JP5512578B2 - Manufacturing method of build-up type multilayer flexible circuit board - Google Patents

Description

  The present invention relates to a method for manufacturing a buildup type multilayer circuit board, and more particularly, to a method for manufacturing a buildup type multilayer flexible circuit board having a flexible cable portion.

  In recent years, miniaturization and high functionality of electronic devices have been increasingly promoted, and for this reason, there is an increasing demand for higher density of circuit boards. Therefore, the circuit board is changed from one side to a double sided circuit board or a multilayer circuit board having three or more layers to increase the density.

  FIG. 15 is a cross-sectional process diagram illustrating a conventional method for manufacturing a build-up type multilayer flexible circuit board having a cable portion in an outer layer and an inner layer. First, as shown in FIG. A double-sided copper-clad laminate 94 having conductive layers 92 and 93 such as copper foil on both sides of the conductive insulating base material 91 is prepared.

  Next, as shown in FIG. 15 (2), a circuit pattern 95 such as a cable is formed on the copper foil layers 92 and 93 of the double-sided copper-clad laminate 94 using an ordinary photofabrication technique. The inner layer circuit 96 is formed. Subsequently, as shown in FIG. 15 (3), a cover 99 is formed by bonding a polyimide film 97 to a circuit pattern 95 such as a cable via an adhesive 98, thereby forming a cable portion 100.

  Thereafter, as shown in FIG. 15 (4), a single-sided copper clad laminate 103 having a conductive layer 102 such as a copper foil on one side of the insulating base material 101, and this was punched into a desired shape using a mold or the like. An adhesive 104 for bonding to the cable portion 100 of FIG. 15 (3) is prepared. The thickness of the conductive layer 102 at this time is preferably 50 μm or less, and particularly preferably 35 μm or less. Next, as shown in FIG. 15 (5), the single-sided copper clad laminate 103 and the adhesive material 104 are bonded together and punched into a desired shape using a mold or the like.

  Next, as shown in FIG. 16 (6), the single-sided copper clad laminate 105 of FIG. 15 (5) is laminated on the cable portion 100 of FIG. 15 (3) via the adhesive 104. Subsequently, as shown in FIG. 16 (7), a conduction hole 106 is formed by an NC drill or the like. If necessary, a desmear process for removing smear generated in the conductive hole 106 is performed.

  After that, as shown in FIG. 17 (8), the conductive hole 106 is subjected to electroless plating or conductive treatment, and then the through hole 107 is formed by electroplating. In this case, the plating thickness of the through hole 107 is preferably about 30 to 50 μm in order to ensure reliability.

  Then, as shown in FIG. 17 (9), the circuit pattern 108 is formed on the through-hole surface by using an etching method by a normal photofabrication method, and the cable of the two-stage build-up type multilayer flexible circuit board is formed. An inner layer core substrate 109 having a portion is obtained.

  Next, as shown in FIG. 18 (10), the copper foil 110 (for example, thickness 100 μm) / nickel foil 111 (for example, thickness 1 μm) / copper foil 112 (for example, thickness) described in Patent Documents 1 and 2 is used. A metal substrate 113 having a three-layer structure of 10 μm) is prepared. The nickel foil 111 at this time is an etching stopper at the time of copper etching, and is not limited to the nickel foil.

  Next, as shown in FIG. 18 (11), the copper foil layers 110 and 112 on both sides of the metal base 113 are conical (conical frustoconical) using an etching method by a normal photofabrication method. A resist layer 114 for forming the conductive protrusions is formed.

  Subsequently, as shown in FIG. 18 (12), using the resist layer 114, the copper foil layers 110 and 112 on both sides of the metal base 113 are etched using a conventional photofabrication technique. A conductive protrusion 115 is formed. As the etchant at this time, an etchant having selectivity is used.

  Thereafter, as shown in FIG. 18 (13), the resist layer 114 is peeled off, and the nickel foil 111 is removed using an etching solution having selectivity described in Patent Document 2. On the copper foil layer 112, the metal base material 116 having the conductive projection 115 in the shape of a cone is obtained.

