201223378 六、發明說明 【發明所屬之技術領域】 本發明是有關多層可撓性印刷配線板及其製造方法， 更詳細是關於具有步進孔構造的多層可撓性印刷配線板及 其製造方法。 【先前技術】 近年來，電子機器的小型化及高機能化越來越進展。 隨之，對印刷配線板及被搭載於印刷配線板的零件之高密 度化的要求提高。特別是有關使用於攜帶型機器的封裝零 件，針腳數增加，且針腳間的窄間距化持續。另一方面， 對於印刷配線板，考量用以搭載封裝零件的配線規則及往 攜帶型機器的裝入，而要求薄型化。爲了使印刷配線板薄 型化，可考慮採用以聚醯氬胺薄膜等的可撓性絕緣基材作 爲起始材料的可撓性印刷配線板。 並且，以往有利於高密度安裝電子零件等的堆積 (Buildup)型多層可撓性印刷配線板爲人所知（參照專利文 獻1的圖15等）。此堆積型多層可撓性印刷配線板是以兩 面可撓性印刷配線板或多層可撓性印刷配線板作爲核心基 板（內層），在此核心基板的兩面或單面形成1〜2層程度的 堆積層（外層），藉此謀求可撓性印刷配線板的高密度化。 如上述般，堆積型多層可撓性印刷配線板是印刷配線 板的薄型化及高密度化的點有利。然而，其構造上，因爲 需要在內層也形成厚的電鍍層，所以難以使外層的配線微 -5- 201223378 細化。因此，難以搭載像晶片大小封裝（CSP : Chip Size Package)那樣多針腳且窄間距的封裝零件》 爲了解決此問題，有具有所謂步進孔構造的堆積型多 層可撓性印刷配線板爲人所知（參照專利文獻Γ的圖5及 圖9)。此印刷配線板的製造方法的槪略是如其次般。首 先，在成爲內層的核心基板上形成微細的配線，然後，在 核心基板層疊成爲外層的堆積層。然後，藉由雷射加工， 形成由大徑的上孔及小徑的下孔所構成的階段狀的步進孔 洞（二重孔）（參照專利文獻1的圖9(14))。然後，在此步進 孔洞的內壁（底面及側面）施以電鍍處理，藉此形成具有作 爲層間導電路機能的步進孔（參照專利文獻1的圖5及圖 9( 1 5))。藉由採用步進孔構造，可使外層的配線微細化， 因此可取得有利於多針腳且窄間距的封裝零件的搭載之多 層可撓性印刷配線板。 其次，利用圖7來說明有關具有以往的步進孔構造之 堆積型多層可撓性印刷配線板的構造及問題點。圖7( 1)是 多層可撓性印刷配線板的上面圖’圖7(2)是沿著圖7(1)的 A-A’線的剖面圖，圖7(3)是沿著圖7(1)的B-B’線的剖面 圖。 由圖7(1)、（2)及（3)可知’步進孔51A、51B、51C及 51D是具有圓形的上部層間導電路51a及圓形的下部層間 導電路5 1 b。上部層間導電路5 1 a是電性連接多層可撓性 印刷配線板的表面的平坦部5 2、及內層的平坦部5 3。另 一方面，下部層間導電路51b是電性連接多層可撓性印刷[Technical Field] The present invention relates to a multilayer flexible printed wiring board and a method of manufacturing the same, and more particularly to a multilayer flexible printed wiring board having a stepping hole structure and a method of manufacturing the same. [Prior Art] In recent years, miniaturization and high performance of electronic devices have progressed. As a result, there is an increasing demand for high density of printed wiring boards and components mounted on printed wiring boards. In particular, regarding the package parts used in portable machines, the number of stitches increases, and the narrow pitch between the stitches continues. On the other hand, in the case of a printed wiring board, the wiring rules for mounting the packaged parts and the loading of the portable device are considered, and the thickness is required. In order to reduce the thickness of the printed wiring board, a flexible printed wiring board using a flexible insulating base material such as a polyarylene nitride film as a starting material can be considered. In addition, a build-up type multilayer flexible printed wiring board which is advantageous for high-density mounting of electronic components and the like is known (refer to Fig. 15 of Patent Document 1 and the like). The stacked multi-layer flexible printed wiring board is a double-sided flexible printed wiring board or a multilayer flexible printed wiring board as a core substrate (inner layer), and one or two layers are formed on both sides or one side of the core substrate. The buildup layer (outer layer) is used to increase the density of the flexible printed wiring board. As described above, the stacked multi-layer flexible printed wiring board is advantageous in that the printed wiring board is made thinner and higher in density. However, in terms of its structure, since it is necessary to form a thick plating layer in the inner layer, it is difficult to refine the wiring of the outer layer. Therefore, it is difficult to mount a package component having a plurality of stitches and a narrow pitch like a chip size package (CSP: Chip Size Package). In order to solve this problem, a stacked multilayer flexible printed wiring board having a so-called step hole structure is used. It is known (refer to FIG. 5 and FIG. 9 of the patent document 。). The method of manufacturing the printed wiring board is as follows. First, fine wiring is formed on the core substrate which becomes the inner layer, and then the core substrate is laminated to form a buildup layer of the outer layer. Then, a stepped hole (double hole) composed of a large hole and a small hole having a small diameter is formed by laser processing (see Fig. 9 (14) of Patent Document 1). Then, the inner wall (bottom surface and side surface) of the stepping hole is subjected to a plating process to form a stepping hole having the function as an interlayer conducting circuit (see Figs. 5 and 9 (15) of Patent Document 1). By adopting the stepping hole structure, the wiring of the outer layer can be made finer, and therefore, a multi-layer flexible printed wiring board in which a package component which is advantageous for a plurality of stitches and has a narrow pitch can be obtained. Next, the structure and problems of the stacked multilayer flexible printed wiring board having the conventional stepping hole structure will be described with reference to Fig. 7 . 7(1) is a top view of a multilayer flexible printed wiring board. FIG. 7(2) is a cross-sectional view taken along line AA' of FIG. 7(1), and FIG. 7(3) is along FIG. (1) A cross-sectional view of the B-B' line. 7(1), (2), and (3), the step holes 51A, 51B, 51C, and 51D have a circular upper interlayer conducting circuit 51a and a circular lower interlayer conducting circuit 5 1 b. The upper interlayer conductive circuit 5 1 a is a flat portion 5 2 electrically connected to the surface of the multilayer flexible printed wiring board, and a flat portion 53 of the inner layer. On the other hand, the lower interlayer conducting circuit 51b is electrically connected to the multilayer flexible printing
S -6- 201223378 配線板的背面的平坦部54 '及內層的平坦部53。 以往的步進孔是圖7(1)所示的步進孔51A，51B， 5 1 D那樣，上部層間導電路5 1 a及下部層間導電路5 1 b爲 形成同心圓狀。 具有上述步進孔構造的堆積型多層可撓性印刷配線板 是例如可以5 00μιη間距來安裝3 00針腳前後的CSP。然 而，例如以感測器模組爲代表那樣，安裝零件的多針腳化 及窄間距化是越來越進展，安裝零件的針腳數是由數百增 加到多時是數千。用以接合零件的平坦部的間距是與安裝 零件的搭載墊的間距同尺寸，因此需要配合安裝零件的窄 間距化來縮小平坦部的間距。而且，在多層可撓性印刷配 線板是被要求電性連接和龐大的針腳接合的平坦部及預定 的連接部。因此，由圖7(2)可知，在步進孔51Α及51Β 間（步進孔51 C及51D間）設有多數條微細的配線55, 55， ··· 〇 例如’步進孔的間距爲400μιη，且形成有微細的配線 的層（內層）的平坦部的間隔爲200μιη時，如圖7(2)所示， 在內層的平坦部53，53間配置6條的配線55時，配線 5 5的配線間距是形成約3 0 μηι。如此，配線5 5，5 5，·.. 所設置的區域是在多層可撓性印刷配線板之中被要求最小 間距的區域。爲了在步進孔間設置微細的配線，不僅平坦 部，有關步進孔洞的直徑也需要小到50〜100μιη程度。 以往’所欲使步進孔洞小徑化時，會有因爲使用捲繞 狀的可撓性基底材料，而造成步進孔洞的上孔與下孔的對 201223378 位困難的問題、或往小徑孔洞的下孔之電鍍附著周圍惡化 的問題。其次，詳細說明有關該等的問題》 首先，說明有關步進孔洞的上孔及下孔的位移問題。 在製造多層可撓性印刷配線板時，起始材料爲使用在可撓 性絕緣基材的單面或兩面設有銅箔的可撓性覆銅層疊板。 此覆銅層疊板是長長地捲取成捲繞狀。一邊藉由捲出滾輪 來捲出此長的覆銅層疊板，一邊在被稱爲席位區域的預定 區域進行曝光等的製程。然後，一旦針對某席位區域完成 處理，則將覆銅層疊板搬送於捲繞方向（搬送方向），針對 其次的席位區域進行處理。予以重複，一旦針對覆銅層疊 板的表面所有席位區域完成處理，則翻轉覆銅層疊板，針 對背面同樣地以席位區域單位進行處理。如此，在多層可 撓性印刷配線板的製造中是將可撓性的覆銅層疊板予以一 邊捲出·捲取一邊使用。因此，會在捲繞方向產生覆銅層 疊板的伸縮，曝光時的對位變得困難。 參照圖8來更具體地說明。如圖8(1)及（2)所示，長 的兩面覆銅層疊板61是藉由捲出滾輪62來捲出一端，藉 由捲取滾輪63來捲取另一端。以此兩面覆銅層疊板61的 席位區域64作爲單位來進行曝光等的處理。一旦對某席 位區域64完成處理，則捲出滾輪62及捲取滾輪63會旋 轉，將席位區域64搬送於捲繞方向，對鄰接的其次的席 位區域實施處理。由此可知，從捲出滾輪62捲出的兩面 覆銅層疊板61容易在捲繞方向產生伸縮。此伸縮成問題 的工程，可想藉由光加工手法在兩面覆銅層疊板61的表S -6- 201223378 The flat portion 54' of the back surface of the wiring board and the flat portion 53 of the inner layer. The conventional stepping holes are the stepping holes 51A, 51B, and 5 1 D shown in Fig. 7 (1), and the upper interlayer conducting circuit 5 1 a and the lower interlayer conducting circuit 5 1 b are formed concentrically. The stacked multilayer flexible printed wiring board having the above-described stepping hole structure is, for example, a CSP before and after the 300-pin stitch can be mounted at a pitch of 500 μm. However, for example, as represented by the sensor module, the multi-pinning and narrow pitch of the mounting parts are progressing, and the number of pins of the mounting parts is increased from hundreds to thousands. The pitch of the flat portions for joining the parts is the same as the pitch of the mounting pads of the mounting parts, and therefore it is necessary to reduce the pitch of the flat portions in accordance with the narrow pitch of the mounting parts. Further, the multilayer flexible printed wiring board is a flat portion to which electrical connection and bulky stitching are required, and a predetermined connecting portion. Therefore, as is clear from Fig. 7 (2), a plurality of fine wirings 55, 55 are provided between the step holes 51A and 51 (between the step holes 51 C and 51D), for example, the pitch of the stepping holes When the interval between the flat portions of the layer (inner layer) in which the fine wiring is formed is 200 μm, as shown in Fig. 7 (2), when six wirings 55 are disposed between the flat portions 53 and 53 of the inner layer. The wiring pitch of the wiring 5 5 is formed to be about 30 μm. Thus, the area provided by the wiring 5 5, 5 5, ... is an area where a minimum pitch is required among the multilayer flexible printed wiring boards. In order to provide fine wiring between the step holes, not only the flat portion but also the diameter of the step hole is required to be as small as 50 to 100 μm. In the past, when the diameter of the stepping hole was reduced, there was a problem that the upper and lower holes of the stepped hole were difficult to be 201223378 due to the use of the wound flexible base material, or the path was small. The plating of the lower hole of the hole adheres to the problem of deterioration around. Next, the problems related to these problems will be described in detail. First, the displacement problems of the upper and lower holes of the stepping hole will be explained. In the production of a multilayer flexible printed wiring board, the starting material is a flexible copper clad laminate in which a copper foil is provided on one or both sides of the flexible insulating substrate. This copper clad laminate is wound up in a long shape in a coil shape. While the long copper clad laminate is unwound by winding up the roller, a process such as exposure is performed in a predetermined area called a seat area. Then, when the processing is completed for a certain seating area, the copper clad laminate is conveyed in the winding direction (transport direction), and the second seat area is processed. This is repeated, and once all the seating areas have been completed on the surface of the copper clad laminate, the copper clad laminate is turned over, and the back surface is treated in the same area as the seat area. As described above, in the manufacture of the multilayer flexible printed wiring board, the flexible copper-clad laminate is wound up and wound up. Therefore, the expansion and contraction of the copper clad laminate is caused in the winding direction, and the alignment at the time of exposure becomes difficult. More specifically, it will be described with reference to FIG. 8. As shown in Figs. 8 (1) and (2), the long double-sided copper clad laminate 61 is wound by the unwinding roller 62, and the other end is taken up by the take-up reel 63. The processing such as exposure is performed by using the seat area 64 of the double-sided copper clad laminate 61 as a unit. When the processing is completed for a certain seating area 64, the take-up roller 62 and the take-up roller 63 are rotated, the seat area 64 is conveyed in the winding direction, and the adjacent seating area is processed. From this, it is understood that the double-sided copper clad laminate 61 which is unwound from the take-up roller 62 is likely to expand and contract in the winding direction. This telescopic problem is a project that can be imagined by a light processing method on a double-sided copper clad laminate 61.
