201206332 六、發明說明： 【發明所屬之技術領域】 [0001] 本發明涉及電路板技術，特別涉及一種柔性電路板及其 製作方法。 【先前技術】 [0002] 隨著折疊手機與滑蓋手機等可折疊數位產品不斷發展， 具有輕、薄、短、小以及可彎折特點之柔性印刷電路板 (Flexible Printed Circuit B0ard，FPCB)被廣泛 應用於數位產品，以實現不同電路間之電性連接。隨著 ^ 消費性數位產品功能日益強大，提升柔性電路板之電磁 遮罩性能成為目前電路板技術領域研究之重要課題之— [0003] ❹ 柔性電路板通常於導電圖形遠離絕緣層之—側形成用於 保護導電圖形之覆蓋層。一種常用避免電磁干擾之方法 為藉由印刷方式於所述覆蓋廣上形成—層導電油墨（如 ，銀漿油墨）層，並使該導電油墨層填充覆蓋層中之開 口，從而電連接於導電圖形之接地線。惟，藉由印刷方 式形成之導電油墨層之厚度範圍通常為8_15以肌，一方面 ’引發電磁干擾之高頻電流具有集膚效應，：得電流僅面 作用於導電油墨層表面極淺約零點幾微米之厚度，如此 ，大量導電油墨將被浪費；另-方面，該導電:墨層之 厚度較大導致其耐折性*佳，於進行折#組裝時，即， 使柔性電路板之撓折部進行料以將Μ性電路板安裳 於數位裝置，會㈣龜裂現象L導電油墨層不能 有效地遮罩電磁干擾。為_上㈣題，出現—種可藉 099123586 表單編號Α0101 第3頁/共22頁 0992041544-0 201206332 由壓合結合於柔性電路板之電磁波防護膜，其包括依次 堆疊之導電黏接層、金屬遮罩層與基底膜層。該電磁波 防護膜之金屬遮罩層藉由導電黏接層與柔性電路板之導 電圖形之接地線電連接。惟，貼附該電磁波防護膜對柔 性電路板之製作工藝要求較高。不同型號之電磁波防護 膜之壓合該防護膜之溫度、壓力等參數直接關係到導電 黏接層之導電粒子之破裂狀況及其與接地線間之接觸面 積，若壓合參數控制不當，該電磁波防護膜難以起到預 期之電磁遮罩效果。 【發明内容】 [0004] 有鑑於此，提供一種柔性電路板及其製作方法，以於不 影響柔性電路板之撓折性之情況下提高柔性電路板之電 磁遮罩性能實屬必要。 [0005] 一種柔性電路板，包括絕緣層、形成於絕緣層之導電圖 形、覆蓋導電圖形之覆蓋層與連續之金屬濺鍍層。所述 導電圖形包括接地線與訊號傳輸線。所述覆蓋層具有通 孔，用於暴露至少部分接地線。所述金屬濺鍍層藉由濺 鍍形成於覆蓋層遠離導電圖形之表面、通孔之孔壁以及 從通孔露出之接地線之表面，從而與所述接地線電性連 接。 [0006] 一種柔性電路板之製作方法，包括步驟：提供柔性覆銅 板，其包括絕緣層與貼合於所述絕緣層之導電層；將所 述導電層製成導電圖形，所述導電圖形包括接地線與訊 號傳輸線；形成覆蓋所述導電圖形之覆蓋層，所述覆蓋 層具有通孔，所述接地線至少部分暴露於所述通孔；以 099123586 表單編號A0101 第4頁/共22頁 0992041544-0 201206332 及藉由濺鍍於所述覆蓋層遠離導電圖形之表面、通孔之 孔壁以及從通孔露出之接地線之表面形成連續之金屬賤 鍍層，所述金屬濺鍍層與所述接地線電性連接。 闕本技術讀提供之柔性電路板之製作方法㈣性覆銅板 上製作導電圖案並形成覆蓋膜以保護所述導電圖案，再 藉由低溫真空濺鍍於所述覆蓋膜上形成電性連接於導電 圖案之接地線之金屬濺鍍層。所述金屬濺鍍層厚度小、 節省原材料，而且與柔性電路板之間附著力強，不易發 生龜裂，有利於提南柔性電路板之電磁遮罩性能。 【實施方式】 [0008] 下面將結合附圖及複數實施例對本技術方案提供之柔性 電路板及其製作方法作進一步詳細說明。 [0009] 請參閱圖1，本技術方案第一實施例提供一種柔性電路板 1〇〇，其包括絕緣層11、導電圖形120、覆蓋層13〇與金 屬藏鍵層140。所述柔性電路板loo.可包括複數依次排列 之柔性電路板單元15。 [0010] 所述絕緣層11可為聚酯（PET)薄膜或聚醯亞胺（ρι )薄 [0011] 所述導電圖形I20形成於所述絕緣層11。所述導電圖形 120之材質可為銅，其包括接地線121與訊號傳輸線122 。本實施例中，所述接地線121與訊號傳輪線122均為長 條形，且並排設置。每一接地線121均具有位於其中心處 之連接部123。 [0012] 099123586 戶斤述覆蓋層130覆蓋所述導電圖形120 表單煸號A0101 第5頁/共22頁 所述覆蓋層130 0992041544-0 201206332 具有第一表面131、第二表面132、側面133與第三表面 134。所述第一表面131遠離所述絕緣層11。所述第三表 面134與所述絕緣層11相接觸。所述第二表面132與側面 133均與所述導電圖形120相接觸。所述第二表面132位 於所述第一表面131與第三表面134之間，且平行於所述 第一表面131。所述側面133連接於所述第二表面132與 第三表面134之間。所述覆蓋層130還具有貫穿所述第一 表面131與第二表面132之通孔135。所述通孔135具有連 接於所述第一表面131與第二表面132之間之孔壁136。 所述接地線121部分暴露於所述通孔135。具體地，所述 接地線121之連接部123暴露於所述通孔135。 [0013] 當然，所述通孔135亦可更大，使得所述接地線121全部 暴露於所述通孔135，如此，所述覆蓋層130不具有平行 於所述第一表面131且與所述導電圖形120相接觸之第二 表面132，所述側面133亦與孔壁136於同一平面上。 [0014] 所述金屬濺鍍層140藉由漱鍍形成於覆蓋層130遠離導電 圖形120之表面、通孔135之孔壁136以及從通孔135露出 之接地線121之表面，從而與所述接地線121電性連接。 所述金屬濺鍍層可為銅、銀、鉻或鋁等導電金屬材質， 其厚度範圍為0. 3-0. 5/zin。本實施例中，由於所述金屬 濺鍍層之厚度小於所述覆蓋層130之厚度，所述金屬濺鍍 層140依次覆蓋所述覆蓋層130之第一表面131、所述孔 壁136、所述接地線121之連接部123。 [0015] 本技術方案第一實施例提供之柔性電路板之金屬濺鍍層 厚度小，可節省大量原材料。 099123586 表單編號A0101 第6頁/共22頁 0992041544-0 201206332 [0016] [0017] [0018] Ο [0019]Ο 本技術方案第—實施例提供__種柔性電路板之製作方法 ，其包括以下步驟： 第一步，st參閱圖2 ’提供柔性覆銅板10，其包括絕緣層 11與貼合於所述絕緣層u之導電層12。所述絕緣層⑽ 為聚sa ( PET )薄骐或聚醯亞胺（⑴薄膜。所述柔性覆 銅板10包括複數依次排列之產品區1〇1。 第一步，明併參閱圖3與圖4,將所述導電層12製成導 電圖形12G，所述導電圖形120包括接地線121與訊號傳 輸線122 °本實施例中’所述導電圖形120於每-產品區 101中均包括一根接地線121與兩根訊號傳輸線122，每 -接地線121均具有位於其中心處之連接部123。具體地 ’可先於所述導電層12上形成光致抗飯劑層 ，再經曝光 、顯影、㈣等工藝去除所述導電層12之部分導電材料 ，剩餘部分導電材料即形成導電圖形12〇。 第三步，請一併參閱圖5與圖6，形成覆蓋所述導電圖形 120之覆蓋層130 ’所述覆蓋層13〇具有通孔135 ,所述接 地線121至少部分暴露於所述通孔135。