201137184 六、發明說明 【發明所屬之技術領域】 本發明有關一種即使電鍍膜甚薄仍然不易發生針孔 (pin hole)，而能形成細緻的電鍍膜之電解硬質鍍金液 (electrolytic hardening gold plating solution)及使用該鍍 金液之鍍敷方法。特別是有關連接器（connector)等電子零 件的部分鍍敷適合使用之電解硬質鍍金液及使用該鍍金液 之鍍敷方法。 【先前技術】 由於近年來的IT(資訊科技）的進步，而急速進展有行 動電I舌或筆記型個人電腦（note book personal computer)等 電子設備的輕量化、小型化、高性能化。隨之，對構成此 等電子設備之電子零件的小型化或可靠性（reliability)提 升之要求亦在升高。爲構成此等電子設備之電子零件，多 採用鍍金處理。 例如，作爲電氣方式連接電子設備或電子零件間之連 接器的電氣接點之接點構件上，施加有抗摩耗性高的硬質 鑛金。 一般，電子零件的接點構件，係依下述方法所製造。 首先，於成爲基材之銅素材等表面施加鍍鎳（nickel plating)，以形成鎳被膜（nickel film)。接著，於鎳被膜之 上施加硬質鍍金，以形成金被膜（gold film)。由此，可製 得經於銅素材上依序形成有鎳被膜、金被膜之接點構件。 -5- 201137184 由於金係高價品之故，如使金被膜薄膜化即可達成省 金化之目的。然而，如採用在來的鍍金液以形成金被膜之 情形，則膜厚0.1 μιη以下的金被膜上會發生多數個針孔。 如金被膜上形成針孔時，則介由針孔而底層的鎳被膜即受 空氣氧化，其結果會生成鎳氧化物。該鎳氧化物，則使接 點部中之電阻上升等，會使電子設備的電氣特性改變。其 結果，電子設備上會發生瑕疵。 亦即，形成有多數個針孔之金被膜，不能充分保護鎳 被膜。因此，金被膜上，不要存在有針孔爲宜。 於專利文獻1中，記載有採用含有光澤劑（gloss agent)之硬質鍍金液而對接點構件施加部分鏟敷（partial plating)之作法。此種鍍金液之均相電沈積性 (homogeneous electrode position ability)很高 〇 但，此種 鍍金液會使光澤劑成分摻雜於金被膜內。如光澤劑成分等 添加劑成分被摻雜於金被膜內時，則金被膜的金純度 (gold purity)會降低。其結果，會增大接點構件的接觸電 阻，或使耐蝕性降低。 [先前技術文獻] [專利文獻] 專利文獻1 :日本專利第3 93 3 93 0號公報 【發明內容】 [發明所欲解決之課題] 本發明所欲解決之課題，在於提供一種很適合使用於 -6- 201137184 部分鍍敷處理等，而即使形成有膜厚爲0.1 μιη以下的金被 膜時，金被膜上仍然不會產生針孔之電解硬質鍍金液。 本發明所欲解決之其他課題，在於提供一種使用該電 解硬質鍍金液之鍍敷方法。 [用以解決課題之手段] 本發明之等爲解決上述課題起見，首先，就部分鑛敷 處理加以硏究。其結果發現，如鍍敷液中調配有機氧化劑 時，則能在低電流密度區域優異地控制金的析出之事實， 而提出專利申請（曰本專利特願2009- 1 65730號）。此種有 機氧化劑，係於低電流密度區域（電流密度20A/dm2以下） 中，能優異地提升金的氧化還原電位（oxidation-reduction potential)以抑制金的析出。另一方面，於中至高電流密 度區域（電流密度20至200A/dm2)中，則不會抑制金的析 出。因此，藉由電流密度之控制，而可控制（control)將形 成鑛敷被膜之處所。因上述理由，調配有有機氧化劑之電 解硬質鎪金液，即可很適合使用於部分鍍敷處理。 其次，本發明人等，就金被膜的薄膜化加以硏究。其 結果發現，如對上述鍍金液調配有關本發明之有機結晶調 整劑（organic crystal regulator)，則即使金被膜的膜厚爲 〇.〇5μιη程度，仍然不會使金被膜中產生針孔之事實。再 者，本發明人發現，上述之鍍金液，能形成金純度高的金 被膜之事實。本發明人等，則根據上述心得，而完成本發 明。 201137184 能解決上述課題之本發明，係如下列所記載者。 [1] —種電解硬質鍍金液，其特徵爲：含有 氰化金與氰化金鹽的至少一種、及 水溶性鈷鹽或水溶性鎳鹽、及 有機酸傳導鹽（organic acid conduction salt)、及 芳香族磺酸化合物、及 選自羧酸、羥基羧酸、以及此等鹽所成群中之1種或 2種以上的組合、以及 含氮之五員雜環式化合物。 [2] 如[1]所記載之電解硬質鍍金液，其中於前述電解 硬質鍍金液中之前述含氮之五員雜環式化合物的濃度，爲 1至5 0g/公升。 [3] 如[1]所記載之電解硬質鍍金液，其中pH在3至7 的範圍。 [4] 一種鍍敷方法，其特徵爲：將Π]所記載之電解硬 質鍍金液，噴塗於希望鍍敷之處所，藉以於希望鍍敷之處 所形成金被膜。 [發明之效果] 採用本發明之電解硬質鍍金液所形成之金被膜，即使 膜厚爲0_〇5μιη程度，仍然不會形成針孔。由於鎳被膜表 面係藉由金被膜而完全被覆並受保護之故，被鍍敷材料@ 耐蝕性很高。又，由於可減少金的使用量之故，經濟性fg 異。 -8 - 201137184 [發明之最佳實施形態] <電解硬質鍍金液> 以下，就本發明之電解硬質鍍金液加以詳細說明。 於本發明之電解硬質鍍金液中，作爲金來源而調配氰 化金與氰化金鹽的至少一種。亦可調配兩種。氰化金鹽而 言’可例示：氰化金鉀、氰化金鈉、氰化金銨。此等可以 單獨方式調配、亦可以2種以上之方式調配。 本發明之電解硬質鍍金液的氰化金與氰化金鹽的濃 度，作爲金濃度之合計爲0.1至20g/公升，較佳爲2至 15g/公升、特佳爲3至10g/公升。如金濃度在〇.lg/公升 以下時，則陰極電流效率（cathode current efficiency)不佳 之故，不能獲得既定的膜厚的金被膜。既使金濃度在20g/ 公升以上時，由於陰極電流效率不會對金濃度成比例增大 之故，並無提高金濃度之有利點。再者，因鍍敷處理中的 鍍金液之帶出量增多之故，鍍金液的損耗會增多。 本發明之電解硬質鍍金液中，將調配芳香族磺酸化合 物。芳香族磺酸化合物，係作爲有機氧化劑而發揮作用。 芳香族磺酸化合物而言，可例示：2-硝基苯磺酸、3-硝基 苯磺酸、4-硝基苯磺酸、2,4-二硝基苯磺酸' 2-胺基苯磺 酸、3-胺基苯磺酸、4-胺基苯磺酸、以及此等的鹽。此等 之中，較佳爲作爲取代基而具有硝基之芳香族磺酸化合 物。此等可以單獨方式調配，亦可以2種以上之方式調 配。 -9 - 201137184 調配有此等芳香族磺酸化合物之電解硬質鍍金液，係 於低電流密度區域（電流密度20A/dm2以下）中，能優異地 提升金的氧化還原電位。其結果，將於低電流密度區域中 控制金的析出。另一方面，調配有此等芳香族磺酸化合物 之電解硬質鍍金液，於中至高電流密度區域（電流密度20 至200A/dm2)中，則不會控制金的析出。其結果，將於中 至高電流密度區域中形成正常的金被膜。 本發明之電解硬質鍍金液，可藉由電流密度之控制而 控制在被鍍敷材的希望鍍敷處所以外之處所形成鍍敷被膜 之情形。 本發明之電解硬質鍍金液中所調配之有機氧化劑的濃 度’爲0.1至20 g/公升、較佳爲0.5至5 g/公升、特佳爲1 至3 g/公升。如有機氧化劑的濃度在〇.lg/公升以下時，則 於低電流密度區域之金析出的抑制效果小。有機氧化劑的 濃度即使在20g/公升以上時，於低電流密度區域之金析出 的抑制效果不變，而仍然高。 於本發明之電解硬質鍍金液中，將調配羧酸或羥基羧 酸或者此等的鹽。此等即將作爲錯合劑（complexing agent) 發揮作用。羧酸或羥基羧酸，此等的鹽而言，可例示：甲 酸、乙醇酸（glycolic acid)、乳酸（lactic acid)、羥基苯二 甲酸、草酸、丙二酸（malonic acid)、丁二酸（succinic acid)、羥基 丁二酸（malic acid)、二羥基 丁二酸（tartaric acid)、鄰苯二甲酸（phthalic acid)、二乙醇酸（diglycolic acid)、檸檬酸（citric acid)、以及此等的鹽。鹽而言，較 -10- 201137184 佳爲鈉鹽、鉀鹽等的鹼金屬鹽，鈣鹽等的 氨、胺等的鹽。此等可以單獨方式調配， 之方式調配。 本發明之電解硬質鍍金液的錯合齊! l〇〇g/公升，較佳爲 5至600g/公升。