JPWO2009069683A1 - Manufacturing method of multilayer printed wiring board - Google Patents

Abstract

A method for exposing an inner layer in a multilayer printed wiring board is provided. In this method, the first wiring pattern 3 is formed on at least one surface 2 a of the first insulating layer 2, and the exposed region 11 exposing the first wiring pattern 3 on the first insulating layer 2 is exposed to alkali. A soluble ink layer 13 is formed. Further, the second insulating layer 4 is formed on the surface of the first insulating layer 2 on the ink layer forming side so that the ink layer 13 is exposed from the second insulating layer 4, and the second insulating layer 4 is formed. A metal layer 14 is formed on the layer 4, the metal layer 14 is patterned to form a second wiring pattern 5, the ink layer 13 is dissolved and removed with an alkaline solution, and the first insulation of the exposed region 11 is formed. The layer 2 and the first wiring pattern 3 are exposed.

Description

  The present invention relates to a method for manufacturing a multilayer printed wiring board in which a part of an inner layer is exposed.

  The multilayer printed wiring board is required to have a partially different number of structural layers due to the recent demand for smaller, lighter, and more sophisticated electronic devices. For example, for the purpose of increasing the degree of freedom in device design, there is a flex-rigid printed wiring board in which multilayer rigid boards are connected to each other with a flexible board cable without using a connector to form an integrated structure. Further, as a package application, it is required to reduce the height, and a part where a semiconductor element is mounted has a so-called cavity structure. Furthermore, recent flex-rigid printed circuit boards not only use the flex part as a cable application between rigid boards, but also actively use it as a component mounting part, LCD connection part or connector connection part of an LCD module. is there.

  A normal flex-rigid printed wiring board is a flexible substrate with a wiring pattern formed on one or both sides of an insulating film such as a polyimide film. Alternatively, an insulating sheet with a copper foil is laminated.

  In this case, the entire flex portion is covered with a cover lay and functions as a cable connecting the rigid portions.

  On the other hand, a flex-rigid printed wiring board using a flex portion as a connector connection portion is provided with a flexible terminal portion protruding from one side of the rigid portion. Such a terminal portion is not covered with a cover lay film, and the wiring pattern of the flexible substrate is exposed.

  Also in a flex rigid printed wiring board used as a component mounting part or an LCD connection part, it is necessary to partially expose the wiring pattern of the flexible substrate in the manufacturing process.

  The wiring pattern exposed in this way must have high functional reliability as a component mounting part, LCD connection part, or connector connection part.

  In the method of manufacturing a flex-rigid printed wiring board, for example, a bonding sheet or prepreg having an opening in a portion corresponding to the flex portion is laminated on a flexible substrate, and further, glass epoxy copper is pasted on the bonding sheet or prepreg. There is a method of laminating a plate or copper foil to form a multilayer, forming a rigid part in which prepregs and the like are laminated, and forming a flex part consisting only of a flexible substrate without the prepreg being laminated by the above-mentioned opening. .

  In this method, since heating and pressurization are performed at the time of laminating a bonding sheet, a prepreg, a copper foil, etc., it is inevitable that the resin constituting the bonding sheet or prepreg flows out to the opening. In particular, when the wiring pattern is exposed at the flex portion, resin is attached to the wiring pattern portion, resulting in an electrical failure. In order to prevent such resin flow, a resin film with high softness called a buffer material is embedded in the opening of the bonding sheet or prepreg to prevent the resin from flowing when bonding sheets, prepregs, copper foils, etc. are laminated. It is usually done.

  However, in such a prevention method, since the wiring pattern of the flex part is etched at the same time when the outer layer wiring pattern of the rigid part is formed later, an additional step of covering the wiring pattern of the flex part with a masking tape or the like is necessary. Thus, not only the process becomes complicated, but also the accuracy of applying the masking tape is required.

  In addition, as another manufacturing method of the flex-rigid printed wiring board, the portion where the flex portion is formed in advance is covered with a polyimide film with an adhesive such as a polyimide tape, and the other portions are multilayered, There is a method for producing a flex-rigid printed wiring board by peeling a polyimide tape to expose a flex portion. However, even with such a method, the accuracy of applying the polyimide tape is required, and when the polyimide tape exposed to high temperature and high pressure during lamination is peeled off, an adhesive residue is generated. In particular, if an adhesive residue adheres to the wiring pattern exposed at the flex portion, a defect occurs in the subsequent wiring pattern plating process, and the connection reliability as a terminal is lowered.

  In addition, in the flex-rigid printed wiring board, as a method for preventing the inflow of resin into the flex portion, for example, a dike that prevents the inflow of resin into the flex portion as described in Patent Literature 1 and Patent Literature 2 below. There is a method of forming. However, even in such a method, when the circuit is exposed to the flex portion, the complicated steps as described above are required.

  Further, in Patent Document 3 below, a heat-resistant film is printed by screen printing on a flex portion corresponding to a planned bending portion of a flex-rigid printed wiring board, and a portion other than the planned bending portion is formed into a multilayer wiring to form a rigid portion. In addition, a flex-rigid printed wiring board that peels and removes a heat-resistant film is described. Patent Document 3 describes that by forming a heat-resistant film in the flex portion, it is possible to prevent the resin in the prepreg from flowing into the planned bending portion when the multilayer is formed. However, in this flex-rigid printed wiring board, no wiring pattern is formed at the bent portion. Moreover, the physical peeling method which peels a heat resistant film by hand is a premise. In such a flex-rigid printed wiring board manufacturing method, the heat-resistant film and the adjacent prepreg bite into each other after the formation of the rigid portion, so that the heat-resistant film is very difficult to peel off, and the boundary with the prepreg In this case, a residue of the heat-resistant film is generated, or scratches and cracks are generated in the insulating layer at the time of peeling, and it is impossible to peel off without being accompanied by these. Moreover, in this manufacturing method of a flex-rigid printed wiring board, since the method of physically peeling a heat resistant film is taken, it is complicated.

  In addition, when this flex-rigid printed wiring board manufacturing method is applied to a case where a wiring pattern is formed at a bent portion, the uneven surface formed by the wiring pattern is different from a flat surface where the wiring pattern is not formed. On the other hand, the heat-resistant film is strongly adhered by the high-temperature, high-pressure lamination process, and it is very difficult to peel off the heat-resistant film without damaging the wiring pattern and without generating a residue between the wiring patterns. Have difficulty.

  Patent Document 4 below describes that a self-peeling adhesive tape is laminated on the flex part. In this Patent Document 4, a self-peeling pressure-sensitive adhesive tape that generates nitrogen gas on the surface of the pressure-sensitive adhesive tape by ultraviolet irradiation is used. Therefore, the self-peeling pressure-sensitive adhesive tape adhered to the flex part can be easily separated from the adhesive surface by ultraviolet irradiation. However, this Patent Document 4 also requires the self-peeling adhesive tape to be peeled off by hand, which is cumbersome and does not damage the wiring pattern when the wiring pattern exposed at the flex portion is formed. Thus, it is extremely difficult to peel off the self-peeling type adhesive tape.

  In addition, there is a construction technique for exposing an inner layer in a rigid multilayer substrate (see, for example, Patent Document 5 and Patent Document 6). These techniques are troublesome in the process because the internal circuit is exposed by scraping off the prepreg and the like to the internal circuit to be exposed after laminating the prepreg and the like.

