201025415 六、發明說明： 【發明所屬之技術領域】 本發明係關於一種場發射陰極之製造方法，尤指適用 於平面顯示器、背光光源(Baeklight Unit; blu)、平面光源 5與其他各類型照明光源之場發射陰極之製造方法。 【先前技術】 電子場發射理論最早是在1928年由R. H. ?(^1打與1^. W Nordheim共同提出，當在兩導電體間施加高電壓，電子在 10陰極表面與真空區的位能會降低，同時位能㈣厚度減 J田電壓很大時，位障厚度小到電子可以不必越過位障 同度，便可直接穿隧障壁進入真空中，電子便可大量自陰 極表面發射出來，此即場發射的基本機制。場發射顯示器 的基本結構大致上是由陽極板（螢光板）、陰極板（尖端 15底板）和隔離器所組成的，兩片平板中間是真空狀態（< 1〇~6 torr)，陽極板為氧化銦錫（IT〇)玻璃基材，其上塗有螢光 Φ &體’陰極板是由場發射陣列所組成，當場發射電子激發 陽極之螢光粉體時，即可發出明亮的光源。 一 1968年，c. A. Spindt首先提出以場發射電子元件做為 2〇顯示器的可行性，在玻璃基材上製作出場發射陣列陰極 板其電子源結構呈尖錐狀，材料主要以鉬金屬為主，但 此結構的大小，受在基材上製作圓孔所需的微影技術與製 作金屬錐的蒸鑛技術的影響，因而嚴重地限制了顯示器成 如的大小；此外，Spindt型場發射子的尖端也容易因為損 4 201025415 耗而降低壽命。 目前極為熱門的場發射顯示器是奈米碳管場發射顯示 器（Carbon Nanotube-Field Emission Display，CNT-FED)， 奈米碳管是日本Iijima教授在1991年發現的，奈米碳管具有 5 極佳導電性與化學安定性，且在幾何上的長度與直徑比 (Aspect Ratio )非常大，因此有很好的場發射特性。由於 奈米碳管具有極佳的場發射特性，各研究團隊皆把奈米碳 管和顯示器結合，應用在開發奈米碳管場發射陰極板或場 ® 發射背光元件技術。 10 目前發展中的奈米碳管場發射顯示器陰極板或場發射 背光元件製備技術主要有網印法、CVD法直接生長碳 管、電鍍法、電泳法以及無電鍍法等製程，但這些方法目 前都各自面臨一些問題。美國專利第6855376號揭示CVD 法直接生長奈米碳管製程雖然具有可在基材上直接成長均 15 勻的奈米碳管、可成長定向排列（Well Aligned )的碳管、 以及可藉由催化劑顆粒圖案化（Pattern )而選區定址成長 φ 碳管等優點，但若欲成長出場發射性良好之碳管，其製程 較繁複且設備昂貴，且生長溫度通常高於玻璃基材之軟化 溫度（Tg,約為550°C)，而且碳管與基材之附著性亦不佳， 20 壽命較短，亦無法控制單一碳管之品質，目前多屬於研究 的階段，工業上較少實際的運用；美國專利第6436221號 Chang，Yu-yang等人所採用網印法是目前工業上應用於大 尺寸化最有潛力之主流技術，使用高分子溶劑、玻璃粉、 銀膠，和碳管混合後以網板印刷方式塗布，再經高溫烘烤 5 201025415 5 ❹ 10 15 ❹ 20 =_分子黏著劑與有機溶劑’其具有製程簡單、無尺寸 放纽制以及成本較CVD直接生長碳管法便宜等優點， 但疋碳管與基材之黏著性不佳、奈米碳 =中的有機溶劑、棋烤製程造成部分碳管燒損： 射體塗布不均勾、發光均勾性不佳等問題，均為網印技術 上面臨之細’·美國專利第7,252,749號⑽ζ. η。。等人 二電泳⑽Ctrophoretic)方式沉積奈米碳管，使用的方法 =改變奈米碳管表面電性，再經由通電方法使奈米碳管聚 集於電極之上’再加以供乾’雖然可改善網印法碳管分佈 均勻性不佳之問題’並節省成本’但碳管與基材之附著性 仍然不是很好’而且鑛層之厚度平坦均句性亦不足，場發 射源壽命及發光均句性仍有改善之空間。另有電鑛（或無電 電鍵）方式將金屬與奈米碳管共同沉積於基材以製作場發 射陰極板；電鍍主要係先將分散好的奈米碳管與金屬鹽類 水溶液共同調配為電解液’再經由通電方式使奈米碳管與 還原的金屬共同沉積在陰極表面’此法可提升奈米碳管與 基材間的附著性，然而在電鍵過程中，會遭遇陰極表面的 電流密度分佈不均，導致奈米碳管分佈在金屬錄層的均勻 性不佳，致使場發射發光不均勻等問題；無電電錢則是利 用奈米碳管與還原的金屬共同沉積在基材表面，得到一奈 =碳管與金屬的複合㈣，以提升奈米碳管與基材間的: 著性，此外，所獲得之場發射發射體分佈均勻佳，可有效 增益發光均勻性，然而無電鍍溶液本身是一個熱力學不穩 定的體系，壽命短，在進行析鍍過程中，如pH值過高、 6 201025415 局部過熱或某些雜質影響（如奈米碳管），使鍍液中出現一 些具催化活性之微小析出物，引起鍍液發生不可控制之激 烈自催化反應，造成整體鍍液毁損。因此，就現有之技術 而言，找尋一技術可同時面對低成本、減化製程、大型化 5的需求，改善碳管與基材之黏著性、增加場發射源壽命、 以及發光均勻度的問題，是目前產業發展的重點。 【發明内容】 擧 I發明之主要目的在於提供-種場發射陰極之製備方 10法，以低成本、製程簡單化及場發射元件大型化的需求下， 達到改善奈米碳材與基材之間的黏著性，同時增加場發射 元件的發射均勻性等目標。 據此，本發明提供一種場發射陰極之製備方法，包括 以下步驟：（a)於一基材表面形成一多孔性金屬層；以— 15表面改質溶液處理該基材之該多孔性金屬層；以及（c)於該 多孔性金屬層表面形成一奈米碳材薄層。 ® 於上述製備方法之步驟（a)中，該基材較佳經過表面粗 化處理，此表面粗化處理可依序以脫脂、清洗及喷砂步驟 處理該基材。此外，該多孔性金屬層較佳藉由微粒燒結或 、:、3射出金屬材料於該基材表面所形成，其中該金屬材 料可選自於由鐵、鈷、鎳、錫、辞、鋁、以及銅所組群組 中其中之一者或其合金。 於上述製備方法之步驟中，以該表面改質溶液處理 的方式’可將該表面改質溶液以喷霧塗佈於該多孔性金屬 25層’或將表面形成有該多孔性金屬層之該基材浸入該表面 7 201025415 改質溶液。此外，該表面改質溶液可含一陽離子型界面活 性劑，其中該陽離子型界面活性劑種類不限，可選自於由 鹵化烷基銨鹽如溴化十六烷三甲基銨（CTAB)、溴化辛基三 甲基銨（OTAB)、溴化十四烷基三甲基銨（TTAB)、氣化十 5六烷三曱基銨（CTAC)、氯化辛基三曱基銨（〇TAC)、氣化 十四烷基二甲基銨（丁TAC)、氟化十六烷三甲基銨（ctaf)、 氟化辛基三甲基銨（0TAF)、以及氟化十四烷基三甲基銨 (TTAF)所組群組中至少一者。 參 於上述製備方法之步驟（c)中’該奈米碳材薄層之形成 10方法，包括以下步驟：（cl)將表面形成有該多孔性金屬層 之該基材改入一含複數個奈求碳材的水溶液中，使該複數 個奈米碳材吸附於該多孔性金屬層上；以及（c2)乾燥該基 材。一般而言，浸入水溶液的時間約為3〜3〇分鐘左右。此 外，該含複數個奈米碳材的水溶液可含一陰離子型界面活 15性劑，其中該陰離子型界面活性劑種類不限，可選自於由 辛基硫酸納（sos)、+二烧基硫酸納（SDS)、十二院基苯續 ❷酸納（SDBS)、以及十二烧基苯確酸（HDBS)所組群組中至少 一者。另外，该含複數個奈米碳材的水溶液可經過超音波 震盈，以藉由該陰離子型界面活性劑改質該水溶液中該複 20數個奈米碳材。而乾燥該基材的方法，可藉由靜置陰乾， 或利用真空加熱（可活化包埋的奈米碳材），其加熱溫度約 為200〜500°C下持續1〇〜60分鐘，更佳為35〇〜45〇<>c下加熱 10~30分鐘左右。 ’ 於上述製備方法中，該奈米碳材薄層可選自於由單壁 201025415 奈米瑗管、雙壁奈米碳管、多壁奈米碳管、奈米碳纖、奈 米螺旋碳纖、奈米石墨、以及奈米鑽石所組群組中至少一 者材料構成。此外，該基材可為玻璃基材或氧化銦錫玻璃 基材。 5 此外’本發明另提供一種場發射陰極之製備方法，包 括以下步驟：（a)粗化一金屬基材；（b)以一表面改質溶液處 理該金屬基材；以及（c)於該金屬基材表面形成一奈米碳材 薄層。 瘳 於上述製備方法中，該金屬基材可選自於由鐵、姑、 10 鎳、錫、辞、鋁、以及銅所組群組中其中之一者或其合金。 