate annealing is usually carried out by a strand annealing method. In the process step (3), a two-layer coating comprising an inner palladium layer and an adjacent outer gold layer is deposited on the surface of the elongated precursor item obtained after the completion of the process step (2), so as to stack the coating Fitted on the surface. Those skilled in the art will appreciate that the inner palladium layer and the outer gold layer are deposited such that the weight of the inner palladium layer is in the range of 1.5 wt.-% to 2.5 wt.-% relative to the weight of the elongated precursor item and the outer gold layer The weight is in the range of 0.09 wt.-% to 0.18 wt.-% relative to the weight of the elongated precursor item. It is known to those skilled in the art how to calculate the thickness of the coating on the elongated precursor item to ultimately obtain (i.e., after final elongation of the coated precursor item) a coating having a layer thickness as disclosed for the wire embodiment. . A variety of techniques are known to those skilled in the art for forming a coating of a material on a copper alloy surface in accordance with an embodiment. Preferred techniques are plating (e.g., electroplating and electroless plating), self-vapor deposition materials (e.g., sputtering, ion plating, vacuum evaporation, and physical vapor deposition) and self-melting deposition materials. Electroplating is a preferred technique in the context of the present invention. In process step (4), the coated precursor item obtained after completion of process step (3) is further elongated until the desired final cross-section or diameter of the wire is obtained. The techniques for elongating the coated precursor articles are the same elongation techniques as those mentioned above in the disclosure of Process Step (2). In the process step (5), the coated precursor obtained after the completion of the process step (4) is finally subjected to strand annealing for 0.1 second to 3 seconds at a furnace set temperature in the range of, for example, 450 ° C to 650 ° C. The exposure time, or in the preferred embodiment, is from 500 ° C to 600 ° C for 0.3 seconds to 1 second. In an exemplary embodiment, particularly in an exemplary embodiment of a wire having a diameter of about 18 μm, the final split anneal can be performed at an oven set temperature of 530 ° C for an exposure time of 0.8 seconds. In a preferred embodiment, the final strand annealed coated precursor (i.e., still hot coated wire) is quenched in water, wherein in embodiments, one or more additives may be included, such as 0 wt.- Additives from ppm to 1000 wt.-ppm. Quenching in water means that the coated precursor, which is finally annealed by dipping or dripping, is subjected to the process step (5), either immediately or rapidly, ie, within 0.2 seconds to 0.6 seconds, for example, by dipping or dripping. The temperature is cooled down to room temperature. The optional sub-step intermediate annealing of process step (2) and the final split annealing of process step (5) can be carried out under an inert or reducing atmosphere. Various types of inert atmospheres and reducing atmospheres are known in the art and are used in purge annealing furnaces. Nitrogen or argon, which is known to be inert, is preferred. It is known that hydrogen in a reducing atmosphere is preferred. Another preferred reducing atmosphere is a mixture of hydrogen and nitrogen. Preferably, the mixture of hydrogen and nitrogen is from 90 vol.-% to 98 vol.-% nitrogen and correspondingly 2 vol.-% to 10 vol.-% hydrogen, wherein the total amount of vol.-% is 100 vol.-%. Preferably, the nitrogen/hydrogen mixture is equal to 93/7, 95/5 and 97/3 vol.-%/vol.-%, each based on the total volume of the mixture. Purging using inert or reducing gases of these types is preferably in the range of 10 min -1 to 125 min -1 , more preferably 15 min -1 to 90 min -1 , optimally 20 min -1 to 50 min -1 The gas exchange rate (= gas flow rate [liters per minute]: inner furnace volume [liters]) is implemented. After the process step (5) and optional quenching are completed, the coated wire of the present invention is formed. In order to fully benefit from its properties, it is advantageous to use it immediately for wire bonding applications (i.e., without delay, for example, no more than 60 days of downtime after completing process step (5)). Alternatively, in order to maintain the wide wire bonding process properties of the wire and to prevent it from being oxidized or otherwise chemically attacked, typically immediately after the completion of process step (5) (ie, without delay, for example, during the completion of the process step (5) The finished product is wound and vacuum sealed and then stored for further use as a bonding wire after <1 hour to 5 hours. Storage under vacuum