[0013] 本發明之無電解鍍鎳浴為，於被鍍物之表面形成無電解鍍鎳被膜（以下單稱為被膜）所使用之物，例如將被鍍物浸漬於無電解鍍鎳浴中，可於上述被鍍物之表面上形成被膜。 [0014] 本發明者們發現，藉由無電解鍍鎳浴中含有還原劑與含硝基芳香族化合物，可得不僅能抑制鎳遺漏及圖型外析出（以下稱為優良圖型性），且具有優良耐蝕性及外觀之被膜，而完成本發明。 [0015] 藉由使用上述含硝基芳香族化合物而發揮上述作用之機構的詳細內容雖不明，但推測如下所述。無電解鍍鎳浴中，藉由無電解鍍鎳浴所含有之還原劑的氧化反應，可由還原劑放出電子。無電解鍍鎳浴中不含含硝基芳香族化合物時，因由還原劑放出電子會使鎳離子還原而過度析出鎳，故恐使高積體化之電路圖型發生圖型外析出。但無電解鍍鎳浴中含有含硝基芳香族化合物時，由還原劑放出之電子比起鎳離子之還原反應會優先使用於硝基之還原反應，因此不會過度析出鎳，可抑制圖型外析出。又，本發明之無電解鍍鎳浴係指含有該等之混合物的總稱，也可使無電解鍍鎳液定位。 [0016] 本發明之無電解鍍鎳浴中，含硝基芳香族化合物及還原劑以外之化合物的種類無特別限定，本發明也可使用無電解鍍鎳浴一般所使用之物。 [0017] ＜含硝基芳香族化合物＞ 上述含硝基芳香族化合物可含有1個以上之硝基。即，芳香族化合物所含有之硝基可為1個或複數。上述含硝基芳香族化合物較佳為含有1～3個硝基，就處理性之觀點又以1～2個硝基為佳，更佳為1個硝基。 [0018] 又，上述含硝基芳香族化合物為，由可具有硝基以外之取代基的苯、可具有硝基以外之取代基的萘，及該等之鹼金屬鹽所成群中所選出之至少一種，上述取代基較佳為，由羧基、羥基、鹵原子、磺酸基、酯基、烷氧基，及胺基所成群中所選出之至少一種。 [0019] 上述取代基更佳為，由羧基、羥基、鹵原子、磺酸基，及胺基所成群中所選出之至少一種。 [0020] 上述含硝基芳香族化合物為鹼金屬鹽時，上述含硝基芳香族化合物較佳為，由鈉鹽及鉀鹽所成群中所選出之至少一種。 [0021] 上述鹵基較佳為，由氯基、溴基，及碘基所成群中所選出之至少一種。 [0022] 無電解鍍鎳浴中含硝基芳香族化合物所佔有之含量（濃度）較佳為0.001mmol/L以上、20mol/L以下，又以0.1mol/L以上、10mol/L以下為佳，更佳為0.5mol/L以上、5mol/L以下。上述含量之下限低於0.001mmol/L時，恐無法提升圖型性。又，上述含量之上限超過20mol/L時，恐發生鎳遺漏。使用複數含硝基芳香族化合物時，含硝基芳香族化合物之含量係指全部含硝基芳香族化合物之合計含量。 [0023] ＜還原劑＞ 還原劑之種類無特別限定，可使用已知之無電解鍍鎳浴中一般所使用之各種還原劑。該類還原劑如，次磷酸鹽、硼化合物等。上述次磷酸鹽如，次磷酸納（次磷酸鹼）、次磷酸鉀等。又，上述硼化合物如，氫化硼納、氫化硼鉀等之氫化硼化合物；二甲基胺甲硼烷（DMAB）、三甲基胺甲硼烷、三乙基胺甲硼烷等之胺甲硼烷化合物等。 [0024] 上述還原劑之較佳濃度會依所使用之還原劑種類而異，例如還原劑係使用次磷酸鈉時，較佳為0.1～0.5mol/L。藉由控制該類濃度，可防止因鍍液中之鎳離子還原減緩而拉長成模時間之不合宜情形，及鍍浴分解等。次磷酸鈉之濃度更佳為0.15～0.35mol/L。藉此可更有效防止上述問題。 [0025] 又，上述還原劑係使用硼化合物之DMAB時，DMAB之濃度較佳為0.01～0.2mol/L。藉此可防止拉長成模時間之不合情形，及防止鍍浴分解等。DMAB之濃度更佳為0.05～0.09mol/L。藉此可更有效防止上述問題。 [0026] 無電解鍍鎳浴為含有含硝基芳香族化合物與還原劑以外之要件下無特定限定，但以可有效發揮所希望之特性般適當調整為佳，又，無電解鍍鎳浴除了含硝基芳香族化合物與還原劑，可含有水溶性鎳鹽、錯合劑、安定劑、含硫化合物，較佳為含有水溶性鎳鹽及錯合劑。下面將具體說明水浴性鎳鹽、錯合劑、安定劑、含硫化合物。 [0027] ＜水溶性鎳鹽＞ 水溶性鎳鹽可為能溶於鍍液，得到一定濃度之水溶液之物，無特別限定。該類水溶性鎳鹽如，硫酸鎳、氯化鎳、次磷酸鎳等之無機水溶性鎳鹽；乙酸鎳、蘋果酸鎳等之有機水溶性鎳鹽等。該等之水溶性鎳鹽可單獨使用或二種以上混合使用。 [0028] 水溶性鎳鹽之濃度較佳如0.05～0.17mol/L。藉由控制為上述範圍，可有效防止因被膜之析出速度非常遲緩而拉長成膜時間之不合宜情形、因提高鍍液之黏度而降低液體流動性故相對於鍍鎳之均勻析出性具有不良影響之不合宜情形、使所形成之被膜生成凹洞等之不合宜情形等。 [0029] ＜錯合劑＞ 錯合劑可有效防止水溶性鎳鹽等之鎳化合物沉澱，及使鎳之析出反應具有適當速度。本發明可使用已知之無電解鍍鎳液一般所使用之各種錯合劑。該類錯合劑之具體例如，乙醇酸、乳酸、葡萄糖酸、丙酸等之單羧酸；蘋果酸、琥珀酸、酒石酸、丙二酸、草酸、己二酸等之二羧酸；甘胺酸、谷胺酸、天冬胺酸、丙胺酸等之胺基羧酸；伸乙基二胺四乙酸、Versenol（N-羥基乙基伸乙基二胺 -N,N’,N’-三乙酸）、Quadrol（N,N,N’,N’-四羥基乙基伸乙基二胺）等之伸乙基二胺衍生物；1-羥基乙烷-1,1-二膦酸、伸乙基二胺四伸甲基膦酸等之膦酸；及該等之可溶性鹽等。該等錯合劑可單獨使用或二種以上混合使用。 [0030] 錯合劑之濃度會依所使用之錯合劑種類而異，無特別限定，大致上以0.001～2mol/L之範圍為佳。藉由將錯合劑之濃度控制於該範圍時，可防止因氫氧化鎳之沉澱、氧化還原反應過快而使鍍浴分解等。另外可防止減緩被膜之析出速度的問題、因提高鍍液之黏度而降低均勻析出性等問題。更佳之錯合劑的濃度為0.002～1mol/L。藉此可更有效防止氫氧化鎳沉澱、鍍浴分解等。 [0031] ＜安定劑＞ 必要時本發明之無電解鍍鎳浴可另含有已知之安定劑。本發明之無電解鍍鎳浴中既使未添加安定劑也可抑制圖型外析出，但添加安定劑時也可抑制鎳遺漏及圖型外析出。上述安定劑可使用專利文獻1或專利文獻2所記載已知之安定劑，例如乙酸鉛等之P6化合物、乙酸鉍等之Bi化合物等之無機化合物；丁炔二醇等之有機化合物安定劑。該等安定劑可單獨使用或二種以上混合使用。 [0032] ＜含硫化合物＞ 必要時本發明之無電解鍍鎳浴可另含有已知之含硫化合物。上述含硫化合物如，硫二甘醇酸、硫乙醇酸、硫基硫酸鹼、亞硫酸鹼等。該等含硫化合物可單獨使用或二種以上混合使用。 [0033] ＜被膜中磷之濃度＞ 藉由被膜中磷之濃度可區分為低磷（被膜中磷之濃度：1.5～3.0%）、中磷（被膜中磷之濃度：6.0～7.5%）、中高磷（被膜中磷之濃度：8.0～9.5%）、高磷（被膜中磷之濃度：10.5～12.0%）四種。因此形成高磷之被膜用的鍍浴中不會含硫，但形成低磷、中磷、中高磷之被膜用的鍍浴中會含有大量硫。無關本發明之無電解鍍鎳浴中有無含硫化合物，均可抑制鎳遺漏及圖型外析出。即，無關被膜中磷之濃度，均可抑制鎳遺漏及圖型外析出。 [0034] ＜無電解鍍鎳浴之pH＞ 本發明之無電解鍍鎳浴之pH較佳為4.0～9.0程度，更佳為4.0～6.5。pH為上述範圍時，可有效率藉由還原劑而發生還原反應，而防止還原劑分解等，又可防止電鍍析出性降低、鍍液分解等。又，pH為上述範圍時可防止因還原劑之還原電位過高而降低鍍浴之安定性。調整上述pH之pH調整劑可使用氨水、氫氧化鈉等之鹼；硫酸、鹽酸、硝酸、磷酸等之酸等。 [0035] ＜其他＞ 必要時本發明之無電解鍍鎳浴可另含有無電解鍍鎳液所添加之已知的各種添加劑。添加劑如，反應促進劑、光澤劑、表面活性劑、機能賦予劑等。該等之種類無特別限制，可採用一般所使用之物。 [0036] 無電解鍍鎳浴中含有鎳以外之金屬成分時，鎳以外之金屬成分恐析出於被膜中，而會因鎳以外之金屬成分改變被膜特性故不宜。無電解鍍鎳浴中鎳以外之金屬成分的濃度較佳為未達1mg/L，更佳為未達0.1mg/L。 [0037] 使用本發明之無電解鍍鎳浴進行無電解電鍍時之電鍍條件及電鍍裝置無特別限定，可依常法適當選擇。具體上可為，使被鍍物浸漬於上述組成之無電解鍍鎳液等而接觸。