JPWO2009099065A1 - RESIST INK AND METHOD FOR PRODUCING MULTILAYER PRINTED WIRING BOARD - Google Patents

Abstract

Provided are a resist ink having improved heat resistance and crack resistance, and a method for producing a multilayer printed wiring board in which an inner layer is partially exposed using the resist ink. The resist ink includes at least one of tetracarboxylic acid, tetracarboxylic dianhydride, and a half esterified product of tetracarboxylic dianhydride, a polyhydric alcohol having three or more hydroxyl groups in one molecule, a filler, And is soluble in an alkaline solution.

Description

  The present invention relates to a resist ink useful for exposing a part of an inner layer in a manufacturing process of a multilayer printed wiring board, and a multilayer printed wiring board in which an exposed region is formed in a part of the inner layer using the resist ink. It relates to a method of manufacturing.

  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 an LCD connection part or connector connection part for component mounting parts and LCD modules. 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.

  The flex-rigid printed wiring board used as a component mounting part or an LCF connecting part also needs to partially expose the wiring pattern of the flexible substrate in the manufacturing process.

  The exposed wiring pattern must have high functional reliability as a component mounting portion, an LCD connection portion, and a connector connection portion.

  In the method of manufacturing a flex-rigid printed wiring board, for example, a bonding sheet or prepreg having an opening in which a portion corresponding to a flex portion is opened in advance is laminated on a flexible substrate, and further glass is formed on the bonding sheet or prepreg. Stacking epoxy copper-clad plates or copper foils to form multilayers, forming a rigid part with prepregs laminated, and forming a flex part consisting only of a flexible substrate without the prepregs being laminated by the openings described above There is a way to do it.

  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. That is, in this method, the resin constituting the bonding sheet or prepreg flows out to the flex portion. 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.

  As a method for preventing the resin from flowing into the flex portion, for example, there is a method as described in Patent Document 1 below. Patent Document 1 discloses a flex-rigid printed wiring in which a heat-resistant film is formed by screen printing on a flex portion corresponding to a bending-scheduled portion of a flex-rigid printed wiring board, and a portion other than the bending-scheduled portion is multilayered to form a rigid portion. A board is described. Patent Document 1 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, this flex-rigid printed wiring board is premised on a physical peeling method in which a wiring pattern is not formed at a bent portion and the heat-resistant film is peeled off by hand. In the manufacturing method of such a flex-rigid printed wiring board, 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 becomes very difficult to peel off and the boundary with the prepreg In this case, a heat-resistant film residue is formed, and scratches and cracks are generated in the insulating layer. It is impossible to cleanly remove them without accompanying them. 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 in the bent portion, the unevenness formed by the wiring pattern is different from a flat surface on which the wiring pattern is not formed. On the other hand, the heat resistant film adheres firmly due to the high temperature and high pressure lamination process. Therefore, it is very difficult to peel off the heat resistant film without damaging the wiring patterns and without leaving a residue between the wiring patterns.

  In addition, the multilayer printed wiring board exposing the inner layer is not limited to the flex-rigid printed wiring board, and there is a construction technique for exposing the inner layer in a rigid multilayer substrate (see, for example, Patent Document 2 and Patent Document 3). ). In these techniques, since the prepreg and the like are stacked and then the internal circuit to be exposed is scraped to the internal circuit to expose the internal circuit, the process becomes complicated.

JP 2001-15917 A Japanese Patent Publication No. 07-19970 JP 2003-179361 A

  In contrast to the method for manufacturing the flex-rigid printed wiring board of Patent Document 1 described above, the ink layer is formed to have approximately the same thickness as the prepreg by printing with an alkali-soluble ink instead of forming a heat-resistant film by screen printing at a planned bending position. And a method of laminating a prepreg around the ink layer. According to this method, the presence of the ink layer at the planned folding location can prevent the resin constituting the prepreg from flowing into the planned folding location when the prepreg is laminated. Further, according to this method, when the resist used for forming the outer layer pattern is removed with an alkaline solution, the ink layer can also be dissolved and removed with the alkaline solution. Does not occur. Furthermore, since it is not peeled off by physical means, the insulating layer is not damaged or cracked, the ink layer can be removed, and a flex portion can be formed.

  As inks for electronic materials that are soluble in an alkaline solution, so-called plating resist inks, ink for filling holes for protecting through holes from etching liquids, printing type etching resists, and the like are already known and commercially available. Yes. These inks are printed in a relatively thin film of 20 μm or less, dried and cured in a relatively short time at a temperature of 150 ° C. or less, and then subjected to a plating process or an etching process.

  However, the ink layer used for forming the flex portion in the manufacturing process of the flex-rigid printed wiring board needs to be formed to the same thickness as the prepreg in order to prevent the resin of the prepreg from flowing into the flex portion. Therefore, thick film printing of 50 μm or more equivalent to a commercially available prepreg is required. In general, in the step of laminating the prepreg, the heating and pressurizing conditions are about 180 ° C., and the time is also 1 hour or more. Therefore, the ink is resistant to cracking against the heating and pressurizing conditions after the thick film is formed. It is necessary that the ink itself has heat resistance that does not melt, flow, or thermally decompose, and that the alkali solubility is sufficiently maintained even after heating and pressurization.

  In general, commercially available alkali-soluble inks have no problem in normal use, but when a thick film is formed, many of them have poor crack resistance, and few have heat resistance. Therefore, when a commercially available alkali-soluble ink is used for forming the flex portion of the flex-rigid printed wiring board, cracks may occur when printed, dried, and cured at a thickness equivalent to an insulating layer such as a prepreg layer, In most cases, the ink is denatured or decomposed by the heating and pressure of the prepreg lamination press, and at that time, cracks occur or the ability to dissolve the alkali is lost due to fusion to the substrate.

  The present invention has been proposed in view of such circumstances, and even when formed into a thick film, it has sufficient crack resistance and does not lose alkali solubility even when heated and pressurized. An object of the present invention is to provide a resist ink and to provide a method for producing a multilayer printed wiring board in which an inner layer is partially exposed using the resist ink.

  The resist ink according to the present invention includes at least one of tetracarboxylic acid, tetracarboxylic dianhydride, and tetraester dianhydride half-esterified products, a polyhydric alcohol having three or more hydroxyl groups in one molecule, It contains a filler and is soluble in an alkaline solution.

Further, in the first 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,
A part of the first insulating layer is coated with the resist ink according to the present invention to form an ink 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 the metal layer is patterned to form a second wiring pattern, the ink layer is dissolved and removed with an alkaline solution to expose a part of the first insulating layer.