sealing conditions should not exceed 6 months. After the vacuum seal is opened, the wire should be used for wire bonding for no more than 60 days. Preferably, all of the processing steps (1) through (5) and the winding and vacuum sealing are performed under clean room conditions (US FED STD 209E clean room standard, 1k standard). A third aspect of the invention is a coated wire obtainable by any of the embodiments disclosed herein by the process disclosed above. The coated wire of the present invention has been found to be very suitable for use as a bonding wire in wire bonding applications. Wire joining techniques are well known to those skilled in the art. During wire bonding, ball bonding (first bonding) and stitch bonding (second bonding, wedge bonding) are typically formed. During the formation of the joint, a certain force (usually measured in grams) is applied, which is supported by applying a scrubbing amplitude (usually measured in μm) or by applying ultrasonic energy (usually measured in mA) To support. In the wire joining process, the difference between the difference between the upper and lower limits of the applied force and the difference between the upper and lower limits of the applied scrubbing amplitude or the upper and lower limits of the applied force and the upper limit of the applied ultrasonic energy the mathematical product of the difference between the lower limit defining a wire bonding process window: (upper limit of the applied force - a lower limit of the power of the applied) · (the upper scrubbing magnitude is applied - the lower limit of the scrubbing magnitude is applied) = the wire bonding process window. Or (upper limit of the applied force - the lower limit of the applied force) · (the upper limit of the ultrasonic energy is applied - the lower limit of the ultrasonic energy is applied) = the wire bonding process window. The wire bonding process window defines a region of force/scrubbing amplitude combination or force/ultrasonic energy combination that allows for the formation of a wire bond that meets the specifications, ie, it passes a customary test, such as a conventional tensile test, a ball shear test, and Ball pull test. In other words, the first joint (ball joint) process window region is the product of the difference between the upper and lower limits of the force applied and the difference between the upper and lower limits of the applied scrubbing amplitude or the difference between the upper and lower limits of the force used in the joint. And the product of the difference between the upper and lower limits of the applied ultrasonic energy, wherein the resulting joint must meet certain ball shear test specifications, such as a ball shear of 0.0085 g/μm 2 , without sticking on the bond pad; The difference between the upper and lower limits of the force used in the joining of the two-joint (pin-joint) process window region and the difference between the upper and lower limits of the applied scrubbing amplitude or the difference between the upper and lower limits of the force used in the joint and the The product of the difference between the upper and lower limits of the applied ultrasonic energy, wherein the resulting joint must meet certain tensile test specifications, such as a pull force of 2.5 grams, and the wire will not stick. For industrial applications, for reasons of robustness of the wire bonding process, it is desirable to have a wide wire bonding process window (the force in g versus the scrubbing amplitude in μm or the force in g versus the ultrasonic energy in mA). The wire of the present invention exhibits a relatively wide wire bonding process window. The following non-limiting examples illustrate the invention. The examples are intended to be illustrative of the invention and are not intended to limit the scope of the invention or the scope of the claims. EXAMPLES Preparation of Free Air Ball (FAB): This was carried out according to the procedure described in FAB KNS Process User Guide (Kulicke & Soffa Industries Inc, Fort Washington, PA, USA, 2002, May 31, 2009). Prepared by standard ignition (single step, 17.8 μm wire, EFO current 50 mA, EFO time 200 μs, 95 vol.-% nitrogen/5 vol.