具體地，可採取 以下步驟· [0020] 首先，提供覆蓋膜13，所述覆蓋膜丨3可包括膠黏層與絕 緣膜層，其具有相對之第一表面131與第二表面132。 [0021] 其次，藉由鑽孔或沖孔方式於覆蓋膜13中形成貫穿所述 第一表面131與第二表面132之通孔135。所述通孔135之 數量及位置均與所述接地線121之連接部123相對應，大 小與所述接地線121之連接部123相對應。每一通孔135 0992041544-0 099123586 201206332 均具有連接於所述第一表面131與第二表面132之間之孔 壁 136。 [0022] 最後，使所述第二表面132靠近所述導電圖形120，將通 孔135對準所述接地線121之連接部123，將所述覆蓋膜 1 3壓合於所述柔性覆銅板1 0之導電圖形1 2 0之一侧，即於 所述柔性覆銅板10上形成一覆蓋層130。先使覆蓋膜13之 膠黏層之一側靠近所述柔性覆銅板10，並使所述複數通 孔135與所述多根接地線121之連接部123相對，將所述 覆蓋膜13貼附於所述柔性覆銅板10得到堆疊板，再將上 述堆疊板放至壓合機内進行壓合。壓合時，覆蓋膜13受 熱發生流動，填充導電圖形120中之空隙，形成與所述絕 緣層11相接觸之第三表面134，以及連接於所述第二表面 132與第三表面134之間之側面133。 [0023] 第四步，請一併參閱圖1與圖7，藉由濺鍍於所述覆蓋層 130遠離導電圖形120之表面、通孔135之孔壁136以及從 通孔135露出之接地線121之表面形成金屬濺鍍層140， 所述金屬濺鍍層140與所述接地線121電性連接。 [0024] 具體地，可包括以下步驟： [0025] 首先，提供真空濺鍍裝置200與金屬靶材。所述真空濺鍍 裝置200包括相對設置之陰極201與陽極202。所述真空 濺鍍裝置200還包括鍍膜腔體203、溫度控制器204、抽 真空裝置205與供氣裝置2 06。所述金屬靶材可為高熔點 之金屬、合金或金屬氧化物。本實施例中，所述金屬乾 材之材質為銀。 099123586 表單編號A0101 第8頁/共22頁 0992041544-0 201206332 [0026] 其次，將所述金屬靶材設置於所述真空濺鍍裝置200之陰 極201。使所述柔性覆銅板10之覆蓋層130與陰極201相 對’將所述柔性覆鋼板10設置於所述真空濺鍍裝置200之 陽極202。 [0027] 再次’對所述真空濺鍍裝置2〇〇抽真空並預熱，充入惰性 氣體後’於所述陰極201與陽極202之間施加高壓直流電 ’以於所述柔性覆銅板10靠近覆蓋層130之一側形成與所 述接地線121電性連接之金屬濺鍍層140。本實施例中， 〇 ❹ 藉由抽真空骏置205對鍍膜腔體203抽真空至壓強約為 1.3x10 Pa ’藉由溫度控制器2〇4預熱至温度約為60°C 。藉由供氣裝置206往鍍膜腔想203内充入氬氣後’由於 輝光放電（glow discharge)...產生之.數位激發或氣’產 生等離子體’等離子體將金屬靶材之原子轟出，沈積於 所述柔性覆鋼板10靠近覆蓋層130之一侧，直至沈積於所 述柔性覆銅板1〇之原子之厚度達到〇. 3-0. 5/zm時，停止 施加電壓，得到如圖1所示之柔性電路板100。金屬靶材 之原子於等離子體之轟擊下，自金屬“材之表面向各個 方向濺射出來，從而所得之柔性覆銅板1〇上’即使覆蓋 膜13之通孔135之孔壁136及其與所述接地線121之連接 處均可均勻之沈積上一層銀原子。由於引起電磁干擾之 高頻電流具有集膚效應，厚度為0.3-0· 5βηι之金屬減鍍 層140即可實現遮罩電磁干擾。藉由低溫真空濺鍍形成之 所述金屬濺鍍層14〇不僅厚度小、節省原材料，而且與柔 性電路板100間附著力強，不易發生龜裂，有利於提高柔 性電路板100之電磁遮罩性能。 099123586 表單編號A0101 第9頁/共22頁 0992041544-0 201206332 mi Μ五步’裁切所述柔性電路板_，得 — 之柔性電路板單元15。如此，即可使 如圖s所不 μ“ 之用柔性電路板單元 衷於餘1^，以實職㈣《之傳輪與處理。 [_當然，上述第五步亦邛於第三步與第四步之間u ，於形成覆蓋所述導電圖形120之覆蓋層1·^二 切所述柔性覆銅板10得到複數柔性雷 扳早元15,再將 =生電路板單元15移至真空賤鍍袭置2。0内進行鍵膜以形 成金屬濺鍍層140。 [0030] 本技術方案提供之柔《路叙製作方法於雜覆銅板 上製作導電圖案並形成覆蓋—保護所述導電圖案再 藉由低溫真空_於所述m形成金屬麟層。所 述金屬麟層厚度小、節省原材料，而且與柔性電路板 之間附著力強，不易發生龜裂’有利於提高柔性電路板 之電磁遮罩性能。 [_綜上所述，本發明確已符合發明專利之要件，遂依法提 出專利申請。惟，以上所述者僅為本發明之較佳實施方 式’自不能以此限制本案之申請專利範圍。舉凡熟悉本 案技在之人錢依本發明之精神所作之等效修飾或變化 ，皆應涵蓋於以下申請專利範圍内。 【圖式簡單說明】 [0032]圖1為本技術方案第一眘# γ 1 _ 茶弟實％例提供之柔性電路板之部分剖 面示意圖。 [0033] 圖2為本技術方案第二實麵i提供之錄Μ板之部分結 構示意圖。 099123586 表單編號Α0101 第10頁/共22頁 0992043544-0 201206332 [0034] 圖3為於上述柔性覆銅板上形成導電圖案後之部分結構示 [0035] 意圖。 圖4為圖3沿IV-IV線之剖面示意圖。 [0036] 圖5為將覆蓋膜貼附於所述柔性覆銅板之結構示意圖。 ； [0037] 圖6為形成有覆蓋層之柔性覆銅板之部分刮面示意圖。 [0038] 圖7為本技術方案第二提供之真空濺鍍裝置之結構示意圖 〇 Q [0039] 圖8為裁切圖1所示之柔性電路板後所得一柔性電路板單 元之剖面示意圖。 [0040] 【主要元件符號說明】 柔性覆銅板：10 [0041] 絕緣層：11 [0042] 導電層：12 [0043] 導電圖形：120 - 〇 闺 接地線：121 [0045] 訊號傳輸線：122 [0046] 連接部：123 [0047] 覆蓋膜：13 [0048] 覆蓋層：130 [0049] 第一表面：131 [0050] 099123586 第二表面：132 表單編號A0101 第11頁/共22頁 09! 0992041544-0 099123586 第11頁/共22頁 201206332 [0051] 侧面：133 [0052] 第三表面：134 [0053] 通孔：135 [0054] 孔壁：136 [0055] 金屬滅鑛層：140 [0056] 柔性電路板單元：15 [0057] 柔性電路板：100 [0058] 產品區：101 [0059] 真空濺鍍裝置：200 [0060] 陰極：201 [0061] 陽極：2 02 [0062] 鍍膜腔體：203 [0063] 溫度控制器：204 [0064] 抽真空裝置：205 [0065] 供氣裝置：206 099123586 表單編號A0101 第12頁/共22頁 0992041544-0201206332 VI. Description of the Invention: [Technical Field] The present invention relates to circuit board technology, and in particular to a flexible circuit