於上述製備方法之步驟（a)中，該粗化可為噴砂處理。 於上述製備方法之步驟（b)中，以該表面改質溶液處理 的方式，可將該表面改質溶液以噴霧塗佈於該金屬基材表 面’或將該金屬基材係浸入該表面改質溶液。 15 於上述製備方法之步驟（c)中，該奈米碳材薄層之形成 方法，包括以下步驟：（cl)將該金屬基材浸入一含複數個 〇 奈米碳材的水溶液中’使該複數個奈米碳材吸附於該金屬 基材上；以及（c2)乾燥該金屬基材。 20 【實施方式】 當使用玻璃基材時，如圖1所示，可藉由溶射法將炼 融、半熔融甚至是固態的金屬或其合金之材料（如線材或微 粒）’噴塗在玻璃基材表面，待冷卻後即形成一多孔性金屬 層，如此則可粗化基材表面。或者，使用微粒燒結法，將 25 塗佈於玻璃基板表面之金屬層燒結成一多孔性金屬層，如 9 201025415 此亦可粗化玻璃基板表面。另外，亦可於玻璃基板表面沉 積金屬、金屬合金或金屬氧化物，再經過化成處理或陽極 處理所形成之多孔性金屬層，如此同樣可以粗化玻璃基板 表面。另一方面，當使用金屬基材時，則可直接利用喷砂 5 等方式粗化金屬基材表面。 待基材表面經過粗化後’使用含離子性界面活性劑之 表面改質溶液處理基板，使基板表面披覆離子如陽離子， 增進基板表面親水特性與電性改質。而後使用相反於基板 β 表面離子電性的相對離子（counterion)如陰離子界面活性 10劑改質奈米碳材，因奈米碳材及基板間因電性相反而相互 吸引，所以含奈米碳材的水溶液可藉由基板表面親水性， 將奈米碳材擴散沉積於多孔性金屬層的孔隙内部，如此可 大幅增加碳材沉積密度，並可增進奈米碳材附著沉積於多 孔金屬導電膜之效果。另一方面，可使用陰離子界面活性 劑處理基板，伴隨使用陽離子界面活性劑處理奈米碳材亦 可達到相同效果。最後，將吸附有奈米碳材之基板經過烘 © 肖步驟處理後’即可得到本發明之陰極板。 一般而言，在陰極板上形成陰極線的技術已為習知， 2〇 2如賤鍵及喷塗方法來形成一金屬層及圖案化該金屬層。 人例而s，使用銅材製成金屬層後，再圖案化此金屬層（包 2於金屬層上塗佈総層、曝光光阻層、顯影被曝光的光 =層、形成-圖案化光阻層、以及使用圖案化光阻層遮罩 像二麵刻或限制場發射材料沉積在金屬層上形成特定圖 10 25 201025415 實施例1:製備多孔金屬鋁_奈米碳管場發射陰極板 先將玻璃基材經脫脂清洗與噴砂處理粗化表面後，以 700〜l〇〇〇°C熱熔射喷塗於玻璃基材表面形成鋁金屬薄層 (厚度約0.05〜0.5 mm，表面平均粗縫度（Ra)約1〇〜35 μηι)， 5 而後靜置室溫冷卻後形成多孔性金屬層。接著，將玻璃基 材浸入溫度約50〜70。(：的表面改質水溶液（含〇1Μ〜1Μ的陽 離子型界面活性劑如CTAB，以氨水或氫氧化鈉將ρΗ值至 8〜1 〇)中約1〜3分鐘後，取出以去離子水或溶劑沖洗基材表 9 面。將玻璃基材浸於溫度約3〇°C之奈米碳材分散水溶液（一 10般含奈米碳管：0.3〜3.0 g/L，以及含陰離子型界面活性劑 如SDS : 3.0〜1 〇·〇 g/L ’本實施例使用2 g/L奈米碳管、及5 g/L 的SDS)中約3〜10分鐘，再將玻璃基材表面置於約45〇<5(：烘 箱中以蒸發基材表面殘餘的水溶液，因此奈米碳管便於玻 璃基材表面形成一薄層結構。 15 完成後之試片經由電子顯微鏡（SEM)觀察，可知奈米 碳管沉積於玻璃基材之多孔性金屬層表面（如圖2所示）。 ❿ #將K片與塗佈螢光粉之陽極板組合封裝，陰陽極中間 隔板厚度160 μιη，在電源供應器作用電場強度在2 丫^爪以 上，可見明亮之發光效果（如圖3所示）。 20 實施例2··製備多孔金料·奈米石墨場發射陰極板 本實施例大致上同於實施例丨的步驟，不同點在於本實 施例使用鋅藉由熱溶射喷塗的方式形成多孔性金屬層另 外使用奈米石墨片分散水溶液（一般可含奈米石墨片·· 25 2〜0.01g/L，且陰離子型界面活性劑如SOS : 2〇〜〇 〇5g/L， 201025415 本實施例使用1 g/L奈米石墨片以及7 g/L的SDS)。 將此試片同實施例1所述方式，與塗佈螢光粉之陽極板 組合封裝’在電源供應器作用電場強度在3 ν/μηι以上，可 見明亮之發光效果（如圖4所示）。 5 實施例3:製備銅金屬基材_奈米鑽石場發射陰極板 先將銅基材試片喷砂處理粗化表面後，再以該基材試 片浸入溫度50〜70。(：之表面改質溶液（1〇 wt %)中，持續浸 ® 1〜3分鐘，取出後以去離子水沖洗基材表面。接續將基材 10浸潰於已分散奈米鑽石之水溶液（一般含奈米鑽石： 2〜O.Olg /L，以及陰離子型界面活性劑如SDS : 2〇〜〇 〇5g/L， 本實施例使用1 g/1之奈米鑽石、及4 §/1的81)8，溫度3〇〇c) 中約3〜5分鐘’待該基材表面溶液於烘箱中450它以下蒸 發’而奈米鑽石於該基材表面自然形成一薄層結構。 15 將此試片與塗佈螢光粉之陽極板組合封裝，在電源供 應器作用電場強度在5v^m以上，可見明亮之發光效果（如 g 圖5所示）。 比較例 20 先將金屬（鐵、銅、鋁、辞基材）試片陽極電解處理以 拋光其表面’再將此金屬試片浸入表面改質溶液（1〇wt%) 中’溫度50〜70°C ’浸潰1〜3分鐘，取出後以去離子水沖洗 基材表面。接續將基材浸潰於已分散奈米碳材之水溶液（奈 米碳材浸潰溶液組成可同實施例1至3中任一者）時間3〜5分 12 201025415 鐘，將金屬試片置於室溫（或烘箱450°C以下）乾燥金屬基材 表面的溶液後，基材表面自然形成薄層結構之奈米碳材。 另將該試片與塗佈螢光粉之陽極板組合封裝，在電源 供應器作用電場強度在5 ν/μιη以上，僅見稀疏之發光亮點 5 ❸ 10 15 Ο 20 (如圖6所示）。 【圖式簡單說明】 圖1係製作本發明場發射陰極之流程示意圖。 圖2係本發明實施例1的奈米碳管沉積場發射陰極板 SEM圖 圖3係本發明實施例1的奈米碳管場發射陰極板與塗 布螢光粉陽極板的組裝被施加電壓後發亮情形。 圖4係本發明實施例2的奈米石墨場發射陰極板與塗 布螢光粉陽極板的組裝被施加電壓後發亮情形。 圖5係本發明實施例3的奈米鑽石場發射陰極板與塗 布螢光粉陽極板的組裝被施加電壓後發亮情形。 圖6本發明比較例中金屬基材-奈米碳管場發射陰極 板與塗布螢光粉陽極板的組裝被施加電壓後發亮情形。 【主要元件符號說明】 無 13201025415 VI. Description of the Invention: [Technical Field] The present invention relates to a method for manufacturing a field emission cathode, and more particularly to a flat panel display, a backlight source (blu), a planar light source 5, and other types of illumination sources. The method of manufacturing the field emission cathode. [Prior Art] The theory of electron field emission was first proposed in 1928 by RH? (^1 and 1^. W Nordheim, when a high voltage is applied between two conductors, the potential of electrons on the surface of the 10 cathode and the vacuum region It will decrease, and at the same time, the potential energy (4) thickness is reduced. When the voltage of the field is large, the thickness of the barrier