-% hydrogen atmosphere) using conventional electric torch (EFO) ignition FAB. Test Methods A. F. To. All tests and measurements were T = 20 ℃ and relative humidity RH = 50% the embodiment. A. Linear Intercept Method The wire was first potted using cold damascene epoxy and then polished (cross cut) by standard metallographic techniques. A multi-prepared semi-automatic polisher is used to grind and polish the specimen at a lower force and at an optimum speed, using minimal deformation stress on the surface of the specimen. Finally, the polished sample was chemically etched using exposed ferrite grains. The average particle size was measured according to the ASTM E112-12 standard using a linear intercept method under an optical microscope using a magnification of 1000. B. FAB morphology The formed FAB was examined by scanning electron microscopy (SEM) using a magnification of 1000. Evaluation: ++, excellent (ball) +, good (ball); 0, acceptable (not completely round, but no significant height on the surface of FAB); -, peach-shaped ball--, severe peach-shaped ball As used herein, the term "peach ball" shall mean the formation of two high platforms with separate hemispheres at the tip of the FAB. C. The FAB formed by the bonded spheres was lowered from the predetermined height (tip of 203.2 μm) and the speed (contact speed of 6.4 μm/sec) to the Al-0.5 wt.-% Cu bonding pad. After accessing the bond pads, a set of defined joint parameters (100 g for engagement force, 95 mA for ultrasonic energy and 15 ms for engagement time) begin to take effect to deform the FAB and form a spliced ball. After the ball was formed, the capillary was raised to a predetermined height (the neck height was 152.4 μm and the ring height was 254 μm) to form a loop. After the loop is formed, the capillary is lowered to the wire to form a stitch. After the stitches are formed, the capillary rises and the wire clamp closes to cut the wire to obtain a predetermined tail length (tail length extends 254 μm). For each sample, five bonded wires were optically inspected using a microscope with a magnification of 1000. Evaluation: +, round; 0, acceptable; -, flower shape. D. Eccentric Ball (OCB) Apply the same method as described in Method C, but measure the center of the ball instead of checking the roundness of the ball. For each sample, 5 bonded wires were optically inspected. Evaluation: ++, fully centralized +, centralized; 0, acceptable off-center; -, off-center; --, extremely off-center. E. Pd Distribution on FAB The FAB was first packaged using cold inlaid epoxy and crosscut by standard metallographic techniques. A multi-prepared semi-automatic polisher is used to grind and polish the specimen at a lower force and at an optimum speed, using minimal deformation stress on the surface of the specimen. The polished sample was finally examined under a microscope at a magnification of 1000. For each sample, 5 FABs were optically inspected. Visual evaluation: ++, Pd covers the FAB shell extremely uniformly, and the Pd coverage is ≥ 80% of the FAB height; +, Pd uniformly covers the FAB shell, and the Pd coverage is ≥ 70% of the FAB height; 0, Pd partially covers the FAB The shell partially diffuses into the sphere, and the Pd coverage of the FAB height is between 50% and 70%; -, Pd diffuses mostly into the sphere, and forms a Cu-Pd alloy, and the Pd coverage of the FAB height ≤ 50%; --, Pd mostly diffuses into the ball, and forms a Cu-Pd alloy, and the Pd coverage of the FAB height is ≤ 30%. F. Corrosion resistance: The wire balls were joined to an Al-0.5 wt.-% Cu bond pad. The test device with the wire thus bonded was stored in a highly accelerated stress test (HAST) chamber at 130 ° C temperature, 85% relative humidity (RH) for 96 hours, and later at a low magnification microscope (Nikon MM-40) The number of lifted balls is checked at 100X magnification. A larger number of elevated balls were observed indicating several interface galvanic corrosion. Evaluation in the grading sense: ++, at least the lifting ball +, less lifting ball; 0, intermediate lifting ball; -, more lifting ball; -, up to lifting ball example 1 : wire sample 1 to 8 A certain amount of at least 99.99% pure ("4N") copper, silver and phosphorus are each melted in a crucible at about 1200 ° C in a vacuum oven. The core precursor item in the form of an 8 mm rod is then continuously cast from the melt. The rod was then stretched in several stretching steps to form a core precursor having a circular cross section with a diameter of 200 μm. The core precursor was electroplated using a two-layer coating consisting of a 840 nm thick palladium layer and a 45 nm thick outer gold layer and then further stretched to a final diameter of 17.8 μm with a final palladium coating thickness of 75 nm and The final gold coating thickness was 4 nm, followed by a final split annealing time of 0.8 seconds at a furnace set temperature of 530 ° C, followed by immediate application of the thus obtained coating in water containing 500 wt.-ppm of surfactant. Wire quenching. A number of palladium and gold coated copper-based wires of the present invention and Comparative Samples 1 to 9 were fabricated by this procedure. Table 1 shows the core composition. Example 2 : Wire samples 9 to 10 were similar to Example 1, Sample 5; however, the layers of the inner palladium and outer gold coatings were different in thickness, as recorded in Table 2. Table 3 below shows some test results.