六、新型說明： 【新型所屬之技術領域】 本新型與一種軟性印刷電路板（flexible printed circuit board, FPC)有關。具體言之，其係關於一種先形 成孔後形成電路佈線(trace)的軟性印刷電路板。 【先前技術】 軟性印刷電路板(flexible printed circuit board，FPC) 具有可撓、質輕、體積小、配線密度高、及可依照產品 需求改變形狀等優點，能有效節省空間讓電子產品得以 朝輕薄短小的方向發展。由於上述優點，軟性印刷電路 板多應用在筆記型電腦、數位相機、手機等可攜式資訊 產品、通訊產品及消費性電子產品上。 傳統的軟性電路板製作方式係先在一軟性銅箔基層 板(flexible copper clad laminate，FCCL)上形成電路佈線 圖形(pattern)後再施以鑽孔步驟在層板上形成連接各層 的孔，之後該些孔會再施以電鍍製程在其内側壁形成導 電層以使各層之電路佈線互連(interc〇nnect)。此傳統的 電路板製作方式有習知的缺點存在。其一，軟性銅箔基 層板主要由一層軟性基板(如聚亞醯胺ρι、聚對苯二曱 一乙鲇PET等材質）與一層壓延銅箔（rolled annealed，RA C〇Pper)或是電鍍銅箔（electro- deposited，ED copper)構 成，其間以接著劑相黏（如環氧樹脂epoxy或丙烯酸樹脂 acrylic)。在孔製作期間，已形成電路圖形之銅箔易受到 鑽孔動作損壞或是與軟性基板脫附，使其結構破壞。其 二，所鑽出之孔於形成後尚需進行電鍍製程，以於孔的 内側壁鍍上導電層，此舉無疑增加了整體製程所需步Sixth, the new description: [New technical field] The new type is related to a flexible printed circuit board (FPC). Specifically, it relates to a flexible printed circuit board in which a circuit trace is formed after forming a hole. [Prior Art] Flexible printed circuit board (FPC) has the advantages of flexibility, light weight, small size, high wiring density, and shape change according to product requirements, which can effectively save space and make electronic products lighter and thinner. Development in a short direction. Due to the above advantages, flexible printed circuit boards are widely used in portable information products, communication products and consumer electronic products such as notebook computers, digital cameras, and mobile phones. The conventional flexible circuit board is formed by first forming a circuit wiring pattern on a flexible copper clad laminate (FCCL) and then applying a drilling step to form a hole connecting the layers on the layer board, after which The holes are then subjected to an electroplating process to form a conductive layer on the inner sidewall thereof to interconnect the circuit wirings of the layers. This conventional circuit board fabrication method has conventional shortcomings. First, the soft copper foil base plate is mainly composed of a soft substrate (such as polyamidamine ρι, polyparaphenylene ruthenium ruthenium PET, etc.) and a laminated annealed (RA C〇Pper) or electroplated. It is composed of an electro- deposited (ED copper) adhesive with an adhesive (such as epoxy epoxy or acrylic). During the fabrication of the hole, the copper foil on which the circuit pattern has been formed is easily damaged by the drilling operation or desorbed from the flexible substrate to cause structural damage. Second, after the hole is drilled, an electroplating process is required to plate the inner side wall of the hole with a conductive layer, which undoubtedly increases the steps required for the overall process.
是以，現今軟性電 何增加電路板成品的可靠有不少缺點，如 前業者亟待克服之難^度及化其相_程，誠為目 【新型内容】 本新型之目的在於提供一 =，其結構中利用介面層讓 =’並在該導電層的基礎上再形 作為軟性印刷魏板的魏佈線。 生層 路板=型二構目中》:::供-種新穎的軟性印刷電 成”、、線在軟性基板上形 的軟性印刷ί i=方η;露了-種新穎 ::板包含‘·：軟性基板，其上設置m匕卩:ι 日形成在该軟性基板表面的電路佈線巴域;1 内側壁上;-導電層，形成在==該;少 導電增生層，形成在該導電層上。 面層上，及- 步二作板製作方*, 孔;在該軟性基板的上下表=以=-彳 上-層介A6層；在齡面層域上—層金上錢 用防焊材覆蓋在該導電金屬層上的非佑:’、使 圖形;在未被該防焊材覆蓋的該導體t = 錢上一層導電金屬增生層；將該’曰上 防焊材覆蓋之非電路佈線輯上的導 先該 :原先該防焊材覆蓋之非電路佈線區域上= 9 在參閱下述詳細的實施方式及相關的圖示與申請專 利範圍後，閱者將更能了解本新型其他的目的、特徵、 及優點。 【實施方式】 本新型播除了傳統軟性印刷電路板製作中先形成電 路佈線(trace)後鑽出孔之作法，於形成電路佈線前先鑽 出孔’此作法可避免習知技術中鑽孔動作造成軟性基板 中的電路佈線損壞或是與軟性基板脫附之問題，並〇簡 化整體製程所需之步驟、解決黃光微影製程所造成之^ 差、減少製程廢棄物的產生’同時可製作出厚度更薄、 孔獲更小的軟性印刷電路板。 以下將進行本新型具體實施例之說明。須注意，所 揭示的實施例僅在於列舉說明。本新型之範疇並未限制 在其所揭露包含特定特徵、結構、或性質的具體實施例 中’而係由文後所附的申請專利範圍所界定。