  Next, as shown in FIG. 18 (14), flexibility having adhesive layers 118 having flexibility and adhesiveness such as thermoplastic polyimide on both surfaces of a flexible base film 117 such as polyimide film. A base insulating material 119 is prepared.

  Next, as shown in FIG. 19 (15), the flexible base insulating material 119 was thermocompression bonded to the metal substrate 116 at a temperature at which the adhesiveness was not exhibited by lamination. As another method for forming the flexible base insulating material 119, casting, coating, or the like can be applied, and an optimal method is selected depending on the type and form (varnish, film) of the insulating resin. Subsequently, as shown in FIG. 19 (16), the top portion 120 of the conductive protrusion 115 on the metal base material 116 is exposed by CMP, mechanical polishing, etc., and the circuit base material 121 is obtained. Thereafter, as shown in FIG. 19 (17), the circuit substrate 121 is laminated on the circuit substrate 109 obtained in the steps up to FIG. 17 (9).

  Next, as shown in FIG. 20 (18), a circuit pattern 122 such as a cable is formed on the laminated copper foil 112 of the circuit substrate 121 using an etching method based on a normal photofabrication method. As the etchant at this time, an etchant having selectivity is used.

  In this case, a resist layer must be formed and exposed to the circuit substrate 121 having a hollow structure, and there is a concern about delamination at the time of resist formation, and the clearance between the resist and the photomask at the time of exposure. Therefore, it is difficult to form a fine circuit with a high yield.

  Next, as shown in FIG. 20 (19), a cover 125 is formed by bonding a polyimide film 123 to a circuit pattern 122 such as a cable through an adhesive 124, and a cable portion 126 is formed. Further, a cover film or a photo solder resist 127 is formed on other component mounting portions.

Here, it is difficult to attach the cover 125 to the cable having a hollow structure, and as shown in FIG. 20 (19), poor adhesion such as delamination tends to occur. Thereafter, surface treatment such as solder plating, nickel plating, and gold plating is performed on the substrate surface as necessary, and external processing is performed to obtain a build-up type multilayer flexible circuit board 128 having cable portions on the outer layer and the inner layer.
JP 2002-141629 A JP 2003-129259 A

  It is an object of the present invention to provide a method for manufacturing a multilayer flexible circuit board with high productivity without causing poor bonding of the cover film.

  In order to achieve the above object, the present invention has the following features.

According to the present invention,
A method of manufacturing a multilayer flexible circuit board having a build-up part having a plurality of layers, in which a cable part connected with an interlayer by a conductive protrusion is laminated on at least one outer layer on which a circuit pattern is formed on an inner layer core board In
a) preparing a first base material having a three-layer structure, the first base material having a first circuit pattern on one surface ;
b) preparing a second base material having a three-layer structure, the first base material having a first conductive protrusion standing on one side for use in interlayer connection ;
c) a step of exposing a top portion of the first conductive protrusion after thermo-compression bonding of the adhesive insulating resin to the second base material ;
d) A circuit in which the first circuit pattern and the first conductive protrusion are electrically connected by thermocompression bonding the first base material and the second base material to form a cable portion. Forming a substrate ;
e) a step of newly forming a second conductive protrusion on one surface of the circuit substrate on the first substrate side;
f) forming a flexible interlayer insulating resin layer to be the cable portion on the surface on which the second conductive protrusion is formed;
g) Using the flexible interlayer insulating resin layer as a mask layer for protecting the second conductive protrusion, a second circuit pattern on the surface of the circuit substrate opposite to the flexible interlayer insulating resin layer Forming a process,
h) forming a cover on the second circuit pattern;
i) exposing the top of the second conductive protrusion;
j) Laminating a circuit base material to be the cable portion after forming the second circuit pattern on which the second conductive protrusion having the flexible interlayer insulating resin layer is formed on the inner core substrate. ,
A method for producing a multilayer flexible circuit board, characterized by comprising:
Is to provide.

  Due to these features, the present invention has the following effects.

