JP2011006773A - Sulfuric acid base copper plating liquid for semi-additive and method for producing printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sulfuric acid base copper plating liquid for a semi-additive which can produce wiring in which the surface of the cross-section in the width direction is made flat as wiring of an ultrafine pitch by a semi-additive process, and to provide a method for producing a printed circuit board using the same.SOLUTION: The sulfuric acid base copper plating liquid for a semi-additive comprises at least one kind selected from 3-mercapto-1-propanesulfonic acid and bis(3-sulfopropyl) disulfide, a quaternary ammonium salt polymer with a cyclic structure and chlorine, and has a copper concentration of 23 to 55 g/L and a sulfuric acid concentration of 50 to 250 g/L.

Description

  The present invention relates to a semi-additive sulfuric acid-based copper plating solution used when a printed wiring board such as a COF film carrier tape is produced by a semi-additive method, and a method for producing a printed wiring board using the same.

  TAB tape having a three-layer structure in which a wiring pattern made of an insulating film, an adhesive layer and a conductive metal foil is formed, or a COF tape having a two-layer structure in which a wiring pattern made of a conductive metal foil is directly formed on an insulating film The output-side outer lead and the input-side outer lead of the printed wiring board are electrically connected to, for example, a liquid crystal panel or a circuit portion of the rigid printed wiring board by an anisotropic conductive film (ACF).

  In recent years, as the fine pitch of the gold bumps on the driver IC chip has increased with the increase in the resolution of the liquid crystal screen, a circuit in which the inner lead pitch is thinned to 20 μm or less is formed on the printed wiring board for IC mounting such as COF. Is becoming necessary, and a pitch of 15 μm has entered the field of view.

  Conventionally, it has been considered that the conductive metal foil to be used needs to be thin in order to form such a thin printed wiring board. For example, when a circuit having a line width of 10 μm or less and a wiring interval of 10 μm or less is to be formed by etching, the thickness of the conductive metal foil (eg, electrolytic copper foil) serving as a conductor is less than the line width (for example, 5 μm or less). Otherwise, there is a problem that the desired thinned line width (for example, the line width of 6 μm or more) cannot be achieved.

  However, if the thickness of the conductive metal foil such as Cu foil is 5 μm or less, the reliability of connection by the anisotropic conductive film (ACF) is significantly lowered. This is because the size of the conductive particles contained in the anisotropic conductive adhesive is large with respect to the thickness or pitch of the conductive metal foil such as Cu foil, and the thickness of the adhesive sheet serving as the binder is thick. It is inferred that this is a mechanical constraint.

  However, recently, a technique for forming an ultrafine pitch wiring pattern by a semi-additive method has progressed, and this technique forms a wiring pattern having a pitch of 20 μm or less even when the conductor thickness such as Cu is as thick as 8 μm. It is possible.

  In such a semi-additive method, an underlayer is formed on an insulator layer, and then a resist pattern opposite to the wiring pattern is formed thereon, followed by electrolytic copper plating, and then the resist is peeled off. A wiring pattern is formed by removing the base layer.

  In such a semi-additive plating process, a copper sulfate plating solution is mainly used. Examples of plating methods include DC plating, PC (constant current) plating, and PPR (periodic reverse current) plating. However, the direct current plating method has become the mainstream because of the ease of management of the plating solution.

  In such a semi-additive method, there is a concern that the flatness of the surface of the wiring pattern will be lower than the method of patterning the copper foil, and when the ultra fine pitch wiring pattern is observed precisely, the width direction of the wiring It has been found that the surface tends to be convex upward in the section cut into two.

  Here, in the semi-additive method, there are the following as conventional techniques considering the flattening of the wiring pattern.

  For example, in Patent Document 1, reverse electrolysis is performed when a via land pad portion and / or a wiring circuit portion formed with a plating resist is filled with copper by acidic electrolytic copper plating to form a wiring circuit by a semi-additive method. Although a technique for flattening the surface of the wiring circuit by performing the above is disclosed, it is a technique related to the flattening of the via land pad portion to the last.

  Patent Document 2 discloses a technique for obtaining a flat pattern by forming a conductor pattern thicker than necessary by PPR plating and then cutting an excessive plating layer on the surface by polishing.

  Patent Document 3 relates to the manufacture of a planar coil, but discloses a technique for reducing variations in plating thickness by PPR plating.