如 1 g/公升以下時，則從被鍍敷材所溶出之 被摻雜於金被膜內。如無機不純物被摻雜 則金被膜的金純度會降低。其結果，會 化、使接點構件的接觸電阻增大、使耐軸 合劑的濃度在100g/公升以上時，則由於 之效果之故，並不經濟。 本發明之電解硬質鍍金液中，將調配 水溶性的鎳鹽。鈷鹽而言，可例示：硫酸 化鈷、鹼性碳酸鈷。鎳鹽而言，可例示： 酸鎳、亞硫酸鎳、氯化鎳。此等可以單獨 以2種以上之方式調配。 本發明之電解硬質鍍金液的鈷鹽或鎳 至l〇g/公升、較佳爲0.1至1.0g/公升。 濃度在〇 _ 〇 1 g /公升以下時，則金被膜的硬 鈷鹽或鎳鹽的濃度在1 0g/公升以上時，貝U 對應之效果之故，並不經濟。如將鈷鹽或 調配時’則金被膜的硬度將成爲15〇至 hardness、維氏硬度）。在此，本發明之電 所調配之鈷鹽或鎳鹽的水溶性，係指能按 驗土類金屬鹽， 亦可以2種以上 丨的濃度爲1至 錯合劑的濃度在 無機不純物容易 於金被膜內時， 使金被膜外觀惡 性惡化。即使錯 不能獲得相對應 水溶性的鈷鹽或 鈷、硝酸鈷、氯 硫酸鎳、胺基磺 方式調配，亦可 鹽的濃度爲〇. 〇 1 如鈷鹽或鎳鹽的 度會降低。即使 由於不能獲得相 鎳鹽按上述濃度 200H V(Vickers 解硬質鍍金液中 上述濃度溶解於 -11 - 201137184 水中之程度的水溶性之意。 本發明之電解硬質鍍金液中，將調配有機酸傳導鹽。 有機酸傳導鹽，甲酸鉀、檸檬酸鉀、磷酸鉀、硝酸鉀、琥 珀酸鉀。此等可以單獨方式調配，亦可以2種以上之方式 調配。 本發明之電解硬質鍍金液的有機酸傳導鹽的濃度爲 10至200g/公升' 較佳爲50至100g/公升。如有機酸傳導 鹽的濃度在1 〇g/公升以下時，則金被膜的外觀會惡化而不 能獲得正常的金被膜。即使有機酸傳導鹽的濃度在200g/ 公升以上時，則由於不能獲得相對應之效果之故，並不經 濟。 本發明之m解硬質鍍金液中，將調配含氮之五員雜環 式化合物。含氮之五員雜環式化合物，即將作爲有機結晶 調整劑發揮作用。本發明人認爲含氮之五員雜環式化合 物，係吸附於鍍敷溶中的氰化金離子、或在電雙層 (electric double layer)去配位子（deligand)(氰離子）後的金 離子所吸附或進行錯合（complex at ion)，藉以控制金的晶 體生長（crystal growth)以形成細緻的金被膜者。又，本發 明中所用之含氮之五員雜環式化合物，並不會被摻雜於金 被膜內。因此，金被膜的金純度甚高。 含氮之五員雜環式化合物而言，可例示：咪唑 (imidazole)、2 -甲基咪唑、吡唑（pyraz〇ie)、3,5-二甲基吡 唑、2-咪唑啉（imidazoline)、2-吡咯烷酮（pyrrolidone)、 海因（hydantoin)、5,5-二甲基海因、尿褒素（aiiantoin)、 -12- 201137184 號拍酿亞胺、DL(消旋）-焦魅胺酸（pyroglutamine acid)、 以及此等的酸。 本發明之電解硬質鍍金液中，含氮之五員雜環式化合 物的濃度’爲1至50g/公升、較佳爲5至20g/公升、特 佳爲8至12g/公升。如含氮之五員雜環式化合物的濃度在 1 g/公升以下時，則晶體調整效果減少，以致不能獲得細 緻的金被膜。即使含氮之五員雜環式化合物的濃度在5 0g/ 公升以上時，則由於不能獲得相對應之效果之故，並不經 濟。 本發明之電解硬質鑛金液，係在pH3.0至7.0即能使 用者，惟較佳爲在PH4.0至5.0下之使用。如pH至4.0 以下時，則陰極電流效率會降低而難於獲得既定的膜厚的 金被膜。另一方面，如pH在5.0以上時，則金被膜的外 觀會紅色化以致難於獲得正常的金被膜。在此，pH的調 整劑而言，可例示：氫氧化鈉、氫氧化鉀、氫氧化銨、稀 硫酸。 本發明之電解硬質鍍金液中，在不影響本發明之效果 之範圍內，可調配其他物質。 使用本發明之電解硬質鎪金液之鍍敷方法，可採用在 來周知之鍍敷方法。又，亦可採用以鉑製噴嘴作爲陽極、 以被鍍敷材作爲陰極，從鉑製噴嘴對被鍍敷材噴塗本發明 之電解硬質鍍金液之部分鍍敷法加以鍍敷。 【實施方式】 -13- 201137184 [實施例] 爲試驗所使用之裝置構成及評價方法，係如下 者。 準備一張 32mmxl50mmx0.2mm的銅板。對於銅 使用胺基磺酸鎳電鍍液按2 μ m的厚度形成鎳被膜， 此作爲試料。對此試料，重铿具有l〇mm xl〇mm正 的開口部之聚矽氧樹膠製的遮罩（mask)板並加以固定 使用泵而將鍍金液送至鍍金液質封□，並從該鍍 噴射口對遮罩板的開口部噴射鍍金液。藉此，對試施 分鍍敷。於鍍金液噴射口安裝直徑5mm的白金噴嘴 將該噴嘴作爲陽極（anode)電極。 金被膜的膜厚之測定，則採用SII社製螢光X射 厚測定器SEA5120。 金被膜中所發生之針孔的有無的評價，係利用 JIS規格中所記載之有孔度試驗（perforation degree 的一種之硝酸充氣試驗方法（nitric acid aeration methodKJIS Η 8 620 1 0.5)所施者。有孔度試驗，係 價鍍金層的針孔大小、數Μ之用之試驗。於硝酸充氣 中，在容器底部中裝有硝酸之保乾器（desiccator)內 製板上，置載試料後在約23 °C下放置1小時。保乾 所發生之硝酸蒸氣，則通過針孔後使鎳被膜腐蝕。如 的鎳被膜遭受腐蝕時，則在金被膜上顯現斑點。該斑 發生狀態，則與ns規格的鍍金的耐蝕性試驗方法 H8502 11.5)中所訂定之標稱數（rating number)標準 所述 板， 並將 方形 〇 金液 加部 ，並 線膜 屬於 test) test 爲評 試驗 的磁 器內 底府 點的 (JIS 圖表 -14- 201137184 相照後加以評價者。 (實施例1) 氰化金鉀：5g/公升（以Au(金）計） 檸檬酸鉀：70g/公升 檸檬酸：50g/公升 甲酸鉀：20g/公升 硫酸鈷·· 〇_96g/公升 2-硝基苯磺酸：2g/公升 咪唑：l〇g/公升 鏟金液’係依上述之調配方式所調製者。將該鍍金液 I周整爲ρ Η 4.2 ’依液溫5 5。(：、電流密度4 0 A / d m 2之條件， 按金膜厚能成爲〇.〇5μηι之方式，對試料施加部分鍍敷。 試料上所形成之金被膜，係色調（col〇r t〇ne)爲檸檬黃 (lemon yellow)而外觀均勻，爲良好的外觀者。耐蝕性評 價’係標稱數爲9.5-5而全腐蝕面積率爲〇.〇2以上0.05% 以下。 (實施例2至5)、（比較例1、2) 按表1所示之調配以調製鍍金液、按與實施例1同樣 方式對試料施加部分鍍敷。經形成於試料上之金被膜，係 色調爲檸檬黃而外觀均勻，爲良好的外觀者。耐蝕性評價 的結果，係如表2中所示。 -15- 201137184 (表1) 實施例1 寶施例2 貪施例3 實施例4 寅施例S 比較例1 比較例2 錢金液 的調配 澳度 (β/L) 氰化細以金計） 5 5 5 5 5 5 5 檸樣酸鉀 7 0 7 0 7 0 7 0 7 0 7 0 7 0 檸檬酸 5 0 5 0 5 0 5 0 5 0 5 0 5 0 甲酸鉀 2 0 2 0 2 0 2 0 2 0 2 0 2 0 硫祕 0. 96 0. 96 0.9 6 — — 0. 96 0.9 6 硫酸鏍 — — — 0. 90 0. 90 — — 2-硝基苯磺酸 2 2 2 2 2 — — 間-硝基苯磺酸納 2 — 咪唑 10 — — 10 —-- — --— 2-吡咯烷酮 — 10 5,5-二甲基海因 --— --- 1 0 — 10 一—一 — 鍍金 條件 PH 4. 2 4. 2 4. 2 4. 2 4. 2 4. 2 4. 2 液溫CC) 5 5 5 5 5 5 5 5 5 5 5 5 5 5 ^流密度<A/dm，） 4 0 4 0 4 0 4 0 4 0 4 0 4 0 (表2) 標稱數 全腐蝕面積率％ 實施例1 9 . 5 — 5 0 . 0 2以上 0 . 0 5 %以下 寅施例2 9 . 3 - 3 0 . 0 5以上 0 . 0 7 %以下 實施例3 9 . 5 — 6 0 . 0 2以上 0 . 0 5 %以下 寅施例4 9 . 5 _ 3 0 . 0 2以上 .〇. 0 5 %以下 實施例5 9 . 3 - 6 0 . 0 5以上 0 . 0 7 %以下 比較例1 4-1 2 . 5 0以上 5 . 0 〇 %以下 比較例2 4 -4 2 . 5 〇以上 5 . 