S -8- 201223378 面及背面形成共型光罩（conformal mask)時。此共型光罩 是爲了利用共型雷射加工法來形成步進孔洞而被使用者。 如圖8(2)所示，在席位區域64的表面形成阻絕層（未圖示） 之後，利用席位區域64上的對準標記Μ1及形成於曝光 用的玻璃遮罩的對準標記M2來進行對位。此對位後，進 行曝光及顯像，形成被加工成預定圖案的阻絕層。但，即 使利用可高精度對位的裝置來精密地進行對準標記Μ 1， M2的對位，還是難以充分地防止兩面覆銅層疊板61因爲 在捲繞方向伸縮而引起的位移。爲了形成步進孔洞形成用 的共型遮罩，而在兩面覆銅層疊板61的兩面形成阻絕層 時，位移的迴避是尤其困難。因爲，爲了在兩面覆銅層疊 板61的兩面形成分別被加工成預定圖案的阻絕層，通常 是首先在兩面覆銅層疊板61的表面之複數的席位區域依 序形成阻絕層，然後將被捲取於捲取滾輪的兩面覆銅層疊 板6 1翻轉，而利用別的玻璃遮罩來按席位區域依序進行 背面的曝光，在背面的席位區域形成阻絕層。此時，使在 將表面曝光時的兩面覆銅層疊板61的伸縮程度與在將背 面曝光時的兩面覆銅層疊板61的伸縮程度完全一致，實 際上是極爲困難。 並且，在上述的曝光製程中，由圖8(1)可知，藉由1 次的曝光而被曝光的兩面覆銅層疊板61上的曝光區域66 的捲繞方向的長度對於兩面覆銅層叠板61的寬度是例如 約1 .5 ~ 2倍爲理想。藉此’增加從1個席位區域6 4取得 的製品（多層可撓性印刷配線板）6 5數量，可使生產性提 201223378 升。但，隨著將曝光區域66擴大於兩面覆銅層叠板61的 捲繞方向，除了難以確保曝光光的平行度以外，越往曝光 區域66的圖8(1)中左右的端，位移越會隨兩面覆銅層疊 板6 1的伸縮而變大。亦即，爲了使生產性提升，一旦對 於兩面覆銅層疊板61的捲繞方向擴大曝光區域66，則兩 面覆銅層疊板61的伸縮對於對位精度的影響會變大。 基於上述的理由，圖7(1)及（3)所示的步進孔51C的 下部層間導電路51b是對捲繞方向（圖中上下方向）產生容 許量以上的位移。當發生如此大的位移時，在形成步進孔 洞時，共型遮罩未適當地產生機能，在步進孔洞的內壁發 生微小的凹陷或坑洞等。因此，在步進孔洞的內壁形成電 鍍層時，因爲電鍍液等的更新性差，所以在內壁的凹陷部 分未形成電鍍層，其結果，產生圖7(3)所示那樣的空隙 56。一旦產生如此的空隙56，則電鍍層容易破斷，恐有 作爲層間導電路的步進孔的可靠度降低之虞。 另外，在圖7(1)雖只在步進孔51C產生位移，但實 際上利用共型雷射加工法等來形成步進孔洞時，可撓性的 基底材料在捲繞方向伸縮，因此在步進孔51C附近的步進 孔（例如步進孔5 1 A，5 1 B，5 1 D)也產生位移的可能性高。 爲了對應於高密度安裝，需要像上述那樣將步進孔洞 的直徑形成1 〇 〇 μηι以下。但，若步進孔洞的小徑化進展 至此程度，則只要稍微產生20〜3 Ομηι程度的位移，便會 形成圖7的步進孔5 1 C那樣的狀態。 其次，說明有關使步進孔洞小徑化時之電鍍附著周圍 -10- 201223378 形狀的惡化。在步進孔洞的內壁施以電鍍處理’形成層間 導電路的步進孔時，當步進孔洞的上孔的直徑小（例如φ ΙΟΟμιη以下）時，電鍍前處理的洗淨液或電鍍處理的電鍍 液等的更新性差。其結果，如圖7(2)及（3)的步進孔51Α 的下部層間導電路51b所示那樣，會有發生電鏟的附著周 圍不良的情形。更具體而言，將形成於步進孔洞內壁的電 鍍層的厚度之設計上的下限値設爲ΙΟμιη，會有形成此下 限値的1 /2以下的厚度之處發生的情況。如此的情況’因 温度循環等的熱衝撃，恐有電鍍層破斷之虞，無法確保步 進孔作爲層間導電路的可靠度。 以往，關於電性連接2層間的層間連接部，有具備長 圓形狀等非正圓形的肓孔及貫通孔爲人所知（參照專利文 獻2、3及4)。然而，該等的文獻皆不是以步進孔構造作 爲對象，有關在形成小徑的步進孔洞時，因爲可撓性基底 材料的伸縮而引起對位精度的降低之課題及對於此的解決 手段未有任何的揭示。 [先行技術文獻] [專利文獻] [專利文獻1 ]特開2 0 0 7 - 1 2 8 9 7 0號公報 [專利文獻2]特開2000-151111號公報 [專利文獻3]特開2002-064274號公報 [專利文獻4 ]特開平1 1 - 2 7 4 6 7 7號公報 【發明內容】 -11 - 201223378 (發明所欲解決的課題） 本發明的目的是在於提供一種便宜且安定地製造具有 小徑的步進孔構造之多層可撓性印刷配線板的方法。 (用以解決課題的手段） 若根據本發明之一形態，則可提供一種多層可撓性印 刷配線板，係以捲繞狀的可撓性基底材料作爲起始材料的 多層可撓性印刷配線板，其特徵係具備： 第1可撓性絕緣基材，其係上述可撓性基底材料的一 部分： 第2可撓性絕緣基材，其係具有彼此對向的第1及第 2面，上述第1面係經由黏著劑層來層疊於上述第1可撓 性絕緣基材的背面：及 步進孔洞，其係具有上孔及下孔，該上孔係將上述第 1可撓性絕緣基材貫通於厚度方向，該下孔係直徑比上述 上孔小，與上述上孔連通，將上述黏著劑層及上述第2可 撓性絕緣基材貫通於厚度方向，且在底面露出設於上述第 2可撓性絕緣基材的上述第2面上的第1外層平坦部； 第2外層平坦部，其係形成於上述第丨可撓性絕緣基 材的表面之上述上孔的周圍； 內層平坦部，其係形成於上述第1可撓性絕緣基材的 背面之上述下孔的周圍；及 步進孔’其係具有上部層間導電路及下部層間導電 路’該上部層間導電路係形成於上述上孔的內壁，電性連S -8- 201223378 When forming a conformal mask on the front and back. This common type mask is used by the user to form a stepping hole by a common laser processing method. As shown in Fig. 8 (2), after a barrier layer (not shown) is formed on the surface of the seat region 64, the alignment mark Μ1 on the seat region 64 and the alignment mark M2 formed in the glass mask for exposure are used. Perform the alignment. After this alignment, exposure and development are performed to form a barrier layer that is processed into a predetermined pattern. However, even if the alignment marks Μ 1, M2 are accurately aligned by means of a device capable of high-precision alignment, it is difficult to sufficiently prevent displacement of the double-sided copper clad laminate 61 due to expansion and contraction in the winding direction. In order to form a common type mask for forming a stepped hole, when the barrier layer is formed on both surfaces of the double-sided copper clad laminate 61, the avoidance of displacement is particularly difficult. Because, in order to form the barrier layers respectively processed into a predetermined pattern on both sides of the double-sided copper clad laminate 61, it is usually first to form a barrier layer on the plurality of seating regions on the surface of the double-sided copper clad laminate 61, and then to be rolled. The two-side copper clad laminate 61 taken from the take-up reel is turned over, and the other glass mask is used to sequentially expose the back surface in the seat area, and a resist layer is formed in the seat area on the back side. At this time, it is extremely difficult to completely match the degree of expansion and contraction of the double-sided copper clad laminate 61 when the surface is exposed, and the degree of expansion and contraction of the double-sided copper clad laminate 61 when the back surface is exposed. Further, in the above-described exposure process, as shown in Fig. 8 (1), the length of the exposure region 66 on the double-sided copper clad laminate 61 exposed by one exposure is in the winding direction of the double-sided copper clad laminate. The width of 61 is ideal, for example, about 1.5 to 2 times. By this, the number of products (multilayer flexible printed wiring boards) 6 obtained from one seat area 164 can be increased, and the productivity can be increased by 201223378 liters. However, as the exposure region 66 is enlarged in the winding direction of the double-sided copper clad laminate 61, it is difficult to ensure the parallelism of the exposure light, and the displacement is more toward the left and right ends of the exposed region 66 in Fig. 8(1). It becomes larger as the double-sided copper clad laminate 6 1 expands and contracts. In other words, in order to improve the productivity, the exposure region 66 is enlarged in the winding direction of the double-sided copper clad laminate 61, and the influence of the expansion and contraction of the double-sided copper clad laminate 61 on the alignment accuracy is increased. For the reason described above, the lower interlayer conducting circuit 51b of the stepping hole 51C shown in Figs. 7 (1) and (3) is displaced by a tolerance amount or more in the winding direction (vertical direction in the drawing). When such a large displacement occurs, the conformal mask does not properly function when the stepping hole is formed, and minute depressions or potholes occur in the inner wall of the stepping hole. Therefore, when the plating layer is formed on the inner wall of the stepping hole, the plating solution or the like is inferior in reflowability, so that the plating portion is not formed in the depressed portion of the inner wall, and as a result, the void 56 as shown in Fig. 7 (3) is generated. When such a void 56 is generated, the plating layer is easily broken, and the reliability of the stepping hole as the interlayer conducting circuit may be lowered. Further, although the displacement is only caused in the stepping hole 51C in Fig. 7 (1), when the stepping hole is actually formed by the common laser processing method or the like, the flexible base material expands and contracts in the winding direction, so Stepping holes near the stepping hole 51C (for example, the stepping holes 5 1 A, 5 1 B, 5 1 D) are also highly likely to be displaced. In order to correspond to high-density mounting, it is necessary to form the diameter of the stepping hole to 1 〇 〇 μηι or less as described above. However, if the diameter reduction of the stepping hole progresses to this extent, a state of 20 to 3 Ομηι is slightly generated, and a state like the stepping hole 5 1 C of Fig. 7 is formed. Next, the deterioration of the shape of the plating adhesion around the -10-201223378 when the stepping hole is made smaller is described. When the inner wall of the stepping hole is subjected to a plating process to form a stepping hole of the interlayer conducting circuit, when the diameter of the upper hole of the stepping hole is small (for example, φ ΙΟΟμηη or less), the cleaning solution or plating treatment before the plating is performed. The plating solution and the like are inferior in renewability. As a result, as shown in the lower interlayer conducting circuit 51b of the stepping hole 51A of Figs. 7 (2) and (3), the adhesion circumference of the shovel may be defective. More specifically, the design lower limit 厚度 of the thickness of the plating layer formed on the inner wall of the stepping hole is ΙΟμηη, which may occur at a thickness of 1 /2 or less which forms the lower limit 値. In such a case, the thermal plating of the temperature cycle or the like may cause the plating layer to be broken, and the reliability of the step hole as the interlayer conduction circuit cannot be ensured. Conventionally, it has been known that the interlayer connection portion between the two layers of the electrical connection has a non-circular aperture such as a long circular shape and