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,
A coverlay is disposed on the surface of the first insulating layer on the wiring pattern forming side,
Applying the above-described resist ink according to the present invention on a part of the coverlay to form an ink layer,
Forming a second insulating layer on the coverlay so that the ink layer is exposed from the second insulating layer, and forming a metal layer on the second insulating layer;
After the metal layer is patterned to form a second wiring pattern, the ink layer is dissolved and removed with an alkaline solution to expose a part of the coverlay.

  The resist ink according to the present invention includes at least one of tetracarboxylic acid, tetracarboxylic dianhydride, and tetraester dianhydride half-esterified products, a polyhydric alcohol having three or more hydroxyl groups in one molecule, Polyhydric alcohol having at least one of tetracarboxylic acid, tetracarboxylic dianhydride, and half esterified product of tetracarboxylic dianhydride and having three or more hydroxyl groups in one molecule because it contains a filler To form a polyester polycarboxylic acid polymer having a high acid value.

  Therefore, when an ink layer is formed on the first insulating layer using this resist ink, the polymer formed by heating and pressurizing the resist ink is soluble in an alkaline solution due to its high acid value. Become. Furthermore, it has heat resistance by three-dimensional crosslinking. In addition, since this polymer is very flexible, even a thick film has sufficient crack resistance.

  In the first and second multilayer printed wiring board manufacturing methods according to the present invention, an ink layer is formed on the first insulating layer or a part of the coverlay using the resist ink described above. Therefore, when the second insulating layer is heated and pressurized after the ink layer is formed, the ink layer has flexibility and heat resistance. Therefore, the ink layer does not crack by pressurization, and does not melt or flow by heating. Thereby, even if the resin of the second insulating layer melts and flows during heating and pressurization of the second insulating layer, the resin can be reliably damped by the ink layer. Further, in this method for producing a multilayer printed wiring board, the solubility of the ink layer in an alkaline solution is not lost even after heating and pressurization, so that the ink layer can be completely removed by dissolving in the alkaline solution. . Therefore, it is possible to manufacture a multilayer printed wiring board in which there is no ink layer residue and a part of the first insulating layer or a part of the coverlay is exposed.

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. In the manufacturing method of the multilayer printed wiring board of a 3rd embodiment, it is a sectional view showing the state where the ink layer was formed in the 1st exposure field and the 2nd exposure field. 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

  DESCRIPTION OF SYMBOLS 1 Multilayer printed wiring board, 2 1st insulating layer (core board | substrate), 2a One side of a core board | substrate, 2b The other side of a core board | substrate, 2c Via, 3 1st wiring pattern, 4 2nd insulating layer ( (First prepreg layer), 4a opening of first prepreg layer, 5 second wiring pattern, 6 third wiring pattern, 7 third insulating layer (second prepreg layer), 7a second prepreg Layer opening, 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), 3 a one side of the core substrate, 31b the other side of the core substrate, 31c via, 32 first wiring pattern, 33 second insulating layer (first prepreg layer), 33a opening of the first prepreg layer, 34 2nd wiring pattern, 35 3rd insulating layer (2nd prepreg layer), 35a Opening part of 2nd prepreg layer, 36 3rd wiring pattern, 37 4th wiring pattern, 38 4th insulation 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 52, a first rigid portion of the flex-rigid printed wiring board 50, 53 a second rigid portion of the flex-rigid printed wiring board 50, 54 a 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 First cover lay film opening, 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 3rd wiring pattern, 63 3rd insulating layer (2nd prepreg layer), 64 4th wiring pattern, 65 via, 66 Via, 67 Exposed area, 68 Through hole, 69 Ink layer, 70 Ink layer, 71 Ink layer, 72 Copper foil, 73 Copper foil, 74 Laminate, 80 Multilayer printed wiring board, 81 Rigid portion of multilayer printed wiring board 80 82, flexible terminal portion of the multilayer printed wiring board 80, 83 flexible terminal portion of the multilayer printed wiring board 80, 84 flexible substrate, 85 first wiring pattern, 86 cover lay film, 87 insulating layer (prepreg layer), 88 second Wiring pattern, 89 solder resist, 90 electronic component mounting area, 91 exposed area, 92 product parts, 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 first multilayer printed wiring board according to the present invention, 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, a multilayer printed wiring board manufactured by this manufacturing method will be described.

  In the multilayer printed wiring board 1, as shown in FIG. 1, the first wiring pattern 3 is formed on one surface 2a of the core substrate 2 to be the first insulating layer, and has adhesiveness and insulating properties thereon. A second insulating layer 4 formed from the first prepreg layer 4 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 layer 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 the first wiring pattern 3 of the core substrate 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 area 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, an ink layer 13 is formed by applying an alkali-soluble resist ink of the present invention, which will be described in detail later, to the exposed region 11 where the first wiring pattern 3 is exposed. The ink layer 13 is formed by printing the resist ink of the present invention on the exposed region 11 by a printing method such as screen printing or ink jet printing, and drying and curing under appropriate conditions.

  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.

  As the ink for forming the ink layer 13, the alkali-soluble resist ink of the present invention is used. Here, the ink is soluble in alkali means that the ink is soluble in an alkaline solution not only before curing but also after curing, preferably not dissolved in a weak alkaline solution for developing a dry film resist. It can be dissolved in an alkaline solution for removing the cured dry film resist.

  The resist ink of the present invention is specifically a polyvalent having at least one of tetracarboxylic acid, tetracarboxylic dianhydride, and half esterified product of tetracarboxylic dianhydride and three or more hydroxyl groups in one molecule. This resist ink is soluble in an alkaline solution and contains alcohol and a filler. According to this resist ink, at least one of tetracarboxylic acid, tetracarboxylic dianhydride, and a half esterified product of tetracarboxylic dianhydride reacts with a polyhydric alcohol having three or more hydroxyl groups in one molecule. Since the polyester polycarboxylic acid polymer having a high acid value is obtained by three-dimensional crosslinking, the cured resist ink is soluble in an alkali solution, has heat resistance, and is very flexible. Even a film does not cause bending cracks. Moreover, by containing the filler, the shape of the layer can be maintained well, and the heat resistance is further improved.

  Specifically, as the tetracarboxylic dianhydride, any one generally known as an epoxy curing agent or a raw material for polyimide synthesis can be used. Examples of the tetracarboxylic dianhydride include pyromellitic dianhydride, 3,3,4,4-biphenyltetracarboxylic dianhydride, 3,3,4,4-benzophenone tetracarboxylic dianhydride, Oxy-4,4-diphthalic dianhydride, ethylene bistrimellitate dianhydride, 2,2-bis (4- (3,4-dicarboxyphenoxy) phenyl) propane dianhydride, 1,2,3 4-butanetetracarboxylic dianhydride, 5- (2,5-dioxotetrahydro-3-furanyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, etc. One or a plurality of them can be used in combination. Among these, 3,3,4,4-benzophenonetetracarboxylic dianhydride, oxy-4,4-diphthalic dianhydride, ethylene bistrimellitic dianhydride, 1,2,3,4 -Butanetetracarboxylic dianhydride, particularly preferably ethylene bistrimellitate dianhydride.