此時之電鍍溫度會依鍍浴之組成等而異，但較佳為50～95℃。該溫度下可防止因電鍍析出反應減緩而發生被膜未析出及外觀不良。又，電鍍處理時間可因應所形成之被膜的膜厚等而適當設定，大致上一般為15～60分鐘程度。 [0038] 又，本發明所使用之被鍍物的種類無特別限定，例如鐵、鈷、鎳、鈀等之金屬或該等之合金般相對於無電解鍍鎳之還原析出具有觸媒性之物；銅等之無觸媒性之金屬、玻璃、陶瓷等。使用前者具有觸媒性之金屬等時，依常法進行前處理後可直接形成被膜。又，使用後者無觸媒性之金屬等時，依常法附著鈀核等之金屬觸媒核後，可進行無電解鍍鎳處理。 [0039] 由此所得之被膜的膜厚大致為3～7μm程度，較佳為4～5μm。得該類膜厚時，因既使為了確保耐蝕性等而使被膜膜厚如上述般加厚，也不會發生裂痕等之觀點故非常有用。 [0040] 又，形成無電解鍍鎳被膜之被鍍物適用於製造印刷基板。 實施例 [0041] 下面將舉實施例更具體說明本發明，但本發明非限制於下述實施例，可得前、後述之要旨的範圍內可變更實施，該等均包含於本發明之技術範圍內。 [0042] （無電解鍍鎳被膜之形成方法） 首先準備聚醯亞胺基板上層合厚18μm之壓延銅箔後形成圖型的上村工業股份公司製上村試驗圖型基板。所準備之上述圖型基板為，具有交互形成線與空間之線與空間圖型，且線L為20μm、空間S為20μm之基板（以下稱為基板A），與線L為40μm、空間S為20μm之基板（以下稱為基板B）。又，線係表示圖型寬（線寬），空間係表示接鄰圖型相互間之間隔（縫隙寬）。 [0043] 以上述基板A或上述基板B作為被鍍物，相對於上述被鍍物依序進行表1之處理。詳細為，首先藉由上村工業股份公司製ACL-007進行清潔（脫脂）處理。其次以100g/L之過硫酸鈉溶液（SPS）進行軟蝕刻處理。接著以10%硫酸（H2
SO4
）溶液去除蝕刻殘渣（酸洗），再以3%硫酸（H2
SO4
）溶液進行預浸處理。其後以上村工業股份公司製MNK-4賦予Pd觸媒（活化處理），將活化處理後上述被鍍物浸漬於後述無電解鍍鎳浴中，形成厚5μm之無電解鍍鎳被膜。最後使用上村工業股份公司製Goblite（登記商標）TIG-10進行無電解鍍金，形成厚0.05μm之無電解鍍金被膜。清潔、軟蝕刻、酸洗、預浸、活化、無電解鍍鎳，及無電解鍍金之各處理的溫度及時間如表1所示。 [0044][0045] （無電解鍍鎳浴） 準備含有作為水溶性鎳鹽之硫酸鎳、作為還原劑之次磷酸鈉，及作為錯合劑之丙二酸、乳酸及己酸之混合液，將表2或表3所記載之添加物加入該混合液，作為無電解鍍鎳浴用。具體上添加物係指，實施例1～39為表2所記載之含硝基芳香族化合物，比較例1～8為表3所記載之苯環的單取代物，比較例9、10為表3所記載之含硫化合物，比較例11～13為表3所記載之金屬成分。又，實施例1～39所使用之含硝基芳香族化合物中，含硝基芳香族化合物（下述（Ι））之R1
、R2
、R3
、R4
及R5
未如表2中特別註明下，係為氫原子。 [0046][0047] 無電解鍍鎳浴中各成分之濃度為，硫酸鎳：20g/L（0.129 mol/L）、添加物：0.5 mol/L、次磷酸鈉：30g/L（0.283 mol/L）、丙二酸：10g/L（0.096 mol/L）、乳酸：10g/L（0.111 mol/L）、己二酸：10g/L（0.068 mol/L）。各鍍浴之pH為4.6。 [0048][0049][0050] 使用上述無電解鍍鎳浴進行下述物性及特性評估。 [0051] （被膜中之磷濃度） 於3cm×3cm之貼銅層合板上形成5μm以上之膜厚的被膜。使用螢光X線分析裝置Rigaku公司製之ZSX Primus IV測定該被膜中之磷濃度。 [0052] （圖型性） 藉由上述被膜之形成方法，各自於上述基板A及上述基板B上形成被膜，再依下述基準以目視觀察。又，圖1（a）及（b）為基板A之表面形成被膜後之相片。 good：空間內無鎳析出（圖1（a）） poor：空間內有鎳析出（圖1（b）） [0053] （耐蝕性（硝酸浸漬試驗）） 將BGA（Ball Grid Array）基板浸漬於上述各無電解鍍鎳浴中，於BGA基板之表面形成膜厚5μm之被膜。將該被膜浸漬於25℃之60%硝酸被水稀釋為2倍之溶液中30秒後，以目視確認被膜有無變色。被膜變色為黑色時評估為「有變色」，未觀察到被膜變色時評估為「未變色」（耐蝕性優良）。 [0054] （被膜分析） 將SUS 304浸漬於無電解鍍鎳浴中，於SUS 304之表面形成膜厚30μm之被膜。將該被膜浸漬於50℃之硝酸中1小時使其完全溶解後，使用堀場製作所公司製Ultima 2之ICP發光分析裝置測定溶解後含有被膜之硝酸中，被膜中有無含有金屬及種類。 [0055] 該等結果併記於表2及表3中。使用本發明之無電解鍍鎳浴的實施例1～39為，可得能抑制鎳遺漏及圖型外析出，且具有優良耐蝕性及外觀之高磷無電解鍍鎳被膜。又，添加物為未含硝基之芳香族化合物的比較例1～8為圖型性較差。添加物為含硫化合物之比較例9、10為耐蝕性比較差。添加物為金屬之比較例11～13為無電解鍍鎳被膜中含有鎳以外之來自添加物的金屬。[0013] The electroless nickel plating bath of the present invention is a material used to form an electroless nickel plating film (hereinafter simply referred to as a film) on the surface of the object to be plated, for example, the object to be plated is immersed in the electroless nickel plating bath A film can be formed on the surface of the above-mentioned object to be plated. [0014] The present inventors have discovered that by including a reducing agent and a nitro-containing aromatic compound in an electroless nickel plating bath, it is possible to obtain not only suppression of nickel leakage and out-of-pattern precipitation (hereinafter referred to as excellent pattern), A film with excellent corrosion resistance and appearance completes the present invention. [0015] Although details of a mechanism that exerts the above-mentioned effect by using the nitro-containing aromatic compound are unknown, it is estimated as follows. In the electroless nickel plating bath, electrons can be emitted from the reducing agent by the oxidation reaction of the reducing agent contained in the electroless nickel plating bath. When the electroless nickel plating bath does not contain a nitro-containing aromatic compound, nickel may be excessively