a through hole (see Patent Documents 2, 3 and 4). However, these documents are not targeted to the stepping hole structure, and the problem of lowering the alignment accuracy due to the expansion and contraction of the flexible base material when forming a stepped hole having a small diameter and the solution thereto There is no disclosure. [Patent Document 1] [Patent Document 1] JP-A-2000-151111 [Patent Document 2] JP-A-2000-151111 (Patent Document 3) [Patent Document 4] Japanese Laid-Open Patent Publication No. Hei No. Hei No. 1 - 2 7 4 6 7 7 [Invention] -11 - 201223378 (Problems to be Solved by the Invention) An object of the present invention is to provide an inexpensive and stable manufacture. A method of multilayer flexible printed wiring board having a small-diameter stepping hole structure. (Means for Solving the Problem) According to one aspect of the present invention, it is possible to provide a multilayer flexible printed wiring board which is a multilayer flexible printed wiring using a wound flexible base material as a starting material The board is characterized by comprising: a first flexible insulating substrate which is a part of the flexible base material: a second flexible insulating base material having first and second faces facing each other, The first surface is laminated on the back surface of the first flexible insulating substrate via an adhesive layer, and a stepping hole having an upper hole and a lower hole, the upper hole insulating the first flexible The base material penetrates in the thickness direction, and the lower hole diameter is smaller than the upper hole, and communicates with the upper hole, and the adhesive layer and the second flexible insulating base material are penetrated in the thickness direction, and the bottom surface is exposed to the bottom surface. a first outer layer flat portion on the second surface of the second flexible insulating base material; and a second outer layer flat portion formed around the upper surface of the surface of the second flexible insulating base material; An inner flat portion formed on the first flexible portion Around the hole at the back surface of the edge of the substrate; and a stepping hole 'which lines an upper layer having a conductive path between a lower layer and a conductive path between' between the inner wall of the upper layer of conductive lines formed in the passage hole, and electrically connected
S -12- 201223378 接上述第2外層平坦部與上述內層平坦部，該下部層間導 電路係形成於上述下孔的內壁，電性連接上述第1外層平 坦部與上述內層平坦部， 對上述捲繞狀的可撓性基底材料的捲繞方向之上述上 孔的直徑與上述下孔的直徑的差之第1差係比對與上述捲 繞方向垂直的方向之上述上孔的直徑與下孔的直徑的差之 第2差更大。 若根據本發明的別形態，則可提供一種多層可撓性印 刷配線板的製造方法，係準備一捲繞狀的兩面覆銅層疊 板，其係具有第1可撓性絕緣基材、及分別於其表面及背 面的第1銅箔及第2銅箔，且被捲於捲出滾輪， 從上述捲取滾輪抽出上述捲繞狀的兩面覆銅層疊板的 一端於捲繞方向， 在上述第1可撓性絕緣基材的表面及背面分別形成具 有上孔用開口部的第1導電圖案層、及具有下孔用開口部 的第2導電圖案層， 準備一單面覆銅層疊板，其係具有第2可撓性絕緣基 材、及於其單面的第3銅箔， 經由黏著劑層來將上述單面覆銅層疊板予以層疊黏著 於上述兩面覆銅層疊板的背面， 從上述上孔用開口部的側照射雷射光，進行以上述上 孔用開口部及上述下孔用開口部作爲共型遮罩的雷射加 工，藉此形成具有上孔及下孔的步進孔洞，該上孔係將上 述第1可撓性絕緣基材貫通於厚度方向，該下孔係與上述 -13- 201223378 上孔連通，將上述黏著劑層及上述第2可撓性絕緣基材貫 通於厚度方向，且在底面露出上述第3銅箔， 在上述步進孔洞的內壁實施電解銅電鍍處理，藉此形 成電性連接上述第1導電圖案層、上述第2導電圖案層及 上述第3銅箔的步進孔， 其特徵爲： 對上述捲繞方向之上述上孔用開口部的直徑與上述下 孔用開口部的直徑的差之第1差係比對與上述捲繞方向垂 直的方向之上述上孔用開口部的直徑與上述下孔用開口部 的直徑的差之第2差更大。 [發明的效果] 藉由該等的特徴，本發明可達成其次那樣的效果。 若根據本發明，則對可撓性絕緣基材的捲繞方向之上 孔（上孔用開口部）的直徑與下孔（下孔用開口部）的直徑的 差是比對與捲繞方向垂直的方向之上孔（上孔用開口部）的 直徑與下孔（下孔用開口部）的直徑的差更大。因此，可使 對捲繞方向的下孔（下孔用開口部）的位移容許量比與捲繞 方向垂直的方向的位移容許量更大。其結果，即使可撓性 絕緣基材對於捲繞方向伸縮時，還是可取得正常的步進孔 洞。 又，若根據本發明，則由於步進孔洞的上孔的開口面 積增大，所以在步進孔洞的內壁形成電鍍層時，電鍍液等 的更新性會提升，其結果，可形成電鏟附著周圍形狀良好S -12-201223378 is connected to the second outer layer flat portion and the inner layer flat portion, and the lower interlayer conductive circuit is formed on an inner wall of the lower hole, and electrically connects the first outer layer flat portion and the inner layer flat portion a first difference between a diameter of the upper hole and a diameter of the lower hole in a winding direction of the wound flexible base material is a diameter of the upper hole in a direction perpendicular to the winding direction The second difference from the difference in diameter of the lower hole is larger. According to another aspect of the present invention, there is provided a method of manufacturing a multilayer flexible printed wiring board, which is provided with a wound double-sided copper-clad laminate having a first flexible insulating substrate and respectively The first copper foil and the second copper foil on the front and back surfaces thereof are wound around the take-up roller, and one end of the wound double-sided copper-clad laminate is taken out from the winding roller in the winding direction. A first conductive pattern layer having an opening for an upper hole and a second conductive pattern layer having an opening for a lower hole are formed on the front surface and the back surface of the flexible insulating substrate, and a single-sided copper-clad laminate is prepared. a second flexible insulating base material and a third copper foil on one side thereof, wherein the single-sided copper-clad laminate is laminated and adhered to the back surface of the double-sided copper clad laminate via an adhesive layer, The upper hole is irradiated with the laser beam on the side of the opening, and the above-described upper hole opening and the lower hole opening are used as a common type of laser beam, thereby forming a stepped hole having an upper hole and a lower hole. The upper hole is insulated from the first flexible The base material penetrates in the thickness direction, and the lower hole communicates with the upper hole of the above-mentioned-13-201223378, and the adhesive layer and the second flexible insulating base material penetrate the thickness direction, and the third copper foil is exposed on the bottom surface. And performing an electrolytic copper plating treatment on the inner wall of the stepping hole to form a stepping hole electrically connecting the first conductive pattern layer, the second conductive pattern layer, and the third copper foil, wherein: The first difference between the diameter of the opening for the upper hole and the diameter of the opening for the lower hole in the winding direction is larger than the diameter of the opening for the upper hole in the direction perpendicular to the winding direction The second difference of the difference in diameter of the opening for the lower hole is larger. [Effect of the Invention] With the above features, the present invention can achieve the next effect. According to the present invention, the difference between the diameter of the hole (the opening for the upper hole) in the winding direction of the flexible insulating base material and the diameter of the lower hole (the opening for the lower hole) is the alignment and the winding direction. The difference between the diameter of the hole in the vertical direction (the opening for the upper hole) and the diameter of the lower hole (the opening for the lower hole) is larger. Therefore, the displacement allowable amount of the lower hole (the lower hole opening portion) in the winding direction can be made larger than the displacement allowable amount in the direction perpendicular to the winding direction. As a result, even if the flexible insulating base material expands and contracts in the winding direction, a normal stepping hole can be obtained. Moreover, according to the present invention, since the opening area of the upper hole of the stepping hole is increased, when the plating layer is formed on the inner wall of the stepping hole, the renewability of the plating solution or the like is improved, and as a result, the electric shovel can be formed. Good shape around the attachment
