1338539 九、發明說明 【發明所屬之技術領域】 本發明是關於可撓性電路基板，特別是關於有高柔 軟性又得以低價來進行製造之可撓性電路基板。 【先前技術】 可撓性電路基板大多的使用目的是利用其柔軟性以 及易彎度的特性，而以側面形狀彎折成u形狀或α型來 組裝到小型資訊機器（行動電話、數位照相機、數位攝 影機、筆記型電腦、硬碟驅動器、光學驅動器等）的可 動部，一面使其動態彎折一面供應訊號或電力。 然則，隨著小型資訊機器的輕薄小型化，基板的組 裝空間也跟著狹小化，彎折成U形狀或α型來組裝到可 動部之可撓性電路基板的曲率半徑也進行小徑化。 此外，小型資訊機器中，持有可撓性電路基板之可 動要件的驅動源大多有馬達，不過爲了要演進爲輕薄小 型化•低耗電力化，已有更加把馬達小型化的傾向。這 種小型馬達其優點是不但小型又是低耗電量，不過驅動 扭力本身也大多變小。 再則用於可動部的可撓性電路基板主要是用彎曲性 優良的單面配線構造，不過近年由於隨著小型資訊機器 的輕薄小型化、多功能化而提高配線密度，因此也對用 於可動部的可撓性電路基板，要求兩面配線構造。這樣 會使可撓性電路基板的彎折性劣化。 -5- 1338539 另外，兩面都有配線構造的兩面型可撓性電路基板 ，爲了要把兩面配線間導電連接，一般是利用NC鑽床、 沖床、雷射、電漿蝕刻、化學蝕刻等的手段在銅箔疊層 板鑽開通孔（through hole )或是非通孔（盲孔），再在 所開口的導通孔以及銅箔疊層板的全面形成電鍍披膜之 所謂形成以全板電鑛法來連接之層間導電路的方法。 但是，由於不只是層間導通部就連彎折部的銅箔也 都厚膜化，電路基板全體的剛性（stiffness )提高而造成 彎折性更加惡化《也就是用於小型資訊機器的可動部之 可撓性電路基板，爲了要求把該彎曲半徑更加縮小就必 須有更大的驅動力，現狀上就會因小型化的結果而減少 馬達的扭力。 然而過去的可撓性電路基板仍存有柔軟性不足而無 法達成所必要足夠的彎折性之問題。 爲了解決這個問題，過去的手法是採用如第2圖所 示，在於要求彎折的電路部分，通孔不披覆電鍍而只在 通孔部施加15〜20/zm厚左右的電鍍之所謂的部分電鍍法 。該第2圖中，圖號1表示可撓性絕緣薄膜，圖號2表 不黏接劑，圖號3表示銅箱，圖號4表示以部分電鍍法 所形成的層間導通電鍍披膜。 【發明內容】 (發明所欲解決之課題） 如第2圖所示’用部分電鍍法時，製造成本會升高 -6 - 1338539 層來把感光性 抗蝕膜的曝光 配線圖案，再 製程。因此比 造成本非常高 本之可撓性電 在不損及可撓 可信度下，以 性電路基板， 兩面，利用黏 電路配線圖案 電路基板，其 5~27ppm / °C 薄膜上，利用 ί前述層間導電 F的鑛銅層。 。也就是部分電鍍法是經過利用印刷或疊 的電鍍抗蝕膜形成在銅箔上後，施行電鍍 製程、顯像製程、固化過程，之後形成銅 進行電鑛抗蝕膜的脫膜製程等之一連串的 通常的全板電鍍法更耗費成本，而造成製 〇 此外市場上對於既是低剛性且是低成 路基板的要求愈加強烈而必須採取對策。 本發明鑑於上述的問題點，其目的是 性電路基板之兩面電路配線圖案間的導通 低成本來提供低剛性的可撓性電路基板。 (用以解決課題之手段） 爲了達成本發明，本發明是提供可撓 而針對在既是可撓性又有絕緣性之基材的 接層來設置銅箔，再在形成在該銅箔上之 的彼此間形成層間導電路之兩面型可撓性 特徵爲：前述電路基板是在熱膨脹係數爲 的範圍，厚度爲25;/m以下的可撓性絕緣 厚度爲0.3〜9/zm的黏接層來黏接銅箔， 路爲以全板電鍍法所形成之厚度9"m以一 【發明效果】 本發明由於構成上是用CTE 20ppm/°C以下的可擦 1338539 性絕緣薄膜且是把所使用黏接劑的厚度、銅箔以及電鑛 層的厚度抑制在一定以下’因而能提供既滿足對小型資 訊機器所要求的低剛性又是低成本的可撓性電路基板。 這結果能對資訊機器的小型化、低耗電化、多功能化以 及低成本化都有所貢獻。 【實施方式】 Φ 參考第1圖來說明本發明的一個實施例子。第1圖 爲表示本發明之可撓性電路基板的剖面，在可撓性絕緣 薄膜1的兩面設置黏接劑層2並在該上面配置銅箔3，再 經由全板電鍍設置電鍍薄膜4來作爲最外層。 構造上的特徵： 用於本發明的可撓性絕緣薄膜列舉有聚醯亞胺、聚 醯胺、液晶聚合物等。另外黏接劑則有環氧樹脂類、酚 醛樹脂類、丙烯酸樹脂類、醯亞胺樹脂類、醯亞胺醯胺 • 類等，最好是環氧樹脂類、醯亞胺樹脂類。 然且，爲了減小尺寸變化的絕對値，選擇5〜27ppm /°C的範圍，最好是選擇10〜20ppm/°C的範圍，來作爲 可撓性絕緣性薄膜的熱膨脹係數（C TE )，且把黏接劑層 的厚度抑制較薄，爲0.3〜9//m。 因此，先施加冷熱負荷來觀察尺寸變化時，能把厚 度（可撓性絕緣薄膜+黏接劑）之尺寸變化的絕對値減 小。然後確認了即使把通孔或盲孔之電鑛層的厚度減到 比過去的電鍍層的厚度更薄，仍能確保與過去的電路基 1338539 板同等的導通可信度。 · 再則用熱膨脹係數（CTE)爲15〜18ppm/t：的範圍 之絕緣性薄膜，則能更加抑制零件插裝時等，加諸溫度 變化時之可撓性電路基板的尺寸變化而更加適用。 另外把黏接劑層的厚度設成3〜7//m，由於可撓性電 路基板的低剛性化而更加理想。 製程上的特徵： 銅箔疊層板用的黏接劑，由於用熱硬化性的黏接劑 ，因而不必用高溫疊層機設備就能在低溫下進行處理。 即是製造達到足夠的耐熱性，例如得到銲錫耐熱性或耐 逆流性來作爲可撓性電路基板之際，若適用熱可塑性的 黏接劑時則不必可升溫到所必要的30(TC以上的高溫疊層 機設備，就能在常溫下塗上黏接劑，以及能在1 〇〇°C左右 的低溫下進行熱滾壓疊層。 因此也能把疊層時所產生之絕緣薄膜與銅箔之尺寸 變化的差或翹起抑制到很小。再則熱硬化性黏接劑大多 比熱可塑性黏接劑還低價；另外用熱硬化性黏接劑能經 由整批來熱硬化，因而能提高銅箔疊層板或是可撓性電 路基板的生產性以及能實現低成本化。 把銅箔厚度設成14/zm以下而可以達到可撓性電路 基板的更低剛性化，也有助於提高NC鑽孔加工或雷射力口 工時的生產性。 再則把可撓性絕緣薄膜或黏接劑的厚度變薄也達到 低剛性化，對於提高NC鑽孔加工或雷射加工時的生產性 -9- 1338539 的層面也有所助益。 . 因此取代爲了低剛性化而造成高成本的部分電鍍’ 改而不但能用低成本的全板電鍍’由於能把電鍍層的本 身厚度變薄，因而也提高全板電鍍的生產性。 (實施例1 ) 構造： Φ 本發明的一個實施例子之構造如下所述。首先在基 材1也就是在12.5 //m厚度的聚醯亞胺薄膜（熱膨脹係 數16ppm/°C、阿丕卡爾NPI)上的兩面塗上厚的 環氧樹脂類的黏接劑並加以烘乾’再經由熱滾壓來對其 兩面疊層1 2 β m厚度的銅箔後’用熱烤箱進行黏接劑的 ' 固化來製造銅箔疊層板。經由NC鑽孔在這銅箱疊層板上 鑽開pO.3mm的孔後，以通孔電鍍來進行厚度的的 銅箔全板電鍍。 Φ 相對於此，過去的構造如以下所述。在25/zm厚度 的聚醯亞胺薄膜（熱膨脹係數26ppm/°C、卡普敦H) 的兩面塗上10# m厚的環氧樹脂類的黏接劑並加以烘乾 ，再經由熱滾壓來對其兩面疊層18#m厚度的銅箔後’ 用熱烤箱來進行黏接劑的固化並製造銅箔疊層板。