0 〇 %以下 實施例1至5，係相較於比較例1 ' 2，爲經大幅度抑 制其腐蝕之程度。 從以上可知，本發明之電解硬質鍍金液，係即使金被 膜的膜厚在〇. 1 μηι以下時，仍能形成針孔極少的細緻的金 被膜。其結果，被鍍敷材的耐蝕性係優異者。 -16-BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic hardening gold plating solution capable of forming a fine plating film even if a plating film is thin and is not easily pinched. And a plating method using the gold plating solution. In particular, it is suitable for electroplating of a hard gold plating liquid suitable for partial plating of electronic parts such as a connector, and a plating method using the gold plating liquid. [Prior Art] Due to the advancement of IT (information technology) in recent years, there has been a rapid progress in weight reduction, miniaturization, and high performance of electronic devices such as mobile phone notebooks and notebook personal computers. As a result, the demand for miniaturization or reliability of electronic components constituting such electronic devices has also increased. In order to constitute the electronic components of such electronic devices, gold plating is often used. For example, a hard mineral having high abrasion resistance is applied to a contact member that electrically connects an electrical contact of an electronic device or a connector between electronic components. Generally, the contact member of an electronic component is manufactured by the following method. First, nickel plating is applied to a surface of a copper material or the like which is a substrate to form a nickel film. Next, hard gold plating is applied on the nickel film to form a gold film. Thereby, a contact member in which a nickel film or a gold film is sequentially formed on the copper material can be obtained. -5- 201137184 Due to the high price of gold, the gold film can be thinned to achieve the goal of saving money. However, when a gold plating solution is used to form a gold film, a plurality of pinholes are formed on the gold film having a film thickness of 0.1 μm or less. When a pinhole is formed in the gold film, the nickel film of the underlayer is oxidized by the pinhole through the pinhole, and as a result, nickel oxide is formed. In the nickel oxide, the electrical resistance in the contact portion is increased, and the electrical characteristics of the electronic device are changed. As a result, flaws can occur on electronic devices. That is, a gold film having a plurality of pinholes is formed, and the nickel film cannot be sufficiently protected. Therefore, it is advisable to have pinholes on the gold film. Patent Document 1 describes a method of applying partial plating to a contact member by using a hard gold plating solution containing a gloss agent. The gold-plated liquid has a high homogeneous electrode position ability. However, such a gold plating solution causes the brightener component to be doped into the gold film. When an additive component such as a gloss component is doped into a gold film, the gold purity of the gold film is lowered. As a result, the contact resistance of the contact member is increased or the corrosion resistance is lowered. [Prior Art Document] [Patent Document] Patent Document 1: Japanese Patent No. 3 93 3 93 0 [Invention] [Problems to be Solved by the Invention] The object of the present invention is to provide a problem that is suitable for use in -6- 201137184 Partial plating treatment, etc., and even if a gold film having a film thickness of 0.1 μm or less is formed, an electrolytic hard gold plating solution having no pinholes is formed on the gold film. Another object to be solved by the present invention