S -14- 201223378 的步進孔。 藉此’若根據本發明，則可便宜且安定地取得具有可 靠度闻小徑的步進孔作爲層間導電路之多層可撓性印刷配 線板。 【實施方式】 以下，一邊參照圖面’一邊說明有關本發明的實施形 態的多層可撓性印刷配線板。 另外’在各圖中對具有同等機能的構成要素附上同一 符號’同一符號的構成要素的詳細說明將不重複。並且， 圖面爲模式性者’以實施形態的特徵部分爲中心來顯示 者，厚度與平面尺寸的關係、各層的厚度的比率等是與實 際不同。 首先，參照圖1乃至圖3來說明具有本實施形態的步 進孔構造的多層可撓性印刷配線板的製造方法。 (1) 首先’準備一在可撓性絕緣基材11(例如厚度 25 μιη的聚醯氬胺薄膜）的兩面分別具有厚度ιμΐΏ的銅箔 12及銅箔13的兩面覆銅層疊板14。此兩面覆銅層疊板 14是被捲於捲出滾輪的捲繞狀者。圖1(1)中的面覆銅層 疊板14是顯示將捲繞狀的兩面覆銅層疊板14的一端從捲 出滾輪拉出於捲繞方向的兩面覆銅層疊板14的一部分的 剖面圖。圖1(1)中，捲繞方向是紙面垂直方向，水平方向 爲捲繞材料的寬度方向。 (2) 其次，在兩面覆銅層疊板14的銅箔12上的席位 -15- 201223378 區域形成阻絕層（未圖示）。此阻絕層的厚度是所形成的配 線層的厚度的1.2〜2倍程度爲理想。因爲，當阻絕層的厚 度比配線層的厚度的1.2倍薄時，藉由半加成工法來進行 電鍍時，因電鍍厚度的不均，電鍍皮膜會成長至阻絕層的 厚度以上，其結果，會有形成配線不良的情況。另一方 面，當阻絕層的厚度比配線層的厚度的2倍厚時，難以形 成微細的配線，仍然有形成配線不良的情況。所以，在此 是將設計上的配線的厚度設爲1〇μηι，將阻絕層的厚度設 爲 1 5 μηι。 (3) 其次，對於在前工程中所被形成的銅箔12上的阻 絕層進行曝光及顯像處理，將阻絕層圖案化成預定的圖 案。藉此，如圖1(1)所示，在兩面覆銅層疊板14的銅范 12上形成電鍍保護層（plating resist)15A。此電鍍保護層 15A是如後述般，爲了藉由半加成工法來形成所望的導電 圖案層而使用。 然後，一面將兩面覆銅層疊板14搬送於捲繞方向， 一面按席位區域來進行上述的工程，形成電鍍保護層 15A。一旦針對兩面覆銅層疊板14的表面的全部的席位 區域完成形成電鍍保護層15A，則將被捲取於捲取滾輪的 兩面覆銅層疊板14翻轉，然後’一邊將一端捲出’一邊 如下述般進行背面的處理。 (4) 其次，在兩面覆銅層疊塚14的銅箔13上的席位 區域形成阻絕層（未圖示）。此阻絕層的厚度是與銅箔12 上的阻絕層時同樣的理由設爲15μηι»Step hole for S -14- 201223378. According to the present invention, a multilayer flexible printed wiring board having a stepping hole having a reliable small diameter as an interlayer conductive circuit can be obtained inexpensively and stably. [Embodiment] Hereinafter, a multilayer flexible printed wiring board according to an embodiment of the present invention will be described with reference to the drawings. In the drawings, the components having the same functions are denoted by the same reference numerals, and the detailed description of the components of the same reference numerals will not be repeated. Further, the figure is a pattern, and the display is centered on the feature portion of the embodiment, and the relationship between the thickness and the plane size, the ratio of the thickness of each layer, and the like are different from the actual ones. First, a method of manufacturing a multilayer flexible printed wiring board having the stepped hole structure of the present embodiment will be described with reference to Figs. 1 to 3 . (1) First, a copper-clad laminate 14 having a copper foil 12 and a copper foil 13 having a thickness of 1 μm on both sides of a flexible insulating substrate 11 (for example, a polyarsenazo film having a thickness of 25 μm) is prepared. The double-sided copper clad laminate 14 is a wound body wound around a take-up roller. The copper-clad laminate 14 in Fig. 1 (1) is a cross-sectional view showing a part of the double-sided copper clad laminate 14 in which one end of the wound double-sided copper clad laminate 14 is pulled from the take-up roller in the winding direction. . In Fig. 1 (1), the winding direction is the vertical direction of the paper surface, and the horizontal direction is the width direction of the winding material. (2) Next, a barrier layer (not shown) is formed in the region of the seat -15-201223378 on the copper foil 12 of the double-sided copper clad laminate 14. The thickness of the barrier layer is preferably 1.2 to 2 times the thickness of the wiring layer to be formed. When the thickness of the barrier layer is thinner than 1.2 times the thickness of the wiring layer, when the plating is performed by a semi-additive method, the plating film is grown to a thickness greater than or equal to the thickness of the barrier layer due to uneven plating thickness, and as a result, There may be cases where wiring is poor. On the other hand, when the thickness of the barrier layer is twice as thick as the thickness of the wiring layer, it is difficult to form fine wiring, and wiring defects may still be formed. Therefore, here, the thickness of the wiring on the design is set to 1 〇 μηι, and the thickness of the barrier layer is set to 1 5 μη. (3) Next, the resist layer on the copper foil 12 formed in the prior art is subjected to exposure and development processing, and the barrier layer is patterned into a predetermined pattern. Thereby, as shown in Fig. 1 (1), a plating resist 15A is formed on the copper body 12 of the double-sided copper clad laminate 14. This plating protective layer 15A is used to form a desired conductive pattern layer by a semi-additive method as will be described later. Then, the two-side copper clad laminate 14 is conveyed in the winding direction, and the above-described work is performed in the seat area to form the plating resist 15A. Once the plating protection layer 15A is formed for all the seating areas of the surface of the double-sided copper clad laminate 14, the two-side copper clad laminate 14 wound up on the take-up reel is turned over, and then 'one end is rolled out' side as follows The back side is treated as described above. (4) Next, a barrier layer (not shown) is formed in the seat region on the copper foil 13 of the double-sided copper clad laminate 14 . The reason why the thickness of the barrier layer is the same as that of the barrier layer on the copper foil 12 is set to 15 μηι»
S -16- 201223378 (5) 其次，對前工程中所被形成的銅箔13上的阻絕層 進行曝光及顯像處理，將阻絕層圖案化成預定的圖案。藉 此，如圖1(2)所示，在兩面覆銅層疊板14的銅箔13上形 成電鍍保護層15B。此電鍍保護層15B是與前述的電鍍保 護層 15A 同樣，爲了藉由半加成工法（semiadditive process)來形成所望的導電圖案層而使用。 (6) 其次，由圖1(3)可知，對於形成有電鍍保護層 15A及15B的兩面覆銅層疊板14的兩面進行電解銅電 鍍。藉此，在電鍍保護層15A及15B的開口部露出的銅 箔12及銅箔13上分別形成電解銅電鍍層16及17。在 此，電解銅電鍍層16，17的厚度是ΙΟμηι。 (7) 其次，如圖1(3)所示，在剝離電鍍保護層15Α及 15Β之後，藉由光刻來除去未以電解銅電鍍層16’ 17所 被覆的銅箔12及銅箔13。此光刻是使用對含於種晶層 (銅箔1 2及銅箔1 3 )的金屬具有選擇性的蝕刻劑。例如’ 種晶層含有鎳時，蝕刻劑可使用硝酸及鹽酸的混合液。 到此的工程，如圖1(3)及（4)所示，取得一在可撓性 絕緣基材11的兩面具有由銅箔12(13)及電解銅電鍍層 16(17)所構成的導電圖案層之兩面電路基材18。圖1(4)是 表示兩面電路基材18的上面圖。由圖1(3)及（4)可知’導 電圖案層是在預定的位置具有開口部。被形成於兩面電路 基材18的表面的導電圖案層的開口部之共型遮罩19(上 孔用開口部）是爲了形成步進孔洞的上孔而作用者。另一 方面，被形成於兩面電路基材18的背面的導電圖案層的 -17- 201223378 開口部之共型遮罩20(下孔用開口部）是爲了形成步進孔洞 的下孔而作用者。在本工程中，若共型遮罩20對共型遮 罩1 9的位置偏移，則步進孔洞的下孔會對上孔產生位 移。其結果，如前述般，會因爲空隙的發生或電鑛附著周 圍形狀的惡化而使得步進孔的可靠度降低。但，本實施形 態，如圖1(4)所示，共型遮罩19是形成長圓形狀，此長 圓的長軸是與捲繞方向平行。因此，即使可撓性絕緣基材 11(兩面覆銅層疊板14)在捲繞方向伸縮，而共型遮罩18 對共型遮罩19在捲繞方向產生位移，還是會因爲捲繞方 向的位移容許量大，所以可形成正常的步進孔洞。 另外，本實施形態是將共型遮罩19的長圓的長軸的 長度設爲短軸的長度的2倍。亦即，將長軸的長度設爲 160μπι’將短軸的長度設爲80μηι。另一方面，由圖1(4) 可知’共型遮罩20是形成正圓形狀（直徑60μηι)。此情 況’對與捲繞方向成90°交叉的方向（亦即，兩面覆銅層疊 板14的寬度方向）之位移容許量是±ι〇 μιη以內。相對於 此’捲繞方向的位移容許量是±50μιη以內，可使對產生伸 縮的方向之位移容許量大幅度地增大。 (8)其次，如圖2(1)所示，在兩面電路基材18的背面 (圖2 (1 )中下側）經由黏著劑層2 4 (例如厚度1 5 μ m)來層# 黏結單面覆銅層疊板23。此單面覆銅層疊板23是在可撓 性絕緣基材21(例如厚度25μηι的聚醯氬胺薄膜）的單面例 如具有厚度12μιη的銅箔22者。單面覆銅層疊板23是以 可撓性絕緣基材2 1能夠接觸於黏著劑層2 4的方式來層叠S -16-201223378 (5) Next, the barrier layer on the copper foil 13 formed in the previous process is subjected to exposure and development processing, and the barrier layer is patterned into a predetermined pattern. Thereby, as shown in Fig. 1 (2), a plating resist 15B is formed on the copper foil 13 of the double-sided copper clad laminate 14. This plating protective layer 15B is used in the same manner as the above-described plating protective layer 15A in order to form a desired conductive pattern layer by a semi-additive process. (6) Next, as shown in Fig. 1 (3), electrolytic copper plating is performed on both surfaces of the double-sided copper clad laminate 14 on which the plating resists 15A and 15B are formed. Thereby, electrolytic copper plating layers 16 and 17 are formed on the copper foil 12 and the copper foil 13 exposed in the openings of the plating protective layers 15A and 15B, respectively. Here, the thickness of the electrolytic copper plating layers 16, 17 is ΙΟμηι. (7) Next, as shown in Fig. 1 (3), after the plating resist layers 15 and 15 are peeled off, the copper foil 12 and the copper foil 13 which are not covered with the electrolytic copper plating layer 16' 17 are removed by photolithography. This lithography uses an etchant selective for the metal contained in the seed layer (copper foil 12 and copper foil 13). For example, when the seed layer contains nickel, a mixture of nitric acid and hydrochloric acid can be used as the etchant. Thus, as shown in Figs. 1 (3) and (4), a copper foil 12 (13) and an electrolytic copper plating layer 16 (17) are formed on both surfaces of the flexible insulating substrate 11. A two-sided circuit substrate 18 of a conductive pattern layer. Fig. 1 (4) is a top view showing the double-sided circuit substrate 18. As is apparent from Figs. 1 (3) and (4), the conductive pattern layer has an opening at a predetermined position. The common type mask 19 (the opening for the upper hole) formed in the opening of the conductive pattern layer on the surface of the double-sided circuit substrate 18 serves to form the upper hole of the stepped hole. On the other hand, the common type mask 20 (opening for the lower hole) of the opening portion of the conductive pattern layer formed on the back surface of the double-sided circuit substrate 18 is a lower hole for forming a stepped hole. . In this project, if the position of the common mask 20 pairs of the common mask is shifted, the lower hole of the stepped hole will shift the upper hole. As a result, as described above, the reliability