is so small that the electrons can pass through the barrier wall and enter the vacuum without passing through the barrier. The electrons can be emitted from the cathode surface in large quantities. This is the basic mechanism of field emission. The basic structure of the field emission display is roughly composed of an anode plate (fluorescent plate), a cathode plate (tip 15 bottom plate) and an isolator, and the two plates are in a vacuum state (<1 〇~6 torr), the anode plate is an indium tin oxide (IT〇) glass substrate coated with a fluorescent Φ & body 'cathode plate is composed of a field emission array, and the field emits electrons to excite the anode of the phosphor powder. In 1968, c. A. Spindt first proposed the feasibility of using field-emitting electronic components as a 2-inch display, and fabricated a field-emitting array cathode plate on a glass substrate with an electron source structure. tip Cone-shaped, the material is mainly molybdenum metal, but the size of this structure is affected by the lithography technology required to make round holes on the substrate and the steaming technology for making metal cones, thus severely limiting the display to In addition, the tip of the Spindt field emitter is also prone to reduce life due to the loss of 2010. The current popular field emission display is the Carbon Nanotube-Field Emission Display (CNT-FED). The carbon nanotubes were discovered by Professor Iijima of Japan in 1991. The carbon nanotubes have excellent electrical conductivity and chemical stability, and the geometric aspect ratio is very large, so it is very good. Field emission characteristics. Due to the excellent field emission characteristics of the carbon nanotubes, various research teams have combined carbon nanotubes and displays for the development of nanocarbon tube field emission cathode plates or field® emission backlight components. 10 Currently developing nano-carbon nanotube field emission display cathode plate or field emission backlight component preparation technology mainly through screen printing, CVD direct growth carbon tube, electroplating, electrophoresis Processes such as electroless plating, but these methods currently face some problems. U.S. Patent No. 6,855,376 discloses that the CVD direct growth nanocarbon control process has a carbon nanotube that can grow directly on the substrate. The carbon tube that can grow and align (Well Aligned) and the ability to select and grow the φ carbon tube by patterning the catalyst particles, but if the carbon tube with good field emission is desired to be grown, the process is complicated. Moreover, the equipment is expensive, and the growth temperature is usually higher than the softening temperature (Tg, about 550 ° C) of the glass substrate, and the adhesion between the carbon tube and the substrate is not good, 20 the life is short, and the single carbon tube cannot be controlled. The quality is currently at the stage of research, and there is less practical use in industry. The screen printing method adopted by Chang, Yu-yang et al. in US Patent No. 6436221 is currently the most promising mainstream technology applied to large-scale industrialization. , using polymer solvent, glass powder, silver glue, and carbon tube mixed, coated by screen printing, and then baked at high temperature 5 201025415 5 ❹ 10 15 ❹ 20 = _ molecular adhesive and The solvent has the advantages