  As described above, when the wiring pattern is formed on the exposed part, the wiring pattern may be damaged when the film or tape provided to prevent the resin of the prepreg from flowing into the exposed part is peeled off. The problem is that the end of the prepreg is peeled off or cracked, and the residue of the film or tape is generated on or between the wiring patterns.

JP 2005-64059 A JP 2006-228887 A JP 2001-15917 A JP 2006-203155 A Japanese Patent Publication No. 07-19970 JP 2003-179361 A

  The present invention has been proposed in view of such conventional circumstances, and is a multilayer printed wiring board such as a flex-rigid multilayer wiring board or a rigid multilayer wiring board, wherein a part of an inner layer region such as a wiring pattern is formed. In manufacturing an exposed or exposed inner layer region that functions as a cable, the inner layer region to be exposed or a region adjacent to the exposed region is not damaged, and a residue is not generated in the exposed region. It aims to provide a method.

In the first multilayer printed wiring board manufacturing method according to the present invention, a wiring pattern is formed on at least one side of the first insulating layer,
Forming an alkali-soluble ink layer in a part including the wiring pattern on the first insulating layer;
A second insulating layer is formed on the surface of the first insulating layer on the ink layer forming side so that the ink layer is exposed from the second insulating layer, and a metal layer is formed on the second insulating layer. Form the
After forming the second wiring pattern by patterning the metal layer, the ink layer is dissolved and removed with an alkaline solution to expose a part of the first insulating layer and the wiring pattern thereon. Features.

Further, in the second multilayer printed wiring board manufacturing method according to the present invention, a wiring pattern is formed on at least one surface of the first insulating layer having flexibility,
Placing a coverlay on the wiring pattern forming surface of the first insulating layer;
Forming an alkali-soluble ink layer on a part of the coverlay;
Forming a second insulating layer on the coverlay so that the ink layer is exposed from the second ink layer, and forming a metal layer on the second insulating layer;
After the metal layer is patterned to form a wiring pattern, the ink layer is dissolved and removed with an alkaline solution to expose a part of the coverlay.

  In the first and second multilayer printed wiring board manufacturing methods according to the present invention, an ink layer is formed on the inner layer, and an insulating layer and a metal layer are formed in order to expose the inner layer for component mounting and connection. Since the ink layer on the inner layer is removed by dissolution with an alkaline solution, the exposed area of the inner layer exposed thereby, the insulating layer adjacent to the exposed area, and the like are not damaged, and no ink layer residue is generated.

It is sectional drawing of the multilayer printed wiring board of 1st Embodiment manufactured by the manufacturing method of the multilayer printed wiring board to which this invention is applied. It is sectional drawing which shows the state of a double-sided copper pasting core substrate. It is sectional drawing which shows the state which formed the 1st wiring pattern and the 3rd wiring pattern on the core board | substrate. It is sectional drawing which shows the state in which the ink layer was formed in the exposure area | region. It is sectional drawing which shows the state which mounted the prepreg layer and copper foil on the core board | substrate. It is sectional drawing which shows the state which laminated | stacked and integrated the core board | substrate, the prepreg layer, and the copper foil. It is sectional drawing which shows the state in which the via | veer and the through hole were formed. It is sectional drawing which shows the state in which the wiring pattern of the outer layer was formed. It is sectional drawing which shows the state which mounted the electronic component in the wiring pattern formed in the exposure area | region. It is sectional drawing of the multilayer printed wiring board of 2nd Embodiment manufactured by the manufacturing method of the multilayer printed wiring board to which this invention is applied. It is sectional drawing which shows the state which formed the ink layer in the exposure area | region in the manufacturing method of the multilayer printed wiring board of 2nd Embodiment. It is sectional drawing which shows the state which laminated | stacked and integrated the core board | substrate, the prepreg layer, and the copper foil in the manufacturing method of the multilayer printed wiring board of 2nd Embodiment. It is sectional drawing which shows the state which formed the wiring pattern of the outer layer in the manufacturing method of the multilayer printed wiring board of 2nd Embodiment. It is sectional drawing of the multilayer printed wiring board of 3rd Embodiment manufactured by the manufacturing method of the multilayer printed wiring board to which this invention is applied. It is sectional drawing which shows the state which exposed the 1st exposure area | region in the manufacturing method of the multilayer printed wiring board of 3rd Embodiment. It is sectional drawing which shows the state which formed the ink layer in the 1st exposure area | region and the 2nd exposure area | region. In the manufacturing method, it is sectional drawing which shows the state in which the laminated body was formed. It is sectional drawing of the flex-rigid printed wiring board of 4th Embodiment manufactured by the manufacturing method of the multilayer printed wiring board to which this invention is applied. It is sectional drawing which shows the state which formed the 1st wiring pattern and the 3rd wiring pattern on the flexible substrate in the manufacturing method of the multilayer printed wiring board of 4th Embodiment. It is sectional drawing which shows the state which laminated | stacked the 1st coverlay film and the 2nd coverlay film on the flexible substrate in the manufacturing method of the multilayer printed wiring board of 4th Embodiment. It is sectional drawing which shows the state which formed the 1st-3rd ink layer on the flexible substrate in the manufacturing method of the multilayer printed wiring board of 4th Embodiment. It is sectional drawing which shows the state which mounted the coverlay film, the prepreg layer, and the copper foil on the flexible substrate in the manufacturing method of the multilayer printed wiring board of 4th Embodiment. It is sectional drawing which shows the state which laminated and integrated the flexible substrate, the coverlay film, the prepreg layer, and the copper foil in the manufacturing method of the multilayer printed wiring board of 4th Embodiment. It is sectional drawing which shows the state in which the via | veer and the through hole were formed in the manufacturing method of the multilayer printed wiring board of 4th Embodiment. It is sectional drawing which shows the state which formed the wiring pattern of the outer layer in the manufacturing method of the multilayer printed wiring board of 4th Embodiment. It is a top view of the multilayer printed wiring board of 5th Embodiment manufactured by the manufacturing method of the multilayer printed wiring board to which this invention is applied. FIG. 27 is a cross-sectional view taken along line XX in FIG. 26. It is sectional drawing which shows the state before stamping of a flexible terminal part in the manufacturing method of the multilayer printed wiring board of 5th Embodiment.