  As the tetracarboxylic acid, for example, a tetracarboxylic acid capable of forming an acid dianhydride in the molecule is obtained by reacting the above tetracarboxylic dianhydride with water and opening the acid anhydride group. It is done. The half esterified product of tetracarboxylic dianhydride is obtained by reacting the above tetracarboxylic dianhydride with an alcohol to open the acid anhydride group.

  The half esterified product of tetracarboxylic dianhydride can be produced according to a conventional method. For example, in the presence of a catalyst at a temperature of room temperature to 120 ° C., tetracarboxylic dianhydride and a half esterifying alcohol Can be made to react.

  Examples of the catalyst include tertiary amines such as triethylamine and tributylamine, quaternary ammonium salts such as benzyltrimethylammonium chloride and benzyltrimethylammonium bromide, 2-methylimidazole, 2-undecylimidazole, and 1,2-dimethyl. Imidazoles such as imidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, and 1-benzyl-2-methylimidazole can be used.

  As the half esterifying agent, any alcohol can be used, but it is preferable to use a low molecular weight alcohol. As the low molecular weight alcohol, methanol, ethanol, n-propanol, i-propanol, n-butanol, allyl alcohol, propargyl alcohol, and the like can be used. Among these, methanol and ethanol are particularly preferable.

  A tetracarboxylic acid capable of forming an acid dianhydride in the molecule can be produced by using water as the alcohol of the half esterifying agent in the method for producing a half esterified product of the tetracarboxylic dianhydride described above.

  These tetracarboxylic acid, tetracarboxylic dianhydride, and half esterified product of tetracarboxylic dianhydride may be contained in the ink, or one or more of them may be contained. When applied as a one-component resist ink, the reaction between the acid anhydride and the polyhydric alcohol proceeds even at room temperature, so from the viewpoint of increasing the pot life, a tetraester of tetracarboxylic acid or tetracarboxylic dianhydride is used. It is preferable to use a compound.

  In addition, tetracarboxylic acid, tetracarboxylic dianhydride, tetracarboxylic dianhydride half-esterified products, dicarboxylic acid, dicarboxylic acid anhydride, dicarboxylic acid anhydride half-esterified products, tricarboxylic acid, tricarboxylic acid anhydride, A half esterified product of tricarboxylic acid anhydride may be used.

  As the dicarboxylic acid, for example, a dicarboxylic acid capable of forming an acid anhydride in the molecule can be used, and more specifically, maleic acid, phthalic acid, and the like can be used. As the dicarboxylic acid anhydride, maleic acid anhydride, phthalic acid anhydride, etc. can be used. As the half esterified product of the dicarboxylic acid anhydride, the half esterified product of maleic acid anhydride, the half ester of phthalic anhydride A compound or the like can be used.

  As the tricarboxylic acid, for example, a tricarboxylic acid capable of forming an acid anhydride in the molecule can be used, and more specifically, trimellitic acid or the like can be used. As the tricarboxylic acid anhydride, trimellitic anhydride or the like can be used, and as the half esterified product of the tricarboxylic acid anhydride, a half esterified product of trimellitic anhydride or the like can be used.

  When adding dicarboxylic acid, dicarboxylic acid anhydride, half esterified product of dicarboxylic acid anhydride and tricarboxylic acid, tricarboxylic acid anhydride, half esterified product of tricarboxylic acid anhydride, if these are added excessively, the resist ink is cured. Since the subsequent three-dimensional crosslink density decreases, the heat resistance of the ink layer 13 decreases, which is not preferable.

  Dicarboxylic acid, dicarboxylic acid anhydride, half-esterified product of dicarboxylic acid anhydride and tricarboxylic acid, tricarboxylic acid anhydride, half-esterified product of tricarboxylic acid anhydride, tetracarboxylic acid, tetracarboxylic acid dianhydride and Tetracarboxylic acid dianhydride half-esterified products are called tetracarboxylic acids, and dicarboxylic acids, dicarboxylic acid anhydrides and dicarboxylic acid anhydride half-esterified products are called dicarboxylic acids, and tricarboxylic acids, tricarboxylic acid anhydrides and tricarboxylic acid anhydrides. When the half-esterified product of the product is referred to as a tricarboxylic acid, the dicarboxylic acid and the tricarboxylic acid with respect to the acid anhydride group in the anhydride state of the tetracarboxylic acid (that is, the state before ring opening of the acid anhydride with water and alcohol) Acid anhydride group in the anhydrous state of Total, a molar ratio of 1: 0 to 1: is preferably 0.2.

  Examples of polyhydric alcohols having 3 or more hydroxyl groups in one molecule that react with these tetracarboxylic acid, tetracarboxylic dianhydride, and tetraester dianhydride half-esterified products include glycerin, diglycerin, and polyglycerin. Polyols such as erythritol, pentaerythritol and trimethylolpropane, polyether polyols obtained by polymerizing and adding alkylene oxides such as ethylene oxide and propylene oxide to these alcohols, polyester polyols containing an ester bond with dicarboxylic acid, ε- Polycaprolactone polyol or the like obtained by polymerizing caprolactone can be used.

  Of these, polycaprolactone polyol is preferred as the polyhydric alcohol from the viewpoint of heat resistance.

  As the filler, inorganic materials are preferable, for example, silica, talc, synthetic mica, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, aluminum borate, alumina, barium sulfate, magnesium oxide, and the like are preferable. Aluminum hydroxide is preferred.

  The preferred blending ratio of at least one of tetracarboxylic acid, tetracarboxylic dianhydride, and half esterified product of tetracarboxylic dianhydride in the resist ink and a polyhydric alcohol having three or more hydroxyl groups in one molecule is It becomes as follows. When tetracarboxylic acids, tetracarboxylic dianhydrides and half-esterified products of tetracarboxylic dianhydrides are referred to as tetracarboxylic acids, the tetracarboxylic acids are in the anhydride state (ie, before ring opening of the acid anhydride with water and alcohol). In this state, the molar ratio of the sum of the acid anhydride groups and the hydroxyl group of the polyhydric alcohol is preferably in the range of 0.6: 1 to 1: 0.6, more preferably 0.8: 1 to 1: 0. It mix | blends so that it may become the range of 8. When the blending ratio is out of this range, a large amount of unreacted substances remain during heating during printing, drying and curing, and the heat resistance tends to be impaired.

  The preferable content of the filler is in the range of 0.8 to 5.0 with respect to the weight 1 of the polyhydric alcohol. When the content of the filler is less than 0.8 with respect to the weight 1 of the polyhydric alcohol, the heat resistance of the ink layer 13 is likely to be impaired. When the ink layer 13 is dissolved by alkali dissolution and removed, a filler residue is likely to occur.