board and a method of fabricating the same. [Prior Art] [0002] With the development of foldable digital products such as folding mobile phones and slider phones, flexible printed circuit boards (FPCBs) with light, thin, short, small and bendable characteristics are Widely used in digital products to achieve electrical connection between different circuits. With the increasing power of consumer digital products, improving the electromagnetic mask performance of flexible circuit boards has become an important topic in the field of circuit board technology. [0003] 柔性 Flexible circuit boards are usually formed on the side of the conductive pattern away from the insulating layer. A cover layer for protecting conductive patterns. A common method for avoiding electromagnetic interference is to form a layer of conductive ink (eg, silver paste ink) on the cover by printing, and fill the opening in the cover layer with the conductive ink layer to electrically connect to the conductive The ground wire of the graphic. However, the thickness of the conductive ink layer formed by printing is generally 8-15 in the muscle, and on the one hand, the high-frequency current causing electromagnetic interference has a skin effect, and the current is only applied to the surface of the conductive ink layer to be extremely shallow at about zero. a thickness of a few microns, so that a large amount of conductive ink will be wasted; on the other hand, the conductivity: the thickness of the ink layer is large, resulting in its folding resistance * good, when the assembly is folded, that is, the flexible circuit board is scratched The folded portion is materialized to mount the inert circuit board on the digital device, and the (four) cracking phenomenon L conductive ink layer cannot effectively shield the electromagnetic interference. For _上(四) questions, appear - can borrow 099123586 Form No. 1010101 Page 3 / Total 22 Page 0992041544-0 201206332 Electromagnetic wave shielding film bonded to flexible circuit board by pressing, including conductive bonding layer and metal stacked in sequence The mask layer and the base film layer. The metal mask layer of the electromagnetic wave shielding film is electrically connected to the ground line of the conductive pattern of the flexible circuit board by the conductive adhesive layer. However, attaching the electromagnetic wave shielding film requires a high manufacturing process for the flexible circuit board. The parameters such as the temperature and pressure of the electromagnetic wave protective film of different types of the protective film are directly related to the rupture condition of the conductive particles of the conductive adhesive layer and the contact area with the grounding wire. If the pressing parameter is improperly controlled, the electromagnetic wave The protective film is difficult to achieve the desired electromagnetic shielding effect. SUMMARY OF THE INVENTION [0004] In view of the above, a flexible circuit board and a method of fabricating the same are provided to improve the electromagnetic mask performance of a flexible circuit board without