is to provide a plating method using the electrolytic hard gold plating solution. [Means for Solving the Problem] In order to solve the above problems, the present invention firstly investigates a part of the mineral deposit treatment. As a result, it has been found that, in the case where the organic oxidizing agent is formulated in the plating liquid, the fact that the precipitation of gold can be excellently controlled in the low current density region is proposed, and a patent application is filed (Japanese Patent Application No. 2009-1650730). Such an organic oxidant is in a low current density region (current density of 20 A/dm 2 or less), and can excellently enhance the oxidation-reduction potential of gold to suppress precipitation of gold. On the other hand, in the medium to high current density region (current density 20 to 200 A/dm2), precipitation of gold is not inhibited. Therefore, by controlling the current density, it is possible to control where the ore film is formed. For the above reasons, an electrolytic hard gold liquid solution containing an organic oxidizing agent can be suitably used for partial plating treatment. Next, the inventors of the present invention conducted a study on the thin film formation of a gold film. As a result, it has been found that, if the organic crystal regulator of the present invention is blended with the above gold plating solution, the fact that the gold coating film does not cause pinholes in the gold film even if the film thickness of the gold film is 〇.5 μm. . Further, the inventors have found that the above gold plating solution can form a gold film having a high gold purity. The inventors of the present invention have completed the present invention based on the above findings. 201137184 The present invention which can solve the above problems is as described below. [1] An electrolytic hard gold plating liquid characterized by comprising at least one of gold cyanide and gold cyanide salts, a water-soluble cobalt salt or a water-soluble nickel salt, and an organic acid conduction salt, And an aromatic sulfonic acid compound, and one or a combination of two or more selected from the group consisting of a carboxylic acid, a hydroxycarboxylic acid, and the like, and a five-membered heterocyclic compound containing nitrogen. [2] The electrolytic hard gold plating solution according to [1], wherein the concentration of the nitrogen-containing five-membered heterocyclic compound in the electrolytic hard gold plating solution is from 1 to 50 g/liter. [3] The electrolytic hard gold plating solution as described in [1], wherein the pH is in the range of 3 to 7. [4] A plating method characterized in that an electrolytic hard gold plating liquid described in Π is sprayed on a place where plating is desired, whereby a gold film formed at a place where plating is desired is used. [Effects of the Invention] The gold film formed by the electrolytic hard gold plating solution of the present invention does not form pinholes even when the film thickness is about 0 〇 5 μm. Since the surface of the nickel film is completely covered and protected by the gold film, the plated material @ has high corrosion resistance. Moreover, since the amount of gold used can be reduced, the economical fg is different. -8 - 201137184 [Best Embodiment of the Invention] <Electrolytic Hard Gold Plating Solution> Hereinafter, the electrolytic hard gold plating solution of the present invention will be described in detail. In the electrolytic hard gold plating solution of the present