precipitated due to the reduction of nickel ions by the release of electrons from the reducing agent. Therefore, the circuit pattern of the high-integration circuit may be precipitated outside the pattern. However, when a nitro-containing aromatic compound is contained in the electroless nickel plating bath, the electrons emitted from the reducing agent are preferentially used for the reduction reaction of the nitro group over the reduction reaction of the nickel ion, so the nickel is not excessively precipitated, and the pattern can be suppressed. Outside precipitation. In addition, the electroless nickel plating bath of the present invention is a general term for a mixture containing these, and it is also possible to position the electroless nickel plating solution. [0016] In the electroless nickel plating bath of the present invention, the types of compounds other than the nitro-containing aromatic compound and the reducing agent are not particularly limited, and in the present invention, those generally used in the electroless nickel plating bath can also be used. [0017] <Nitro-containing aromatic compound> The nitro-containing aromatic compound may contain one or more nitro groups. That is, the number of nitro groups contained in the aromatic compound may be one or plural. The above-mentioned nitro-containing aromatic compound preferably contains 1 to 3 nitro groups, and from the viewpoint of handleability, 1 to 2 nitro groups are more preferable, and 1 nitro group is more preferable. [0018] The nitro-containing aromatic compound is selected from the group consisting of benzene which may have a substituent other than nitro, naphthalene which may have a substituent other than nitro, and alkali metal salts thereof. At least one of the above-mentioned substituents is preferably at least one selected from the group consisting of a carboxyl group, a hydroxyl group, a halogen atom, a sulfonic acid group, an ester group, an alkoxy group, and an amine group. [0019] The substituent is more preferably at least one selected from the group consisting of a carboxyl group, a hydroxyl group, a halogen atom, a sulfonic acid group, and an amine group. [0020] When the nitro-containing aromatic compound is an alkali metal salt, the nitro-containing aromatic compound is preferably at least one selected from the group consisting of a sodium salt and a potassium salt. [0021] The halogen group is preferably at least one selected from the group consisting of a chloro group, a bromo group, and an iodo group. [0022] The content (concentration) of the nitro-containing aromatic compound in the electroless nickel plating bath is preferably 0.001 mmol / L or more and 20 mol / L or less, and more preferably 0.1 mol / L or more and 10 mol / L or less. , More preferably 0.5 mol / L or more and 5 mol / L or less. When the lower limit of the above content is less than 0.001 mmol / L, the pattern property may not be improved. When the upper limit of the content is more than 20 mol / L, nickel leakage may occur. When a plurality of nitro-containing aromatic compounds are used, the content of the nitro-containing aromatic compounds refers to the total content of all the nitro-containing aromatic compounds. [0023] <Reducing agent> The type of the reducing agent is not particularly limited, and various reducing agents commonly used in known electroless nickel plating baths can be