  According to the present invention, it is possible to form a fine circuit pattern on the cable portion of the outer layer without using a complicated process, and it is possible to place the cable on the inner layer core substrate without fear of bonding failure such as delamination of the cover. .

Further, according to the present invention , it is possible to select and stack a pre-made good two-stage build-up portion and a good inner layer core substrate, and it is possible to manufacture the build-up portion and the inner core substrate in separate steps.

  Due to the above effects, a multilayer flexible circuit board having a cable portion on the outer layer can be provided stably and inexpensively with high productivity.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

Embodiment 1

1 to 6 are cross-sectional process diagrams illustrating a manufacturing method of a build-up type multilayer flexible circuit board having a cable portion in an inner layer in a reference example of the present invention. In this method, first, as shown in FIG. 1A, a so-called double-sided copper-clad laminate 4 having conductive layers 2 and 3 such as copper foil on both surfaces of a flexible insulating base material 1 such as polyimide is provided. prepare.

  Next, as shown in FIG. 1 (2), a circuit pattern 5 such as a cable is formed on the copper foil layers 2 and 3 of the double-sided copper-clad laminate 4 by using an etching method based on a normal photofabrication method. To form an inner layer circuit 6. Next, as shown in FIG. 1 (3), a cover 9 is formed by bonding a polyimide film 7 to a circuit pattern 5 such as a cable via an adhesive 8, and a cable portion 10 is formed.

  Subsequently, as shown in FIG. 1 (4), a so-called single-sided copper-clad laminate 13 having a conductive layer 12 such as a copper foil on one side of the insulating base material 11, and this is punched into a desired shape by a mold or the like. An adhesive 14 is prepared for bonding to the processed cable portion 10 in FIG. The thickness of the conductive layer 12 at this time is preferably 50 μm or less, and particularly preferably 35 μm or less.

  Thereafter, as shown in FIG. 1 (5), the single-sided copper-clad laminate 13 and the adhesive material 14 are bonded together and punched into a desired shape using a mold or the like.

  Next, as shown in FIG. 2 (6), the single-sided copper clad laminate 15 of FIG. 2 (5) is laminated on the cable portion 10 of FIG. 2 (3) via an adhesive 14. Next, as shown in FIG. 2 (7), the conduction hole 16 is formed by an NC drill or the like. If necessary, a desmear process for removing smear generated in the conduction hole 16 is performed.

  Subsequently, as shown in FIG. 3 (8), the through hole 17 is formed by electroplating after the electroconductive plating 16 is subjected to electroless plating or conductive treatment. The plating thickness of the through hole 17 at this time is preferably about 30 to 50 μm in order to ensure reliability.

  Thereafter, as shown in FIG. 3 (9), a circuit pattern 18 is formed on the through-hole surface by using an etching method by a normal photofabrication method, and a two-stage build-up type multilayer flexible circuit board is formed. An inner layer core substrate 19 having a cable portion is obtained.

  Next, as shown in FIG. 4 (10), a metal substrate having a three-layer structure of copper foil 20 (for example, thickness 100 μm) / nickel foil 21 (for example, thickness 1 μm) / copper foil 22 (for example, thickness 10 μm). A material 23 is prepared. The nickel foil 21 at this time is an etching stopper at the time of copper etching, and is not limited to the nickel foil.

  Next, as shown in FIG. 4 (11), conical-shaped conductive protrusions are formed on the copper foil layers 20 and 22 on both surfaces of the metal base 23 by using an etching method by a normal photofabrication method. A resist layer 24 is formed.

  Subsequently, as shown in FIG. 4 (12), using the resist layer 24, the copper foil layers 20 and 22 on both surfaces of the metal base 23 are etched using a conventional photofabrication technique. A conductive protrusion 25 is formed. As an etching solution at this time, for example, ferric chloride which is an acidic etching solution or an ammonium hydroxide solution which is an alkaline etching solution is used.