of simple process, no size, and cost, and is cheaper than the CVD direct growth carbon tube method, but the adhesion of the carbon nanotube to the substrate is poor, the organic solvent in the nanocarbon = the baking process Some of the carbon tube burned out: the problem of uneven coating of the shot body, poor light-emitting properties, etc., are all in the face of the screen printing technology. · US Patent No. 7,252,749 (10) ζ. η. . Etc. electrophoresis (10) Ctrophoretic) deposition of carbon nanotubes, the method used = change the surface electrical properties of the carbon nanotubes, and then through the electrification method to make the carbon nanotubes on the electrode 'and then dry', although the network can be improved The problem of poor uniformity of printing carbon tube distribution 'and cost savings', but the adhesion of carbon tube to the substrate is still not very good' and the thickness of the layer is flat and the sentence is not enough, the lifetime of the field emission source and the luminescence uniformity There is still room for improvement. In addition, the electric ore (or no electric key) method is used to deposit the metal and the carbon nanotube on the substrate to prepare the field emission cathode plate; the electroplating mainly consists of firstly dispersing the dispersed carbon nanotubes and the metal salt aqueous solution. The electrolyte 'co-deposits the carbon nanotubes with the reduced metal on the surface of the cathode. This method can improve the adhesion between the carbon nanotubes and the substrate. However, during the keying, the current on the cathode surface is encountered. Uneven density distribution, resulting in poor uniformity of the distribution of carbon nanotubes in the metal recording layer, resulting in uneven field emission luminescence; no electricity and electricity is deposited on the surface of the substrate by using carbon nanotubes and reduced metals. , a composite of carbon nanotubes and metal (4) is obtained to enhance the compatibility between the carbon nanotubes and the substrate, and in addition, the obtained field emission emitters are uniformly distributed, and the luminous uniformity can be effectively improved, however, The electroplating solution itself is a thermodynamically unstable system with a short lifetime. During the plating process, such as excessive pH, 6 201025415 local overheating or some impurities (such as carbon nanotubes), Solution occurred with some of the catalytic activity of the fine precipitates, causing uncontrolled plating occurs autocatalytic reaction of intense, resulting in damage to the overall bath. Therefore, in terms of the existing technology, the search for a technology can simultaneously meet the needs of low cost, reduced process, large size 5, improved adhesion of carbon tube to substrate, increased lifetime of field emission source, and uniformity of illumination. The problem is the focus of current industrial development. SUMMARY OF THE INVENTION The main object of the invention is to provide a method for preparing a field emission cathode, which can improve the nano carbon material and the substrate under the demand of low cost, simple process and large-scale field emission components. Adhesiveness, while increasing the uniformity of emission of field emission elements. Accordingly, the present invention provides a method for preparing a field