used. Such reducing agents are, for example, hypophosphites, boron compounds, and the like. Examples of the above hypophosphite include sodium hypophosphite (base hypophosphite), potassium hypophosphite, and the like. In addition, the above boron compounds are, for example, boron hydride compounds such as sodium borohydride, potassium borohydride, and the like; dimethylamines such as dimethylamine borane (DMAB), trimethylamine borane, and triethylamine borane. Borane compounds, etc. [0024] The preferred concentration of the reducing agent will vary depending on the type of reducing agent used. For example, when sodium hypophosphite is used as the reducing agent, it is preferably 0.1 to 0.5 mol / L. By controlling such concentrations, it is possible to prevent the unfavorable situation that the mold time is lengthened due to the slowing down of nickel ion reduction in the plating solution, and the decomposition of the plating bath. The concentration of sodium hypophosphite is more preferably 0.15 to 0.35 mol / L. This can prevent the above problems more effectively. [0025] When the boron compound is used as the reducing agent, the concentration of DMAB is preferably 0.01 to 0.2 mol / L. This can prevent the inconsistency of the prolonged molding time and prevent the decomposition of the plating bath. The concentration of DMAB is more preferably 0.05 to 0.09 mol / L. This can prevent the above problems more effectively. [0026] The electroless nickel plating bath is not particularly limited as long as it contains a nitro-containing aromatic compound and a reducing agent, but it is preferably adjusted appropriately so that the desired characteristics can be effectively exhibited. The nitro-containing aromatic compound and the reducing agent may contain a water-soluble nickel salt, a complexing agent, a stabilizer, and a sulfur-containing compound, preferably a water-soluble nickel salt and a complexing agent. Hereinafter, a water-bathable nickel salt, a complexing agent, a stabilizer, and a sulfur-containing compound will be specifically described. [0027] <Water-soluble nickel salt> The water-soluble nickel salt can be dissolved in a plating solution to obtain a certain concentration of an aqueous solution, and is not particularly limited. Such water-soluble nickel salts include inorganic water-soluble nickel salts such as nickel sulfate, nickel chloride, and nickel hypophosphite; and organic water-soluble nickel salts such as nickel acetate and nickel malate. These water-soluble nickel salts can be used alone or in combination of two or more. [0028] The concentration of the water-soluble nickel salt is preferably, for example, 0.05 to 0.17 mol / L. By controlling to the above-mentioned range, it is possible to effectively prevent the unfavorable situation that the film formation time is prolonged due to the very slow deposition rate of the film, and the fluidity of the liquid is reduced due to the increase in the viscosity of the plating solution, which is inferior to the uniform precipitation property of the nickel plating. Unfavorable conditions of influence, unfavorable conditions of forming pits in the formed film, etc. [0029] <Complex agent> The complex agent can effectively prevent the precipitation of nickel compounds such as water-soluble nickel salts, and allow the precipitation reaction of nickel to have an appropriate speed. In the present