此外，說 明書中所參照之圖示並未具體描繪出所有本新型不必 要之特徵，且所描纟會出之元件可能以簡化、示意之方式 來表達，圖示中各類元件的尺寸可能為說明之便而加以 誇大或不符合實際比例。不論上述之簡略為何，或是相 關特徵是否有被詳盡描述，其皆意表所描述者係位於相 關領域中熟習該項技藝之人士可據以連同其他與該等 特徵、結構或性質相關的其他具體實施例來實施之知識 範脅内。 睛參照第一圖’其為本新型軟性印刷電路板結構之 示意圖。如圖所示’首先本新型中會提供一軟性基板100 來作為軟性印刷電路板之基底。在一實施例中，該軟性 基板可用聚亞醯胺(polyimide，PI)、聚對苯二甲二 5 乙酉旨（polyethylene terephthalate，PET)、聚對萘二甲酸乙 二醋（polyethylene naphthalate，PEN)、聚丙稀 (polypropylene，PP)、聚謎石風(Polyethersulfone，PES)、 聚次苯基醚艰（Polyphenylene Sulfone，PPSU)、聚苯口惡 唾共聚合物（Poly-p-phenylenebenzobisox azole，PBO)、 液晶聚合物(Liquid Crystal Polymer，LCP)等材質形成， 其厚度可能介於10〜30μιη之間。軟性基板100上會利用 鑽孔製程在預先定義的位置處鑽出孔102,作為該軟性 印刷電路板中各層的互連結構，如鍍通孔(plated through hole)、導通孔（via)、盲孔(blind via)、及埋孔(buried via) 等結構’其功能可能包含供電子元件之引腳插銲，或是 讓電路板各層間電性導通，因此，孔1〇2之結構可為貫 穿通孔或非貫穿凹孔。在實施例中，雷射鑽孔機或機械 鑽孔機可用來在軟性基板100上預先定義之位置鑽出一 個以上的孔102。視孔102分佈的密度及後續的鍍膜製 私而疋’其孔控可介於100-25Oum之間。 接著請參照第二圖，其為本新型軟性印刷電路板結 構之示意圖。在孔102形成後，軟性基板1〇()的表面及 孔102的内側壁上會形成一層金屬層作為軟性基板100 與電路佈線之間的介面層104以增加兩者間的接著強 度。舉例言之，本新型可採用濺鍍製程(sputter)在軟性 基板100表面及孔102内側壁上形成介面層1〇4。採用 濺鍍製程將可製得厚度較薄之介面層104,其厚度約介 於10〜30nm之間，達成基板薄型化之目的。該介面層 104之材質可能為鎳鉻合金(NiCr)、氧化鋅（ZnO)、鈦 (Τι)、及鉻(〇)等’其中以鎳鉻合金為佳。 接著請參照第三圖，其為本新型軟性印刷電路板結 構之示意圖。在介面層1〇4形成後，該介面層1〇4表面 M383270 9 的導電層106,作為後續形成負責傳導電子訊號的導電 增生層之基礎。舉例言之，本新型可利用濺鍍製程在介 面，故導電層106可以穩固地鍍覆在軟性基板10〇上。Therefore, today's soft power has increased the reliability of the finished circuit board. There are many shortcomings, such as the difficulties that the predecessors need to overcome and the phase of the process. The purpose of this new model is to provide a =, In its structure, the interface layer is used to make =' and on the basis of the conductive layer, it is shaped as a Wei wiring of a soft printed Wei board. Raw layer road plate = type two configuration "::: for a novel soft printed electricity", the line on the soft substrate shaped soft printing ί i = square η; exposed - novel:: board contains '·: a flexible substrate on which m匕卩: ι is formed on the surface of the circuit board of the flexible substrate; 1 on the inner side wall; - a conductive layer formed at ==; a less conductive accretion layer formed in the On the conductive layer, on the surface layer, and - the second step is made in the plate *, the hole; on the upper surface of the flexible substrate = = - 彳 - - layer A6 layer; on the age layer - layer of gold on the money Covering the conductive metal layer with a solder resist material: ', making a pattern; the conductor t = money not covered by the solder resist material; a layer of conductive metal accelerating layer; The non-circuit wiring on the first part of the circuit: the original non-circuit wiring area covered by the solder mask = 9 See the following detailed implementation and related diagrams and patent claims, the reader will be better able to understand Other objects, features, and advantages of the present invention. [Embodiment] The present invention first forms a power in the production of a conventional flexible printed circuit board. After the trace is drilled, the hole is drilled before the circuit wiring is formed. This method can avoid the damage of the circuit wiring in the flexible substrate or the debonding of the flexible substrate caused by the drilling operation in the prior art. And simplifies the steps required for the overall process, solves the problem caused by the yellow lithography process, and reduces the generation of process waste. At the same time, it can produce a soft printed circuit board with a thinner thickness and a smaller hole. The description