經由 NC鑽孔在這銅箔疊層板上鑽開P 〇.3mm的孔後’以通孔 電鍍來進行15;/ m厚度的銅箔全板電鍍。 測試結果： -10- 1338539 之環路剛性 的可信度， 進行100循環 ”具有與過去 利用本發明，經由成爲剛性指標的一種 測試所得到的値爲過去構造的1 / 4以下。 另外爲了確認利用本發明所形成之通孔 經由冷熱衝擊測試而在- 6 5 °C與1 2 5 °C之間 。其結果：電阻變化率爲20%以內，確認7 的電路基板同等的所必要充足的連接可信度 【圖式簡單說明】 的剖面構造 剖面構造之 第1圖爲表示本發明之可撓性電路基板 之說明圖。 第2圖爲表示過去的可撓性電路基板的 說明圖。 【主要元件符號說明】 1 基材 2 黏接劑層 3 銅箔 4 層間導電路 5 可撓性絕緣薄膜 6 黏接層 7 銅箔 8 鍍銅層 -11 -[1] [Technical Field] The present invention relates to a flexible circuit board, and more particularly to a flexible circuit board which is manufactured at a low cost and which is highly flexible. [Prior Art] A flexible circuit board is often used for small information machines (mobile phones, digital cameras, digital devices) by bending the side shape into a u shape or an α shape by utilizing its flexibility and flexibility. The movable part of a camera, a notebook computer, a hard disk drive, an optical drive, etc., is supplied with a signal or power while being dynamically bent. However, with the miniaturization and miniaturization of the small information device, the assembly space of the substrate is also narrowed, and the radius of curvature of the flexible circuit board that is bent into the U shape or the α type and assembled to the movable portion is also reduced in diameter. In addition, in a small information machine, a motor having a movable element of a flexible circuit board is often provided with a motor. However, in order to be thinner and lighter, and to reduce power consumption, the motor has become smaller. The advantage of this small motor is that it is not only small but also low in power consumption, but the driving torque itself is mostly small. In addition, the flexible circuit board used for the movable portion is mainly a single-sided wiring structure having excellent flexibility. However, in recent years, the size of the small information device has been reduced in size and size, and the wiring density has been increased. The flexible circuit board of the movable portion requires a double-sided wiring structure. This deteriorates the bendability of the flexible circuit board. -5- 1338539 In addition, a two-sided flexible circuit board having a wiring structure on both sides, in order to electrically connect the wiring between the two sides, generally uses an NC drilling machine, a punch, a laser, a plasma etching, a chemical etching, or the like. The copper foil laminate is drilled through holes or non-through holes (blind holes), and then the entire surface of the open via holes and the copper foil laminate is formed by electroplating. A method of connecting interlayer conduction circuits. However, since the copper foil of the bent portion is not thicker than the interlayer conduction portion, the rigidity of the entire circuit board is improved, and the bending property is further deteriorated, that is, the movable portion for a small information machine. In order to reduce the bending radius, the flexible