invention, various complexing agents commonly used in known electroless nickel plating solutions can be used. Specific examples of such complexes include monocarboxylic acids such as glycolic acid, lactic acid, gluconic acid, and propionic acid; dicarboxylic acids such as malic acid, succinic acid, tartaric acid, malonic acid, oxalic acid, and adipic acid; glycine Amino acids such as glutamic acid, glutamic acid, aspartic acid, alanine, etc .; Ethylenediaminetetraacetic acid, Versenol (N-Hydroxyethylethylenediamine-N, N ', N'-triacetic acid) Ethylenediamine derivatives such as Quadrol (N, N, N ', N'-tetrahydroxyethyl ethylenediamine), etc .; 1-hydroxyethane-1,1-diphosphonic acid, ethylenediamine Phosphonic acids such as amine tetramethylphosphonic acid; and soluble salts thereof. These complexing agents can be used alone or in combination of two or more. [0030] The concentration of the complexing agent varies depending on the kind of the complexing agent used, and is not particularly limited, but is preferably in the range of 0.001 to 2 mol / L. By controlling the concentration of the complexing agent within this range, it is possible to prevent the plating bath from being decomposed due to the precipitation of nickel hydroxide and the excessive redox reaction. In addition, it can prevent the problem of slowing down the deposition rate of the coating, and reduce the uniform precipitation by increasing the viscosity of the plating solution. More preferably, the concentration of the complexing agent is 0.002 to 1 mol / L. This can more effectively prevent precipitation of nickel hydroxide and decomposition of the plating bath. [0031] <Stabilizer> If necessary, the electroless nickel plating bath of the present invention may further contain a known stabilizer. In the electroless nickel plating bath of the present invention, even if no stabilizer is added, the out-of-pattern precipitation can be suppressed, but when the stabilizer is added, nickel leakage and out-of-pattern precipitation can be suppressed. As the stabilizer, known stabilizers described in Patent Literature 1 or Patent Literature 2 can be used, such as inorganic compounds such as P6 compounds such as lead acetate, Bi compounds such as bismuth acetate, and organic compound stabilizers such as butynediol. These stabilizers can be used alone or in combination of two or more. [0032] <Sulfur-containing compound> If necessary, the electroless nickel plating bath of the present invention may further contain a known sulfur-containing compound. Examples of the sulfur-containing compound include thiodiglycolic acid, thioglycolic acid, thiosulfate, and sulfite. These sulfur-containing compounds may be used alone or in combination of two or more. [0033] <Concentration of phosphorus in film> The phosphorus concentration in the film can be divided into low phosphorus (concentration of phosphorus in the film: 1.5 to 3.0%), medium phosphorus (concentration of phosphorus in the film: 6.0 to 7.5%), Medium and high phosphorus (concentration of phosphorus in the film: 8.0 to 9.5%), high phosphorus (concentration of phosphorus in the film: 10.5 to 12.0%). Therefore, the plating bath for forming a high-phosphorus coating does not contain sulfur, but the plating bath for forming a low-, medium-, and high-phosphorus coating contains a large amount of sulfur. Regardless of the presence or absence of sulfur-containing