of the novel embodiments is intended to be illustrative, and is not intended to limit the scope of the specific embodiments disclosed herein. The accompanying drawings are defined by the scope of the claims, and the descriptions of the drawings are not specifically described, and the elements described herein may be described in a simplified and schematic manner. The dimensions of the various components shown may be exaggerated or not in proportion to the actual description. Regardless of the above, or whether the relevant features are The detailed description is intended to be within the scope of the teachings of those skilled in the art in the field of <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; Figure 1 is a schematic view showing the structure of a novel flexible printed circuit board. As shown in the figure, first, a flexible substrate 100 is provided as a base of a flexible printed circuit board. In an embodiment, the flexible substrate can be gathered. Polyimide (PI), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polypropylene (PP), poly mystery Polyethersulfone (PES), Polyphenylene Sulfone (PPSU), Poly-p-phenylenebenzobisoxazole (PBO), Liquid Crystal Polymer (LCP) When the material is formed, the thickness may be between 10 and 30 μm. A hole 102 is drilled in the flexible substrate 100 at a predetermined position by using a drilling process as an interconnection structure of layers in the flexible printed circuit board, such as a plated through hole, a via, and a blind. Structures such as blind vias and buried vias may have functions such as soldering the leads of the electronic components or electrically connecting the layers of the board. Therefore, the structure of the holes 1〇2 may be Through or through the recess. In an embodiment, a laser drill or mechanical drill can be used to drill more than one hole 102 in a predetermined location on the flexible substrate 100. The density of the distribution of the viewing holes 102 and the subsequent coating process are 疋', and the hole control can be between 100-25 Oum. Next, please refer to the second figure, which is a schematic diagram of the structure of the novel flexible printed circuit board. After the hole 102 is formed, a metal layer is formed on the surface of the flexible substrate 1 and the inner sidewall of the hole 102 as the interface layer 104 between the flexible substrate 100 and the circuit wiring to increase the bonding strength therebetween. For example, the present invention can form an interface layer 1〇4 on the surface of the flexible substrate 100 and the inner sidewall of the hole 102 by using a sputtering process. By using a sputtering process, a thinner interface layer 104 having a thickness of about 10 to 30 nm can be obtained to achieve a thinner substrate. The material of the interface layer 104 may be nickel-chromium alloy (NiCr), zinc oxide (ZnO), titanium (Τι), and chromium (〇), etc. Among them, a nickel-chromium alloy is preferred. Next, please refer to the third figure, which is a schematic diagram of the structure of the novel flexible printed circuit board. After the formation of the interface layer 1〇4, the conductive layer 106 of the interface layer 1〇4 surface M383270 9 serves as the basis for the subsequent formation of a conductive accretion layer responsible for conducting electronic signals. For example, the present invention can utilize a sputtering process on the interface, so that the conductive layer 106 can be stably plated on the flexible substrate 10A.