affecting the flexibility of the flexible circuit board. [0005] A flexible circuit board comprising an insulating layer, a conductive pattern formed on the insulating layer, a cover layer covering the conductive pattern, and a continuous metal sputter layer. The conductive pattern includes a ground line and a signal transmission line. The cover layer has a through hole for exposing at least a portion of the ground line. The metal sputter layer is formed by sputtering on a surface of the cover layer away from the conductive pattern, a hole wall of the through hole, and a surface of the ground line exposed from the through hole, thereby being electrically connected to the ground line. [0006] A method for fabricating a flexible circuit board, comprising the steps of: providing a flexible copper clad laminate comprising an insulating layer and a conductive layer bonded to the insulating layer; forming the conductive layer into a conductive pattern, the conductive pattern comprising a ground line and a signal transmission line; forming a cover layer covering the conductive pattern, the cover layer having a through hole, the ground line being at least partially exposed to the through hole; and 099123586 Form No. A0101 Page 4 / Total 22 Page 0992041544 -0 201206332 and forming a continuous metal ruthenium plating by sputtering a surface of the cover layer away from the surface of the conductive pattern, a hole wall of the through hole, and a ground line exposed from the through hole, the metal sputter layer and the ground Wire electrical connection. The manufacturing method of the flexible circuit board provided by the technical reading (4) is to form a conductive pattern on the copper clad plate and form a cover film to protect the conductive pattern, and then electrically connected to the conductive film by low temperature vacuum sputtering on the cover film. The metal sputter of the ground wire of the pattern. The metal sputter layer has small thickness, saves raw materials, and has strong adhesion to the flexible circuit board, and is not easy to crack, which is beneficial to the electromagnetic shielding performance of the smart circuit board of the South. [Embodiment] The flexible circuit board provided by the present technical solution and the manufacturing method thereof will be further described in detail below with reference to the accompanying drawings and the embodiments. Referring to FIG. 1, a first embodiment of the present technical solution provides a flexible circuit board 1B including an insulating layer 11, a conductive pattern 120, a cover layer 13 and a metal bond layer 140. The flexible circuit board loo. may include a plurality of flexible circuit board units 15 arranged in sequence. [0010] The insulating layer 11 may be a polyester (PET) film or a polyimide (ρι) thin [0011] The conductive pattern I20 is formed on the insulating layer 11. The material of the conductive pattern 120 may be copper, which includes a ground line 121 and a signal transmission line 122. In this embodiment, the grounding wire 121 and the signal transmission line 122 are both elongated and