  In addition to fillers, additives such as thixotropic agents such as Aerosil, silicone, fluorine-based leveling agents, antifoaming agents, phthalocyanine blue, phthalocyanine green, titanium oxide and other colorants are also appropriately added to the resist ink. Can be used.

  The resist ink preferably contains a metal deactivator or an antioxidant from the viewpoint of protecting the wiring pattern. Examples of metal deactivators include amines, mercaptans such as 2-mercaptoimidazole, benzotriazole, methylbenzotriazole, triazoles such as 3- (N-salicyloyl) amino-1,2,4-triazole, N, N Hydrazines such as bis [3- (3,5-ditbutyl-4-hydroxyphenyl) proponyl] hydrazine and bis (2-phenoxypropionylhydrazine) isophthalic acid can be used. As the antioxidant, hindered phenols, hindered amines and the like can be used. The metal deactivator and the antioxidant may be appropriately contained in amounts that exhibit these effects, but are preferably contained in an amount of about 0.1 to 5 wt% with respect to the ink weight.

  Further, the resist ink may contain an alkali-soluble resin separately. By including a resin in the ink, flexibility can be imparted by the formed ink layer 13. Examples of the resin include an acrylic resin containing a monomer having a carboxyl group such as acrylic acid or methacrylic acid as a copolymerization component, a copolymer of a polyvinyl phenol resin and an acrylic resin, a phenol novolac resin, and a styrene-maleic acid copolymer. Etc. can be used.

  If necessary, the resist ink of the present invention may contain an epoxy resin to such an extent that the alkali solubility is not impaired. Examples of the epoxy resin to be used include bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac, polyglycidyl ether obtained by reaction of cresol novolaks with epichlorohydrin, butanediol diglycidyl ether, neopentyl glycol. Examples thereof include aliphatic epoxy resins such as diglycidyl ether and diethylene glycol diglycidyl ether, and alicyclic diglycidyl ether compounds such as cyclohexanedimethanol diglycidyl ether.

  The resist ink can contain a solvent as necessary. As the solvent, those which do not increase in viscosity due to volatilization during the operation, do not impose a load on drying after printing, have a boiling point in the range of about 130 ° C to 230 ° C and are not primary alcohols. preferable.

  The resist ink of the present invention can be produced by mixing the above-described components by a conventional method.

  The ink layer 13 can be formed as shown in FIG. 5 by printing the resist ink of the present invention on the exposed region 11 by screen printing or the like, and heating and drying and curing in an oven or the like. In the ink layer 13, at least one of tetracarboxylic acid, tetracarboxylic dianhydride, and tetracarboxylic dianhydride half-esterified products is generated by heat during printing of resist ink, heat during drying, and curing. A polyhydric alcohol reacts to produce a three-dimensionally crosslinked polyester polycarboxylic acid polymer. Since this polyester polycarboxylic acid polymer is a three-dimensionally crosslinked polymer and has a very high acid value, the obtained ink layer 13 has sufficient heat resistance and alkali solubility. Further, since it is very flexible, the occurrence of a bending crack can be prevented even with a thick film having a thickness substantially the same as the thickness of the first prepreg layer 4, and the first wiring pattern 3 can be protected.

  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 13 formation 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 2a of the core substrate 2 on which the ink layer 13 is formed, on which the ink layer 13 is not formed, and the entire surface of the other surface 2b of the core substrate 2 is disposed. A second prepreg layer 7 is disposed. 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 at a position corresponding to the ink layer 13 is preliminarily molded. For example, 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 and a bonding sheet may be used and a thermoplastic resin film etc. can also be used if the function as an insulating layer can be fulfill | performed.

  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 method of manufacturing a multilayer printed wiring board, instead of the first prepreg layer 4 and the copper foil 14 and the second prepreg layer 7 and the copper foil 15, a copper-clad insulating substrate with a copper foil attached thereto is used. It 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 during heating and pressurization, it is formed from the resist ink described above, has heat resistance, is very flexible, and does not generate bending cracks. The ink layer 13 can prevent the resin constituting the first prepreg layer 4 from flowing into the exposed region 11, and the first wiring pattern 3 to be exposed is attached with resin, or the exposed region 11 is blocked with the resin. Can be prevented.

  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 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 a part of 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. Thus, the ink layer 13 can be easily and completely removed because it is dissolved and removed with an alkaline solution without being peeled off by hand or removed by 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, the ink layer 13 is formed with the resist ink of the present invention in the exposed region 11 where the first wiring pattern 3 is exposed. As a result, even if the first prepreg layer 4 is heated and pressurized and laminated on the core substrate 2, the ink layer 13 maintains its shape, has heat resistance without losing alkali solubility, and is very flexible. Even if the first prepreg layer 4 is formed to have a thickness substantially the same as the thickness of the first prepreg layer 4, no bending cracks are generated. For this reason, even if the first prepreg layer 4 is laminated on the core substrate 2 and heated and pressurized, the ink layer 13 can prevent the resin constituting the first prepreg layer 4 from flowing into the exposed region 11. 1 wiring pattern 3 can be protected, and electrical failure can be prevented from occurring.

  Further, in the method for manufacturing the multilayer printed wiring board 1, since the first wiring pattern 3 is formed in the exposed region 11, the exposed region 11 is uneven, and the ink layer 13 is exposed by the lamination press. 11, the ink layer 13 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, and even if the exposed region 11 has a fine shape, the exposed region 11 and the first wiring pattern 3 can be prevented. The wiring pattern 3 can be appropriately protected.

  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.

  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, since 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, an electronic component is formed on the first wiring pattern 3. Even if 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, no wiring pattern is formed in the exposed region 11 and only the core substrate 2 may be exposed. In the multilayer printed wiring board 1 described above, the wiring pattern is provided on both surfaces of the core substrate 2. However, the present invention is not limited to this, and the wiring pattern may be provided only on one surface 2 a 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 insulating layer and a wiring pattern may be further formed on the other surface 2b of the core substrate 2 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 to form three or more layers, the wiring pattern on the core substrate 2 is exposed. In addition, other wiring patterns located inside may be exposed.

  Next, as a second embodiment, using a resist ink, 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. A mode of forming the exposed region 21 will be specifically described. 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 the multilayer printed wiring board 20, the first insulating layer 4 formed from the first prepreg layer is not laminated in the exposed region 11 provided on the one surface 2 a side of the core substrate 2. In addition to the part of the wiring pattern 3 being exposed, the third insulating layer 7 formed of the second prepreg layer is exposed in the exposed region 21 provided on the other surface 2b side of the core substrate 2. A part of the third wiring pattern 6 is exposed because it is not laminated.