  Thus, in the prior art, there is no technique for solving the problem that the surface of the cross section in the width direction of the wiring becomes convex when forming a wiring pattern with an ultra fine pitch by the semi-additive method.

JP 2005-146328 A JP 2002-246744 A JP 2006-203013 A

  In view of the above-described circumstances, the present invention provides a semi-additive sulfuric acid-based copper plating solution capable of manufacturing a wiring having a flat cross-section (transverse section) in the width direction by a semi-additive method even as an ultra-fine pitch wiring. It aims at providing the manufacturing method of the used printed wiring board.

  A first aspect of the present invention is a semi-additive sulfuric acid-based copper plating solution having a cyclic structure and at least one selected from 3-mercapto-1-propanesulfonic acid or bis (3-sulfopropyl) disulfide. A sulfuric acid-based copper plating solution for semi-additives comprising a quaternary ammonium salt polymer and chlorine, having a copper concentration of 23 to 55 g / L and a sulfuric acid concentration of 50 to 250 g / L.

  In the first aspect, since the copper plating solution has a predetermined bath composition, when used for plating by a semi-additive method, a wiring having a flat vertical cross section and a horizontal cross section can be formed.

  According to a second aspect of the present invention, the semimer according to the first aspect has a total concentration of 8 to 12 mg / L of the 3-mercapto-1-propanesulfonic acid and / or bis (3-sulfopropyl) disulfide. It is in sulfuric acid-based copper plating solution for additive.

  In the second aspect, since the additive is in the predetermined concentration range, it is possible to more reliably form a wiring with a flat surface.

  The third aspect of the present invention is the sulfuric acid copper plating solution for semi-additives according to the first or second aspect, wherein the concentration of the quaternary ammonium salt polymer having a cyclic structure is 35 to 85 mg / L.

  In the third aspect, since the additive is contained in a predetermined concentration range, it is possible to more reliably form a wiring with a flat surface.

  A fourth aspect of the present invention is the sulfate-based copper for semi-additives according to any one of the first to third aspects, wherein the quaternary ammonium salt polymer having a cyclic structure is a diallyldimethylammonium chloride (DDAC) polymer. In the plating solution.

  In the fourth aspect, since the diallyldimethylammonium chloride polymer is contained as a quaternary ammonium salt polymer having a cyclic structure, a wiring with a flat surface can be more reliably formed.

  A fifth aspect of the present invention is the semiadditive sulfuric acid copper plating solution according to the fourth aspect, wherein the diallyldimethylammonium chloride polymer is a mixture of different molecular weights.

  In the fifth aspect, a flat wiring can be formed more stably.

  A sixth aspect of the present invention is the sulfuric acid-based copper plating solution for semi-additives according to any one of the first to fifth aspects, wherein the chlorine concentration is 30 to 55 mg / L.

  In the sixth aspect, since the chlorine concentration is in the predetermined range, it is possible to more reliably form a wiring with a flat surface.

According to a seventh aspect of the present invention, a conductive underlayer is formed on the surface of an insulating substrate, a photoresist layer is formed on the surface of the underlayer, and a predetermined pattern is exposed and developed on the photoresist layer. Forming a recess exposing the underlayer by patterning, forming a copper plating layer on the underlayer of the recess, then peeling the patterned photoresist layer, and then peeling the photoresist layer In the method for manufacturing a printed wiring board in which the exposed underlayer is removed to form a wiring pattern, the formation of the copper plating layer is performed using the sulfuric acid-based copper plating solution for semi-additive according to any one of the first to sixth aspects. In the method for producing a printed wiring board, the bath temperature is 15 to 30 ° C., and the current density is 10 A / dm ² or less.

  In the seventh aspect, a printed wiring board having a wiring with a flat cross-sectional surface is manufactured by performing a semi-additive plating under a predetermined plating condition using a copper plating solution having a predetermined bath composition. be able to.

An eighth aspect of the present invention is the method for manufacturing a printed wiring board according to the seventh aspect, wherein the current density is 5 A / dm ² or less.

  In the eighth aspect, by setting the current density within a predetermined range, a printed wiring board having wiring with a flat surface can be manufactured more reliably.

It is a schematic plan view which shows an example of the printed wiring board manufactured with the manufacturing method of the printed wiring board which concerns on one Embodiment of this invention. It is sectional drawing explaining each process of the manufacturing method of the printed wiring board which concerns on one Embodiment of this invention.

  Hereinafter, a method for manufacturing a printed wiring board according to an embodiment of the present invention will be described.