arranged side by side. Each of the grounding wires 121 has a connecting portion 123 at its center. [0012] 099123586 The cover layer 130 covers the conductive pattern 120 Form No. A0101 Page 5 / Total 22 The cover layer 130 0992041544-0 201206332 has a first surface 131, a second surface 132, a side 133 and Third surface 134. The first surface 131 is away from the insulating layer 11. The third surface 134 is in contact with the insulating layer 11. Both the second surface 132 and the side surface 133 are in contact with the conductive pattern 120. The second surface 132 is located between the first surface 131 and the third surface 134 and is parallel to the first surface 131. The side 133 is coupled between the second surface 132 and the third surface 134. The cover layer 130 also has a through hole 135 penetrating the first surface 131 and the second surface 132. The through hole 135 has a hole wall 136 connected between the first surface 131 and the second surface 132. The ground line 121 is partially exposed to the through hole 135. Specifically, the connection portion 123 of the ground line 121 is exposed to the through hole 135. [0013] Of course, the through hole 135 may also be larger, so that the grounding wire 121 is entirely exposed to the through hole 135, such that the cover layer 130 does not have parallel to the first surface 131 and The second surface 132 in contact with the conductive pattern 120 is also in the same plane as the hole wall 136. [0014] The metal sputter layer 140 is formed on the surface of the cap layer 130 away from the conductive pattern 120, the hole wall 136 of the through hole 135, and the surface of the ground line 121 exposed from the through hole 135 by ruthenium plating, thereby being grounded The wire 121 is electrically connected. 5/zin。 The metal sputter layer may be a copper, silver, chrome or aluminum conductive metal material, the thickness of the range of 0. 3-0. 5 / zin. In this embodiment, since the thickness of the metal sputter layer is less than the thickness of the cover layer 130, the metal sputter layer 140 sequentially covers the first surface 131 of the cover layer 130, the hole wall 136, and the ground. The connection portion 123 of the line 121. [0015] The metal sputter layer of the flexible circuit board provided by the first embodiment of the present invention has a small thickness and can save a large amount of raw materials. 099123586 Form No. A0101 Page 6 / Total 22 Page 0992041544-0 201206332 [0018] [0019] [0019] The first embodiment of the present invention provides a method for manufacturing a flexible circuit board, which includes the following Step: First, st, referring to FIG. 2, provides a flexible copper clad laminate 10 comprising an insulating layer 11 and a conductive layer 12 bonded to the insulating layer u. The insulating layer (10) is a poly sa (PET) thin crucible or a polyimine (1) film. The flexible copper clad laminate 10 includes a plurality of product regions arranged in sequence. The first step is as shown in FIG. 3 and 4. The conductive layer 12 is formed into a conductive pattern 12G. The conductive