  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 and the second prepreg layer 7, respectively. At this time, since the ink layers 13 and 22 are formed of the above-described resist ink of the present invention, even the thick films having the same thickness as the first prepreg layer 4 and the second prepreg layer 7 are bent. Generation of cracks can be prevented.

  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 arranged on the first wiring pattern 3 and the third wiring pattern 6 so that the ink layers 13 and 22 are exposed from the first and second prepreg layers 4 and 7, and each prepreg layer The copper foils 14 and 15 are arranged on the 4 and 7. And it is set as the integrated multilayer laminated body 23 shown in FIG. 12 by heating and pressurizing similarly to the manufacturing method of the multilayer printed wiring board 1 mentioned above. At this time, since the ink layers 13 and 22 have heat resistance, they do not melt or flow, and since they have flexibility, no cracking occurs. This can 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 addition, since the ink layers 13 and 22 are formed of the resist ink described above, the alkali solubility is not lost even when heated and pressurized in the laminating process, and is reliably removed with an alkali solution.

  In the manufacturing method of the multilayer printed wiring board 20 as described above, the first wiring pattern 3 is formed on both the one surface 2a and the other surface 2b of the core substrate 2 by using the alkali-soluble resist ink of the present invention. It is possible to form the exposed region 11 where the third electrode pattern is exposed and the exposed region 21 where the third wiring pattern 6 is exposed at the same time. 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 method for manufacturing a multilayer printed wiring board 30 as shown in FIG. 14 using ink will be specifically described.

  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. The 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 to protect the second wiring pattern 34. In addition, adjacent third wiring patterns 34 are insulated from each other, and a third insulating layer 35 having adhesiveness is laminated, and a third wiring pattern 36 is formed on the third insulating layer 35. 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 first wiring pattern 32 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 first exposed region 45, but also in the second exposed region 46. A part of the second wiring pattern 34 formed on the insulating layer 35 is exposed.

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

  First, as shown in FIG. 15, a multilayer printed wiring board having a first 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, the resist ink of the present invention 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 includes the first exposed region 45 and the second wiring pattern in which the first wiring pattern 32 is exposed when the second prepreg layer 35 is heated and pressed in a later step and laminated. The uncured resin of the second insulating layer 33 and the resin of the second prepreg layer 35 are prevented from flowing into the second exposed region 46 where the 34 is exposed. Therefore, as shown in FIG. 16, the ink layer 47 has a depth in the opening 33a of the second insulating layer 33 and a second prepreg laminated on the first prepreg layer 33 in the next step. The second insulating layer 33 is formed around the opening 33 a and in the second exposed region 46 with substantially the same thickness as the layer 35. Since the ink layer 47 is formed of the resist ink of the present invention, even if the first prepreg layer 33 and the second prepreg layer 35 are formed to have substantially the same thickness, bending cracks are generated. Never do.

  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 35. 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 disposed so as to be exposed in the opening 35a. . 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.

  When heating and pressurizing, the ink layer 47 is formed in the first exposed region 45 and the second exposed region 46, so that the second insulating layer 33 and the second prepreg layer 35 melt and flow. However, since the ink layer 47 has heat resistance, the ink layer 47 does not melt and flow, and since it has flexibility, no wrinkles are generated. Thus, the resin constituting the second insulating layer 33 and the second prepreg layer 35 can be prevented from flowing into the first exposed region 45 and the second exposed region 46, and the first exposed region 45 can be prevented from flowing into the first exposed region 45. Resin is attached to the formed first wiring pattern 32 and the second wiring pattern 34 formed in the second exposed region 46, or the first exposed region 45 and the second exposed region 46 are made of resin. It can be prevented from blocking.

  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. . At this time, since the ink layer 47 is formed of the resist ink of the present invention, the alkali solubility is not lost even after being heated and pressurized in the laminating step, and is reliably removed with an alkali solution.

  In the method of manufacturing the multilayer printed wiring board 30, different inks formed on the core substrate 31 and the second insulating layer 33 are formed by forming the ink layer 47 on the core substrate 31 and the second insulating layer 33. Since the first wiring pattern 32 and the second wiring pattern 34 can be exposed in the same process, the manufacturing process can be simplified.

  In the method for manufacturing the multilayer printer wiring board 30, the first prepreg layer is formed by forming the ink layer 47 in the first exposed region 45 and the second exposed region 46 with the resist ink of the present invention. 33. Even if the second prepreg layer 35 is laminated by heating and pressing on the core substrate 31, the shape of the ink layer 47 is maintained, heat resistance is maintained without losing alkali solubility, and very flexible. Even if the first prepreg layer 33 and the second prepreg layer 35 are formed with a thickness substantially the same as that of the first prepreg layer 33, the bending crack does not occur. For this reason, when the first prepreg layer 33 and the second prepreg layer 35 are laminated on the core substrate 31, the resin constituting the first prepreg layer 33 and the second prepreg layer 35 is exposed to the exposed regions 45 and 46. Inflow can be prevented by the ink layer 47, the first wiring pattern 32 and the second wiring pattern 34 can be protected, and an electrical failure can be prevented.

  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 of 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. By being formed, the surface is uneven, and when the ink layer 47 is pressed against the uneven surface of the first exposed region 45 and the second exposed region 46 by the laminating press, the first exposed region 45 and the first exposed region 45 Although the ink layer 47 can be completely removed with an alkaline solution, the first wiring pattern 32, the second wiring pattern 34, and the first wiring pattern 32 are in close contact with each other. In addition, it is possible to prevent a residue of the ink layer 47 from being generated between the second wiring patterns 34.

  Next, as a fourth embodiment, a method for manufacturing a flex-rigid printed wiring board 50 as shown in FIG. 18 using the ink 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 wiring pattern 55 that electrically connects the first rigid portion 52 and the second rigid portion 53 on one surface 54a of the flexible substrate 54 of a flexible insulating substrate. The first cover lay film 56 is formed to protect the first wiring pattern 55 and insulate the adjacent first wiring patterns 55 from each other, and the second cover lay film 57 is formed on the other surface 54b. Is formed. The flex portion 51 has a region 58 where the first cover lay film 56 is exposed by not laminating the first prepreg layer 60 on the one surface 54 a side of the flexible substrate 54, and is opposed to the region 58. And it has the area | region 59 which exposed the 2nd coverlay film 57 by not laminating | stacking the 2nd prepreg layer 63 on the other surface 54b side.