invention, at least one of gold cyanide and gold cyanide salt is blended as a gold source. Two types can also be deployed. The gold cyanide salt can be exemplified by gold potassium cyanide, gold sodium cyanide, and gold ammonium cyanide. These can be formulated individually or in more than two ways. The concentration of the gold cyanide and the gold cyanide salt of the electrolytic hard gold plating solution of the present invention is 0.1 to 20 g/liter, preferably 2 to 15 g/liter, particularly preferably 3 to 10 g/liter, as the total gold concentration. When the gold concentration is 〇.lg/liter or less, the cathode current efficiency is not good, and a gold film having a predetermined film thickness cannot be obtained. Even when the gold concentration is 20 g/liter or more, since the cathode current efficiency does not increase proportionally to the gold concentration, there is no advantage in increasing the gold concentration. Further, since the amount of the gold plating liquid in the plating treatment is increased, the loss of the gold plating liquid is increased. In the electrolytic hard gold plating solution of the present invention, an aromatic sulfonic acid compound is formulated. The aromatic sulfonic acid compound functions as an organic oxidizing agent. The aromatic sulfonic acid compound can be exemplified by 2-nitrobenzenesulfonic acid, 3-nitrobenzenesulfonic acid, 4-nitrobenzenesulfonic acid, and 2,4-dinitrobenzenesulfonic acid '2-amino group. Benzenesulfonic acid, 3-aminobenzenesulfonic acid, 4-aminobenzenesulfonic acid, and the like. Among these, an aromatic sulfonic acid compound having a nitro group as a substituent is preferred. These can be configured individually or in more than two ways. -9 - 201137184 The electrolytic hard gold plating solution containing these aromatic sulfonic acid compounds is excellent in the oxidation-reduction potential of gold in a low current density region (current density of 20 A/dm2 or less). As a result, gold precipitation is controlled in the low current density region. On the other hand, an electrolytic hard gold plating solution prepared with such an aromatic sulfonic acid compound does not control the precipitation of gold in a medium to high current density region (current density of 20 to 200 A/dm 2 ). As a result, a normal gold film is formed in the medium to high current density region. The electrolytic hard gold plating solution of the present invention can be controlled by a current density to control a plating film formed at a desired plating place of the plated material. The concentration of the organic oxidizing agent formulated in the electrolytic hard gold plating solution of the present invention is 0.1 to 20 g/liter, preferably 0.5 to 5 g/liter, and particularly preferably 1 to 3 g/liter. When the concentration of the organic oxidizing agent is 〇.lg/liter or less, the effect of suppressing gold precipitation in the low current density region is small. When the concentration of the organic oxidizing agent is at least 20 g/liter, the effect of suppressing the precipitation of gold in the low current density region does not change, but is still high. In the electrolytic hard gold plating solution of the present invention, a carboxylic acid or a hydroxycarboxylic acid or a salt thereof may be formulated. These will soon function as complexing agents. A carboxylic acid or a hydroxycarboxylic acid, and examples of the salt include formic acid, glycolic acid, lactic acid, hydroxyphthalic acid, oxalic acid, malonic acid, and succinic acid. (succinic