  Thereafter, as shown in FIG. 4 (13), the resist layer 24 is peeled off, and the nickel foil 21 is oxidized with a selective etching solution, for example, ferric chloride which is an acidic etching solution or a hydroxide which is an alkaline etching solution. Remove with ammonium solution. On the copper foil layer 22, a metal substrate 26 having a conductive projection 25 in the shape of a coneide (a truncated frustoconical shape) is obtained. Next, as shown in FIG. 4 (14), a flexible base having adhesive layers 28 having flexibility and adhesiveness such as thermoplastic polyimide on both surfaces of a flexible base film 27 such as polyimide film. An insulating material 29 is prepared.

  Next, as shown in FIG. 5 (15), the flexible base insulating material 29 was thermocompression bonded to the metal substrate 26 at a temperature at which the adhesiveness was not exhibited by lamination. Casting, coating, and the like can be applied as other flexible base insulating material 29 forming methods, and an optimal method is selected depending on the type and form (varnish, film) of insulating resin.

  Subsequently, as shown in FIG. 5 (16), a resist layer 30 for forming a circuit pattern such as a cable on the copper foil layer 22 of the base material 26 by using an etching method by a normal photofabrication method. Form. At this time, the pair of copper foil layers 22 are protected from the etching solution by the flexible base insulating material 29 formed on the metal base 26 in FIG. If it is this form, since the method of forming a circuit pattern in a single-sided copper clad laminated board is applicable as it is, fine circuit formation can also be performed with a sufficient yield.

  Thereafter, as shown in FIG. 5 (17), a circuit pattern 31 such as a cable is formed by using a resist layer 30 and an etching method by a normal photofabrication method, and the resist layer 30 is peeled off to form a circuit. A substrate 32 is obtained.

  Next, as shown in FIG. 5 (18), the cover 35 is formed by bonding a polyimide film 33 to the circuit pattern 31 such as a cable of the circuit substrate 32 via an adhesive 34. Also in this case, the cover can be easily formed as in the case of manufacturing a single-sided circuit board. Next, as shown in FIG. 5 (19), the top portion 36 of the conductive protrusion 25 on the metal substrate 26 is exposed by CMP, mechanical polishing or the like to obtain a circuit substrate 37 having a cable portion.

Subsequently, as shown in FIG. 6 (20), prepared as the circuit substrate 37 having a cable portion, an inner layer core substrate 19 having a cable portion obtained in the steps up to FIG. (9).

  Thereafter, as shown in FIG. 6 (21), the die-cut circuit base material 37 is laminated on the inner layer core substrate 19 having the cable portion obtained in the steps up to FIG. 3 (9). A cover film or a photo solder resist 38 is formed on other component mounting portions. Thereafter, surface treatment such as solder plating, nickel plating, and gold plating is performed on the substrate surface as necessary, and external processing is performed to obtain a build-up type multilayer flexible circuit substrate 39 having cable portions on the outer layer and the inner layer.

Embodiment 2

7 to 14 are cross-sectional process diagrams showing the manufacturing method of the embodiment of the present invention. In this method, first, as shown in FIG. 7A, a double-sided copper clad laminate 44 having conductive layers 42 and 43 such as copper foil on both sides of an insulating base material 41 is prepared.

  Next, as shown in FIG. 7B, a circuit pattern 45 is formed on the copper foil layers 42 and 43 of the double-sided copper-clad laminate 44 by using an etching method based on a normal photofabrication method. The inner layer circuit 46 is used.

  Next, as shown in FIG. 7 (3), a so-called single-sided copper-clad having a conductive layer 48 such as a copper foil on one side of an adhesive interlayer insulating resin 47 having adhesiveness such as glass epoxy prepreg in a B-stage state. A laminated plate 49 is prepared.

  Subsequently, as shown in FIG. 7 (4), the single-sided copper-clad laminate 49 of FIG. 3 (3) is bonded to both surfaces of the inner layer circuit 46 of FIG. 2 (2) with adhesion such as glass epoxy prepreg. Bonding and bonding via a conductive interlayer insulating resin 47.

  After that, as shown in FIG. 8 (5), the base material in which the single-sided copper clad laminate 49 is bonded to both surfaces of the inner layer circuit 46 in FIG. 7 (4) is punched into a desired shape using a mold or the like. Next, as shown in FIG. 8 (6), a conduction hole 51 is formed in the base material punched in FIG. 8 (5) using an NC drill or the like. Note that the conduction hole 51 may be formed before the punching process of FIG.