compounds in the electroless nickel plating bath of the present invention, nickel leakage and precipitation outside the pattern can be suppressed. That is, regardless of the concentration of phosphorus in the film, nickel leakage and out-of-pattern precipitation can be suppressed. [0034] <pH of the electroless nickel plating bath> The pH of the electroless nickel plating bath of the present invention is preferably about 4.0 to 9.0, and more preferably 4.0 to 6.5. When the pH is in the above range, a reduction reaction with a reducing agent can be efficiently performed to prevent decomposition of the reducing agent and the like, and it is possible to prevent degradation of plating precipitation and decomposition of the plating solution. In addition, when the pH is in the above range, it is possible to prevent the stability of the plating bath from being reduced due to an excessively high reduction potential of the reducing agent. As the pH adjusting agent for adjusting the pH, alkalis such as ammonia water and sodium hydroxide; acids such as sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid can be used. [Others] If necessary, the electroless nickel plating bath of the present invention may further contain various known additives added to the electroless nickel plating solution. Additives include, for example, a reaction accelerator, a gloss agent, a surfactant, a function imparting agent, and the like. These types are not particularly limited, and generally used ones can be used. [0036] When a metal component other than nickel is contained in the electroless nickel plating bath, metal components other than nickel are likely to be precipitated in the coating, and it is not suitable for the metal components other than nickel to change the characteristics of the coating. The concentration of metal components other than nickel in the electroless nickel plating bath is preferably less than 1 mg / L, and more preferably less than 0.1 mg / L. [0037] The electroplating conditions and electroplating device when using the electroless nickel plating bath of the present invention for electroless plating are not particularly limited, and can be appropriately selected according to a conventional method. Specifically, the object to be plated may be immersed in the electroless nickel plating solution or the like having the above composition and brought into contact. The plating temperature at this time varies depending on the composition of the plating bath, etc., but is preferably 50 to 95 ° C. At this temperature, it is possible to prevent the non-precipitation of the film and the appearance failure due to the slowdown of the plating precipitation reaction. The plating time can be appropriately set according to the film thickness of the film to be formed, and is generally approximately 15 to 60 minutes. [0038] In addition, the type of the object to be plated used in the present invention is not particularly limited. For example, metals such as iron, cobalt, nickel, and palladium, or alloys thereof, have catalytic properties as compared to the reduction and precipitation of electroless nickel plating. Non-catalytic metals, glass, ceramics, etc. When using the former catalyst metal, etc., the coating can be formed directly after pretreatment according to the usual method. In the case of using the latter non-catalytic metal or the like, after attaching a metal