pattern 120 includes a ground line 121 and a signal transmission line 122. In the embodiment, the conductive pattern 120 includes a ground in each of the product areas 101. The line 121 and the two signal transmission lines 122 each have a connection portion 123 at the center thereof. Specifically, a photo-resistance layer can be formed on the conductive layer 12, and then exposed and developed. (4) and the like process to remove a portion of the conductive material of the conductive layer 12, and the remaining conductive material forms a conductive pattern 12A. In the third step, please refer to FIG. 5 and FIG. 6 to form a cover layer covering the conductive pattern 120. 130' The cover layer 13 has a through hole 135, and the ground line 121 is at least partially exposed to the through hole 135. Specifically, the following steps may be taken. [0020] First, a cover film 13 is provided, the cover film丨3 may include an adhesive layer and an insulating film layer, The second surface 131 and the second surface 132 are formed in the cover film 13 by drilling or punching. The number and position of the through holes 135 correspond to the connecting portion 123 of the grounding wire 121, and the size corresponds to the connecting portion 123 of the grounding wire 121. Each of the through holes 135 0992041544-0 099123586 201206332 has a connection The hole wall 136 between the first surface 131 and the second surface 132. [0022] Finally, the second surface 132 is brought close to the conductive pattern 120, and the through hole 135 is aligned with the connection portion 123 of the ground line 121. The cover film 13 is pressed against one side of the conductive pattern 120 of the flexible copper clad plate 10, that is, a cover layer 130 is formed on the flexible copper clad plate 10. The glue of the cover film 13 is first used. One side of the adhesive layer is adjacent to the flexible copper clad laminate 10, and the plurality of through holes 135 are opposite to the connecting portion 123 of the plurality of grounding wires 121, and the cover film 13 is attached to the flexible copper clad laminate 10. The stacked plates are obtained, and the stacked plates are placed in a press machine for pressing. The cover film 13 is heated to flow, filling a void in the conductive pattern 120, forming a third surface 134 in contact with the insulating layer 11, and a side surface 133 connected between the second surface 132 and the third surface 134. [0023] In the fourth step, please refer to FIG. 1 and FIG. 7 together, by sputtering the surface of the cover layer 130 away from the conductive pattern 120, the hole wall 136 of the through hole 135, and the ground line exposed from the through hole 135. A metal sputter layer 140 is formed on the surface of the surface 121, and the metal sputter layer 140 is electrically connected to the ground line 121. [0024] Specifically, the following steps may be included: [0025] First, a vacuum sputtering apparatus 200 and a metal target are provided. The vacuum sputtering apparatus 200 includes a cathode 201 and an anode 202 disposed opposite each other. The vacuum sputtering apparatus 200 further includes a coating chamber 203, a temperature controller 204, a vacuuming device 205, and a gas supply unit 206. The metal target may be a high melting point metal, alloy or metal oxide. In this embodiment, the material of the metal dry material is silver. 