  Next, as shown in FIG. 8 (7), the through hole 52 is formed by electroplating after conducting the electroless plating or the conductive treatment on the conduction hole 51.

  Subsequently, as shown in FIG. 9 (8), a circuit pattern 53 is formed on the through-hole surface by using an etching method by a normal photofabrication method, and the inner core of the build-up type multilayer flexible circuit board is formed. A substrate 54 is obtained.

  Thereafter, as shown in FIG. 10 (9), the metal base having a three-layer structure of copper foil 55 (for example, thickness 100 μm) / nickel foil 56 (for example, thickness 1 μm) / copper foil 57 (for example, thickness 10 μm). A material 58 is prepared. The nickel foil 56 at this time is an etching stopper at the time of copper etching, and is not limited to the nickel foil. When repeated bending or the like is required, a special electrolytic foil or rolled copper foil having excellent flexibility is preferably used for the copper foil 57 serving as the cable portion.

  Next, as shown in FIG. 10 (10), a resist layer 59 for forming a circuit pattern is formed on the copper foil layer 57 of the metal substrate 58 by using an etching method based on a normal photofabrication method. Form.

  Next, as shown in FIG. 10 (11), a circuit pattern 60 including a cable portion is formed by using an etching technique based on a photofabrication technique. As an etchant at this time, ferric chloride as an acidic etchant or an ammonium hydroxide solution as an alkaline etchant is used as an etchant having selectivity. Subsequently, as shown in FIG. 10 (12), the resist layer 59 is peeled off to obtain a substrate 61 having a circuit pattern 60.

  Thereafter, as shown in FIG. 10 (13), the metal base having a three-layer structure of copper foil 62 (for example, thickness 100 μm) / nickel foil 63 (for example, thickness 1 μm) / copper foil 64 (for example, thickness 10 μm). A material 65 is prepared. The nickel foil 63 at this time is an etching stopper at the time of copper etching, and is not limited to the nickel foil. When repeated bending or the like is required, a special electrolytic foil or rolled copper foil having excellent flexibility may be used for the copper foil 64 serving as the cable portion. Further, it is preferable that the thickness of the copper foil is equal to that of the copper foil 57.

  Next, as shown in FIG. 11 (14), a resist for forming a conical-shaped conductive protrusion on the copper foil layer 62 of the metal substrate 65 by using an etching method by a normal photofabrication method. Layer 66 is formed.

  Next, as shown in FIG. 11 (15), a conical-shaped conductive protrusion 67 is formed by using a resist layer 66 and using an etching method by a normal photofabrication method. As an etching solution at this time, ferric chloride which is an acidic etching solution or an ammonium hydroxide solution which is an alkaline etching solution is used as an etching solution having selectivity. The resist layer 66 is peeled off, and the substrate 68 on which the conductive protrusions are erected is obtained through the steps so far.

  Subsequently, as shown in FIG. 11 (16), an adhesive insulating resin layer 69 such as a liquid crystal polymer or polyimide having flexibility and adhesiveness is laminated on the base material 68 on which the conductive protrusions are erected. The adhesive insulating resin layer 69 was thermocompression bonded at a temperature at which the adhesiveness was not exhibited. As another method for forming the adhesive insulating resin layer 69, casting, coating, or the like can be applied, and an optimal method is selected depending on the type and form (varnish, film) of the insulating resin. Further, the top portion 70 of the conductive protrusion 67 on the base material 68 on which the conductive protrusion is erected is exposed by CMP, mechanical polishing or the like, and the circuit base material 71 is obtained.