catalyst core such as a palladium core according to a conventional method, electroless nickel plating can be performed. [0039] The film thickness of the film thus obtained is approximately 3 to 7 μm, and preferably 4 to 5 μm. When such a film thickness is obtained, it is very useful from the viewpoint of preventing the occurrence of cracks and the like even if the film thickness of the coating film is increased as described above in order to ensure corrosion resistance and the like. [0040] In addition, an object to be plated to form an electroless nickel-plated film is suitable for manufacturing a printed circuit board. EXAMPLES [0041] The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples, and can be modified and implemented within the scope of the gist described above and below, all of which are included in the technology of the present invention Within range. [0042] (Formation method of non-electrolytic nickel plating film) First, a rolled copper foil having a thickness of 18 μm is laminated on a polyimide substrate to form a patterned Uemura test pattern substrate manufactured by Uemura Industrial Co., Ltd. The prepared pattern substrate is a substrate having a line and space pattern that alternately forms a line and a space, and the line L is 20 μm and the space S is 20 μm (hereinafter referred to as substrate A). The line L is 40 μm and the space S A substrate of 20 μm (hereinafter referred to as a substrate B). The line system indicates the pattern width (line width), and the space system indicates the interval (gap width) between adjacent patterns. [0043] With the substrate A or the substrate B as the object to be plated, the processing in Table 1 is sequentially performed with respect to the object to be plated. For details, first, clean (degrease) with ACL-007 manufactured by Uemura Industrial Co., Ltd. Secondly, a soft etching process was performed with a 100 g / L sodium persulfate solution (SPS). Then, the 10% sulfuric acid (H 2 SO 4 ) solution is used to remove the etching residues (acid washing), and then the 3% sulfuric acid (H 2 SO 4 ) solution is used for pre-soaking treatment. Thereafter, MNK-4 manufactured by Kuramura Industry Co., Ltd. was given a Pd catalyst (activation treatment), and the above-mentioned plated matter was immersed in an electroless nickel plating bath described later after the activation treatment to form an electroless nickel plating film having a thickness of 5 μm. Finally, electroless gold plating was performed using Goblite (registered trademark) TIG-10 manufactured by Uemura Industrial Co., Ltd. to form an electroless gold plating film having a thickness of 0.05 μm. The temperatures and times of cleaning, soft etching, pickling, prepreg, activation, electroless nickel plating, and electroless gold plating are shown in Table 1. [0044] [Electroless nickel plating bath] Prepare a mixed solution containing nickel sulfate as a water-soluble nickel salt, sodium hypophosphite as a reducing agent, and malonic acid, lactic acid, and hexanoic acid as a complexing agent. Table 2 or The additives described in Table 3 were added to the mixed solution and used as an electroless nickel plating bath. Specifically, the additives refer to Examples 1 to 39 as the nitro-containing aromatic compounds described in Table 2, Comparative Examples 1 to 8 as the mono-substituted products of the benzene ring described in Table 