acid), hydroxy succinic acid (micic acid), tartaric acid, phthalic acid, diglycolic acid, citric acid, and Etc. Salt. In terms of salt, it is preferably an alkali metal salt such as a sodium salt or a potassium salt or a salt such as an ammonia or an amine such as a calcium salt. These can be deployed in a separate manner. The electrolytic hard gold plating solution of the present invention is misaligned! l〇〇g/liter, preferably 5 to 600 g/liter. When it is 1 g/liter or less, it is eluted from the material to be plated and is doped into the gold film. If the inorganic impurities are doped, the gold purity of the gold film will decrease. As a result, when the contact resistance of the contact member is increased and the concentration of the resistance-resistant agent is 100 g/liter or more, the effect is uneconomical. In the electrolytic hard gold plating solution of the present invention, a water-soluble nickel salt is formulated. The cobalt salt is exemplified by cobalt sulfate and basic cobalt carbonate. Examples of the nickel salt include nickel acid, nickel sulfite, and nickel chloride. These can be formulated in two or more ways. The electrolytic hard gold plating solution of the present invention has a cobalt salt or nickel to 10 g/liter, preferably 0.1 to 1.0 g/liter. When the concentration is 〇 〇 〇 1 g / liter or less, when the concentration of the hard cobalt salt or the nickel salt of the gold film is 10 g / liter or more, the effect of the shell U is uneconomical. For example, when the cobalt salt is blended, the hardness of the gold film will be 15 〇 to hardness, Vickers hardness. Here, the water solubility of the cobalt salt or the nickel salt formulated by the electric station of the present invention means that the metal salt of the soil can be used, or the concentration of the two or more kinds of cerium is from 1 to the concentration of the wrong agent, and the inorganic impurity is easy to be used in gold. When the film is inside the film, the appearance of the gold film is deteriorated. Even if the wrong water-soluble cobalt salt or cobalt, cobalt nitrate, nickel chlorosulfate or amine sulfonate is not obtained, the salt concentration may be 〇. 〇 1 If the degree of cobalt salt or nickel salt is lowered. Even if the phase nickel salt is not obtained at the above concentration of 200H V (Vickers dissolves the above-mentioned concentration in the hard gold plating solution to the extent of water solubility in the water of -11 - 201137184. In the electrolytic hard gold plating solution of the present invention, organic acid conduction is formulated. Salt, organic acid conductive salt, potassium formate, potassium citrate, potassium phosphate, potassium nitrate, potassium succinate. These may be formulated separately or in two or more ways. The organic acid of the electrolytic hard gold plating solution of the present invention. The concentration of the conductive salt is 10 to 200 g/liter, preferably 50 to 100 g/liter. When the concentration of the organic acid-conductive salt is 1 〇g/liter or less, the appearance of the gold film deteriorates and the normal gold film cannot be obtained. Even if the concentration of the organic acid-conductive salt is 200 g/liter or more, it is not economical because the corresponding effect cannot be obtained. In the m-solution hard gold plating solution of the present invention, a nitrogen-containing five-membered heterocyclic ring is formulated. A nitrogen-containing five-membered heterocyclic compound that functions as an organic crystal modifier. The