接著凊參照第四圖，其為本新型軟性印刷電路板結 構之示意圖。在導電層106形成後，該導電層106上預 先定義的區域可以形成一層防焊材（Peelable s〇lder mask)108來作為後續鑛膜步驟之防鍍層。舉例言之，本 新型可在該導電層106表面的非電路佈線區域上選擇性 印上一層具有可剝除性(peelable)的防焊材1〇8 ’在導電 層106上形成預定的電路佈線圖形(pattern)。該防焊材 108可為環氧樹脂(Ep0Xy)、丙烯酸樹脂(Acryiate)、石夕氧 烷化物（Siloxane)、及感光油墨等金屬無法鍍覆於苴上之 材質。Next, referring to the fourth figure, it is a schematic diagram of the structure of the novel flexible printed circuit board. After the conductive layer 106 is formed, a pre-defined area on the conductive layer 106 may form a layer of a solder mask 108 as an anti-plating layer for the subsequent filming step. For example, the present invention can selectively form a peelable solder resist 1'8' on the non-circuit wiring area on the surface of the conductive layer 106 to form a predetermined circuit wiring on the conductive layer 106. Pattern. The solder resist 108 may be made of a material such as an epoxy resin (Ep0Xy), an acrylic resin (Acryiate), a siloxane, or a photosensitive ink which cannot be plated on the crucible.
年月曰、IT補充贷 (包含軟性基板100表面及孔102内側壁）會形成一層薄 面層104上快速形成厚度介於7〇〜ΐ〇〇ηιη之間的薄導電 層106。該導電層之材質最好為銅(Cu)。由於導電層1〇6 與軟性基板1〇〇之間有介面層1〇4作為兩者間的接著介 接著請參照第五圖，其為本新型軟性印刷電路板結 構之示意圖。在防焊材1〇8形成後，導電層1〇6上未受 該防焊材108覆蓋之區域（包含孔1〇2的内側壁）會形成 一層導電增生層110,作為軟性印刷電路板主要的電路 佈線部位。舉例言之，本新型可對整片軟性基板施以電 鍍製程(electroplating)，此時未受該防焊材1〇8覆蓋之導 電層106上可鍍上一層導電增生層11〇，而受防焊材1〇8 覆蓋之區域會因為防焊材108的阻擋緣故而不會被鍍上 導電增生層110。該導電增生層11〇的材質最好與導電 層106的材質相同，且以銅(Cu)為佳。藉由電鍍之方式， 該導電增生層110的厚度可達3〜12μηι，遠大於以濺鍍 7 辦·修正一 年月^補充- 製程形成的導電層106。如圖所示，位於軟性基板1〇〇 上下表面的導電增生層可藉由孔1G2導通，所形成的導 電增生層110即為該軟性印刷電路板的電路佈線。 接著請參照$六® ’其為本新型軟性印刷電路板結 構之示意圖。在形成導電增生層11〇後，該可剝除性的 防焊材108可直接從導電層1〇6上剝除或利用簡單的溶 劑洗掉，以裸露th其下方未有導電增生層形成的導電層 106(即軟性印刷電路板的非電路佈線區）。此時由於整個 軟性電路表面仍附有具導電性的導電層1〇6及介面層 104，所形成的電路佈線（即導電增生層11〇)彼此間仍會 呈短路狀態，故須於後續製程中移除該非電路佈線區域 上具導電性的導電層106與介面層1〇4。 接著請參照第七圖，其為本新型軟性印刷電路板結 構之示意圖三在防焊材1〇8移除後，導電層1〇6原先為 防焊材所覆蓋之區域會使用餘刻液體來移除，裸露出該 些區域下方的介面層104。舉例言之，本新型中可採用 將整片軟性基板100浸入硫酸、鹽酸等蝕刻液中之方式 讓軟性基板的所有表面區域（包含作為電路佈線的導電 增生層110與裸露出的導電層106)都受蝕。由於本新型 中所形成的導電增生層110厚度（約介於3〜12μηι)遠大於 導電層106(約介於70〜l〇〇nm)，且兩者材質相同。故在 相同的蝕刻速率下，本新型可控制蝕刻的時間來移除裸 露出來的導電層同時保留已形成的導電增生層11〇。 接f請參照第八圖，其為本新型軟性印刷電路板結 構之示意圖。在非電路佈線區的導電層1〇6移除後，^ 下層的介面層104會裸露出來，為使所形成的電路佈線 不互相短路，5玄非電路佈線區的介面層會被移除。舉例 言之，本新型中可採用將整片軟性基板100浸入硫酸、 9! >· 4. 2 9 倐止； ^年月日 補充f 鹽酸等㈣m之+或是採用電㈣财^讓軟性基板 的所有表面區域（包含作為電路佈線的導電增生層11〇 與裸路出的介面層1〇4)都受姓。由於本新型中所形成的 導電增生層110厚度（約介於3〜12μιη)遠大於介面層 約介於10〜30nm)’故本新型可控制钱刻的時間來移 除裸露出來的介面層1G4同時㈣已形成的導電增生層 U〇。該非電路佈線區的介面層1〇4被移除後會露出其 下方的軟性基板100本體，使所形成的電路佈線不互相 短路。 文中所述之實施例與圖說係供予閱者，俾其對於本 新j各不同實施例結構有通盤性的瞭解。在不f障離本新 型範疇的情況下，新型中可以進行結構與邏輯的置換盥 改變。據此，本新型之揭露與圖式理視為描述而非限希; 性質，並將由下文中的申請專利範圍來限制。 【圖式簡單說明】 參閱後續的圖式與描述將可更了解本新型的系统及 方法。文中未詳列暨非限制性之實施例則請參考 圖式H圖式中的組成元件並不—定芯t弋 係以強調的方式描繪出本新型的原理。在圖式中，相同 的元件係於不同圖示中標出相同對應之部分。 第一圖描繪出根據本新型實施例一軟性印刷電路板 結構之示意圖； 第二圖描繪出根據本新型實施例一軟性印刷電路板 結構之示意圖； 第三圖描繪出根據本新型實施例一軟性印刷電路板 結構之示意圖； 第四圖描繪出根據本新型實施例一軟性印刷電路板 嫩&S.2牙㊁修正 年月曰補充曼 結構之不意圖， 第五圖描繪出根據本新型實施例一軟性印刷電路板 結構之不意圖， 第六圖描繪出根據本新型實施例一軟性印刷電路板 結構之不意圖， 第七圖描繪出根據本新型實施例一軟性印刷電路板 結構之不意圖，及 第八圖描繪出根據本新型實施例一軟性印刷電路板 結構之不意圖， 【主要元件符號說明】 100 軟性基板 102 104 介面層 106 導電層 108 防焊材 110 導電增生層 10The thin layer, the IT replenishment loan (including the surface of the flexible substrate 100 and the inner sidewall of the hole 102) forms a thin conductive layer 106 on the thin surface layer 104 to rapidly form a thickness between 7 Å and ΐ〇〇 ηηη. The material of the conductive layer is preferably copper (Cu). Since the conductive layer 1〇6 and the flexible substrate 1〇〇 have an