circuit board requires a larger driving force, and the torque of the motor is reduced as a result of miniaturization. However, in the past, the flexible circuit board still has a problem that the flexibility is insufficient and the necessary bending property is not obtained. In order to solve this problem, the conventional method is to use a circuit portion that requires bending as shown in Fig. 2, the through hole is not coated with plating, and only a plating of about 15 to 20/zm thick is applied to the through hole portion. Partial plating method. In Fig. 2, reference numeral 1 denotes a flexible insulating film, Fig. 2 shows an adhesive, Fig. 3 shows a copper case, and Fig. 4 shows an interlayer conduction plating film formed by a partial plating method. SUMMARY OF THE INVENTION (Problems to be Solved by the Invention) As shown in Fig. 2, when the partial plating method is used, the manufacturing cost is increased by -6 - 1338539 layers, and the exposed wiring pattern of the photosensitive resist film is reprocessed. Therefore, on the 5~27ppm / °C film, the flexible circuit is used to make the flexible circuit without damage to the flexible reliability. The aforementioned copper layer of conductive F between the layers. . That is, the partial plating method is a series of processes such as performing a plating process, a developing process, and a curing process after forming a copper foil on a copper foil by using a printed or stacked plating resist film, and then forming a copper stripping process for forming an electric ore resist film. The usual full-plate plating method is more costly, and in addition to the market, there is a need to take countermeasures against the demand for both low rigidity and low-circuit substrates. The present invention has been made in view of the above problems, and an object thereof is to provide a flexible circuit board having low rigidity at a low cost by conduction between two circuit wiring patterns on a circuit board. (Means for Solving the Problems) In order to attain the present invention, the present invention provides a copper foil which is flexible and is provided for a bonding layer which is a flexible and insulating substrate, and is formed on the copper foil. The two-sided flexible structure forming the interlayer conducting circuit between each other is characterized in that the circuit substrate is an adhesive layer having a flexible insulating thickness of 0.3 to 9/zm in a range of a thermal expansion coefficient and a thickness of 25 Å/m or less. To bond the copper foil, the thickness is 9"m formed by the full-plate plating method. [Inventive effect] The present invention is composed of a CEE 20ppm/°C or less erasable 1338539 insulating film and is a The thickness of the adhesive, the thickness of the copper foil and the electric ore layer are suppressed to be lower than certain, and thus it is possible to provide a flexible circuit substrate which satisfies both the low rigidity and