Explanation of symbols

1 multilayer printed wiring board 2 first insulating layer (core substrate)
2a One surface of the core substrate 2b The other surface of the core substrate 2c Via 3 First wiring pattern 4 Second insulating layer (first prepreg layer)
4a Opening portion of first prepreg layer 5 Second wiring pattern 6 Third wiring pattern 7 Third insulating layer (second prepreg layer)
7a Opening of second prepreg layer 8 Fourth wiring pattern 9 Via 10 Through hole 11 Exposed area 12 Copper foil 13 Ink layer 14 Copper foil 15 Copper foil 16 Laminate 17 Dry film resist 18 Dry film resist 19 Electronic component 20 Multilayer printed wiring board 21 Exposed area 22 Ink layer 23 Multilayer laminate 30 Multilayer printed wiring board 31 First insulating layer (core substrate)
31a One surface of the core substrate 31b The other surface of the core substrate 31c Via 32 First wiring pattern 33 Second insulating layer (first prepreg layer)
33a First prepreg layer opening 34 Second wiring pattern 35 Third insulating layer (second prepreg layer)
35a Opening of second prepreg layer 36 Third wiring pattern 37 Fourth wiring pattern 38 Fourth insulating layer (third prepreg layer)
39 Fifth wiring pattern 40 Fifth insulating layer (fourth prepreg layer)
41 Sixth Wiring Pattern 42 Via 43 Via 44 Through Hole 45 First Exposed Area 46 Second Exposed Area 47 Ink Layer 48 Copper Foil 49 Copper Foil 50 Flex Rigid Printed Wiring Board 51 Flex Rigid Printed Wiring Board 50 Flex Section 52 First rigid portion of the flex-rigid printed wiring board 50 53 Second rigid portion of the flex-rigid printed wiring board 50 54 First insulating layer (flexible substrate)
54a One surface of the flexible substrate 54b The other surface of the flexible substrate 55 First wiring pattern 56 First cover lay film 56a Opening portion of the first cover lay film 57 Second cover lay film 58 region 59 region 60 first 2 insulating layers (first prepreg layer)
60a First prepreg layer opening 60b First prepreg layer opening 60c First prepreg layer opening 61 Second wiring pattern 62 Third wiring pattern 63 Third insulating layer (second prepreg layer)
64 Fourth wiring pattern 65 Via 66 Via 67 Exposed area 68 Through hole 69 First ink layer 70 Second ink layer 71 Third ink layer 72 Copper foil 73 Copper foil 74 Laminate 75 Resist 76 Resist 80 Multilayer print Wiring board 81 Rigid part of multilayer printed wiring board 80 Flexible terminal part of multilayer printed wiring board 80 83 Flexible terminal part of multilayer printed wiring board 80 84 Flexible substrate 85 First wiring pattern 86 Coverlay film 87 Insulating layer 88 Second Wiring pattern 89 Solder resist 90 Electronic component mounting area 91 Exposed area 92 Product part 93 Product exterior

  Hereinafter, a method for producing a multilayer printed wiring board to which the present invention is applied will be described in detail with reference to the drawings. In each figure, the same numerals indicate the same or equivalent components.

  First, as a first embodiment of a method for manufacturing a multilayer printed wiring board to which the first invention is applied, a method for manufacturing a double-sided multilayer printed wiring board (hereinafter simply referred to as a multilayer printed wiring board) will be described. Prior to the description of the manufacturing method, a multilayer printed wiring board manufactured by this manufacturing method will be described.

  As shown in FIG. 1, the multilayer printed wiring board 1 has a first wiring pattern 3 formed on one surface 2a of a core substrate 2 serving as a first insulating layer, and has adhesiveness and insulating properties thereon. A second insulating layer 4 formed from the first prepreg is laminated, and a second wiring pattern 5 is formed on the second insulating layer 4. A third wiring pattern 6 is formed on the other surface 2b of the core substrate 2, and a third insulating layer 7 formed of a second prepreg having adhesiveness and insulating properties is laminated thereon. A fourth wiring pattern 8 is formed on the third insulating layer 7. In the multilayer printed wiring board 1, vias 2 c that electrically connect the first wiring pattern 3 and the third wiring pattern 6 are formed on the core substrate 2. Further, the multilayer printed wiring board 1 includes a via 9, a first wiring pattern 3, a second wiring pattern 5, and a third wiring that electrically connect the first wiring pattern 3 and the second wiring pattern 5. A through hole 10 is formed to electrically connect the wiring pattern 6 and the fourth wiring pattern 8.

  The multilayer printed wiring board 1 includes a part of the core substrate 2 and a first portion thereon because the second insulating layer 4 is not laminated on a part including the first wiring pattern 3 on the core substrate 2. The exposed pattern 11 is exposed. For this reason, in this multilayer printed wiring board 1, the exposed region 11 has a concave shape. For example, when an electronic component is mounted on the first wiring pattern 3 in the exposed region 11, the height can be reduced. it can.

  Such a multilayer printed wiring board 1 can be manufactured as follows.

  First, as shown in FIG. 2, the core substrate 2 provided with the copper foil 12 on both sides is prepared. The core substrate 2 is excellent in heat resistance, mechanical strength, and electrical characteristics. For example, a resin such as polyimide, epoxy resin, phenol resin, or BT resin is used.

  Next, as shown in FIG. 3, the first wiring pattern 3, the third wiring pattern 6, and the via 2 c that electrically connects the first wiring pattern 3 and the third wiring pattern 6 are formed. As a method of forming the via 2c, for example, a method of forming a hole in the copper foil 12 and the core substrate 2 where the via 2c is to be formed by laser from the other surface 2b of the core substrate 2 of FIG. There is a method of drilling the core substrate 2 with a laser or the like after removing the portion of the copper foil 12 to be formed by etching, and the like by electroless copper plating method or electrolytic copper plating method on the entire surface of the hole formed by these. Copper plating is performed to form the via 2c. Further, as the via 2c, a through hole may be formed by forming a through hole by a drill or the like and then performing copper plating. Next, a resist is formed on the via 2c and the copper foil 12 forming the first wiring pattern 3 so that the formed via 2c is not etched, and the copper foil provided on the one surface 2a of the core substrate 2 is formed. 12 is etched by, for example, a subtractive method to form the first wiring pattern 3. Similarly, the third wiring pattern 6 is formed by etching the copper foil 12 provided on the other surface 2b of the core substrate 2 by, for example, a subtractive method.

  Next, as shown in FIG. 4, the ink layer 13 is formed by applying alkali-soluble ink to the exposed region 11 where the first wiring pattern 3 is exposed. The ink layer 13 is formed by printing alkali-soluble ink on the exposed region 11 by a printing method such as screen printing or inkjet printing, and drying and curing under appropriate conditions. As the ink, an ink which is alkali-soluble, preferably not soluble in a weak alkali solution for developing a dry film resist, but soluble in an alkali solution for removing the dry film resist cured by exposure is used.

  As shown in FIG. 5, the ink layer 13 is formed with substantially the same thickness as the first prepreg layer 4 laminated on the first wiring pattern 3 in the next step.

  Next, as shown in FIG. 5, the first prepreg layer 4 is formed on the surface of the core substrate 2 on the ink layer forming side with the ink layer 13 facing outward. That is, the first prepreg layer 4 is formed so that the ink layer 13 is exposed from the first prepreg layer 4. Specifically, the first prepreg layer 4 is disposed on the portion of the one surface 2 a of the core substrate on which the ink layer 13 is formed, on which the ink layer 13 is not formed, and the first prepreg layer 4 is disposed on the entire other surface 2 b of the core substrate 2. Two prepreg layers 7 are arranged. Before the first prepreg layer 4 is laminated on the first wiring pattern 3, an opening 4 a having a size capable of inserting the ink layer 13 is provided in advance in a mold or the like at a position corresponding to the ink layer 13. It is formed by punching out. In order to prevent the opening 4a from overlapping with the ink layer 13 and displacement, the resin in the first prepreg layer 4 does not overlap the ink layer 13 even if the resin in the first prepreg layer 4 flows to the ink layer 13 side in the subsequent lamination process. The ink layer 13 may be formed larger than the ink layer 13. When the first prepreg layer 4 is formed on the first wiring pattern 3, the ink layer 13 is inserted into the opening 4 a and the first prepreg layer 4 is disposed on the first wiring pattern 3. . In addition, as what is laminated | stacked on the core board | substrate 2, it replaces with a prepreg, a bonding sheet may be used, the insulation board | substrate which the prepreg hardened may be used, and if the function as an insulation layer can be fulfilled, A thermoplastic resin film or the like can also be used.