of the stepping hole is lowered due to the occurrence of voids or deterioration of the shape of the boundary of the electric ore. However, in the present embodiment, as shown in Fig. 1 (4), the common type mask 19 is formed in an elliptical shape whose major axis is parallel to the winding direction. Therefore, even if the flexible insulating base material 11 (the double-sided copper-clad laminate 14) expands and contracts in the winding direction, and the common-type mask 18 shifts the common-type mask 19 in the winding direction, it is because of the winding direction. The displacement tolerance is large, so a normal stepping hole can be formed. Further, in the present embodiment, the length of the major axis of the long circle of the common type mask 19 is twice the length of the short axis. That is, the length of the major axis is set to 160 μπι', and the length of the minor axis is set to 80 μm. On the other hand, as shown in Fig. 1 (4), the common-type mask 20 has a perfect circular shape (diameter 60 μm). In this case, the displacement tolerance amount in the direction intersecting the winding direction by 90° (i.e., the width direction of the double-sided copper clad laminate 14) is within ± 〇 μ μηη. The displacement tolerance amount in the 'winding direction' is within ±50 μm, and the displacement tolerance in the direction in which the contraction is generated can be greatly increased. (8) Next, as shown in Fig. 2 (1), the back surface of the double-sided circuit substrate 18 (the lower side in Fig. 2 (1)) is layered via the adhesive layer 24 (for example, a thickness of 15 μm). Single-sided copper clad laminate 23. This single-sided copper clad laminate 23 is a single surface of a flexible insulating base material 21 (e.g., a polypyridamine film having a thickness of 25 μm), for example, a copper foil 22 having a thickness of 12 μm. The single-sided copper clad laminate 23 is laminated in such a manner that the flexible insulating substrate 21 can contact the adhesive layer 24
S -18- 201223378 於兩面電路基材18的背面。另外，黏著劑層24是使用低 流動型的半固化片（prepreg)或接合薄片等流出少的黏著劑 來形成爲理想。 (9)其次，如圖2(2)所示，從共型遮罩19的側（圖2(2) 中上側）照射雷射光，利用共型遮罩19及20來進行共型 雷射加工。藉此，形成具有上孔26及下孔27的步進孔洞 (導通用孔）25。上孔26是貫通可撓性絕緣基材11，在底 面露出電解銅電鍍層17。下孔27是與上孔26連通，貫 通黏著劑層24與可撓性絕緣基材21。並且，下孔27是 直徑比上孔2 6更小，在下孔2 7的底面露出銅箔2 2。如 前述般，在進行本工程的雷射加工時，共型遮罩19是作 爲用以形成上孔26的遮罩用，共型遮罩20是作爲用以形 成下孔27的遮罩用。另外，在形成步進孔洞25的雷射加 工中，可使用UV-.YAG雷射、碳酸雷射、準分子雷射等 的雷射光。 在此，說明有關本工程的雷射加工的詳細。加工用雷 射是使用加工速度快，生產性佳的二氧化碳雷射（三菱電 機（株）製，ML605GTXIII-5100U2)。藉由孔徑等來將雷射 的射束徑調整成200μηι後，照射5次脈衝寬lOpSec，脈 衝能量5mJ的雷射脈衝，而形成步進孔洞25。先將雷射 的射束徑調整成比長圓形的共型遮罩19的長軸的長度更 大，瞄準共型遮罩1 9的長圓的中心來照射雷射脈衝，藉 此可適當地形成長圓形的上孔26及正圓形的下孔27。另 外，無法將雷射的射束徑調整成比共型遮罩19的長軸的 -19- 201223378 長度更大時，亦可將照射靶位置分成長軸上的例如3或4 個點，一邊使雷射脈衝移動於長軸方向，一邊照射。藉由 搖動電流計鏡，可使雷射射束的照射靶位置移動於比長軸 的長度更廣的範圍。因此，分割照射靶位置也可不影響生 產性來進行雷射加工。依上述的雷射條件，與以往的同心 圓狀的步進孔洞同樣，可形成具有長圓形的上孔26的步 進孔洞25。 (1 〇)其次，進行電漿處理及溼蝕刻，作爲用以除去步 進孔洞2 5內的樹脂殘渣的去渣工程。藉由此蝕刻，如圖 2 (2)所示，步進孔洞25內的銅箔13會被除去。 (1 1)其次，在電解銅電鍍層16上及步進孔洞25的內 壁實施導電化處理及接著的電解銅電鍍處理。藉此，如圖 2 (3)所示，在步進孔洞25的內壁（側面及底面）及電解銅電 鍍層16上形成電解銅電鍍層28。爲了確保層間導通，電 解銅電鍍層28的厚度是例如設爲15〜20μηι。藉此，形成 具有上部層間導電路29a及下部層間導電路29b的步進孔 29。步進孔29的上部層間導電路29a是電性連接表面側 的平坦部30與內層的平坦部17b者，下部層間導電路 29b是電性連接內層的平坦部1 7b與背面側的平坦部3 1。 本工程的電鍍處理，因爲步進孔洞25的開口面只在 一側（圖中上側），所以只對步進孔洞2 5的開口面側實施 電鍍處理，所謂的單面電鍍。因此，在背面的銅箔22上 是未形成電解銅電鍍層28。另外，單面電鍍亦可在形成 電鍍遮罩而使覆蓋背面的銅箔22之後進行電鍍處理，或 -20- 201223378 者在電鍍裝置或電鍍治具等設置遮蔽板之後進行電鑛處 理。在如此不是兩面電鍍，而是單面電鍍下，多餘的銅電 鍍皮膜不會被形成於銅箔22上，可防止銅箔22的膜厚變 厚。藉由保持薄的銅箔22，可高精度地加工銅箔22’而 形成平坦部等微細的圖案。 (12)其次，如圖2(4)所示，利用光加工法來將電解銅 電鍍層28加工成預定的圖案，藉此形成平坦部30。同 樣，利用光加工法來將銅箔22加工成預定的圖案，藉此 在背面形成平坦部3 1。 經由以上的工程來取得具有本實施形態的步進孔構造 的多層可撓性印刷配線板3 2。之後，因應所需，在不需 要錫焊的部分形成保護用的感光防焊層（Photo Solder Resist layer)，在平坦部等的表面實施鍍錫、鍍鎳、鍍金 等的表面處理。然後，將製作有複數個多層可撓性印刷配 線板32，32，···的捲繞材料予以按席位區域切斷。最 後，藉由利用金屬模具的衝模等來進行外形加工。另外， 捲繞材料的切斷是只要在電鍍保護層15A及15B的形成 後且外形加工前，即可在任意的工程進行。 其次，利用圖3來詳細說明有關本實施形態的多層可 撓性印刷配線板的構造。 圖3是具有本實施形態的長孔步進孔構造的多層可撓 性印刷配線板3 2的上面圖及剖面圖。圖3 (1 )是多層可撓 性印刷配線板3 2的上面圖。圖3 (2)是沿著圖3 (1)的A - A ’ 線的剖面圖，圖3(3)是沿著圖3(1)的B-B’線的剖面圖。 -21 - 201223378 由圖3(1)、（2)及（3)可知，形成於多層可撓性印刷配 線板32的步進孔29是具有長圓形的上部層間導電路29a 及正圓形的下部層間導電路29b。 並且，在多層可撓性印刷配線板3 2的表面設有平坦 部3 0，在背面設有平坦部3 1。平坦部3 1因爲無步進孔的 開口面，所以平坦性佳，因此適合作爲用以安裝零件的平 坦部（1 a n d )。 內層的配線17a及平坦部17b是在前述的製造工程中 加工電解銅電鍍層1 7而形成者。此配線1 7 a是電性連接 多層可撓性印刷配線板32的平坦部1 7b、及與外部的連 接部。平坦部17b是藉由步進孔29來與平坦部30及平坦 部3 1電性連接。 利用圖4來詳細說明配線1 7a及平坦部1 7b »圖4是 表示沿著圖3(2)的C-C’線的剖面圖。由此圖4可知，配 線17a是作爲與上部層間導電路29a(上孔26)的長軸方向 平行走向者，被配置於步進孔29，29間。藉由如此配置 配線17a，可不使配線17a的配線密度降低地來擴大步進 孔29(上孔26)的開口面積。 其次，利用數値來具體地說明有關步進孔洞的上孔 (共型遮罩19)及下孔（共型遮罩20)的尺寸與位移容許量的 關係。 表1是分別針對以往的上孔、下皆爲正圓形時、及本 實施形態的上孔爲長圓形、下孔爲正圓形時，彙整位移容 許量的長軸短軸比者。在此，所謂“位移容許量的長軸短 € -22- 201223378 軸比”是意味長軸方向的位移容許量（X)與短軸方向的位移 容許量（y)的比（x/y)。 [表1] 以往 (正圓形） 實施形態（上孔:長圓形） 例1 例2 例3 上孔(長軸/短軸） 80 120/80 160/80 240/80 下孔(正圓形） 60 60 60 60 長軸的長度與短軸的長度的比 1.0 1.5 2.0 3.0 長軸方向的位移容許量 ±10 ±30 ±50 ±90 短軸方向的位移容許量 ±10 ±10 ±10 ±10 位移容許量的長軸短軸比 1.0 3.0 5.0 9.0 (單位：/X m) 在表1是顯示上孔的長軸的長度不同的3個例。亦 即，上孔的長軸的長度在例1是120μιη，在例2是 160μιη，在例 3是 240μιη。短軸的長度在哪個例皆爲 8 0 μηι。如此’上孔（共型遮罩19)的長軸的長度是短軸的 長度的1 .5〜3倍程度爲理想。小於1.5倍時，有可能位移 容許量不夠充分。另一方面，大於3倍時，雖位移容許量 增加，但以雷射加工來形成前述的步進孔洞2 5所要的時 間會增加’其結果，有可能生產性降低。 如表1所示，長軸的長度與短軸的長度的比，在例 1、例2及例3中’分別是1 · 5倍、2倍及3倍。若將此長 軸的長度與短軸的長度的比分別變換成“位移容許量的長 軸短軸比”’則成爲3倍、5倍、9倍。如此，若根據本實 施形態’則將長軸方向的位移容許量相較於短軸方向的位 移容許量（亦即以往的位移容許量），可使大幅度地增大3 倍乃至9倍。 -23- 201223378 如以上說明那樣，本實施形態是將步進孔洞2 5的上 孔26設爲長圓形，且將下孔27設爲正圓形。藉此，可使 對下孔27用的共型遮罩20的長軸方向的位移之容許量， 比以往更大幅度地增大。因此，在多層可撓性印刷配線板 的製造過程中即使可撓性絕緣基材11在捲繞方向（搬送方 向）伸縮時，還是可形成正常的步進孔洞25。其結果，若 根據本實施形態，則可取得具有可靠度高的步進孔29作 爲層間導電路的多層可撓性印刷配線板。 而且，相較於以往，因爲步進孔洞25的上孔26變 大，所以在步進孔洞的內壁施以電鍍處理時之電鍍液等的 更新性會提升。因此，可形成電鍍周圍安定的步進孔。其 結果，若根據本實施形態，則可使作爲層間導電路的步進 孔的可靠度更提升。 其次，利用圖5來說明有關本實施形態的步進孔洞的 變形例。圖5(1 )~(4)皆表示可使對捲繞方向（圖中上下方 向）的位移容許量增加之步進孔洞的上面圖。 圖5(1)所示的步進孔洞101是不僅上孔l〇la，連下 孔1 〇 1 b也被形成長圓形。如此的形狀時，與以往的同心 圓狀的步進孔洞作比較，可使對長軸方向的位移容許量增 加。並且，此變形例時，下孔1 01 b的開口面積也比以往 的正圓形大，所以可使電鍍液等的更新性更提升。 圖5(2)所示的步進孔洞102是具有長圓形的上孔 l〇2a、及橢圓形的下孔102b。由於下孔102b爲橢圓形， 因此可使電鍍液等的更新性提升的同時，可使旋轉方向 -24- 201223378 (圖5(2)中的箭號方向）的位移界限增大。亦即，爲了形成 前述的電鍍保護層15B，而使阻絕層曝光時，只要下孔 102b的角比長圓形圓，便可比圖5(1)的步進孔洞1〇1更 使對旋轉方向的位移的容許量增加。 圖5(3)所示的步進孔洞103是具有正圓形的上孔 l〇3a、及長圓形的下孔103b。如圖5(3)所示，雖長圓形 的下孔103b是設於長軸與捲繞方向正交的方向，但由於 上孔l〇3a爲正圓形，因此可使對旋轉方向（圖5(3)中的箭 號方向）的位移容許量增大。 圖5 (4)所示的步進孔洞104是具有大略正方形的上孔 l〇4a、及大略長方形的下孔104b。雖此大略長方形的下 孔l〇4b是設於長邊與捲繞方向正交的方向，但由於上孔 l〇4a爲大略正方形，因此可使對旋轉方向（圖5(4)中的箭 號方向）的位移容許量增加。 並非限於上述的變形例，可組合各例的上孔及下孔。 例如，上孔及下孔皆爲橢圓形的步進孔洞。此下孔的長軸 的方向是與上孔的長軸的方向平行。又，亦可爲正圓形的 上孔、及大略長方形的下孔所構成的步進孔洞。此下孔的 長邊的方向是與捲繞方向垂直的方向。 其他，亦可爲上孔具有與捲繞方向平行的方向的長軸 之橢圓形，下孔爲正圓形，或在與上孔相同的方向具有長 軸的橢圓形。 其次，利用圖6來說明有關往本實施形態的多層可擦 性印刷配線板之零件的安裝例。圖6( 1)是表示在本實施形 -25- 201223378 態的多層可撓性印刷配線板安裝零件44的狀態的上面 圖。圖6(2)是沿著圖6(1)的A-A’線的剖面圖。由圖6(1) 可知，零件44是被安裝於零件搭載區域41。 由圖6(2)可知，零件44是在多層可撓性印刷配線板 32的背面的平坦部31經由凸塊45來安裝。藉此，相較 於安裝在平坦部30時，可在平坦度高的狀態下安裝零件 44。其結果，不會有在接合部分產生空隙等之虞，可取得 可靠度高的接合。 由圖6(1)可知，設於多層可撓性印刷配線板32的內 層的配線17a是從零件搭載區域41A(41B)通過配線區域 42A(42B)來繞拉至連接部43A(43B)，電性連接零件搭載 區域41的平坦部31與連接部43 A，43B。更詳細是電性 連接零件搭載區域41的上半區域的零件搭載區域41A的 平坦部31與連接部43 A的配線17a是從配置於零件搭載 區域41A的平坦部31通過配線區域42 A來繞拉至連接部 43A。同樣，電性連接零件搭載區域41的下半區域的零 件搭載區域41B的平坦部31與連接部43B的配線17a是 從配置於零件搭載區域41B的平坦部31通過配線區域 42B來繞拉至連接部43B。 被安裝的零件44是例如針腳數非常多的感測器模 組，微細的配線1 7 a的繞拉方向是大致限於1方向。如此 的情況是以能夠行進於步進孔29的長軸方向之方式設置 配線1 7a，藉此可不損配線1 7a的配線密度，擴大步進孔 29的開口部的面積。S -18- 201223378 is on the back side of the two-sided circuit substrate 18. Further, it is preferable that the adhesive layer 24 is formed using a low flow type prepreg or a bonding sheet or the like which has a small amount of an adhesive. (9) Next, as shown in Fig. 2 (2), the laser beam is irradiated from the side of the common type mask 19 (upper side in Fig. 2 (2)), and the common type masks 19 and 20 are used for the common type laser processing. . Thereby, a stepping hole (guide hole) 25 having the upper hole 26 and the lower hole 27 is formed. The upper hole 26 penetrates the flexible insulating base material 11, and the electrolytic copper plating layer 17 is exposed on the bottom surface. The lower hole 27 communicates with the upper hole 26, and penetrates the adhesive layer 24 and the flexible insulating base material 21. Further, the lower hole 27 has a smaller diameter than the upper hole 26, and the copper foil 22 is exposed at the bottom surface of the lower hole 27. As described above, in performing the laser processing of the present project, the common type mask 19 is used as a mask for forming the upper holes 26, and the common type mask 20 is used as a mask for forming the lower holes 27. Further, in the laser processing for forming the stepping holes 