  Thereafter, as shown in FIG. 11 (17), the circuit base 71 formed in FIG. 11 (16) is thermocompression bonded to the base 61 having the circuit pattern 60 formed in FIG. Thus, the circuit base material 72 to be the cable portion is obtained. At this time, the circuit pattern 60 is completely filled with the adhesive insulating resin 69. This adhesive insulating resin 69 becomes a flexible base material of the cable portion. At this time, the conductive protrusion 67 of the circuit base 71 formed in FIG. 11 (16) is electrically connected to the circuit pattern 60 of the base 61 formed in FIG. 10 (12). Since the copper foil 55 of the circuit substrate 72 is smooth, not only can the conductive protrusions 67 be sufficiently deformed, but also sufficient adhesion can be obtained for the circuit pattern 60 including the cable.

  Next, as shown in FIG. 11 (18), the copper foil layer 55 of the circuit base 72 is etched using a conventional photofabrication technique to form a conical conductive protrusion and an interlayer insulating resin cable. A resist layer 73 is formed to form wall-like conductive protrusions that prevent flow out to the part.

  Next, as shown in FIG. 12 (19), using the resist layer 73, a cone-shaped conductive protrusion 74 is formed by an etching method using a normal photofabrication method. As an etching solution at this time, ferric chloride which is an acidic etching solution or an ammonium hydroxide solution which is an alkaline etching solution is used as an etching solution having selectivity. In order to improve the density of the conductive protrusions, the conductive protrusions 67 and the conductive protrusions 74 can be formed on the same axis as necessary. Subsequently, as shown in FIG. 12 (20), the resist layer 73 is peeled off.

  Thereafter, as shown in FIG. 12 (21), the nickel foil 56 is removed using an etching solution having selectivity described in Patent Document 2. The base material 75 on which the conductive protrusion 74 is erected is obtained through the steps so far.

  Next, as shown in FIG. 12 (22), an adhesive insulating resin layer 76 such as a polyimide having flexibility and adhesiveness that serves as a cover of the cable portion, and an adhesive insulating resin 77 such as a prepreg in a B stage state. Prepare a die-cut one.

  Next, as shown in FIG. 12 (23), the adhesive insulating resin layer 76 such as polyimide is made adhesive by laminating the adhesive insulating resin layer 76 on the base material 75 on which the conductive protrusions are erected, and B The adhesive insulating resin 77 such as a prepreg in a stage state was subjected to thermocompression bonding at a temperature at which the adhesiveness was not exhibited. By this process, the flexible base insulating material 78 (adhesive insulating resin layer 76 + adhesive insulating resin 77) was formed on the base material 75.

  Subsequently, as shown in FIG. 13 (24), a resist layer 79 for forming a circuit pattern such as a cable on the copper foil layer 64 of the base material 75 by using an etching method based on a normal photofabrication method. Form. At this time, the pair of copper foil layers 64 are protected from the etchant by the flexible base insulating material 78 formed on the base 75 in FIG. If it is this form, since the method of forming a circuit pattern in a single-sided copper clad laminated board is applicable as it is, fine circuit formation can also be performed with a sufficient yield.

  Thereafter, as shown in FIG. 13 (25), a circuit pattern 80 such as a cable is formed by using a resist layer 79 and an etching method by a normal photofabrication method, the resist layer 79 is peeled off, and a circuit is formed. A substrate 81 is obtained.

  Next, as shown in FIG. 13 (26), a cover 84 is formed by laminating a polyimide film 82 with a bonding material 83 on a circuit pattern 80 such as a cable of the circuit substrate 81. Also in this case, the cover can be easily formed as in the case of manufacturing a single-sided circuit board. Next, as shown in FIG. 13 (27), the top portion 85 of the conductive protrusion 74 on the substrate 75 is exposed by CMP, mechanical polishing, or the like to obtain a circuit substrate 86 having a cable portion.

  Subsequently, as shown in FIG. 14 (28), the die-cut circuit base material 87 is laminated on the inner layer core substrate 54 obtained through the steps up to (8) in FIG.

  Thereafter, as shown in FIG. 14 (29), after lamination, a cover film or a photo solder resist 88 is formed on other component mounting portions. Thereafter, surface treatment such as solder plating, nickel plating, and gold plating is performed on the substrate surface as necessary, and external processing is performed to obtain a build-up type multilayer flexible circuit wiring board 89 having a double-sided cable portion on the outer layer.