  Next, as shown in FIG. 5, the copper foil 14 that becomes the second wiring pattern 5 on the first prepreg layer 4 and the copper foil 15 that becomes the fourth wiring pattern 8 on the second prepreg layer 7. Deploy. In this multilayer printed wiring board manufacturing method, instead of the first prepreg layer 4 and the copper foil 14, and the second prepreg layer 7 and the copper foil 15, the copper foil is pasted. A coated copper-clad insulating substrate may be used. In this case, an area corresponding to the ink layer 13 of the copper-clad insulating substrate is opened in advance.

  Next, the first prepreg layer 4, the second prepreg layer 7, and the copper foils 14, 15 are arranged and heated toward the core substrate 2 side while being heated with a laminating press, so that the semi-cured first When the first prepreg layer 4 and the second prepreg layer 7 are melted and flowed and then cured, the layers are bonded and integrated to form a laminate 16 having a multilayer structure as shown in FIG. .

  At this time, even when the first prepreg layer 4 melts and flows when heated and pressurized, the ink layer 13 can prevent the resin constituting the first prepreg layer 4 from flowing into the exposed region 11, It is possible to prevent the first wiring pattern 3 to be exposed from being attached with resin, and the exposed region 11 from being blocked with resin.

  Next, as shown in FIG. 7, vias 9 and through holes 10 are formed. The via 9 forms a hole from the copper foil 14 that forms the second wiring pattern 5 to the first wiring pattern 3 by using a drill or by laser processing, and electroless copper plating is performed on the entire surface of the formed hole. It can form by performing the copper plating by the method and the electrolytic copper plating method. The through hole 10 forms a through hole that penetrates from the copper foil 14 that forms the second wiring pattern 5 to the copper foil 15 that forms the fourth wiring pattern 8 by using a drill or by laser processing. The burrs remaining in the holes can be removed, and the entire surface of the through holes can be formed by performing copper plating by an electroless copper plating method or an electrolytic copper plating method.

  Next, as shown in FIG. 8, the second wiring pattern 5 and the fourth wiring pattern 8 are formed by the subtractive method. Specifically, first, dry film resists 17 and 18 are formed on the entire surface of the copper foil 14 and the copper foil 15, and the dry film resists 17 and 18 are exposed using a mask in order to form a desired wiring pattern. . Thereafter, the dry film resist in the unexposed area is dissolved and removed with a solution such as sodium hydrogen carbonate, and then etched by an ordinary method using an iron chloride or copper chloride solution, whereby the second wiring pattern 5 and the fourth wiring pattern. 8 is formed. At the time of etching, the copper foil 14 on the ink layer 13 is dissolved and removed, but the ink layer 13 remains, and the first wiring pattern 3 formed in the exposed region 11 is removed from the wet etching etchant. Can be protected.

  Next, the dry film resists 17 and 18 on the second wiring pattern 5 and the fourth wiring pattern 8 are removed with an alkaline solution such as sodium hydroxide, and the ink layer 13 is also dissolved and removed with the alkaline solution. The multilayer printed wiring board 1 of FIG. 1 in which a part of the core substrate 2 and the first wiring pattern 3 are exposed to the outside in the exposed region 11 is obtained. If the ink layer 13 cannot be completely removed in this step, the ink layer 13 may be completely removed by dipping in an alkaline solution. In this way, the ink layer 13 can be easily and completely removed by dissolving and removing the ink layer 13 with an alkaline solution without manually peeling the ink layer 13 or removing it by a physical means. The removal of the dry film resists 17 and 18 and the removal of the ink layer 13 may be performed in separate steps.

  In the manufacturing method of the multilayer printed wiring board 1 as described above, since the ink layer 13 is formed in the exposed region 11 where the first wiring pattern 3 is exposed, the first prepreg layer 4 can be heated and pressurized. The resin constituting the first prepreg layer 4 can be prevented from flowing into the exposed region 11, the first wiring pattern 3 can be protected, and electrical problems can be prevented from occurring. Moreover, in this manufacturing method of the multilayer printed wiring board 1, since the ink layer 13 is formed from an alkali-soluble ink, the ink layer 13 can be easily and completely removed with an alkaline solution. Therefore, even if the exposed region 11 has a fine shape, the exposed region 11 and the first wiring pattern 3 can be appropriately protected, and the residue of the ink layer 13 can be prevented from occurring in the exposed region 11.

  Moreover, in the manufacturing method of this multilayer printed wiring board 1, since the ink layer 13 is dissolved and removed with an alkaline solution, the end face of the adjacent second insulating layer 4 can be prevented from being damaged or peeled off. The end surface of the second insulating layer 4 adjacent to the exposed region 11 on the exposed region 11 side is flat.

  Further, in the method for manufacturing the multilayer printed wiring board 1, the first wiring pattern 3 is formed in the exposed region 11, so that the exposed region 11 is uneven, and the ink layer 13 is exposed by the lamination press. When pressed against the concavo-convex surface of the region 11, it is in close contact with the exposed region 11, but can be completely removed by dissolving with an alkaline solution. For this reason, it is possible to prevent the residue of the ink layer 13 from being generated on the first wiring pattern 3 or between the first wiring patterns 3.

  In the obtained multilayer printed wiring board 1, as shown in FIG. 9, the first wiring pattern 3 in the exposed region 11 serves as a connection terminal for mounting the electronic component 19. In this case, the thickness of the multilayer printed wiring board 1 in the exposed region 11 is thinner than the portion where the second wiring pattern 5 is provided, and is formed in a concave shape, so that electrons are formed on the first wiring pattern 3. Even if the component 19 is mounted, the height does not become too high, and the height can be reduced.

  In the multilayer printed wiring board 1 described above, the wiring patterns are provided on both surfaces of the core substrate 2. However, the present invention is not limited to this, and the wiring patterns may be provided only on one surface 2a of the core substrate 2. In the multilayer printed wiring board 1, the second insulating layer 4 and the second wiring pattern 5 are formed on the one surface 2 a of the core substrate 2. It is good also as a layer more than a layer. Similarly, an exposed region may be formed on the other surface 2b of the core substrate 2 as shown in FIG. 10 to be described later, and an insulating layer and a wiring pattern may be formed to form three or more layers. In the multilayer printed wiring board 1, when an insulating layer and a wiring pattern are further formed on one surface 2a and the other surface 2b of the core substrate 2 so that each of the surfaces 2a and 2b has three or more layers, the core substrate In addition to exposing the wiring pattern on 2, other wiring patterns located inside may be exposed on both surfaces 2 a and 2 b.

  Next, as a second embodiment, ink is used to expose not only on one surface 2a side of the core substrate 2 but also on the other surface 2b side as in the multilayer printed wiring board 20 shown in FIG. Region 21 can also be formed. In addition, in this multilayer printed wiring board 20, about the structure similar to the multilayer printed wiring board 1 mentioned above, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  In this multilayer printed wiring board 20, the first wiring pattern 3 is exposed in the exposed region 11 provided on the one surface 2 a side of the core substrate 2, so that the first wiring pattern 3 is exposed, and the core substrate 2 is exposed. Since the third insulating layer 7 is not formed in the exposed region 21 provided on the other surface 2b side, a part of the third wiring pattern 6 is exposed.

  The manufacturing method of the multilayer printed wiring board 20 is similar to the manufacturing method of the multilayer printed wiring board 1 described above. After forming the first wiring pattern 3 and the third wiring pattern 6, as shown in FIG. The ink layer 13 is formed on one of the two surfaces 2a, and the ink layer 22 is also formed on the other surface 2b. The ink layers 13 and 22 are formed with substantially the same thickness as the first prepreg layer 4 serving as the second insulating layer and the second prepreg layer 7 serving as the third insulating layer, respectively.