25, laser light such as a UV-.YAG laser, a carbonic acid laser, or an excimer laser can be used. Here, the details of the laser processing of this project will be described. The processing laser is a carbon dioxide laser (ML605GTXIII-5100U2, manufactured by Mitsubishi Electric Corporation) with a fast processing speed and good productivity. After the beam diameter of the laser beam is adjusted to 200 μm by an aperture or the like, a laser pulse having a pulse width of 10 μps and a pulse energy of 5 mJ is irradiated five times to form a stepping hole 25. First, the beam diameter of the laser is adjusted to be longer than the long axis of the long circular common mask 19, aiming at the center of the long circle of the common mask 19 to illuminate the laser pulse, thereby appropriately terrain A circular upper hole 26 and a right circular lower hole 27 are formed. Further, when the beam diameter of the laser cannot be adjusted to be longer than the length of -19-201223378 of the long axis of the common type mask 19, the irradiation target position may be divided into, for example, 3 or 4 points on the growth axis. The laser pulse is moved while moving in the direction of the long axis. By shaking the galvanometer mirror, the position of the illumination target of the laser beam can be moved over a wider range than the length of the long axis. Therefore, the division of the irradiation target position can also perform laser processing without affecting the productivity. According to the above-described laser condition, the step hole 25 having the elongated circular upper hole 26 can be formed in the same manner as the conventional concentric round stepping hole. (1 〇) Next, plasma treatment and wet etching were performed as a slag removal process for removing the resin residue in the step hole 25. By this etching, as shown in Fig. 2 (2), the copper foil 13 in the stepping hole 25 is removed. (1 1) Next, a conductive treatment and an electrolytic copper plating treatment are performed on the electrolytic copper plating layer 16 and the inner wall of the step hole 25. Thereby, as shown in Fig. 2 (3), an electrolytic copper plating layer 28 is formed on the inner wall (side surface and bottom surface) of the stepping hole 25 and the electrolytic copper plating layer 16. In order to ensure interlayer conduction, the thickness of the electrolytic copper plating layer 28 is, for example, 15 to 20 μm. Thereby, the stepping hole 29 having the upper interlayer conducting circuit 29a and the lower interlayer conducting circuit 29b is formed. The upper interlayer conducting circuit 29a of the stepping hole 29 is a flat portion 30b electrically connecting the front side and the flat portion 17b of the inner layer, and the lower interlayer conducting circuit 29b is a flat portion 17b electrically connected to the inner layer and flat on the back side. Department 3 1. In the plating treatment of this step, since the opening surface of the stepping hole 25 is only on one side (upper side in the drawing), only the opening surface side of the stepping hole 25 is subjected to plating treatment, so-called single-sided plating. Therefore, the electrolytic copper plating layer 28 is not formed on the copper foil 22 on the back surface. Further, the single-sided plating may be performed by forming a plating mask to cover the copper foil 22 on the back surface, or by electroplating after the shielding plate is provided in a plating apparatus or a plating fixture. In the case where the plating is not performed on both sides, the excess copper plating film is not formed on the copper foil 22, and the film thickness of the copper foil 22 can be prevented from becoming thick. By keeping the copper foil 22 thin, the copper foil 22' can be processed with high precision to form a fine pattern such as a flat portion. (12) Next, as shown in Fig. 2 (4), the electrolytic copper plating layer 28 is processed into a predetermined pattern by a photo processing method, whereby the flat portion 30 is formed. Also, the copper foil 22 is processed into a predetermined pattern by a photo processing method, whereby the flat portion 31 is formed on the back surface. The multilayer flexible printed wiring board 3 2 having the stepping hole structure of the present embodiment is obtained through the above process. After that, a photo solder resist layer (Photo Solder Resist layer) for protection is formed in a portion where soldering is not required, and a surface treatment such as tin plating, nickel plating, or gold plating is applied to the surface of the flat portion or the like. Then, the wound material on which the plurality of multilayer flexible printed wiring boards 32, 32, ... are formed is cut by the seating area. Finally, the outer shape processing is performed by using a die of a metal mold or the like. Further, the cutting of the wound material can be carried out in any process as long as the plating protective layers 15A and 15B are formed and before the outer shape is processed. Next, the structure of the multilayer flexible printed wiring board according to the present embodiment will be described in detail with reference to Fig. 3 . Fig. 3 is a top view and a cross-sectional view of a multilayer flexible printed wiring board 3 2 having the long hole stepping hole structure of the embodiment. Fig. 3 (1) is a top view of the multilayer flexible printed wiring board 32. Fig. 3 (2) is a cross-sectional view taken along line A - A' of Fig. 3 (1), and Fig. 3 (3) is a cross-sectional view taken along line B-B' of Fig. 3 (1). -21 - 201223378 It is understood from Fig. 3 (1), (2), and (3) that the stepping hole 29 formed in the multilayer flexible printed wiring board 32 is an upper interlayer conducting circuit 29a having an oblong shape and a perfect circular shape. Lower inter-layer conducting circuit 29b. Further, a flat portion 30 is provided on the surface of the multilayer flexible printed wiring board 3 2, and a flat portion 31 is provided on the back surface. Since the flat portion 3 1 has no open surface of the stepping hole, it has good flatness, and is therefore suitable as a flat portion (1 a n d ) for mounting the component. The inner layer wiring 17a and the flat portion 17b are formed by processing the electrolytic copper plating layer 17 in the above-described manufacturing process. The wiring 177a is a flat portion 17b electrically connected to the multilayer flexible printed wiring board 32, and a connection portion with the outside. The flat portion 17b is electrically connected to the flat portion 30 and the flat portion 31 by the step hole 29. The wiring 1 7a and the flat portion 1 7b will be described in detail with reference to Fig. 4. Fig. 4 is a cross-sectional view taken along line C-C' of Fig. 3 (2). As can be seen from Fig. 4, the wiring 17a is disposed parallel to the longitudinal direction of the upper interlayer conducting circuit 29a (upper hole 26), and is disposed between the stepping holes 29 and 29. By arranging the wiring 17a in this manner, the opening area of the stepping hole 29 (upper hole 26) can be enlarged without lowering the wiring density of the wiring 17a. Next, the relationship between the size of the upper hole (conformal mask 19) and the lower hole (conformal mask 20) of the stepping hole and the displacement tolerance amount will be specifically described using the number 値. Table 1 shows the long-axis short-axis ratios of the consolidation displacements when the upper holes and the lower ones are both circular and the upper holes are oblong and the lower holes are perfectly circular. Here, the "long axis short displacement tolerance of -22-201223378" is the ratio of the displacement tolerance (X) in the long axis direction to the displacement tolerance (y) in the short axis direction (x/y). . [Table 1] Conventional (Round Circle) Embodiment (Upper Hole: Oblong) Example 1 Example 2 Example 3 Upper Hole (Long Axis/Short Axis) 80 120/80 160/80 240/80 Lower Hole (Positive Circle) 60 60 60 60 Ratio of the length of the long axis to the length of the short axis 1.0 1.5 2.0 3.0 The tolerance of the displacement in the long axis direction ±10 ± 30 ±50 ±90 The tolerance of the displacement in the short axis direction ±10 ±10 ±10 ± 10 Long-axis short-axis ratio of displacement tolerance 