the low cost required for a small information machine. This result can contribute to the miniaturization, low power consumption, multi-function, and cost reduction of information equipment. [Embodiment] Φ An embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a cross-sectional view showing a flexible circuit board of the present invention, in which an adhesive layer 2 is provided on both surfaces of a flexible insulating film 1, and a copper foil 3 is placed thereon, and a plating film 4 is provided by full-plate plating. As the outermost layer. Structural Features: The flexible insulating film used in the present invention is exemplified by polyimine, polyamine, liquid crystal polymer and the like. Further, the adhesive is an epoxy resin, a phenol resin, an acrylic resin, a quinone imine resin, a quinone imide or the like, and is preferably an epoxy resin or a quinone imine resin. However, in order to reduce the absolute enthalpy of the dimensional change, a range of 5 to 27 ppm / ° C is selected, preferably a range of 10 to 20 ppm / ° C is selected as the thermal expansion coefficient (C TE ) of the flexible insulating film. And the thickness of the adhesive layer is suppressed to be thin, and is 0.3 to 9 / / m. Therefore, when the temperature change is first applied to observe the dimensional change, the absolute thickness of the thickness (flexible insulating film + adhesive) can be reduced. It was then confirmed that even if the thickness of the electric ore layer of the through hole or the blind hole was reduced to be thinner than the thickness of the past plating layer, the same conduction reliability as that of the conventional circuit substrate 1338539 was ensured. In addition, when an insulating film having a coefficient of thermal expansion (CTE) of 15 to 18 ppm/t: is used, it is possible to further suppress the dimensional change of the flexible circuit board when the component is inserted, and the temperature is more suitable. . Further, the thickness of the adhesive layer is set to 3 to 7 / / m, which is more preferable because of the low rigidity of the flexible circuit board. Characteristics of the process: The adhesive for the copper foil laminate is treated with a thermosetting adhesive, so that it can be processed at a low temperature without using a high-temperature laminator. In other words, when the heat resistance is sufficient, for example, solder heat resistance or backflow resistance is obtained as the flexible circuit board, if a thermoplastic adhesive is applied, it is not necessary to raise the temperature to 30 (TC or more). The high-temperature laminating machine can apply the adhesive at normal temperature and can be laminated by hot rolling at a low temperature of about 1 ° C. Therefore, the insulating film and copper foil which are produced during lamination can also be used. The difference in dimensional change or the lift resistance is suppressed to a small extent. Further, the thermosetting adhesive