  Next, the first prepreg layer 4 and the second prepreg layer in which openings 4a and 7a of a size capable of inserting the ink layers 13 and 22 are formed at positions corresponding to the ink layers 13 and 22, respectively. 7 is disposed on the first wiring pattern 3 and the third wiring pattern 6 so that the ink layers 13 and 22 face outward, and copper foils 14 and 15 are provided on the prepreg layers 4 and 7, respectively. Deploy. And like the manufacturing method of the multilayer printed wiring board 1 mentioned above, it becomes the integrated multilayer laminated body 23 shown in FIG. 12 by heating and pressurizing. At this time, since the ink layers 13 and 22 are formed, it is possible to prevent the resin from flowing into the exposed regions 11 and 21 from the first prepreg layer 4 and the second prepreg layer 7.

  Next, as shown in FIG. 13, the second wiring pattern 5 and the second wiring pattern 5 are formed by forming the through hole 10 and the via 9 and etching the copper foils 14 and 15 in the same manner as in the method for manufacturing the multilayer printed wiring board 1 described above. 4 wiring patterns 8 are formed. Thereafter, when the dry film resists 17 and 18 used in forming the second wiring pattern 5 and the fourth wiring pattern 8 are removed with an alkaline solution, the ink layers 13 and 22 formed in the exposed regions 11 and 21 are removed. Also dissolve and remove. When the second wiring pattern 5 and the fourth wiring pattern 8 are formed, since the ink layers 13 and 22 are formed in the exposed regions 11 and 21, the first exposed in the exposed regions 11 and 21. The wiring pattern 3 and the third wiring pattern 6 can be protected from the etching solution.

  In the manufacturing method of the multilayer printed wiring board 20 as described above, the first wiring pattern 3 is exposed on both the one surface 2a and the other surface 2b of the core substrate 2 by using alkali-soluble ink. The exposed region 11 and the exposed region 21 where the third wiring pattern 7 is exposed can be formed simultaneously. The same effect as that of the method for manufacturing the multilayer printed wiring board 1 described above can be obtained in both the exposed region 11 and the exposed region 21.

  Next, as a third embodiment, a multilayer printed wiring board 30 as shown in FIG. 14 can be manufactured using ink.

  Specifically, in the multilayer printed wiring board 30, a first wiring pattern 32 is formed on one surface 31a of the core substrate 31 that is a first insulating layer, and the first wiring pattern 32 is protected and adjacent to the first wiring pattern 32. The first wiring patterns 32 are insulated from each other, and a second insulating layer 33 having adhesiveness is laminated, and a second wiring pattern 34 is formed on the second insulating layer 33. A third insulating layer 35 that protects the pattern 34 and insulates the adjacent second wiring patterns 34 from each other, is laminated, and a third wiring pattern 36 is formed on the third insulating layer 35. Has been. A fourth wiring pattern 37 is formed on the other surface 31 b of the core substrate 31. The fourth insulating layer 38 protects the fourth wiring pattern 37 and insulates the adjacent fourth wiring patterns 37 from each other. And a fifth wiring pattern 39 is formed on the fourth insulating layer 38 to protect the fifth wiring pattern 39 and to insulate adjacent fifth wiring patterns 39 from each other. A layer 40 is laminated, and a sixth wiring pattern 41 is formed on the fifth insulating layer 40. The multilayer printed wiring board 30 includes a via 31c that electrically connects the first wiring pattern 32 and the fourth wiring pattern 37 to the core substrate 31, and the second wiring pattern 34 and the third wiring pattern. A via 42 electrically connecting 36, a via 43 electrically connecting the fifth wiring pattern 39 and the sixth wiring pattern 41, a first wiring pattern 32, a second wiring pattern 34, and a third wiring pattern. Through-holes 44 for electrically connecting the wiring pattern 36, the fourth wiring pattern 37, the fifth wiring pattern 39, and the sixth wiring pattern 41 are formed.

  In this multilayer printed wiring board 30, not only a part of the first wiring pattern 32 formed on the core substrate 31 is exposed in the exposed region 45, but also on the second insulating layer 33 in the exposed region 46. A part of the second wiring pattern 34 formed on the outside is also exposed to the outside.

  The multilayer printed wiring board 30 can be manufactured as follows.

  First, as shown in FIG. 15, a multilayer printed wiring board having an exposed region 45 is manufactured. Since this can be manufactured in the same manner as the multilayer printed wiring board 1 described above, a detailed description thereof will be omitted.

  Next, as shown in FIG. 16, an alkali-soluble ink is printed on the first exposed region 45 and the second exposed region 46 by screen printing or the like to form an ink layer 47. The ink layer 47 is formed on the first exposed region 45 and the second exposed region 46 when the second prepreg layer 35 to be a third insulating layer is heated and pressed in a later step and laminated. This prevents the uncured resin contained in the insulating layer 33 and the resin of the second prepreg layer 35 from flowing in. For this reason, as shown in FIG. 16, the ink layer 47 is a second prepreg layer 35 that is laminated on the second insulating layer 33 in the next step around the opening 33a of the second insulating layer 33. It is formed to have substantially the same thickness as

  Next, as shown in FIG. 17, the second prepreg layer 35 to be the third insulating layer is disposed on the second insulating layer 33 so that the ink layer 47 faces outward. That is, the second prepreg layer 35 is disposed so that the ink layer 47 is exposed from the second prepreg layer. More specifically, the second prepreg layer 35 in which the opening 35a having a size capable of inserting the ink layer 47 is used, and the ink layer 47 is inserted into the opening 35a. To do. Then, a copper foil 48 for forming the third wiring pattern 36 is disposed on the second prepreg layer 35. On the other hand, on the fourth insulating layer 38, a fourth prepreg layer 40 serving as a fifth insulating layer is disposed, and a copper foil 49 for forming a sixth wiring pattern 41 is disposed thereon. The second prepreg layer 35, the fourth prepreg layer 40, and the copper foils 48 and 49 are pressurized while being heated toward the core substrate 31 side, and these are laminated and integrated.

  Even when the second insulating layer 33 and the second prepreg layer 35 are softened by the formation of the ink layer 47 in the first exposed region 45 and the second exposed region 46 during heating and pressurization. The resin constituting them can be prevented from flowing into the first exposed area 45 and the second exposed area 46, and the first wiring pattern 32 and the second exposed pattern formed in the first exposed area 45 can be prevented. It is possible to prevent the second wiring pattern 34 formed in the region 46 from being attached with resin or blocking the first exposed region 45 and the second exposed region 46 with resin.

  Next, in the same manner as in the method for manufacturing the multilayer printed wiring board 1 described above, vias 42 and 43 and through holes 44 are formed, and the copper foils 48 and 49 are formed on the third wiring pattern 36 and the sixth wiring by a subtractive method. A pattern 41 is formed. Since the ink layer 47 remains when the third wiring pattern 36 and the sixth wiring pattern 41 are formed, the first wiring pattern 32 and the second exposure formed in the first exposed region 45. The second wiring pattern 34 formed in the region 46 can be protected from the wet etching solution.

  Next, the dry film resist used in forming the third wiring pattern 36 and the sixth wiring pattern 41 is removed with an alkaline solution such as sodium hydroxide, and the ink layer 47 is also dissolved and removed with the alkaline solution. Then, as shown in FIG. 14, the multilayer printed wiring board 30 in which the first wiring pattern 32 is exposed in the first exposed region 45 and the second wiring pattern 34 is exposed in the second exposed region 46 is obtained. .