emission cathode, comprising the steps of: (a) forming a porous metal layer on a surface of a substrate; and treating the porous metal of the substrate with a surface modification solution. And (c) forming a thin layer of nano carbon material on the surface of the porous metal layer. In the step (a) of the above preparation method, the substrate is preferably subjected to surface roughening treatment, and the surface roughening treatment may sequentially treat the substrate by a degreasing, washing and blasting step. In addition, the porous metal layer is preferably formed by sintering or:, 3, a metal material is formed on the surface of the substrate, wherein the metal material may be selected from the group consisting of iron, cobalt, nickel, tin, rhodium, aluminum, And one of the group of copper groups or alloys thereof. In the step of the above preparation method, in the manner of treating the surface modification solution, the surface modification solution may be spray-coated on the porous metal 25 layer or the surface may be formed with the porous metal layer. The substrate is immersed in the surface 7 201025415 modified solution. In addition, the surface modification solution may contain a cationic surfactant, wherein the cationic surfactant is not limited, and may be selected from an alkylammonium halide such as cetyltrimethylammonium bromide (CTAB). , octyltrimethylammonium bromide (OTAB), tetradecyltrimethylammonium bromide (TTAB), gasified decafluorotridecyltrimonium (CTAC), octyltrimethylammonium chloride ( 〇TAC), gasified tetradecyldimethylammonium (butyl TAC), hexadecane trimethylammonium hydride (ctaf), octyltrimethylammonium fluoride (0TAF), and tetradecane fluoride At least one of the group consisting of trimethylammonium (TTAF). The method for forming the thin layer of the nano carbon material in the step (c) of the above preparation method comprises the following steps: (cl) changing the substrate on which the porous metal layer is formed into a plurality of substrates In the aqueous solution of the carbon material, the plurality of nanocarbon materials are adsorbed on the porous metal layer; and (c2) the substrate is dried. In general, the time of immersion in an aqueous solution is about 3 to 3 minutes. In addition, the aqueous solution containing a plurality of nano carbon materials may contain an anionic interfacial active agent, wherein the anionic surfactant is not limited in type, and may be selected from sodium octyl sulfate (sos) and +2. At least one of the group consisting of sodium sulphate (SDS), sodium benzoate benzoate (SDBS), and dodecapine benzoic acid (HDBS). Further, the aqueous solution containing a plurality of nanocarbon materials may undergo ultrasonic shock absorption to modify the complex number of nano carbon materials in the aqueous solution by the anionic surfactant. The method of drying the substrate can be carried out by standing still or by vacuum heating (activated embedded nano carbon material), and the heating temperature is about 200 to 500 ° C for 1 〇 to 60 minutes, and more. It is heated for 35~45〇<>c for about 10~30 minutes. In the above preparation method, the nano carbon material layer may be selected from the group consisting of a single wall 201025415 nano tube, a double-walled carbon tube, a multi-walled carbon tube, a nano carbon fiber, a nano spiral carbon fiber, At least one of the nano graphite group and the nano diamond group is composed of materials. Further, the substrate may be a glass substrate or an indium tin oxide glass substrate. 