  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. In addition, a third insulating layer 63 and a fourth wiring pattern 64 are formed. 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, a first ink layer 69 is formed in and around the opening 56 a of the first coverlay film 56 corresponding to the exposed region 67. The thickness of the first ink layer 69 around the opening 56a is set to be approximately the same as the thickness of the first prepreg layer 60 laminated on the first coverlay film 56 in the next step. Further, the second ink layer 70 having a thickness substantially the same as the thickness of the first prepreg layer 60 is applied to the area corresponding to the area 58 where the first prepreg layer 60 is not laminated on the first cover lay film 56. It is formed by printing. On the second cover lay film 57, the thickness of the second prepreg layer 63 laminated on the second cover lay film 57 is substantially the same as the area 59 corresponding to the area 59 where the second prepreg layer 63 is not laminated. The third ink layer 71 is formed with the same thickness. At this time, even if the first ink layer 69 is formed to have substantially the same thickness as the combined thickness of the first coverlay film 56 and the first prepreg layer 60, the second ink layer 70 and the first ink layer 69 Even if the third ink layer 71 is formed with substantially the same thickness as the first prepreg layer 60 and the second prepreg layer 63, the formation of cracks can be prevented by the formation of the resist ink described above.

  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 formed on the first coverlay film 56 so that the first ink layer 69 and the second ink layer 70 are exposed from the 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 the method for manufacturing the multilayer printed wiring board 1 described above, heating and pressurizing are performed, and a laminate 74 is formed by a lamination press as shown in FIG.

  Even when the resin forming 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. Since the layer 71 has heat resistance, it does not melt and flow, and since it has flexibility, it does not crack by heating and pressurization. As a result, the resin constituting the first prepreg layer 60 and the second prepreg layer 63 can be prevented from flowing into the regions 58, 59 and the exposed region 67, and the resin is attached to the exposed first wiring pattern 55. It is possible to prevent the regions 58 and 59 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 resist used for forming the second wiring pattern 61 and the fourth wiring pattern 64 is removed with an alkaline solution, the first ink layer 69, the second ink layer 70, the third wiring pattern The ink layer 71 is also dissolved and removed with an alkaline solution. Since the first ink layer 69, the second ink layer 70, and the third ink layer 71 are formed of the above-described ink of the present invention, the alkali solubility is lost even when heated and pressurized in the laminating process. I will not. By removing the resist, 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 second ink layer A flex part 51 in which the first prepreg layer 60 and the second prepreg layer 63 are not laminated is formed by the region 59 in which the prepreg layer 63 is not laminated, and the first prepreg layer 60 and the second prepreg layer 63 are formed through the flex part 51. A flex-rigid printed wiring board 50 in which the first rigid portion 52 and the second rigid portion 53 having the exposed region 67 where the second prepreg layer 63 is laminated and the first wiring pattern 55 is exposed are connected to each other. Is manufactured.

  In the exposed region 67 of the first rigid portion 52 formed by the manufacturing method of the flex-rigid printed wiring board 50, the first wiring pattern 55 formed inside is exposed. It can be. Further, in the flex portion 51, flexibility is maintained because the prepreg layers 60 and 63 are not laminated, and the first wiring pattern 55 is covered with the first cover lay film 56 and the second cover lay film 57. Therefore, the flex part 51 can be functioned as a cable.

  Further, in the method for manufacturing the flex-rigid printed wiring board 50, the laminate 74 is formed by forming the second ink layer 70 and the third ink layer 71 in the regions 58 and 59 with the resist ink of the present invention. At this time, even if the first prepreg layer 60 and the second prepreg layer 63 are heated and pressurized, the second ink layer 70 and the third ink layer 71 maintain their shapes and have heat resistance. Since the resin is very flexible and does not generate a bending crack, 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. Thus, the flexibility of the flexible substrate 54 can be maintained well. Similarly, the resin of the first prepreg layer 60 can be prevented from flowing into the exposed region 67 by forming the first ink layer 69 using the resist ink of the present invention. 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 cover lay film 56, the second cover lay film 57, the second The first ink layer 69, the second ink layer 70, and the third ink layer 71 can be removed without peeling off the insulating layer 60 and the third insulating layer 63. Furthermore, the end surface of the second insulating layer 60 adjacent to the region 58, the end surface of the third insulating layer 63 adjacent to the region 59, the end surface of the first coverlay film 56 adjacent to the exposed region 67, and the second surface. The end surface of the insulating layer 60 is flat.

  Further, in the manufacturing method of the flex-rigid printed wiring board 50, since the exposed region 67 is uneven due to the formation of the first wiring pattern 55, the first ink layer 69 is formed on the uneven surface of the exposed region 67 by the lamination press. 1, the first ink layer 69 adheres to the exposed region 67, but the ink layer 69 can be completely removed by dissolving with an alkaline solution. It is possible to prevent the residue of the first ink layer 69 from being generated between the first wiring patterns 55. 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.

  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. In the rigid portion 81, a first wiring pattern 85 is formed on the flexible substrate 84, and the coverlay film 86 that protects the first wiring pattern 85 and insulates the first wiring patterns 85 from each other on the flexible substrate 84. The insulating layer 87 formed from the prepreg layer is laminated on the cover lay film 86, and the second wiring pattern 88 is further formed thereon. 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.

  Also in the flexible terminal portions 82 and 83, the first wiring pattern 85 is formed on the flexible substrate 84. On the first wiring pattern 85, an insulating layer 87 formed of a coverlay film 86 and a prepreg layer is provided. By not being laminated, a portion where the first wiring pattern 85 is exposed is formed.

  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 shown in FIG. 28 can be manufactured by using the resist ink described above 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, the multilayer printed wiring board 80 may further manufacture a wiring board having a plurality of rigid parts and connecting the rigid parts with a flex cable part.

  Examples of resist ink and comparative examples will be described below.

(1) Preparation of Resist Ink First, the tetracarboxylic dianhydride half-esterified solutions 1 and 2, the alkali-soluble resin solution 1, and the alkali-soluble resin solution 2 used in preparing the resist ink will be described.

In a 0.5 l flask equipped with a stirrer, a tetraester dianhydride half-esterified solution 1 is 150 g of dipropylene glycol dimethyl ether and 1.875 g of imidazole (trade name: 2E4MZ) manufactured by Shikoku Kasei Co., Ltd. And stirred until the imidazole was dissolved. Thereafter, 23.41 g of methanol was added, and further 150 g of ethylene bis (trimellitate) dianhydride (trade name: TMEG200) with an acid anhydride equivalent of 205 manufactured by Shin Nippon Rika Co., Ltd. was added and stirred at room temperature for 24 hours. Reaction was performed to obtain a half esterified product of tetracarboxylic dianhydride. After the reaction, the produced substance was analyzed by infrared spectroscopy (IR), and it was confirmed that the absorption (1785 cm ⁻¹ ) derived from the acid anhydride group had completely disappeared.