  In the method of manufacturing the multilayer printed wiring board 30, different first wiring patterns 32 and second wiring patterns 34 respectively formed on the core substrate 31 and the second insulating layer 33 are made identical by using ink. Since it can expose in this process, a manufacturing process can be simplified.

  Further, in the method for manufacturing the multilayer printed wiring board 30, the ink layer 47 is not removed by physical means, but the ink layer 47 is dissolved and removed, so that the first exposed region 45 and the second exposed region are exposed. It is possible to prevent the first wiring pattern 32 and the second wiring pattern 34 exposed in the region 46 from being damaged, and the second insulating layer 33 and the third insulating layer 35 from being peeled off. The end surfaces of the second insulating layer 33 and the third insulating layer 35 adjacent to the exposed region 45 and the second exposed region 46 on the first exposed region 45 side and the second exposed region 46 side are flat.

  In the method for manufacturing the multilayer printed wiring board 30, the first wiring pattern 32 is formed in the first exposed region 45, and the second wiring pattern 34 is formed in the second exposed region 46. Therefore, when the ink layer 47 is pressed against the uneven surfaces of the first exposed region 45 and the second exposed region 46 by the lamination press, the first exposed region 45 and the second exposed region 46 are formed. However, since the ink layer 47 can be completely removed with an alkaline solution, the first wiring pattern 32, the second wiring pattern 34, the first wiring pattern 32, and the second wiring It is possible to prevent the residue of the ink layer 47 from being generated between the patterns 34.

  Next, as a fourth embodiment, a method of manufacturing a flex-rigid printed wiring board 50 as shown in FIG. 18 by applying the first and second aspects of the present invention will be described. In the flex-rigid printed wiring board 50, a first rigid portion 52 and a second rigid portion 53 are connected by a flexible flex portion 51.

  The flex portion 51 is a first electrically connecting the first rigid portion 52 and the second rigid portion 53 on one surface 54a of the flexible substrate 54 which is a flexible first insulating layer. Is formed, a first coverlay film 56 is formed to protect the first wiring pattern 55 and to insulate the adjacent first wiring patterns 55 from each other, and a second cover 54b is formed on the other surface 54b. The cover lay film 57 is formed. The flex portion 51 is a region 58 in which the first coverlay film 56 is exposed by not laminating the first prepreg layer 60 on the first coverlay film 56 on the one surface 54 a side of the flexible substrate 54. The second cover lay film 57 is exposed by not laminating the second prepreg layer 63 on the second cover lay film 57 on the other surface 54b side opposite to the region 58. The region 59 is made to have.

  The first rigid portion 52 includes a first wiring pattern 55, a first cover lay film 56, a second insulating layer 60 formed of a first prepreg layer, a second surface 54 a of the flexible substrate 54. Wiring patterns 61 are laminated. The first rigid portion 52 includes a third insulating layer 63 formed of a third wiring pattern 62, a second coverlay film 57, and a second prepreg layer on the other surface 54b of the flexible substrate 54. A fourth wiring pattern 64 is laminated. The first rigid portion 52 is formed with a via 65 that electrically connects the first wiring pattern 55 and the third wiring pattern 62 to the flexible substrate 54, and the first wiring pattern 55 and the second wiring pattern are formed. A via 66 that electrically connects 61 is formed. Further, the first rigid portion 52 has an exposed region 67 that exposes the first wiring pattern 55.

  Similar to the first rigid portion 52, the second rigid portion 53 includes a first wiring pattern 55, a first coverlay film 56, and a first prepreg layer on one surface 54 a of the flexible substrate 54. The formed second insulating layer 60 and the second wiring pattern 61 are laminated, and the third wiring pattern 62, the second coverlay film 57, and the second prepreg layer are formed on the other surface 54b. Further, a third insulating layer 63 and a fourth wiring pattern 64 are laminated. The second rigid portion 53 is formed with a through hole 68 that electrically connects the first wiring pattern 55, the second wiring pattern 61, the third wiring pattern 62, and the fourth wiring pattern 64. .

  The flex-rigid printed wiring board 50 can be manufactured as follows. First, as shown in FIG. 19, a flexible substrate having copper foil on both sides is prepared and vias 65 are formed in the same manner as in the method for manufacturing the multilayer printed wiring board 1 described above. A first wiring pattern 55 is formed on 54a by a subtractive method, and a third wiring pattern 62 is formed on the other surface 54b.

  Next, as shown in FIG. 20, a first coverlay film 56 having an opening 56a formed in a region corresponding to the exposed region 67 is laminated on one surface 54a by a press or the like. On the other surface 54b, the second coverlay film 57 is also laminated by pressing or the like.

  Next, as shown in FIG. 21, the thickness of the first prepreg layer 60 laminated on the first coverlay film 56 in the next step around the opening 56 a of the first coverlay film 56. The first ink layer 69 is formed up to the periphery of the opening 56a so as to have substantially the same thickness as that of the first cover lay film 56, and the first prepreg layer 60 is not stacked on the first cover layer film 56. In addition, the second ink layer 70 is formed by screen printing or the like with a thickness substantially the same as the thickness of the first prepreg layer 60 laminated on the first coverlay film 56. On the second cover lay film 57, a second prepreg layer 63 that is laminated on the second cover lay film 57 in a later step in a region corresponding to the region 59 where the second prepreg layer 63 is not laminated. The third ink layer 71 is formed with substantially the same thickness as that of the first ink layer 71.

  Next, as shown in FIG. 22, the first prepreg layer 60 is disposed on the first coverlay film 56 with the first ink layer 69 and the second ink layer 70 facing outward. That is, the first prepreg layer 60 is disposed on the first cover lay film 56 so that the first ink layer 69 and the second ink layer 70 are exposed from the first prepreg layer 60. More specifically, the first prepreg layer 60 in which openings 60 a and 60 b are formed at positions corresponding to the first ink layer 69 and the second ink layer 70 is disposed on the first coverlay film 56. To do. Further, on the second cover lay film 57, the second prepreg layer 63 having an opening 63a formed at a position corresponding to the third ink layer 71 is disposed, whereby the third ink layer 71 is disposed. A second prepreg layer 63 facing outward is formed.

  Further, a copper foil 72 for forming the second wiring pattern 61 is disposed on the first prepreg layer 60, the first ink layer 69, and the second ink layer 70, and the second prepreg layer 63, the third A copper foil 73 for forming a fourth wiring pattern 64 is disposed on the ink layer 71.

  Next, in the same manner as in the method for manufacturing the multilayer printed wiring board 1 described above, heating and pressing are performed to form a laminate 74 as shown in FIG.

  Even when the resin constituting the first prepreg layer 60 and the second prepreg layer 63 melts and flows during heating and pressurization, the first ink layer 69, the second ink layer 70, and the third ink are used. The layer 71 can prevent the resin constituting the first prepreg layer 60 and the second prepreg layer 63 from flowing into the regions 58 and 59 and the exposed region 67, and the resin is attached to the exposed first wiring pattern 55. Further, it is possible to prevent the regions 58 and 59 where the prepreg layer is not laminated and the exposed region 67 from being blocked with resin.

  Next, as shown in FIG. 24, vias 66 and through holes 68 are formed in the multilayer body 74, as in the case of the vias 11 and the through holes 12 of the multilayer printed wiring board 1 described above.