5 Further, the present invention further provides a method of preparing a field emission cathode, comprising the steps of: (a) roughening a metal substrate; (b) treating the metal substrate with a surface modification solution; and (c) The surface of the metal substrate forms a thin layer of nano carbon material. In the above preparation method, the metal substrate may be selected from one of the group consisting of iron, australis, nickel, tin, rhodium, aluminum, and copper or an alloy thereof. In the step (a) of the above preparation method, the roughening may be a sand blasting treatment. In the step (b) of the above preparation method, the surface modification solution may be spray-coated on the surface of the metal substrate by the surface modification solution or the metal substrate may be immersed in the surface. Quality solution. 15 in the step (c) of the above preparation method, the method for forming a thin layer of the nano carbon material, comprising the steps of: (cl) immersing the metal substrate in an aqueous solution containing a plurality of carbon nanomaterials; The plurality of nano carbon materials are adsorbed on the metal substrate; and (c2) drying the metal substrate. 20 [Embodiment] When a glass substrate is used, as shown in Fig. 1, a material of a fused, semi-molten or even solid metal or an alloy thereof (such as a wire or a particle) can be sprayed on a glass base by a spray method. On the surface of the material, a porous metal layer is formed after being cooled, so that the surface of the substrate can be roughened. Alternatively, the metal layer coated on the surface of the glass substrate is sintered into a porous metal layer by a particle sintering method, such as 9 201025415, which also roughens the surface of the glass substrate. Further, a metal, a metal alloy or a metal oxide may be deposited on the surface of the glass substrate, and then the porous metal layer formed by the chemical conversion treatment or the anode treatment may be used to roughen the surface of the glass substrate. On the other hand, when a metal substrate is used, the surface of the metal substrate can be roughened by sandblasting or the like directly. After the surface of the substrate is roughened, the substrate is treated with a surface modifying solution containing an ionic surfactant to coat the surface of the substrate with ions such as cations to enhance the hydrophilic properties and electrical modification of the substrate surface. Then, a counterion such as an anionic interface active 10-modified nanocarbon material opposite to the surface ionicity of the substrate β is used, and the nanocarbon material and the substrate are mutually attracted by the opposite electrical properties, so the nanocarbon is contained. The aqueous solution of the material can diffuse and deposit the nano carbon material inside the pores of the porous metal layer by the hydrophilicity of the surface of the substrate, so that the carbon material deposition density can be greatly increased, and the adhesion and deposition of the nano carbon material to the porous metal conductive film can be enhanced. The effect. On the other hand, the substrate can be treated with an anionic surfactant, and the same effect can be obtained