In a 0.5 l flask equipped with a stirrer, 150 g of propylene glycol monobutyl ether and 3.75 g of imidazole (trade name: 2E4MZ) manufactured by Shikoku Kasei Co., Ltd. were added to the half esterified solution 2 of tetracarboxylic dianhydride. And stirred until the imidazole was dissolved. Thereafter, 35.08 g of methanol was added, and 150 g of ethylene bis (trimellitate) dianhydride (trade name: TMEG200) manufactured by Shin Nippon Rika Co., Ltd. was added, followed by stirring at room temperature for 48 hours. Thus, a half-esterified solution 2 of tetracarboxylic dianhydride was obtained. When the substance produced | generated after reaction was analyzed by infrared spectroscopy (IR), it has confirmed that the absorption (1785 cm < ^-1 >) derived from an acid anhydride group was lose | disappeared completely.

  The alkali-soluble resin solution 1 was placed in a 0.5 liter flask equipped with a stirrer, and 100 g of diethylene glycol dimethyl ether and 150 g of a carboxyl group-containing acrylic resin (trade name: ARUFON UC3000) manufactured by Toagosei Co., Ltd. were added at room temperature. Stirred for hours and dissolved.

  Alkali-soluble resin solution 2 was prepared by adding 150 g of propylene glycol ethyl ether acetate and 150 g of polyvinylphenol resin (trade name: Marcalinker S-2P) manufactured by Maruzen Petrochemical Co., Ltd. to a 0.5-liter flask equipped with a stirrer. It was obtained by stirring and dissolving at room temperature for 24 hours.

  Using these tetracarboxylic dianhydride half-esterified product solutions 1 and 2, alkali-soluble resin solution 1, alkali-soluble resin solution 2 and the materials shown in Table 1 below, the composition shown in Table 1 is used for planetary stirring type Resist inks A to H of the examples and resist inks I to L of the comparative examples were prepared by dispersing and mixing with a mixer.

  In Table 1, TMEG200 is ethylene bis (trimellitate) dianhydride manufactured by Shin Nippon Chemical Co., Ltd. EPICLON B-4400 is 5- (2,5-dioxotetrahydro-3-furanyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride manufactured by Dainippon Ink and Chemicals, Inc. Plaxel 308 is a polycaprolactone triol (molecular weight 850) having a hydroxyl value of 197.6 [KOHmg / g] and an average molecular weight of 850 manufactured by Daicel Chemical Industries, Ltd. Plaquel 205 is a polycaprolactone diol having a hydroxyl value of 197.6 [KOHmg / g] and an average molecular weight of 850, manufactured by Daicel Chemical Industries, Ltd. Hygielite H-42M is aluminum hydroxide fine particles manufactured by Showa Denko KK and is a filler. The average particle diameter of this filler is 1.0 μm. ADK STAB CDA-1 is a metal deactivator and is 3- (N-salicyloyl) amino-1,2,4-triazole manufactured by ADEKA Corporation.

(2) Production of printing sample and mounting sample
(2-1) Printing Samples Samples A to L were produced as printing samples using the resist inks A to H of the examples shown in Table 1 and the resist inks I to L of the comparative examples. Sample A to Sample L were cut into a 150 × 120 mm size double-sided copper-bonded flexible board (trade name: Iupicel N) manufactured by Ube Industries, Ltd., which has 9 μm thick copper foil on both sides of 25 μm thick polyimide. In the center of one side, resist inks A to L are screen-printed with an area of 70 × 40 mm, and dried and cured for 40 minutes in a hot air oven adjusted to 150 ° C. to form an ink printing part (ink layer). Produced. In each sample, the thickness of the ink printing part after drying and curing was set to 70 μm by selecting printing conditions.

(2-2) Mounting Sample Samples M to X were prepared as mounting samples using the resist inks A to H of the examples shown in Table 1 and the resist inks I to L of the comparative examples. Samples M to X were prepared by preparing an epoxy-impregnated glass cloth base prepreg having a thickness of 70 μm and the same size as a flexible substrate in which a 70.1 × 40.1 mm window was opened in the same place as the ink printing unit by punching. Next, samples similar to Sample A to Sample H in (2-1) were prepared, and an epoxy-impregnated glass cloth base material prepreg was laid thereon so that the ink printing portion did not overlap. Further, an electrolytic copper foil having a thickness of 12 μm was laid up thereon as an outer layer, and pressed in a vacuum at a hot plate temperature of 180 ° C. and a pressure of 40 kg / cm ² for 1 hour to laminate and integrate them. Subsequently, the copper foil of the outer layer was completely etched away with a cupric chloride etchant at 48 ° C. at a spray pressure of 0.15 MPa to expose the epoxy-impregnated glass cloth substrate prepreg and the ink printing part. An implementation sample was used.

(3) Evaluation
(3-1) Evaluation of tackiness of printed surface The tackiness of the printed surfaces of Sample A to Sample L is determined according to the following criteria depending on the degree of adhesion of absorbent cotton to the printed surface when rubbing cotton on the printed surfaces of Sample A to Sample L. It was evaluated with.
○: Absorbent cotton is not attached to the printed surface ×: Absorbent cotton is attached to the printed surface

The evaluation results are shown in Table 2 below. In actual use, it is desirable that the evaluation is ◯.

  From the results shown in Table 2, since Sample I uses Ink I using a polyhydric alcohol having two hydroxyl groups, the polyhydric alcohol does not three-dimensionally crosslink with the tetraester dianhydride half-esterified product. It became a sticky film. In Sample J, since the ink J containing no filler was used, the film was slightly sticky. Thereby, in sample I and sample J, when the ink surface was rubbed with absorbent cotton, absorbent cotton adhered to the ink printing part.

  On the other hand, in Sample A to Sample H using the ink of the example of the present invention, since polyhydric alcohol having three hydroxyl groups is used, polyhydric alcohol reacts with tetracarboxylic dianhydride half esterified product. As a result, a three-dimensionally cross-linked polyester polycarboxylic acid polymer was produced, and the stickiness of the ink surface was reduced. Further, the stickiness of the ink surface disappeared even when the filler was contained, and the absorbent cotton did not adhere.