1.0 3.0 5.0 9.0 (Unit: /X m) Table 1 shows three examples in which the length of the long axis of the upper hole is different. That is, the length of the long axis of the upper hole is 120 μm in Example 1, 160 μm in Example 2, and 240 μηη in Example 3. In the case of the length of the short axis, it is 8 0 μηι. The length of the long axis of the upper hole (conformal mask 19) is preferably 1.5 to 3 times the length of the short axis. When it is less than 1.5 times, there is a possibility that the displacement tolerance is insufficient. On the other hand, when the displacement tolerance is increased by more than 3 times, the time required to form the aforementioned step hole 25 by laser processing is increased, and as a result, productivity may be lowered. As shown in Table 1, the ratio of the length of the major axis to the length of the minor axis was 1.5 times, 2 times, and 3 times in Examples 1, 2, and 3, respectively. When the ratio of the length of the major axis to the length of the minor axis is converted into "the major axis short axis ratio of the displacement tolerance", the ratio is three times, five times, and nine times. As described above, according to the present embodiment, the displacement tolerance in the longitudinal direction can be greatly increased by three times or even nine times as compared with the displacement tolerance in the short-axis direction (that is, the conventional displacement tolerance). -23- 201223378 As described above, in the present embodiment, the upper hole 26 of the stepping hole 25 is formed in an elliptical shape, and the lower hole 27 is formed in a perfect circular shape. Thereby, the allowable amount of displacement in the longitudinal direction of the common type mask 20 for the lower hole 27 can be increased more than ever. Therefore, even in the manufacturing process of the multilayer flexible printed wiring board, even if the flexible insulating base material 11 expands and contracts in the winding direction (transport direction), the normal stepping hole 25 can be formed. As a result, according to the present embodiment, it is possible to obtain a multilayer flexible printed wiring board having the stepping holes 29 having high reliability as the interlayer conducting circuit. Further, since the upper hole 26 of the stepping hole 25 is larger than in the related art, the renewability of the plating solution or the like is increased when the inner wall of the stepping hole is subjected to the plating treatment. Therefore, a stepping hole that is stable around plating can be formed. As a result, according to the present embodiment, the reliability of the stepping hole as the interlayer conducting circuit can be further improved. Next, a modification of the stepping hole according to the present embodiment will be described with reference to Fig. 5 . 5(1) to (4) show the top view of the stepping hole which can increase the displacement tolerance in the winding direction (upper and lower in the drawing). The stepping hole 101 shown in Fig. 5 (1) is not only the upper hole l〇la, but the lower hole 1 〇 1 b is also formed into an oblong shape. In such a shape, the displacement tolerance in the long axis direction can be increased as compared with the conventional concentric round stepping holes. Further, in this modification, since the opening area of the lower hole 010b is larger than that of the conventional perfect circle, the renewability of the plating solution or the like can be further improved. The stepping hole 102 shown in Fig. 5 (2) is an upper hole l〇2a having an oblong shape and a lower hole 102b having an elliptical shape. Since the lower hole 102b has an elliptical shape, the renewability of the plating solution or the like can be improved, and the displacement limit of the rotation direction -24 - 201223378 (arrow direction in Fig. 5 (2)) can be increased. That is, in order to form the plating resist 15B as described above, when the barrier layer is exposed, as long as the corner of the lower hole 102b is longer than the oblong circle, the direction of rotation can be made more than the stepped hole 1〇1 of FIG. 5(1). The tolerance of the displacement increases. The stepping hole 103 shown in Fig. 5 (3) is an upper hole l〇3a having a perfect circular shape and a lower circular hole 103b having an oblong shape. As shown in Fig. 5 (3), although the oblong hole 103b is formed in a direction in which the major axis is orthogonal to the winding direction, since the upper hole l3a is a perfect circle, the direction of rotation can be made ( The displacement tolerance of the arrow direction in Fig. 5 (3) is increased. The stepping hole 104 shown in Fig. 5 (4) is an upper hole 104a having a substantially square shape and a lower hole 104b having a substantially rectangular shape. Although the substantially rectangular lower hole l〇4b is disposed in a direction in which the long side is orthogonal to the winding direction, since the upper hole l〇4a is a substantially square, the direction of rotation can be made (the arrow in FIG. 5(4)). The displacement tolerance of the direction direction is increased. It is not limited to the above-described modification, and the upper hole and the lower hole of each example can be combined. For example, both the upper and lower holes are elliptical step holes. The direction of the major axis of the lower hole is parallel to the direction of the long axis of the upper hole. Further, it may be a stepped hole formed by a right circular hole and a substantially rectangular lower hole. The direction of the long side of the lower hole is a direction perpendicular to the winding direction. Alternatively, the upper hole may have an elliptical shape having a long axis parallel to the winding direction, the lower hole may be a perfect circle, or an elliptical shape having a long axis in the same direction as the upper hole. Next, an example of mounting the components of the multilayer erasable printed wiring board of the present embodiment will be described with reference to Fig. 6 . Fig. 6 (1) is a top view showing a state in which the multilayer flexible printed wiring board mounting member 44 of the present embodiment is in the form of -25 to 201223378. Fig. 6 (2) is a cross-sectional view taken along line A-A' of Fig. 6 (1). As can be seen from Fig. 6 (1), the component 44 is attached to the component mounting region 41. As is apparent from Fig. 6 (2), the component 44 is attached to the flat portion 31 on the back surface of the multilayer flexible printed wiring board 32 via the bumps 45. Thereby, the component 44 can be mounted in a state where the flatness is high as compared with the case where the flat portion 30 is mounted. As a result, no gap or the like is formed in the joint portion, and a highly reliable joint can be obtained. As shown in Fig. 6 (1), the wiring 17a provided in the inner layer of the multilayer flexible printed wiring board 32 is drawn from the component mounting region 41A (41B) to the connecting portion 43A (43B) through the wiring region 42A (42B). The flat portion 31 of the component mounting region 41 and the connecting portions 43 A, 43B are electrically connected. More specifically, the flat portion 31 of the component mounting region 41A in the upper half region of the electrical connection component mounting region 41 and the wiring 17a of the connection portion 43 A are wound from the flat portion 31 disposed in the component mounting region 41A through the wiring region 42 A. Pulled to the connecting portion 43A. Similarly, the flat portion 31 of the component mounting region 41B in the lower half region of the electrical connection component mounting region 41 and the wiring 17a of the connection portion 43B are pulled from the flat portion 31 disposed in the component mounting region 41B through the wiring region 42B. Part 43B. The mounted component 44 is, for example, a sensor module having a very large number of stitches, and the winding direction of the fine wiring 17 7 is substantially limited to one direction. In this case, the wiring 17a is provided so as to be able to travel in the longitudinal direction of the stepping hole 29, whereby the area of the opening of the stepping hole 29 can be enlarged without impairing the wiring density of the wiring 17a.