by treating the nanocarbon material with a cationic surfactant. Finally, the cathode plate of the present invention can be obtained by subjecting the substrate to which the nanocarbon material is adsorbed to the substrate after the crystallization process. In general, it has been conventional to form a cathode wire on a cathode plate, such as a ruthenium bond and a spray coating method to form a metal layer and pattern the metal layer. For example, after using a copper material to form a metal layer, the metal layer is patterned (package 2 is coated on the metal layer, the photoresist layer is exposed, the exposed light is developed, the layer is formed, and the patterned light is formed). Resisting layer, and using patterned photoresist layer mask like two-sided engraving or limiting field emission material deposition on the metal layer to form a specific figure 10 25 201025415 Example 1: Preparation of porous metal aluminum_nano carbon tube field emission cathode plate The glass substrate is subjected to degreasing cleaning and sandblasting to roughen the surface, and then sprayed on the surface of the glass substrate by heat spraying at 700 to 1 ° C to form a thin layer of aluminum metal (thickness of about 0.05 to 0.5 mm, rough surface) The degree of sag (Ra) is about 1 〇 to 35 μηι), 5 and then left to stand at room temperature to form a porous metal layer. Then, the glass substrate is immersed in a temperature of about 50 to 70. (: Surface modified aqueous solution (containing yttrium) 1 Μ ~ 1 Μ of a cationic surfactant such as CTAB, with ammonia or sodium hydroxide to ρ Η to 8~1 〇) for about 1 to 3 minutes, remove the surface of the substrate with deionized water or solvent. The glass substrate is immersed in a nanometer carbon material dispersion aqueous solution at a temperature of about 3 ° C. Carbon tube: 0.3~3.0 g/L, and anionic surfactant such as SDS: 3.0~1 〇·〇g/L 'This example uses 2 g/L carbon nanotubes, and 5 g/L In about 3 to 10 minutes in SDS), the surface of the glass substrate is placed in an atmosphere of about 45 〇 < 5 (: oven to evaporate the residual aqueous solution on the surface of the substrate, so that the carbon nanotubes facilitate the formation of a thin layer on the surface of the glass substrate. Structure 15 After completion, the test piece was observed by electron microscopy (SEM), and it was found that the carbon nanotubes were deposited on the surface of the porous metal layer of the glass substrate (as shown in Fig. 2). Powder anode plate combination package, the anode and cathode intermediate separator thickness is 160 μιη, and the electric field strength of the power supply is above 2 丫^ claws, and the bright illuminating effect is visible (as shown in Fig. 3). 20 Example 2·· Preparation Porous gold/nano-graphite field emission cathode plate This embodiment is substantially the same as the step of the embodiment, except that the present embodiment uses zinc to form a porous metal layer by thermal spray coating, and further uses nano graphite. a piece of dispersed aqueous solution (generally containing nanographite sheets · 25 2~0.01g/L, Anionic surfactant such as SOS: 2〇~〇〇5g/L, 201025415 This example uses 1 g/L nanographite sheet and 7 g/L of SDS). This test piece is the same as described in Example 1. In combination with the anode plate coated with phosphor powder, the electric field strength at the power supply is above 3 ν/μηι, and the bright illuminating effect is visible (as shown in Fig. 4). 