  Next, as shown in FIG. 25, the copper foil 72 is etched by the subtractive method to form the second wiring pattern 61, and the copper foil 73 is also etched by the subtractive method to form the fourth wiring pattern 64. To do. When the second wiring pattern 61 is formed, the first ink layer 69 is formed in the exposed region 67, thereby protecting the first wiring pattern 55 exposed in the exposed region 67 from the etching solution. be able to.

  Next, when the resists 75 and 76 used for forming the second wiring pattern 61 and the fourth wiring pattern 64 are removed with an alkaline solution, the first ink layer 69, the second ink layer 70, The third ink layer 71 is also dissolved and removed with an alkaline solution. By removing the resists 75 and 76, the first ink layer 69, the second ink layer 70, and the third ink layer 71, as shown in FIG. 18, the region 58 in which the first prepreg layer 60 is not laminated and The flex portion 51 is formed by the region 59 where the second prepreg layer 63 is not laminated, and the first rigid portion 52 and the second rigid portion 53 having the exposed region 67 are connected via the flex portion 51. The flex-rigid printed wiring board 50 is manufactured.

  As described above, according to the method of manufacturing the flex-rigid printed wiring board 50, the first ink layer 69 is formed in the exposed region 67 where the first wiring pattern 55 is exposed using ink. The second ink layer 70 is formed in the region 58 where the first coverlay film 56 is exposed without laminating the first prepreg layer 60. The third ink layer 71 is formed in the region 59 where the second coverlay film 57 is exposed without laminating the second prepreg layer 63. Then, the first ink layer 69, the second ink layer 70, and the third ink layer 71 are dissolved and removed with an alkaline solution, thereby exposing the first wiring pattern 55 formed therein in the exposed region 67. Let Therefore, this exposed region 67 can be used as a connection terminal for an electronic component. Further, since the prepreg layer is not formed in the flex portion 51, flexibility is maintained, and the first wiring pattern 55 is covered with the first cover lay film 56 and the second cover lay film 57. The flex part 51 can function as a cable.

  Further, in the manufacturing method of the flex-rigid printed wiring board 50, the first prepreg layer 60 and the first prepreg layer 60 are formed when the laminate 74 is formed by forming the second ink layer 70 and the third ink layer 71. Even if the second prepreg layer 63 is heated and pressurized, the resin constituting the first prepreg layer 60 and the second prepreg layer 63 can be prevented from flowing into the region 58 and the region 59. The flexibility of the flexible substrate 54 can be maintained well. Further, by forming the first ink layer 69, it is possible to prevent the resin of the first prepreg layer 60 from flowing into the exposed region 67 when the stacked body 74 is formed. Accordingly, in the exposed region 67, it is possible to prevent the resin from adhering to the exposed first wiring pattern 55, thereby preventing an electrical failure.

  Further, in the method of manufacturing the flex-rigid printed wiring board 50, the first ink layer 69, the second ink layer 70, and the third ink layer 71 are not removed by physical means but dissolved by an alkaline solution. Therefore, the first wiring pattern 55 exposed in the exposed region 67 of the first rigid portion 52 is damaged, or the first coverlay film 56, the second coverlay film 57, and the first The first ink layer 69, the second ink layer 70, and the third ink layer 71 can be removed without the prepreg layer 60 and the second prepreg layer 63 being peeled off. Furthermore, the end surface of the first cover lay film 56 adjacent to the region 58 and the end surface of the second insulating layer 60, the end surface of the second cover lay film 57 adjacent to the region 59 and the end surface of the third insulating layer 63, The end surface of the first coverlay film 56 adjacent to the exposed region 67 and the end surface of the second insulating layer 60 become flat.

  Further, in the manufacturing method of the flex-rigid printed wiring board 50, since the exposed region 67 is uneven by the first wiring pattern 55, the first ink layer 69 is pressed against the uneven surface of the exposed region 67 by a lamination press. Then, the first ink layer 69 adheres to the exposed region 67, but the first ink layer 69 can be completely removed by dissolving with an alkaline solution. In addition, poor connection due to the residue of the first ink layer 69 occurring between the first wiring patterns 55 can be prevented. In addition, since the second ink layer 70 and the third ink layer 71 are also dissolved and removed with an alkaline solution, residues of the second ink layer 70 and the third ink layer 71 are generated in the regions 58 and 59. Therefore, it is possible to prevent a decrease in flexibility at the flex part 51.

  In the flex-rigid printed wiring board 50 described above, an exposed region 67 where the first wiring pattern 55 is exposed is formed in the first rigid portion 52, but the exposed region 67 is formed in the first rigid portion 52. You may manufacture the flex-rigid printed wiring board which formed the flex part 51 by the area | region 58 and the area | region 59 by the method of this invention, without forming.

  Further, in the above-described flex-rigid printed wiring board, an exposed region where the third wiring pattern 62 is exposed is also formed on the other surface 54b of the flexible substrate 54 in the same manner as the multilayer printed wiring board 20 shown in FIG. May be.

  Next, as a fifth embodiment, a multilayer printed wiring board 80 as shown in FIG. 26 can be manufactured using ink. The multilayer printed wiring board 80 includes a rigid portion 81 on which electronic components and the like are mounted, and flexible terminal portions 82 and 83 provided so as to protrude from two sides of the rigid portion 81. The multilayer printed wiring board 80 electrically connects the flexible terminal portions 82 and 83 to connectors of other electronic components, and electrically connects the electronic components mounted on the rigid portion 81 and other electronic components. .

  FIG. 27 shows a cross section taken along line XX in FIG. 26. In the rigid portion 81, the first wiring pattern 85 is formed on the flexible substrate 84, and the first wiring pattern 85 is formed on the flexible substrate 84. A cover lay film 86 that protects one wiring pattern 85 and insulates the first wiring patterns 85 is laminated, and an insulating layer 87 formed of a prepreg layer is formed on the cover lay film 86, and further thereon A second wiring pattern 88 is formed. As shown in FIG. 26, the surface of the rigid portion 81 is covered with a solder resist 89 except for the electronic component mounting region 90 where the second wiring pattern 88 is exposed as a terminal.

  In the flexible terminal portions 82 and 83, a first wiring pattern 85 is formed on the flexible substrate 84. The coverlay film 86 and the insulating layer 87 are not laminated on the first wiring pattern 85, and the flexible terminal portions 82 and 83 have portions where the first wiring pattern 85 is exposed.

  Here, the first wiring pattern 85 and the second wiring pattern 88 need to be electrically connected by through holes or vias, but are omitted here. Further, the flexible terminal portion 83 is the same as the flexible terminal portion 82 and is not shown.

  Specifically, in the structure of the flexible terminal portion 82 of the multilayer printed wiring board 80, the exposed region 91 of the first wiring pattern 85 extends not only to the product portion 92 but also to the product exterior 93, as shown in FIG. It can be formed by punching with ZZ as a cut surface in the figure. The structure of FIG. 28 can be manufactured by the same method as that for forming the exposed region 67 described in the fourth embodiment, and the same effect can be obtained.

  In addition, as a multilayer printed wiring board manufactured with the method of this invention, it is good also as a wiring board which has multiple rigid parts and was connected between the rigid parts by the flex cable part.