is mostly lower than the thermoplastic adhesive; in addition, the thermosetting adhesive can be thermally hardened by the entire batch, thereby improving Copper foil laminated board or flexible circuit board can be produced and can be reduced in cost. When the thickness of the copper foil is 14/zm or less, the rigidity of the flexible circuit board can be reduced and the number of the flexible circuit board can be improved. The productivity of NC drilling or laser working hours. The thickness of the flexible insulating film or adhesive is also reduced to a low rigidity, which improves the production of NC drilling or laser processing. The level of sex-9- 1338539 also has It is therefore helpful to replace the high-cost part of the plating for low rigidity, not only to use low-cost full-plate plating, but also to improve the thickness of the plating layer itself, thereby improving the productivity of full-plate plating. (Example 1) Structure: Φ The structure of an embodiment of the present invention is as follows. First, a polyimide film having a thickness of 12.5 //m at a substrate 1 (thermal expansion coefficient of 16 ppm/°C, aunt) On both sides of Karl NPI), apply a thick epoxy resin adhesive and dry it. Then, by hot rolling, laminate the copper foil with a thickness of 1 2 β m on both sides, and then bond it with a hot oven. The 'curing of the agent' is used to manufacture a copper foil laminate. After drilling a hole of pO.3 mm through the NC hole, the copper plate is plated by a through hole to perform full thickness plating of the copper foil. Here, the past structure is as follows. 10# m thick epoxy resin adhesive is applied on both sides of a 25/zm thick polyimide film (thermal expansion coefficient: 26 ppm/° C., Kapudun H). After the agent is baked and then laminated by hot rolling to the copper foil of 18#m thickness on both sides Hot oven to cure the adhesive and make a copper foil laminate. After drilling a hole of P 〇.3mm on the copper foil laminate through NC drilling, 'pass-hole plating is performed for 15; / m thickness Copper foil full-plate plating. Test results: -10- 1338539 The reliability of the loop rigidity, 100 cycles" has the past structure of the past using the present invention, which is obtained by a test that becomes a rigid index. In addition, in order to confirm that the through hole formed by the present invention is between -65 ° C and 1 25 ° C via the thermal shock test, the result is that the resistance change rate is within 20%, and the circuit of 7 is confirmed. (1) The cross-sectional structure of the cross-sectional structure of the present invention is an explanatory view showing the flexible circuit board of the present invention. Fig. 2 is an explanatory view showing a conventional flexible circuit board. [Main component symbol description] 1 Substrate 2 Adhesive layer 3 Copper foil 4 Interlayer conductive circuit 5 Flexible insulating film 6 Adhesive layer 7 Copper foil 8 Copper plating layer -11 -