  FIG. 1 shows a COF film carrier tape that is a printed wiring board manufactured by a method for manufacturing a printed wiring board according to an embodiment.

  The COF film carrier tape 1 of this embodiment shown in FIG. 1 is obtained by forming a wiring pattern 20 having a desired pattern made of a conductor layer on an insulating base material 10 made of a polyimide layer. In general, a wiring having inner leads 20A and 20B and outer leads 20C and 20D serving as terminals is provided. Sprocket holes 2 are generally formed on both sides of the insulating base material 10 of the COF film carrier tape 1 in the width direction, and the areas other than the inner leads 20A and 20B and the outer leads 20C and 20D of the wiring pattern 20 are A solder resist layer 3 is provided so as to cover the wiring pattern 20.

  Here, the manufacturing method of the printed wiring board of FIG. 1 will be specifically described with reference to the drawings.

  FIG. 2 is a diagram showing an example of a cross section of the substrate in each step of the method for manufacturing a printed wiring board according to the embodiment of the present invention.

  As shown in FIGS. 2A and 2B, in the method for manufacturing a printed wiring board according to the present embodiment, a seed layer 21 made of a thin conductive metal layer is formed on at least one surface of the insulating base 10. Here, the insulating substrate 10 can be used without particular limitation as long as it is used as a normal insulating substrate such as a plate, film, sheet, prepreg made of an insulating resin. However, in order to continuously manufacture the printed wiring board of the present invention on a reel-to-reel basis, it is desirable that the insulating base material 10 has flexibility, and the printed wiring board is manufactured. In this process, the insulating substrate 10 is preferably excellent in chemical resistance because it may come into contact with an acidic solution or an alkaline solution, and further, it is excellent in heat resistance because it may be exposed to high temperatures. It is desirable that Moreover, since a wiring pattern is manufactured by a plating process using this insulating base material 10, it is desirable that it is not modified or deformed by contact with water. From this point of view, it is preferable to use a heat-resistant synthetic resin film as the insulating substrate 10 used in the present invention, and in particular, a polyimide film, a polyamideimide film, a polyester resin film, a fluororesin film, a liquid crystal polymer resin film, etc. It is preferable to use a resin film that is usually used in the production of a printed wiring board, and among these, a polyimide film excellent in characteristics such as heat resistance, chemical resistance, and water resistance is particularly preferable.

  In the present invention, the insulating base material 10 is not necessarily in the form of a film as described above, and may be a plate-like insulating base material made of a composite material such as a fibrous material and an epoxy resin.

  In the present invention, in addition to the sprocket hole 2, necessary insulating through holes such as a device hole, a bending slit, and a positioning hole can be formed in the insulating base material 10 as described above. These through holes can be formed by a punching method, a laser drilling method, or the like.

  In the present embodiment, as described above, the seed layer 21 made of a thin conductive metal layer is formed on at least one surface of the insulating substrate 10. This seed layer 21 is a layer that becomes an electrode when a metal layer is laminated on the surface by electroplating, and is usually nickel, chromium, copper, iron, nickel-chromium alloy, Ni—Zn, Ni—Cr—. It can be formed of a metal such as Zn or an alloy containing these metals. Such a seed layer 21 is not particularly limited as long as the conductive metal is deposited on the surface of the insulating substrate 10 as described above, but it is advantageous to form the seed layer 21 by sputtering. By forming the seed layer 21 by sputtering, the sputtered metal or alloy bites the surface of the insulating base material 10, and the insulating base material 10 and the sputtered seed layer 21 are firmly bonded. Therefore, it is not necessary to provide an adhesive layer between the insulating base material 10 and the seed layer 21 when manufacturing the printed wiring board of the present invention.

  The average thickness of the seed layer 21 is usually in the range of 10 to 1000 mm, preferably 50 to 300 mm.

  In the present embodiment, the seed layer 21 is formed using a nickel-chromium alloy.

  After forming the seed layer 21 in this way, it is preferable to form a copper thin film layer 22 on the surface of the seed layer 21 and to form the underlayer 23 together with the seed layer 21 as shown in FIG. . In the present invention, the copper thin film layer 22 is preferably formed, for example, by sputtering. However, the copper thin film layer 22 is not limited to sputtering, but can be formed by various methods such as a vacuum evaporation method and an electroless plating method. However, when the copper thin film layer is formed by sputtering, the copper thin film layer 22 is bonded. A copper metal circuit having good strength and high strength can be formed. Although this copper thin film layer 22 is a layer which has copper as a main component, metals other than copper may be contained within the range in which the characteristics of this layer are not impaired. The average thickness of the copper thin film layer is usually in the range of 0.01 to 5 μm, preferably 0.1 to 3 μm. By forming the copper thin film layer 22 with such an average thickness, the affinity with the copper layer formed on the surface of the copper thin film layer 22 by the semi-additive method is improved.