099123586 Form No. A0101 Page 8 of 22 0992041544-0 201206332 [0026] Next, the metal target is placed on the cathode 201 of the vacuum sputtering apparatus 200. The cover layer 130 of the flexible copper clad laminate 10 is opposed to the cathode 201. The flexible clad steel sheet 10 is placed on the anode 202 of the vacuum sputtering apparatus 200. [0027] Again, the vacuum sputtering device 2 is evacuated and preheated, and after the inert gas is charged, 'high voltage direct current is applied between the cathode 201 and the anode 202' to allow the flexible copper clad plate 10 to approach. One side of the cover layer 130 forms a metal sputter layer 140 electrically connected to the ground line 121. In this embodiment, the coating chamber 203 is evacuated to a pressure of about 1.3 x 10 Pa ' by a vacuum chamber 205 to be preheated by a temperature controller 2 to 4 to a temperature of about 60 ° C. After the argon gas is filled into the coating chamber by the gas supply device 206, the atom of the metal target is ejected by the digital discharge or the gas generated by the glow discharge. Deposited on the side of the flexible coated steel sheet 10 near the cover layer 130 until the thickness of the atoms deposited on the flexible copper clad laminate reaches 3. 3-0. 5 / zm, stop applying voltage, and obtain the figure A flexible circuit board 100 as shown in FIG. The atoms of the metal target are sputtered from the surface of the metal material in various directions under the bombardment of the plasma, so that the obtained flexible copper clad plate is turned on, even if the hole wall 136 of the through hole 135 of the cover film 13 and its The connection of the grounding wire 121 can uniformly deposit a layer of silver atoms. Since the high-frequency current causing electromagnetic interference has a skin effect, the metal plating layer 140 having a thickness of 0.3-0·5βηι can realize the electromagnetic interference of the mask. The metal sputter layer 14 formed by low-temperature vacuum sputtering not only has a small thickness, saves raw materials, but also has strong adhesion to the flexible circuit board 100, is less prone to cracking, and is advantageous for improving the electromagnetic mask of the flexible circuit board 100. Performance. 099123586 Form No. A0101 Page 9 of 22 0992041544-0 201206332 mi Μ Five steps 'cut the flexible circuit board _, get the flexible circuit board unit 15. So, you can make the figure s The "flexible circuit board unit for μ" is dedicated to the remaining 1^, to the actual (4) "transfer and processing. [_ Of course, the fifth step is also between the third step and the fourth step. In the formation of the cover layer covering the conductive pattern 120, the flexible copper clad laminate 10 is obtained to obtain a plurality of flexible lightning rods. In