3, and Comparative Examples 9 and 10 as the tables. For the sulfur-containing compound described in 3, Comparative Examples 11 to 13 are metal components described in Table 3. In addition, among the nitro-containing aromatic compounds used in Examples 1 to 39, R 1 , R 2 , R 3 , R 4 and R 5 of the nitro-containing aromatic compound (hereinafter (I)) are not as shown in Table 2 It is specifically noted that it is a hydrogen atom. [0046] [0047] The concentration of each component in the electroless nickel plating bath is: nickel sulfate: 20 g / L (0.129 mol / L), additives: 0.5 mol / L, sodium hypophosphite: 30 g / L (0.283 mol / L), Malonic acid: 10 g / L (0.096 mol / L), lactic acid: 10 g / L (0.111 mol / L), and adipic acid: 10 g / L (0.068 mol / L). The pH of each plating bath was 4.6. [0048] [0049] [0050] The following physical properties and characteristics were evaluated using the electroless nickel plating bath. [0051] (Phosphorus concentration in the film) A film having a film thickness of 5 μm or more was formed on a 3 cm × 3 cm copper-clad laminate. The phosphorous concentration in the film was measured using a fluorescent X-ray analyzer Rigaku company ZSX Primus IV. [0052] (Schematic) According to the method for forming a film, a film is formed on each of the substrate A and the substrate B, and then visually observed according to the following reference. 1 (a) and (b) are photographs after a film is formed on the surface of the substrate A. good: no nickel precipitation in the space (Figure 1 (a)) poor: nickel precipitation in the space (Figure 1 (b)) [0053] (corrosion resistance (nitric acid impregnation test)) BGA (Ball Grid Array) substrate is immersed in In each of the foregoing electroless nickel plating baths, a film having a film thickness of 5 μm was formed on the surface of the BGA substrate. This film was immersed in a solution of 60% nitric acid diluted twice with water at 25 ° C. for 30 seconds, and the presence or absence of discoloration of the film was visually confirmed. When the film was discolored to black, it was evaluated as "discolored", and when no film discoloration was observed, it was evaluated as "no discoloration" (excellent corrosion resistance). [0054] (Film Analysis) SUS 304 was immersed in an electroless nickel plating bath to form a film with a thickness of 30 μm on the surface of SUS 304. This film was immersed in nitric acid at 50 ° C. for 1 hour to completely dissolve it, and the ICP luminescence analysis device of Ultima 2 manufactured by Horiba, Ltd. was used to measure the nitric acid containing the film after dissolution, and whether the film contained metals and types. [0055] The results are shown in Tables 2 and 3. Examples 1 to 39 using the electroless nickel plating bath of the present invention are high phosphorous electroless nickel plating films that can suppress nickel leakage and external precipitation, and have excellent corrosion resistance and appearance. In addition, Comparative Examples 1 to 8 in which the additive was an aromatic compound that did not contain a nitro group had poor patterning properties. Comparative Examples 9 and 10 in which the additive was a sulfur-containing compound had relatively poor corrosion resistance. Comparative Examples 11 to 13 in which the additive is a metal include metals derived from additives other than nickel in the electroless nickel plating film.