inventors believe that a nitrogen-containing five-membered heterocyclic compound is adsorbed on a plating. The gold cyanide ion, or the gold ion after the deligand (cyanide ion) in the electric double layer is adsorbed or complex at ion, thereby controlling the crystal growth of gold. (crystal growth) to form a fine gold film. Further, the nitrogen-containing five-membered heterocyclic compound used in the present invention is not doped into the gold film. Therefore, the gold film has a high gold purity. The nitrogen-containing five-membered heterocyclic compound can be exemplified by imidazole, 2-methylimidazole, pyrazinie, 3,5-dimethylpyrazole, and 2-imidazoline (imidazoline). ), 2-pyrrolidone, hydantoin, 5,5-dimethylhydantoin, urinary ain (iiantoin), -12-201137184, brewing imine, DL (racemic)-focus Pyroglutamine acid, and the like. In the electrolytic hard gold plating solution of the present invention, the concentration of the nitrogen-containing five-membered heterocyclic compound is '1 to 50 g/liter, preferably 5 to 20 g/liter, Particularly preferred is 8 to 12 g / liter. If the concentration of the nitrogen-containing five-membered heterocyclic compound is below 1 g / liter, the crystal The adjustment effect is reduced, so that a fine gold film cannot be obtained. Even if the concentration of the five-membered heterocyclic compound containing nitrogen is above 50 g/liter, it is not economical because the corresponding effect cannot be obtained. Electrolytic hard ore gold liquid can be used at pH 3.0 to 7.0, but it is preferably used at pH 4.0 to 5.0. If the pH is below 4.0, the cathode current efficiency is lowered and it is difficult to obtain a predetermined one. A film of gold film. On the other hand, if the pH is 5.0 or more, the appearance of the gold film is reddened to make it difficult to obtain a normal gold film. Here, the pH adjusting agent may, for example, be sodium hydroxide, potassium hydroxide, ammonium hydroxide or dilute sulfuric acid. In the electrolytic hard gold plating solution of the present invention, other substances may be blended within a range that does not impair the effects of the present invention. The plating method using the electrolytic hard sheet metal liquid of the present invention can be carried out by a known plating method. Further, a partial plating method in which the electrolytic hard gold plating liquid of the present invention is sprayed on the material to be plated from a platinum nozzle may be used by using a platinum nozzle as an anode and a plated material as a cathode. [Embodiment] -13-201137184 [Examples] The apparatus configuration and evaluation method used for the test are as follows. Prepare a 32mmxl50mmx0.2mm copper plate. For the copper, a nickel film was formed using a nickel sulfamate plating solution to a thickness of 2 μm, which was used as a sample. For this sample, a mask plate of a polyxylene gum having a positive opening of l〇mm xl〇mm is placed and fixed, and a gold plating liquid is sent to the gold plating liquid seal by using a pump. The plating jet ejects a gold plating solution to the opening of the mask. Thereby, the test is applied to the plating. A platinum nozzle having a diameter of 5 mm was attached to the gold plating liquid ejection port, and this nozzle was used as an anode electrode. For the measurement of the film thickness of the gold film, a fluorescent X-ray thickness measuring device SEA5120 manufactured by SII Corporation was used. The presence or absence of the pinhole generated in the gold film was evaluated