interface layer 1〇4 as a follow-up between them, please refer to the fifth figure, which is a schematic diagram of the structure of the novel flexible printed circuit board. After the solder resist 1 〇 8 is formed, the region of the conductive layer 1 〇 6 not covered by the solder resist 108 (including the inner sidewall of the hole 1 〇 2) forms a conductive accelerating layer 110 as a flexible printed circuit board. Circuit wiring parts. For example, the present invention can apply an electroplating process to the entire flexible substrate, and the conductive layer 106 not covered by the solder resist 1 8 can be plated with a conductive accelerating layer 11 〇, and is protected. The area covered by the welding material 1〇8 will not be plated with the conductive accretion layer 110 due to the blocking of the solder resist 108. The material of the conductive accelerating layer 11A is preferably the same as that of the conductive layer 106, and copper (Cu) is preferred. By electroplating, the thickness of the conductive accelerating layer 110 can be up to 3~12μηι, which is much larger than that of the conductive layer 106 formed by the sputtering process. As shown in the figure, the conductive accelerating layer on the upper and lower surfaces of the flexible substrate 1b can be electrically connected through the hole 1G2, and the conductive accelerating layer 110 formed is the circuit wiring of the flexible printed circuit board. Next, please refer to $6®' for a schematic diagram of the structure of the new flexible printed circuit board. After the conductive accelerating layer 11 is formed, the strippable solder resist 108 can be directly stripped from the conductive layer 1〇6 or washed away with a simple solvent to expose the underlying conductive layer without the conductive layer. Conductive layer 106 (ie, a non-circuit wiring area of a flexible printed circuit board). At this time, since the conductive layer 1〇6 and the interface layer 104 are still attached to the surface of the entire flexible circuit, the formed circuit wiring (ie, the conductive accelerating layer 11〇) is still short-circuited with each other, and therefore needs to be processed in a subsequent process. The electrically conductive conductive layer 106 and the interface layer 1〇4 on the non-circuit wiring area are removed. Next, please refer to the seventh figure, which is a schematic diagram of the structure of the novel flexible printed circuit board. After the solder resist 1〇8 is removed, the conductive layer 1〇6 originally used for the area covered by the solder resist will use the residual liquid. Remove, exposing the interface layer 104 below the regions. For example, in the present invention, all of the surface regions of the flexible substrate (including the conductive accelerating layer 110 as a circuit wiring and the exposed conductive layer 106) may be immersed in an etching solution such as sulfuric acid or hydrochloric acid. Both are eroded. Since the thickness of the conductive accelerating layer 110 (about 3 to 12 μm) formed in the present invention is much larger than that of the conductive layer 106 (about 70 to 1 〇〇 nm), the materials are the same. Therefore, at the same etch rate, the present invention can control the etching time to remove the exposed conductive layer while retaining the formed conductive growth layer 11〇. Please refer to the eighth figure for the connection, which is a schematic diagram of the structure of the new flexible printed circuit board. After the conductive layer 1〇6 of the non-circuit wiring region is removed, the interface layer 104 of the lower layer is exposed. In order to prevent the formed circuit wiring from being short-circuited to each other, the interface layer of the 5 non-circuit wiring area is removed. For example, in the present invention, the entire flexible substrate 100 can be immersed in sulfuric acid, 9! >· 4. 