The conceptual cross-sectional block diagram which shows process (1) thru | or (5) of the manufacturing method by the reference example of this invention. The conceptual cross-sectional block diagram which shows process (6) thru | or (7) of the manufacturing method by the reference example of this invention. The conceptual cross-section block diagram which shows process (8) thru | or (9) of the manufacturing method by the reference example of this invention. The conceptual cross-section block diagram which shows process (10) thru | or (14) of the manufacturing method by the reference example of this invention. The conceptual cross-sectional block diagram which shows process (15) thru | or (19) of the manufacturing method by the reference example of this invention. The conceptual cross-section block diagram which shows process (20) thru | or (21) of the manufacturing method by the reference example of this invention. The conceptual cross-sectional block diagram which shows process (1) thru | or (4) of the manufacturing method by the Example of this invention. The conceptual cross-sectional block diagram which shows process (5) thru | or (6) of the manufacturing method by the Example of this invention. The conceptual cross-sectional block diagram which shows process (7) thru | or (8) of the manufacturing method by the Example of this invention. The conceptual cross-sectional block diagram which shows process (9) thru | or (13) of the manufacturing method by the Example of this invention. The conceptual cross-sectional block diagram which shows process (14) thru | or (18) of the manufacturing method by the Example of this invention. The conceptual cross-section block diagram which shows process (19) thru | or (23) of the manufacturing method by the Example of this invention. The conceptual cross-section block diagram which shows process (24) thru | or (27) of the manufacturing method by the Example of this invention. The conceptual cross-sectional block diagram which shows process (28) thru | or (29) of the manufacturing method by the Example of this invention. The conceptual cross-section block diagram which shows process (1) thru | or (5) of the manufacturing method of the conventional flexible circuit board. The conceptual cross-section block diagram which shows process (1) thru | or (5) of the manufacturing method of the conventional flexible circuit board. The conceptual cross-section block diagram which shows process (6) thru | or (7) of the manufacturing method of the conventional flexible circuit board. The conceptual cross-section block diagram which shows process (8) thru | or (9) of the manufacturing method of the conventional flexible circuit board. The conceptual cross-section block diagram which shows process (10) thru | or (14) of the manufacturing method of the conventional flexible circuit board. The conceptual cross-section block diagram which shows process (15) thru | or (17) of the manufacturing method of the conventional flexible circuit board.