(3-2) Evaluation in practical use Using samples M to X prepared as mounting samples, a. Heat resistance (flow state of prepreg and ink), b. Bending crack resistance, c. Alkali solubility, d Etching resistance was evaluated as follows. The evaluation results are shown in Table 3 below.

a. Evaluation of heat resistance The appearance of Sample M to Sample X was observed, and the flow state of the prepreg and the ink was observed to make a determination based on the following criteria.
A: When the boundary between the ink and the prepreg is clear and the boundary at the time of printing is maintained. ○: When the boundary between the ink and the prepreg is clear, but slightly distorted as compared with the time of printing. Δ: The ink is a prepreg. When the boundary is blurred and further distorted: X: When the ink is flowing largely under or above the prepreg In practical use, it is desirable that the evaluation is 0 or more.

b. Evaluation of Bending Crack Resistance Samples M to X were evaluated according to the following criteria based on the diameter of the arc where cracks occur when the printed surface is turned into an arc shape.
○: When cracks do not occur even when bent 180 degrees Δ: When cracks occur when the arc diameter is 5 mm or less ×: When cracks occur when the arc diameter is 30 mm or less XX: Cracks occur when slightly bent In actual use, it is desirable that the evaluation is Δ or more.

c. Evaluation of Alkali Solubility The printed surfaces of Sample M to Sample X were exposed to a 3 wt% sodium hydroxide aqueous solution at 50 ° C. for 2 minutes at a spray pressure of 0.15 MPa, and evaluated according to the following criteria based on the dissolved state of the ink.
○: When the printed layer is completely dissolved and removed in 1 minute. Δ: When the printed layer is completely dissolved and removed in 2 minutes. ×: When there is a residue even after 2 minutes. desirable.

d. Evaluation of etching resistance The printed surfaces of Sample M to Sample X were exposed to a cupric chloride based etchant at 48 ° C. for 1 minute at a spray pressure of 0.15 MPa, washed with water, and then 3 wt% hydroxylated at 50 ° C. The ink layer was removed by immersing in sodium, and the degree of erosion of the copper foil under the ink layer by the etching solution was observed and evaluated according to the following criteria.
○: Not eroded at all △: Slightly eroded ×: When eroded severely For practical use, it is desirable to be ◯.

  From the results shown in Table 3, since the sample U as a comparative example uses the ink I using a polyhydric alcohol having two hydroxyl groups, it should not be three-dimensionally crosslinked with the tetraester dianhydride half-esterified product. As a result, the heat resistance did not improve, the ink melted and flowed due to heat, and the etching resistance was not obtained. In addition, since the sample V uses the ink J containing no filler, the heat resistance is not improved, the ink melts and flows due to heat, and the etch resistance is not obtained. Samples W and X consist of an alkali-soluble resin and a filler, and do not contain tetracarboxylic dianhydride or its half-esterified product or polyhydric alcohol, so a three-dimensionally crosslinked polyester polycarboxylic acid polymer is produced. As a result, heat resistance and flexibility were not obtained, bending cracking properties were deteriorated, and etching resistance was also deteriorated. Samples W and X had severe cracks in the ink printing part and were severely eroded by the etching solution.

  In contrast to these samples U to X, in samples M to T using the inks of the examples, tetracarboxylic dianhydride or tetraester dianhydride half-esterified product and polyhydric acid having three hydroxyl groups Since a polyhydric alcohol is contained, tetracarboxylic dianhydride or a half esterified product of tetracarboxylic dianhydride reacts with a polyhydric alcohol to produce a three-dimensionally cross-linked polyester polycarboxylic acid polymer. By containing the filler, it was not melted by heat, heat resistance was obtained, flexibility was obtained, cracking was prevented, and etching resistance was also obtained.

  From the above, the resist ink of the present invention has excellent heat resistance, bending cracking resistance, etching resistance, and alkali solubility, so that a multilayer printed wiring board in which a part of the inner layer or lower layer is exposed is used. It can be seen that can be easily produced. In particular, when the resist ink of the present invention is printed on the exposed area of the inner layer of the multilayer printed wiring board and the prepreg is laminated after that, the resin constituting the prepreg is also exposed to the exposed area by heat and pressure during the prepreg lamination. It is possible to protect the wiring pattern in the exposed region from the etching solution when forming the outer layer wiring pattern without finally flowing in, and finally, with an alkali that removes the etching resist used to form the wiring pattern. Since the resist ink can also be completely removed, a multilayer printed wiring board in which the inner layer is partially exposed can be easily produced.

Claims (10)

At least one of tetracarboxylic acid, tetracarboxylic dianhydride, tetracarboxylic dianhydride half-esterified product, and
A polyhydric alcohol having three or more hydroxyl groups in one molecule;
A resist ink comprising a filler and soluble in an alkaline solution. Forming a wiring pattern on at least one side of the first insulating layer;
Applying the resist ink according to claim 1 on a part of the first insulating layer to form an ink 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 the metal layer is patterned to form a second wiring pattern, the ink layer is dissolved and removed with an alkaline solution, and a part of the first insulating layer is exposed. Manufacturing method.   3. The method for producing a multilayer printed wiring board according to claim 2, wherein the ink layer and the resist provided for forming the wiring pattern are simultaneously removed with the alkaline solution.   4. The method for producing a multilayer printed wiring board according to claim 2, wherein a wiring pattern is formed on a part of the first insulating layer in a region exposed by removing the ink layer.   The second insulating layer and the metal layer heat a prepreg disposed so that the ink layer is exposed on the surface of the first insulating layer on the ink layer forming side, and a metal foil disposed on the prepreg. The method for producing a multilayer printed wiring board according to claim 2, wherein the multilayer printed wiring board is formed by stacking and integrating by applying pressure.   The second insulating layer and the metal layer are disposed on the surface of the first insulating layer on the ink layer forming side with an insulating substrate having a metal foil attached so that the ink layer is exposed and heated. The method for producing a multilayer printed wiring board according to any one of claims 2 to 4, wherein the multilayer printed wiring board is formed by stacking and integrating by applying pressure.   A method for manufacturing a multilayer printed wiring board, wherein a part of the first insulating layer is exposed on both surfaces of the first insulating layer by the method according to claim 2. The first insulating layer is flexible;
After forming the wiring pattern on the first insulating layer and before forming the ink layer, at least a part of the first insulating layer is covered with a coverlay except for the exposed portion of the first insulating layer. The manufacturing method of the multilayer printed wiring board in any one of Claims 2-7.   The resist ink according to claim 1 is applied to a part of the coverlay to form a second ink layer, and the second ink layer on the coverlay together with the ink layer on the first insulating layer Forming the second insulating layer so as to be exposed from the second insulating layer, and dissolving and removing the second ink layer on the coverlay together with the ink layer on the first insulating layer with an alkaline solution; The manufacturing method of the multilayer printed wiring board of Claim 8 which exposes a part of coverlay. Forming a wiring pattern on at least one surface of the flexible first insulating layer;
A coverlay is disposed on the surface of the first insulating layer on the wiring pattern forming side,
Applying the resist ink according to claim 1 to a part of the coverlay to form an ink layer;
Forming a second insulating layer on the coverlay so that the ink layer is exposed from the second insulating layer, and forming a metal layer on the second insulating layer;
A method for producing a multilayer printed wiring board, wherein the metal layer is patterned to form a second wiring pattern, and then the ink layer is dissolved and removed with an alkaline solution to expose a part of the coverlay.

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