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Multilayer printed wiring board and process for producing the sameRelated Patent Categories: Electricity: Conductors And Insulators, Conduits, Cables Or Conductors, Preformed Panel Circuit Arrangement (e.g., Printed Circuit), With Particular Conductive Connection (e.g., Crossover), FeedthroughMultilayer printed wiring board and process for producing the same description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060180344, Multilayer printed wiring board and process for producing the same. Brief Patent Description - Full Patent Description - Patent Application Claims
TECHNICAL FIELD [0001] The present invention relates to a multi-layer wiring board and a method for manufacturing the same. BACKGROUND ART [0002] Recent electronic apparatuses have been made smaller and light weight in addition to developments in the applicability to high-frequency signals and digitized devices, and along with these developments, there have been demands for small-size devices, a high-density packaging property and the like in printed circuit boards being installed in the electronic apparatuses. [0003] There is a rigid flex printed circuit board satisfying these demands which includes a rigid portion and a flex portion (for example, Japanese Patent Application Laid Open Publication No. 2002-158445). [0004] With reference to FIGS. 1A to 2B, a manufacturing process of a conventional rigid flex printed circuit board will be described bellow. FIGS. 1A to 1D are flow charts that show manufacturing processes of the rigid flex printed circuit board. FIG. 2A is a perspective view that shows the substrate and the like shown in FIGS. 1A and 1B and FIG. 2B is a perspective view of a rigid flex wiring board shown in FIG. 1D. [0005] As shown in FIG. 1A, wiring circuits 104 are formed by a subtractive method on both of the surfaces of a flex substrate 101 made of a polyimide film, both of the surfaces of an inner-layer rigid substrate 102 made from a prepreg and the like, and one surface of an outer layer rigid substrate 103. [0006] Substantially, as shown in FIG. 1A and FIG. 2A, flex-portion exposing holes 109 are formed through a bonding sheet 105, the inner-layer rigid substrate 102 and the outer-layer rigid substrate 103, by using a press-punching process and the like. Next, a flex-substrate-use cover layer 106, the inner-layer rigid substrate 102, the bonding sheet 105 and the outer-layer rigid substrate 103 are superposed and placed on the surface and rear surface of the flex substrate 101, and subjected to a laminating process to prepare a laminated member 100 shown in FIG. 1B. In this case, as shown in FIG. 2A, a peripheral portion of a portion (for example, indicated by 103a) that forms a circuit board upon completion of the processes is punched out so that the portion (for example, 103a) to form the circuit board is joined to a frame member (for example, 103b) by using a micro-joint (for example, 103c). [0007] Next, as shown in FIG. 1C, the laminated member 100 is subjected to a drilling process, a plating process and etching so that a through hole 107, an outer-layer wiring circuit 108 and the like are formed therein. [0008] Lastly, the micro-joints (for example, 103c), which have joined a rigid portion B and a flex portion A to the frame member (for example, 103b), are simultaneously punched out by using a die so that a rigid flex printed circuit board 110, shown in FIGS. 1D and 2B, is obtained. In this case, the frame member (for example, 103b) for the substrates 101, 102 and 103 and portions that have been punched out so as to form the substrates 101 are disposed. [0009] Moreover, those circuit boards having an arrangement in which a built-up layer is formed on the surface layer of the rigid flex printed circuit board, and interlayer-connected thereto through IVHS (Interstitial Via Holes) and SVHS (Surface Via Holes) have also been proposed. DISCLOSURE OF INVENTION [0010] However, according to the conventional rigid flex printed circuit board and the manufacturing method thereof, after the lamination of the rigid portion, the outer shapes of the rigid portion and the flex portion need to be simultaneously cut out (a cutting process). Therefore, it is necessary to use substrates having sufficient margin portions required for positioning processes for the respective substrates. Moreover, in most of cases, after the cutting process, these margin portions are disposed as the frame members. In other words, in the conventional rigid flex printed circuit board, since the rigid portion needs to be laminated at a predetermined position of the flex substrate, assembling processes of the rigid portions on the inner layer and outer layer rigid substrates, which are carried out so as to place the rigid portions at predetermined positions on the flex substrate when formed as laminated layers, are limited by factors such as an outer shape and positions of the flex substrate. In other words, even when an attempt is made so as to carry out a laminating process only on one portion of the flex substrate, it is necessary to prepare an assembling-use member that is as large as the flex substrate. [0011] For this reason, excessive multi-layered areas exist on the rigid portion, causing wasteful material costs. Further, there is a limitation in positions in which multi-layered areas are placed, resulting in little design freedom for wiring. [0012] The