  Although the copper thin film layer 22 is formed on the seed layer 21 as described above to form the base layer 23, it can be transferred to the next step as it is, but an oxide film or the like is formed on the surface of the copper thin film layer 22. Therefore, after the surface of the copper thin film layer 22 is pickled for a short time with a strong acid such as sulfuric acid or hydrochloric acid, it is desirable to shift to the next step.

  In this embodiment, after the copper thin film layer 22 is formed, a photoresist layer 31 made of a photosensitive resin is formed on the entire surface of the copper thin film layer 22 as shown in FIG. The resin for forming the photoresist layer 31 includes a negative type in which a portion irradiated with light is cured and is not dissolved in a developer, and a positive type in which a portion irradiated with light is dissolved in a developer. A type of photosensitive resin can also be used. Moreover, it is not limited to a liquid state, and a film resist such as a dry film may be laminated and used. In this embodiment, a negative type dry film resist is laminated to form the photoresist layer 31.

  Here, it is preferable that the photoresist layer 31 has substantially the same thickness as the wiring pattern 20 to be formed. For example, the thickness of the photoresist layer 31 is 5 to 20 μm, preferably 7 to 15 μm. It is.

  Next, as shown in FIG. 2E, a photomask 32 on which a desired pattern is formed is arranged on the surface of the photoresist layer 31, and light is irradiated from above the photomask 32 to irradiate the photoresist layer 31. Is exposed to light and then developed to remove a portion of the photosensitive resin forming the wiring circuit and form a resist pattern 33. As shown in FIG. 2 (f), the copper thin film layer 22 formed in FIG. 2 (c) is exposed at the bottom of the recess 33A of the resist pattern 33 thus formed.

Subsequently, in the present embodiment, with the copper thin film layer 22 exposed, the substrate is transferred to an electric copper plating bath containing a predetermined semi-additive sulfuric acid-based copper plating solution, and the copper thin film layer 22 is moved to one side. A plating voltage is applied between the other electrode provided in the plating bath as an electrode, and plating is performed under conditions where the bath temperature is room temperature and the current density is 10 A / dm ² or less, preferably 5 A / dm ² or less. A copper plating layer 24 is formed on the surface of the copper thin film layer 22 (FIG. 2G).

  As described above, since the copper plating layer 24 is formed by a plating method using a predetermined semi-additive sulfuric acid-based copper plating solution, the surface of the copper plating layer 24 becomes flat, particularly a pitch of 30 μm or less, preferably 20 μm or less. The surface of the cross section in the width direction (transverse section) of the wiring formed at the pitch can be flat without being convex. The bath composition of the semi-additive sulfuric acid copper plating solution will be described later.

  It is preferable that the thickness of the copper plating layer 24 is about the same as the thickness of the resist pattern 33, preferably slightly smaller. This is because the subsequent peeling of the resist pattern 33 is performed smoothly.

  In the present embodiment, as shown in FIG. 2H, after the copper plating layer 24 is formed, the resist pattern 33 is removed. For removing the resist pattern 33, an alkali cleaning solution, an organic solvent, or the like can be used. However, it is preferable to remove the resist pattern 33 using an alkali cleaning solution. This is because the alkaline cleaning liquid does not adversely affect the material constituting the printed wiring board of the present invention and does not cause environmental pollution due to evaporation of organic solvents. Examples of the alkaline cleaning liquid include amine-based stripping liquid (RS-081; manufactured by Ebara Densan Co., Ltd.).

  Next, as shown in FIG. 2I, the underlying layer 23 composed of the copper thin film layer 22 in the region exposed by removing the resist pattern 33 and the seed layer 21 therebelow is removed. Specifically, the base layer 23 is dissolved and removed using an etchant that can dissolve the base layer 23, particularly a soft etchant that does not adversely affect the formed wiring circuit. In the present embodiment, the seed layer 21 is formed of, for example, Ni—Cr, but can be removed by contacting with an aqueous solution containing a strong acid. In order to remove the seed layer 21, the treatment with the hydrochloric acid aqueous solution and the treatment with the sulfuric acid / hydrochloric acid mixed aqueous solution are combined 1 to 5 times, preferably 2 to 4 times, respectively. The seed layer 21 exposed on the surface of the insulating base material 10 that is not formed can be almost completely removed. The treatment with the acid aqueous solution can be performed by setting the treatment time for one time to 1 to 30 seconds, preferably 5 to 30 seconds.