2 9 ;; ^ year and month to add f hydrochloric acid, etc. (4) m + or use electricity (four) to make soft All surface areas of the substrate (including the conductive accelerating layer 11 电路 as a circuit wiring and the interface layer 1 〇 4 of the bare side) are subject to the surname. Since the thickness of the conductive accelerating layer 110 formed in the present invention (about 3 to 12 μm) is much larger than the interface layer is about 10 to 30 nm), the present invention can control the time of the engraving to remove the exposed interface layer 1G4. At the same time (4) the conductive accretion layer U〇 has been formed. The interface layer 1〇4 of the non-circuit wiring region is removed to expose the body of the flexible substrate 100 underneath, so that the formed circuit wirings are not short-circuited with each other. The embodiments and figures described herein are intended to be read by readers, and they have a general understanding of the structure of the various embodiments of the present invention. In the case of the new type of category, the new type can be replaced by structural and logical changes. Accordingly, the disclosure of the present invention is intended to be illustrative and not restrictive, and is limited by the scope of the claims. [Simple description of the drawings] The system and method of the present invention will be better understood by referring to the following drawings and descriptions. For the non-limiting examples in the text, please refer to the constituent elements in the schema of the diagram H. The core principle is not emphasized. The principle of the novel is drawn in an emphasized manner. In the drawings, the same elements are labeled in the different drawings. 1 is a schematic view showing a structure of a flexible printed circuit board according to an embodiment of the present invention; FIG. 2 is a schematic view showing a structure of a flexible printed circuit board according to an embodiment of the present invention; and FIG. 3 is a view showing a softness according to an embodiment of the present invention A schematic diagram of a printed circuit board structure; the fourth figure depicts a soft printed circuit board according to the embodiment of the present invention, and the second figure depicts the implementation of the structure according to the present invention. Example 1 is a schematic diagram of a flexible printed circuit board structure, a sixth drawing depicts a structure of a flexible printed circuit board according to an embodiment of the present invention, and a seventh drawing depicts a structure of a flexible printed circuit board according to an embodiment of the present invention. And the eighth drawing depicts a structure of a flexible printed circuit board according to the embodiment of the present invention. [Main component symbol description] 100 flexible substrate 102 104 interface layer 106 conductive layer 108 solder resist 110 conductive layer 10