present invention has been devised to solve the above-mentioned problems, and the first objective thereof is to provide a multi-layer wiring board which provides higher design freedom for wiring, and makes it possible to cut material costs, and also to reduce the substrate capacity, and a manufacturing method for such a wiring board. [0013] In order to achieve the above-mentioned objects, according to a first aspect of a multi-layer wiring board, wherein at least one base material with wiring circuit being preliminarily formed into a predetermined outer shape is bonded to a motherboard, and the base material on the motherboards are electrically connected to each other through at least an inner via hole. [0014] Moreover, conventionally, when a substrate that includes a plurality of substrates with single-sided wiring circuits is bent, a separation tends to occur between the substrates due to inter-layer stress of the layers of the motherboard printed substrate and the substrate with single-sided wiring circuits or between the layers of the laminated substrates with single-sided wiring circuits. [0015] Therefore, a second object of the present invention is to provide a multi-layer wiring board which has higher anti-bending strength (peel strength) as compared with the conventional substrate, and a manufacturing method for such a wiring board [0016] In order to achieve this objective, according to a second aspect of a multi-layer wiring board, wherein two or more substrates, each of which has been preliminarily formed into a predetermined outer shape with single-sided wiring circuit formed thereon, are laminated and bonded to a motherboard, and at least one inter-layer portion thereof is electrically connected through an inner via hole, and in this arrangement, the two or more laminated substrates, each with single-sided wiring circuit formed thereon, are positioned in a manner so as to place the outer shape of a second substrate bonded to the first substrate inside the outer shape of the first substrate being bonded to the motherboard side [0017] Moreover, in the case when a circuit substrate that allows double-sided assembling processes is formed by using the conventional manufacturing method, a double-sided circuit substrate is required as a core substrate. In the case, however, as described above, upon forming a conductive pattern, most of the conductive layer on one side needs to be removed, resulting in wasteful use of materials and resources. Another problem is that complex manufacturing processes are required to form through holes and the like. [0018] Therefore, a third object of the present invention is to provide a circuit substrate that allows double-sided packaging processes so that electronic parts can be assembled on double sides by using a single-sided circuit substrate as a core substrate (main circuit substrate), that is, as a motherboard [0019] In order to achieve this object, according to a third aspect of a multi-layer wiring board, wherein at least one portion of an insulating base material of a main single-sided circuit substrate having a conductive pattern on one surface of the insulating substrate is partially removed so that the rear face of the conductive pattern is exposed at the removed portion, and from the other side of the insulating base material of the main single-sided circuit substrate, an electronic part is laminated with the main single-sided circuit substrate with the rear-face exposed portion of the conductive pattern of the main single-sided circuit substrate is electrically connect with the electrical part, and/or a single-sided circuit board for multi-layer wiring board having an interlayer conductive portion and a conductive pattern formed on one face of an insulating base material is laminated with the main single-sided circuit substrate with the rear-face exposed-portion of the conductive pattern is electrically connect with the single-sided circuit board for multi-layer wiring board. [0020] Furthermore, the conventional printed wiring board that allows double-sided packaging processes uses a double-sided copper coat laminated plate (double-sided CCL) as a starting member for a relay board. In this technique, however, since plated through holes are used, time-consuming complex metal plating processes are required, and the thickness of a copper foil of the double-sided CCL tends to increase, causing the problem that it is difficult to form a fine pattern through chemical etching. Moreover, it is difficult to form a via hole to the upper layer or the like right above a through hole, and circuit designing is, ipso, restricted. [0021] In order to solve this problem, a fourth object of the present invention is to provide a multi-layer wiring board that allows double-sided packaging processes so that electronic parts can be assembled on double sides by using a base material with single-sided circuit substrate formed thereon as a starting member for a relay board, and a manufacturing method for such a multi-layer wiring board Continue reading about Multilayer printed wiring board and process for producing the same... Full patent description for Multilayer printed wiring board and process for producing the same Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Multilayer printed wiring board and process for producing the same patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. 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