Below, the Example and comparative example of a multilayer printed wiring board are demonstrated.
<Example>
In the example, a multilayer printed wiring board was produced as follows. First, a double-sided copper-clad flexible substrate having a copper foil with a thickness of 18 μm on both sides of a polyimide insulating layer was prepared, and a wiring pattern was formed on both sides by a normal subtractive method. Next, a coverlay film having a 12.5 μm-thick polyimide film and an adhesive layer of 25 μm in which a region corresponding to an exposed region exposing the wiring pattern is previously punched on both surfaces of the flexible substrate and being exposed to vacuum in vacuum. The inner layer substrate was produced by coating by hot pressing. Next, an alkali-soluble ink (trade name: SER-451B, manufactured by Yamaei Chemical Co., Ltd.) is printed on the exposed area of the wiring pattern by screen printing, and dried and cured at 150 ° C. for 20 minutes to form an ink layer. did. The thickness of the printed film (ink layer) after drying and curing was set to 60 μm.

Next, an epoxy-impregnated glass cloth prepreg having a thickness of 60 μm, in which openings are formed by punching in the same position and shape as the ink layer, is arranged on both sides of the inner layer substrate so that the ink layer is inserted, and further on both outer sides, The copper foil was laid up and pressed in a vacuum at 40 ° C./cm ² at 180 ° C. for 90 minutes to form a laminate. The appearance of the laminate after pressing was flat.

  Next, a dry film resist was laminated on the copper foil provided on the outer layer of the laminate, exposed, developed, and etched by spraying an aqueous iron chloride solution to form a wiring pattern on the copper foil. In this case, the ink layer remained even after the copper foil corresponding to the unexposed portion of the dry film resist was completely etched away. Next, the laminate was immersed in a 3 wt% aqueous sodium hydroxide solution set at 50 ° C. As a result, the ink layer was dissolved and removed, and an internal wiring pattern appeared.

  In this example, there is no appearance of the resin constituting the epoxy-impregnated glass cloth prepreg flowing on the wiring pattern, and the end face at the boundary between the coverlay film and the ink of the epoxy-impregnated glass cloth prepreg is not damaged, The shape was very steep, and no residue was observed on or between the wiring patterns.

<Comparative example>
In the comparative example, a multilayer printed wiring was formed in the same manner as in the example except that the ink layer was formed using an ink (trade name: Solder Shield SSZ-100SCB) manufactured by Taiyo Ink Manufacturing Co., Ltd. instead of the alkali-soluble ink. A plate was made.

  In the comparative example, since the ink was not alkali-soluble, the ink layer was not removed and the internal wiring pattern did not appear. When the ink layer was carefully peeled by hand, the ink layer digged into the prepreg, and an ink layer residue was formed at the boundary with the prepreg ink. Conversely, a part of the prepreg was taken together with the peeled ink layer, and the prepreg was cracked. Furthermore, when the wiring pattern after peeling was observed with a microscope, residue was observed between the wiring patterns.

  From these examples and comparative examples, when producing a multilayer printed wiring board in which a wiring pattern formed inside is exposed, the present invention using an alkali-soluble ink is applied, which is extremely simple and wiring. It turns out that a multilayer printed wiring board can be produced without damaging a pattern, a coverlay film, and a prepreg.

  Useful for the manufacture of multilayer printed wiring boards such as flex-rigid multilayer wiring boards and rigid multilayer wiring boards that expose a part of the inner layer area such as the wiring pattern or the inner layer area that functions as a cable. .

Claims (14)

Forming a wiring pattern on at least one side of the first insulating layer;
Forming an alkali-soluble ink layer in a part including the wiring pattern on the first insulating layer;
A second insulating layer is formed on the surface of the first insulating layer on the ink layer forming side so that the ink layer is exposed from the second insulating layer, and a metal layer is formed on the second insulating layer. Form the
After forming the second wiring pattern by patterning the metal layer, the ink layer is dissolved and removed with an alkaline solution to expose a part of the first insulating layer and the wiring pattern thereon. A method for producing a multilayer printed wiring board, which is characterized.   2. The method for producing a multilayer printed wiring board according to claim 1, wherein the resist provided on the second insulating layer and the ink layer are simultaneously removed with the alkaline solution to form the second wiring pattern.   The second insulating layer and the metal layer include a prepreg arranged so that the ink layer is exposed on the surface on the ink layer forming side on the first insulating layer, and a metal foil arranged on the prepreg. The manufacturing method of the multilayer printed wiring board of Claim 1 formed by carrying out lamination | stacking integration by pressurizing while heating.   The second insulating layer and the metal layer are disposed on the ink forming surface of the first insulating layer so that an insulating substrate having a metal foil attached is exposed so that the ink layer is exposed, and the pressure is applied while heating. The method for producing a multilayer printed wiring board according to claim 1, wherein the multilayer printed wiring board is formed by stacking and integrating.   A method of manufacturing a multilayer printed wiring board, wherein a part of the first insulating layer and a wiring pattern thereon are exposed on both surfaces of the first insulating layer by the method according to claim 1. A method for manufacturing a multilayer printed wiring board, wherein a multilayer structure is formed by sequentially forming an insulating layer and a wiring pattern on the second insulating layer on which the second wiring pattern is formed,
Forming a new alkali-soluble ink layer in a part including the second wiring pattern on the second insulating layer;
Forming a new insulating layer on the second insulating layer so that the new ink layer is exposed from the new insulating layer, and forming a new metal layer on the new insulating layer;
The new metal layer is patterned to form a new wiring pattern, the new ink layer is dissolved and removed with an alkaline solution, a part of the second insulating layer and the second wiring pattern thereon The manufacturing method of the multilayer printed wiring board of Claim 1 which exposes. The first insulating layer has flexibility;
After the wiring pattern on the first insulating layer is formed and before the ink layer is formed, the first insulating layer is covered with a coverlay except for the exposed portion of the first insulating layer and the wiring pattern. Item 8. A method for producing a multilayer printed wiring board according to Item 1.   A second ink layer is formed on a part of the coverlay, and the second ink layer is exposed from the second insulating layer together with the ink layer on the first insulating layer from the second insulating layer. 8. The multilayer print according to claim 7, wherein the second ink layer on the cover lay is dissolved and removed together with the ink layer on the first insulating layer with the alkaline solution to expose a part of the cover lay. A method for manufacturing a wiring board.   9. The method for producing a multilayer printed wiring board according to claim 8, wherein the exposed portions of the coverlay are formed on both sides of the first insulating layer so as to face each other.   2. The method for manufacturing a multilayer printed wiring board according to claim 1, wherein the exposed wiring pattern on the first insulating layer is used as a connection terminal of an electronic component.   The method for producing a multilayer printed wiring board according to claim 7, wherein the first insulating layer exposed by removing the ink layer is cut.   12. The method for producing a multilayer printed wiring board according to claim 11, wherein the exposed wiring pattern on the first insulating layer is used as a connection terminal of an electronic component. Forming a wiring pattern on at least one surface of the flexible first insulating layer;
Placing a coverlay on the wiring pattern forming surface of the first insulating layer;
Forming an alkali-soluble ink layer on a part of the coverlay;
Forming a second insulating layer on the coverlay so that the ink layer is exposed from the second ink layer, and forming a metal layer on the second insulating layer;
A method for producing a multilayer printed wiring board, wherein after forming the wiring pattern by patterning the metal layer, the ink layer is dissolved and removed with an alkaline solution to expose a part of the coverlay.   The method for producing a multilayer printed wiring board according to claim 13, wherein on both surfaces of the first insulating layer, the exposed portions of the coverlay are formed so as to face each other.

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