the element 15, the green board unit 15 is moved to a vacuum ruthenium plating device to perform a key film to form a metal sputtering layer 140. [0030] The flexible method provided by the technical solution forms a conductive pattern on the copper clad laminate and forms a cover—protecting the conductive pattern and forming a metal lining layer by the low temperature vacuum. The metal lining layer has a small thickness, saves raw materials, and has strong adhesion to the flexible circuit board, and is less prone to cracking, which is advantageous for improving the electromagnetic shielding performance of the flexible circuit board. [_ In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application according to law. However, the above description is only a preferred embodiment of the present invention, which is not intended to limit the scope of the patent application of the present invention. Equivalent modifications or variations made by those skilled in the art in light of the spirit of the invention are intended to be included within the scope of the following claims. BRIEF DESCRIPTION OF THE DRAWINGS [0032] FIG. 1 is a partial cross-sectional view showing a flexible circuit board provided by a first example of the technical solution of the first caution # γ 1 _ tea brother. [0033] FIG. 2 is a schematic diagram showing a part of a structure of a recording board provided by a second solid surface i of the present technical solution. 099123586 Form No. Α0101 Page 10 of 22 0992043544-0 201206332 [0034] FIG. 3 is a partial structural view showing the formation of a conductive pattern on the above flexible copper clad laminate. Figure 4 is a cross-sectional view of Figure 3 taken along line IV-IV. [0036] FIG. 5 is a schematic view showing the structure of attaching a cover film to the flexible copper clad laminate. [0037] FIG. 6 is a partial schematic view of a scraped surface of a flexible copper clad laminate formed with a cover layer. 7 is a schematic structural view of a vacuum sputtering apparatus according to a second aspect of the present invention. FIG. 8 is a schematic cross-sectional view showing a flexible circuit board unit obtained by cutting the flexible circuit board shown in FIG. 1. [Description of main component symbols] Flexible copper clad laminate: 10 [0041] Insulation layer: 11 [0042] Conductive layer: 12 [0043] Conductive pattern: 120 - 〇闺 Ground wire: 121 [0045] Signal transmission line: 122 [ 0046] Connection: 123 [0047] Cover film: 13 [0048] Cover: 130 [0049] First surface: 131 [0050] 099123586 Second surface: 132 Form number A0101 Page 11 of 22 09! 0992041544 -0 099123586 Page 11 of 22 201206332 [0051] Side: 133 [0052] Third surface: 134 [0053] Through hole: 135 [0054] Hole wall: 136 [0055] Metal mine layer: 140 [0056] Flexible Circuit Board Unit: 15 [0057] Flexible Circuit Board: 100 [0058] Product Area: 101 [0059] Vacuum Sputtering Device: 200 [0060] Cathode: 201 [0061] Anode: 2 02 [0062] Coating Cavity : 203 [0063] Temperature controller: 204 [0064] Vacuuming device: 205 [0065] Gas supply device: 206 099123586 Form number A0101 Page 12 of 22 0992041544-0