5 Example 3: Preparation of copper metal substrate _Nylon diamond field emission cathode plate First, the copper substrate test piece is sandblasted to roughen the surface, and then the substrate test piece is immersed in a temperature of 50 to 70. (: Surface modification solution (1 〇 wt %) , Continue to dip for 1 to 3 minutes, remove and rinse the surface of the substrate with deionized water. Next, the substrate 10 is immersed in an aqueous solution of dispersed nano-diamonds (generally containing nanodiamonds: 2 to O. Olg / L, and anionic surfactants such as SDS: 2 〇 ~ 〇〇 5 g / L, this embodiment) For example, use 1 g / 1 of nano diamond, and 4 § / 1 of 81) 8, temperature 3 〇〇 c) about 3 to 5 minutes 'wait the substrate surface solution in the oven 450 below it evaporation' The rice diamond naturally forms a thin layer structure on the surface of the substrate. 15 Combine the test piece with the anode plate coated with phosphor powder. The electric field strength of the power supply is above 5v^m, and the bright light effect can be seen (as shown in Figure 5). Comparative Example 20 First, a metal (iron, copper, aluminum, ruthenium substrate) test piece was anodized to polish the surface thereof, and then the metal test piece was immersed in the surface modification solution (1 〇 wt%) 'temperature 50 to 70 °C 'Immerse for 1 to 3 minutes, remove and rinse the surface of the substrate with deionized water. Then, the substrate is immersed in an aqueous solution of the dispersed nano carbon material (the composition of the nano carbon material impregnation solution can be the same as in any of the embodiments 1 to 3). The time is 3 to 5 minutes 12 201025415 minutes, and the metal test piece is placed. After drying the solution on the surface of the metal substrate at room temperature (or below 450 ° C in an oven), the surface of the substrate naturally forms a thin layer of nano carbon material. In addition, the test piece is packaged with the anode plate coated with the phosphor powder, and the electric field intensity is above 5 ν/μιη in the power supply, and only the sparse illumination bright spot is 5 ❸ 10 15 Ο 20 (as shown in Fig. 6). BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing the flow of a field emission cathode of the present invention. 2 is a SEM image of a carbon nanotube deposition field emission cathode plate according to Embodiment 1 of the present invention. FIG. 3 is a view showing an assembly of a carbon nanotube field emission cathode plate and a coated phosphor powder anode plate of Embodiment 1 of the present invention after a voltage is applied. Light up. Fig. 4 is a view showing the case where the assembly of the nanographite field emission cathode plate and the coated phosphor powder anode plate of Embodiment 2 of the present invention is applied with a voltage. Fig. 5 is a view showing the case where the assembly of the nano-diamond field emission cathode plate and the coated phosphor powder anode plate of Embodiment 3 of the present invention is applied with a voltage. Fig. 6 shows a case where the assembly of the metal substrate-nanocarbon tube field emission cathode plate and the coated phosphor powder anode plate in the comparative example of the present invention is applied with a voltage. [Main component symbol description] None 13