-26- S 201223378 如以上說明，本實施形態是將步進孔洞的上孔設爲長 圓形，其長軸方向是對可撓性印刷配線板的捲繞材料的捲 繞方向形成平行。藉此，在形成步進孔洞用的共型遮罩的 曝光工程中，即使可撓性的基底材料在捲繞方向伸縮時， 還是可形成正常的步進孔洞。其結果，若根據本實施形 態，則可取得具有可靠度高的步進孔作爲層間導電路的多 層可撓性印刷配線板。 而且，本實施形態相較於以往的步進孔洞，由於上孔 變大，所以在步進孔洞的內壁形成電鍍層時之電鍍液等的 更新性會提升。因此，可形成電鑛附著周圍形狀良好的步 進孔。亦即，若根據本實施形態，則可取得具有可靠度更 高的步進孔作爲層間導電路的多層可撓性印刷配線板。 又，若根據本實施形態，則藉由位移容許量的增大， 可將曝光區域擴展於捲繞方向，擴大1個席位區域的面 積。藉此，可增加從1個席位區域取得的多層可撓性印刷 配線板的數量，可使生產性提升。 由以上的本實施形態達成的效果可明確，若根據本發 明，則可不用導入新的工程或裝置，便宜且安定地的製造 具有小徑的步進孔構造之多層可撓性印刷配線板。 另外，本發明的步進孔洞的上孔及下孔的形狀並非限 於上述實施形態及變形例。一般是只要對可撓性基底材料 的捲繞方向之共型遮罩19(上孔26)的直徑與共型遮罩 20(下孔27)的直徑的差’比對與捲繞方向垂直的方向之共 型遮罩19(上孔26)的直徑與共型遮罩20(下孔27)的直徑 -27- 201223378 的差更大即可。如此一來’可使對捲繞方向的位移容許量 增加。 根據上述的記載，只要是該當業者，便可想到本發明 的追加效果或各種的變形’但本發明的形態並非限於上述 實施形態。可在不脫離申請專利範圍所規定的內容及由其 均等物導出之本發明的槪念性的思想及主旨的範圍，實施 各種的追加、變更及部分的削除。 【圖式簡單說明】 圖1是用以說明具有本發明的實施形態的步進孔構造 的多層可撓性印刷配線板的製造方法的圖，（1)、（2)及（3) 是工程剖面圖，（4)是對應於（3)的上面圖。 圖2是接續於圖1，用以說明具有本發明的實施形態 的步進孔構造的多層可撓性印刷配線板的製造方法的工程 剖面圖。 圖3是用以說明具有本發明的實施形態的步進孔構造 的多層可撓性印刷配線板的構造的圖，（1)是多層可撓性 印刷配線板的上面圖，（2)是沿著（1)的A-A’線的剖面圖， (3)是沿著（1)的B-B’線的剖面圖。 圖4是沿著圖3(2)的C-C’線的剖面圖。 圖5是表示本發明的實施形態的步進孔洞的變形例的 上面圖。 圖6是表示往本實施形態的多層可撓性印刷配線板之 零件的安裝例的圖，（1 )是安裝有零件的多層可撓性印刷 -28- 201223378 配線板的上面圖，（2)是沿著（1)的A-A’線的剖面圖。 圖7是用以說明具有以往的步進孔構造的堆積型多層 可撓性印刷配線板的構造的圖，（1)是多層可撓性印刷配 線板的上面圖，（2)是沿著（1)的A-A’線的剖面圖，（3)是 沿著（1)的B-B’線的剖面圖。 圖8是用以說明對捲繞狀的兩面覆銅層疊板的g彳呈@ 圖，（1)是兩面覆銅層疊板的上面圖，（2)是兩面覆銅 板與曝光用玻璃遮罩的側面圖。 【主要元件符號說明】 11，2 1 :可撓性絕緣基材 12 ， 13 ， 22 :銅箔 1 4 :兩面覆銅層疊板 15A，15B :電鍍保護層 16，17，28:電解銅電鍍層 1 7 a，5 5 :配線 17b，30，31，52，53，5 4 ：平坦部 18 :兩面電路基材 19，20 :共型遮罩 23 :單面覆銅層疊板 24 :黏著劑層 25，101，102，103，104:步進孔洞 26， l〇la， 102a， 103a - 104a：上孑L 27， l〇lb， 102b， 103b， 104b:下孔 -29- 201223378 29，51A，51B，51C，51D:步進孔 2 9 a，5 1 a :上部層間導電路 2 9b，5 1b :下部層間導電路 32 :多層可撓性印刷配線板 4 1，4 1 A，4 1 B :零件搭載區域 4 2 A，4 2 B :配線區域 43 A，43B :連接部 4 4 :零件 45 :凸塊 5 6 :空隙 61 :(捲繞狀的）兩面覆銅層疊板 62 :捲出滾輪 63 :捲取滾輪 64 :席位區域 65 :製品（多層可撓性印刷配線板） 6 6 :曝光區域-26- S 201223378 As described above, in the present embodiment, the upper hole of the stepping hole is formed in an elliptical shape, and the longitudinal direction thereof is parallel to the winding direction of the winding material of the flexible printed wiring board. Thereby, in the exposure process of forming the common type mask for the stepping holes, even if the flexible base material expands and contracts in the winding direction, a normal stepping hole can be formed. As a result, according to the present embodiment, a multi-layer flexible printed wiring board having a highly reliable stepping hole as an interlayer conductive circuit can be obtained. Further, in the present embodiment, since the upper hole is larger than the conventional step hole, the renewability of the plating solution or the like is increased when the plating layer is formed on the inner wall of the step hole. Therefore, it is possible to form a stepped hole in which the electric ore adheres to a good shape. In other words, according to the present embodiment, a multilayer flexible printed wiring board having a more reliable stepping hole as an interlayer conductive circuit can be obtained. Further, according to the present embodiment, the exposure area can be expanded in the winding direction by the increase in the displacement allowance, and the area of one seat area can be enlarged. Thereby, the number of the multilayer flexible printed wiring boards obtained from one seat area can be increased, and the productivity can be improved. According to the above-described effects of the present embodiment, it is possible to manufacture a multilayer flexible printed wiring board having a small-diameter stepping hole structure inexpensively and stably without introducing a new project or device according to the present invention. Further, the shapes of the upper and lower holes of the stepping hole of the present invention are not limited to the above-described embodiments and modifications. Generally, the difference between the diameter of the common mask 19 (upper hole 26) and the diameter of the common mask 20 (lower hole 27) in the winding direction of the flexible base material is perpendicular to the winding direction. The difference between the diameter of the common type mask 19 (upper hole 26) and the diameter of the common type mask 20 (lower hole 27) -27 - 201223378 is larger. In this way, the displacement tolerance to the winding direction can be increased. According to the above description, the additional effects or various modifications of the present invention are conceivable as long as the person skilled in the art is described. However, the form of the present invention is not limited to the above embodiment. Various additions, modifications, and partial deletions can be made without departing from the scope of the invention and the scope of the spirit of the invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view for explaining a method of manufacturing a multilayer flexible printed wiring board having a stepping hole structure according to an embodiment of the present invention, wherein (1), (2) and (3) are engineering The cross-sectional view, (4) is the above figure corresponding to (3). Fig. 2 is a cross-sectional view showing the construction of a method of manufacturing a multilayer flexible printed wiring board having a stepping hole structure according to an embodiment of the present invention, continued from Fig. 1; 3 is a view for explaining a structure of a multilayer flexible printed wiring board having a stepping hole structure according to an embodiment of the present invention, wherein (1) is a top view of a multilayer flexible printed wiring board, and (2) is along A cross-sectional view of the line A-A' of (1), and (3) is a cross-sectional view taken along line BB' of (1). Fig. 4 is a cross-sectional view taken along line C-C' of Fig. 3 (2). Fig. 5 is a top view showing a modification of the stepping hole according to the embodiment of the present invention. 6 is a view showing an example of mounting a component of the multilayer flexible printed wiring board of the embodiment, and (1) is a top view of a multilayer flexible printed -28-201223378 wiring board on which components are mounted, and (2) It is a sectional view along the line A-A' of (1). FIG. 7 is a view for explaining a structure of a stacked multilayer flexible printed wiring board having a conventional stepping hole structure, wherein (1) is a top view of a multilayer flexible printed wiring board, and (2) is along ( 1) A cross-sectional view of the A-A' line, and (3) is a cross-sectional view taken along line BB' of (1). Fig. 8 is a view showing the upper side of the wound double-sided copper-clad laminate, (1) is a top view of the double-sided copper-clad laminate, and (2) is a double-sided copper-clad laminate and an exposure glass cover. side view. [Explanation of main component symbols] 11, 2 1 : Flexible insulating substrate 12, 13 , 22 : Copper foil 1 4 : Double-sided copper clad laminate 15A, 15B: Electroplated protective layer 16, 17, 28: Electrolytic copper plating 1 7 a, 5 5 : Wiring 17b, 30, 31, 52, 53, 5 4 : Flat portion 18: Two-sided circuit substrate 19, 20: Common mask 23: Single-sided copper clad laminate 24: Adhesive layer 25,101,102,103,104: step hole 26, l〇la, 102a, 103a - 104a: upper L 27, l〇lb, 102b, 103b, 104b: lower hole -29- 201223378 29, 51A, 51B, 51C, 51D: Stepping hole 2 9 a, 5 1 a : Upper interlayer conducting circuit 2 9b, 5 1b : Lower interlayer conducting circuit 32 : Multilayer flexible printed wiring board 4 1,4 1 A, 4 1 B : part mounting area 4 2 A, 4 2 B : wiring area 43 A, 43B : connecting portion 4 4 : part 45 : bump 5 6 : gap 61 : (winding) double-sided copper clad laminate 62 : rolled out Roller 63: take-up roller 64: Seat area 65: Product (multilayer flexible printed wiring board) 6 6 : Exposure area
S -30-S -30-