DESCRIPTION OF SYMBOLS 1 Flexible insulating base material 2 Copper foil layer 3 Copper foil layer 4 Double-sided copper clad laminated board 5 Circuit pattern 6 Inner layer circuit 7 Polyimide film 8 Adhesive 9 Cover 10 Cable part 11 Flexible insulating base material 12 Copper foil layer 13 Single-sided copper-clad laminate 14 Adhesive 15 Die-cut single-sided copper-clad laminate 16 Conductive hole 17 Through hole 18 Circuit pattern 19 Inner layer core substrate 20 Copper foil 21 Nickel foil 22 Copper foil 23 Metal substrate 24 Resist layer 25 Conductivity Substrate 26 on which conductive protrusions are formed Flexible base film 28 Adhesive layer (thermoplastic polyimide)
29 Flexible base insulating material 30 Resist layer 31 Circuit pattern 32 Circuit base material 33 Polyimide film 34 Adhesive material 35 Cover 36 Top portion of conductive protrusion 37 Circuit base material 38 Photo solder resist 39 Cable portions are formed on the outer layer and the inner layer according to the present invention. Build-up type multilayer flexible circuit board 41 Flexible insulating base material 42 Copper foil layer 43 Copper foil layer 44 Double-sided copper-clad laminate 45 Circuit pattern 46 Inner layer circuit 47 Adhesive interlayer insulation resin 48 Conductive layer 49 Single-sided copper-clad laminate 50 Punched base material 51 Conductive hole 52 Through hole 53 Circuit pattern 54 Inner layer core substrate 55 Copper foil 56 Nickel foil 57 Copper foil 58 Metal base material 59 Resist layer 60 Circuit pattern 61 Base material 62 having circuit pattern Copper foil 63 Nickel foil 64 Copper foil 65 Metal base material 66 Resist layer 67 Conide Conductive protrusion 68 Base material 69 on which conductive protrusion is erected Adhesive insulating resin 70 Top portion 71 of conductive protrusion 72 Circuit base material 72 Circuit base material 73 serving as cable portion Resist layer 74 Conical conductive protrusion 75 Circuit base Material 76 Flexible insulating resin layer 77 such as polyimide 77 Die cut insulating insulating resin layer 78 such as prepreg Flexible base insulating material 79 Resist layer 80 Circuit pattern 81 Circuit substrate 82 Polyimide film 83 Adhesive material 84 Cover 85 Top part 86 of conductive protrusion Circuit base 87 having cable part Die cut circuit base 88 Photo solder resist 89 Build-up type multilayer flexible circuit board 91 having cable part on outer layer Flexible insulating base material 92 Copper foil layer 93 Copper foil layer 94 Double-sided copper-clad laminate 95 Circuit pattern 96 Inner layer circuit 97 Polyimide film 98 Adhesive 99 Bar 100 Cable portion 101 Flexible insulating base material 102 Copper foil layer 103 Single-sided copper-clad laminate 104 Adhesive 105 Die-cut single-sided copper-clad laminate 106 Conductive hole 107 Through hole 108 Circuit pattern 109 Inner core substrate 110 Copper Foil 111 Nickel foil 112 Copper foil 113 Metal base material 114 Resist layer 115 Conide-like conductive protrusion 116 Metal base material 117 Flexible base film 118 adhesive layer (thermoplastic polyimide)
119 Flexible Base Insulating Material 120 Top of Conductive Protrusion 121 Circuit Base 122 Circuit Pattern 123 Polyimide Film 124 Adhesive 125 Cover 126 Circuit Base 127 Photo Solder Resist 128 Build-up Type Multilayer Flexible Circuit Board by Conventional Method

Claims (3)

A method of manufacturing a multilayer flexible circuit board having a build-up part having a plurality of layers, in which a cable part connected with an interlayer by a conductive protrusion is laminated on at least one outer layer on which a circuit pattern is formed on an inner layer core board In
a) preparing a first base material having a three-layer structure, the first base material having a first circuit pattern on one surface ;
b) preparing a second base material having a three-layer structure, the first base material having a first conductive protrusion standing on one side for use in interlayer connection ;
c) a step of exposing a top portion of the first conductive protrusion after thermo-compression bonding of the adhesive insulating resin to the second base material ;
d) A circuit in which the first circuit pattern and the first conductive protrusion are electrically connected by thermocompression bonding the first base material and the second base material to form a cable portion. Forming a substrate ;
e) a step of newly forming a second conductive protrusion on one surface of the circuit substrate on the first substrate side;
f) forming a flexible interlayer insulating resin layer to be the cable portion on the surface on which the second conductive protrusion is formed;
g) Using the flexible interlayer insulating resin layer as a mask layer for protecting the second conductive protrusion, a second circuit pattern on the surface of the circuit substrate opposite to the flexible interlayer insulating resin layer Forming a process,
h) forming a cover on the second circuit pattern;
i) exposing the top of the second conductive protrusion;
j) Laminating a circuit base material to be the cable portion after forming the second circuit pattern on which the second conductive protrusion having the flexible interlayer insulating resin layer is formed on the inner core substrate. ,
A method for manufacturing a multilayer flexible circuit board, comprising: In the method for producing a multilayer flexible circuit board according to claim 1,
A method for producing a multilayer flexible circuit board, wherein the adhesive insulating resin is a single layer of thermoplastic or thermosetting polyimide or liquid crystal polymer, or a multilayer comprising a combination of other adhesive resins. In the method for producing a multilayer flexible circuit board according to claim 1,
In the metal foil formed on the base material provided with the conductive protrusions to be the cable portion, at least one of the conductive protrusion and the metal foil formed on the base material provided with the conductive protrusions is rolled copper. A method for producing a multilayer flexible circuit board, comprising a foil.

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