by the nitric acid aeration method (KJIS Η 8 620 1 0.5) described in the JIS standard. Porosity test, test for pinhole size and number of ruthenium-plated layers. In nitric acid aeration, a desiccator is placed on the inner plate of the container with nitric acid, and the sample is placed after loading. It is left at about 23 ° C for 1 hour. The nitric acid vapor generated by the drying is passed through the pinhole to corrode the nickel film. If the nickel film is corroded, spots appear on the gold film. The ns specification of the gold plating corrosion resistance test method H8502 11.5) specified in the rating number of the standard plate, and the square sheet metal liquid plus part, and the line film belongs to test) test for the test of the magnet The bottom point is judged by JIS Chart-14-201137184. (Example 1) Potassium cyanide: 5 g/liter (in terms of Au) / liter of potassium formate: 2 0g/liter of cobalt sulfate··〇_96g/liter of 2-nitrobenzenesulfonic acid: 2g/liter of imidazole: l〇g/liter of shovel gold liquid is prepared according to the above-mentioned mixing method. The gold plating solution is I week. The whole is ρ Η 4.2 ' depending on the liquid temperature of 5 5. (:, current density 4 0 A / dm 2, according to the way the gold film thickness can become 〇.〇5μηι, part of the plating is applied to the sample. The gold film, the color tone (col〇rt〇ne) is lemon yellow and the appearance is uniform, which is a good appearance. The corrosion resistance evaluation 'the nominal number is 9.5-5 and the total corrosion area ratio is 〇. 〇2 or more and 0.05% or less. (Examples 2 to 5), (Comparative Examples 1 and 2) According to the preparation shown in Table 1, a gold plating solution was prepared, and partial plating was applied to the sample in the same manner as in Example 1. The gold film on the sample has a hue of lemon yellow and a uniform appearance, and is a good appearance. The results of the evaluation of corrosion resistance are shown in Table 2. -15- 201137184 (Table 1) Example 1 Example 2 Greedy Example 3 Example 4 寅 Example S Comparative Example 1 Comparative Example 2 Preparation of Qianjin Liquid Aussie (β/L) Cyanide Fine in Gold) 5 5 5 5 5 5 5 Potassium citrate 7 0 7 0 7 0 7 0 7 0 7 0 7 0 Citric acid 5 0 5 0 5 0 5 0 5 0 5 0 5 0 Potassium formate 2 0 2 0 2 0 2 0 2 0 2 0 2 0 sulfur secret 0. 96 0. 96 0.9 6 — — 0. 96 0.9 6 barium sulfate — — — 0. 90 0. 90 — — 2-nitrobenzenesulfonic acid 2 2 2 2 2 — — Sodium nitrobenzenesulfonate 2 - imidazole 10 - 10 --- -- -- 2-pyrrolidone - 10 5,5-dimethylhydantoin --- --- 1 0 — 10 —one — gold plating conditions PH 4. 2 4. 2 4. 2 4. 2 4. 2 4. 2 4. 2 Liquid temperature CC) 5 5 5 5 5 5 5 5 5 5 5 5 5 5 ^Flow density <A/dm,) 4 0 4 0 4 0 4 0 4 0 4 0 4 0 (Table 2) Nominal total corrosion area ratio % Example 1 9 . 5 — 5 0 . 0 2 or more 0 . 0 5 % or less Example 2 9 3 - 3 0 . 0 5 or more 0 . 0 7 % Below Example 3 9 . 5 — 6 0 . 0 2 or more 0 . 0 5 % or less Example 4 9 . 5 _ 3 0 . 0 2 or more. 0 5 % Below Example 5 9 . 3 - 6 0 . 0 5 or more 0 . 0 7 % or less Comparative Example 1 4-1 2 . 5 0 or more 5 . 0 〇 % or less Comparative Example 2 4 -4 2 . 5 〇 above 5% 〇% below Examples 1 to 5, compared to the comparative example 1 ' 2 is the extent to which corrosion is greatly suppressed. As described above, the electrolytic hard gold plating solution of the present invention can form a fine gold film having few pinholes even when the film thickness of the gold film is less than 1 μηι. As a result, the corrosion resistance of the plated material is excellent. -16-