  In addition, after performing the process which removes the seed layer 21 in this way, this printed wiring board can be washed and used as it is, but when the seed layer 21 is formed by sputtering as described above, A metal such as Ni or Cr may remain on the surface of the insulating substrate 10, and it is preferable to passivate such a remaining metal. For this passivation treatment, for example, it is preferable to use an aqueous solution containing an oxidizing substance such as permanganate adjusted to be alkaline. By processing in this way, even if a very small amount of conductive metal remains, the characteristics of the printed wiring board are not changed by these residual metals.

  In the removal process of the base layer 23 in the removed portion of the resist pattern 33, the surface of the copper plating layer 24 is removed before removing the resist pattern 33 in order not to adversely affect the surface of the copper plating layer 24. Other metal plating layers may be provided. Examples of such a metal plating layer include a metal plating layer such as a gold plating layer, a tin plating layer, a nickel plating layer, a silver plating layer, a palladium plating layer, a solder plating layer, and a lead-free solder plating layer, or these metals. A metal alloy plating layer in which another metal is contained in the plating layer forming metal can be mentioned, but considering the influence in the removal process of the base layer 23 and subsequent mounting of electronic components, the gold plating layer is used. Is preferred.

  In addition, the above-described solder resist layer 3 can be formed on the surface of the printed wiring board on which the wiring pattern 20 is formed in this manner to obtain the COF film carrier tape 1.

  Here, the composition of the predetermined semi-additive sulfuric acid-based copper plating solution will be described.

  Such a semi-additive sulfuric acid-based copper plating solution is 3-mercapto-1-propanesulfonic acid (hereinafter referred to as “MPS”) or bis (3-sulfopropyl) disulfide (hereinafter referred to as “SPS” in the present application). A quaternary ammonium salt polymer having a cyclic structure and chlorine, and a copper concentration of 23 to 55 g / L, preferably 25 to 40 g / L, and a sulfuric acid concentration of 50 to 250 g. / L, preferably 80-220 g / L. By using a plating solution having such a composition, it is possible to perform wiring formation by a semi-additive method with high efficiency, and the formed wiring is free from burns and abnormal shapes and has a flat surface.

  Here, the copper concentration and the sulfuric acid concentration are optimal for plating by the semi-additive method. If the copper concentration and the sulfuric acid concentration are out of the above-mentioned range, the current efficiency is reduced, or the formed wiring is burnt or abnormal in shape. The surface of the cross section is rounded, which is not preferable.

  In addition, the sulfuric acid-based copper plating solution for semi-additives requires at least one selected from MPS or SPS, a quaternary ammonium salt polymer having a cyclic structure, and the presence of three components of chlorine. Even if lacks, the above-mentioned effects cannot be fully exhibited.

  The concentration of MPS and / or SPS in the semi-additive sulfuric acid copper plating solution of the present invention is desirably 8 to 12 mg / L. If the concentration of MPS and / or SPS is smaller than the above range, the current efficiency tends to decrease, whereas if it is larger, the surface of the cross section of the wiring tends to be rounded, which is not preferable.

  In addition, MPS or SPS as used in the present invention is meant to include each salt, and the stated value of concentration is sodium 3-mercapto-1-propanesulfonate as a sodium salt (hereinafter referred to as “MPS-” in this application). (Referred to as “Na”). And MPS takes SPS structure by dimerizing in the sulfuric acid type copper plating solution for semiadditives concerning the present invention. Therefore, the concentration of MPS or SPS is a concentration that includes MPS alone or MPS-Na and other salts added as SPS, and also includes a modified product that has been added to the electrolyte as MPS and then polymerized into SPS or the like. is there. The concentration of the quaternary ammonium salt polymer having a cyclic structure in the sulfuric acid-based copper electrolyte is 35 to 85 mg / L, preferably 40 to 80 mg / L.

  Here, various polymers can be used as the quaternary ammonium salt polymer having a cyclic structure, but considering the above-described effects, a diallyldimethylammonium chloride (referred to as “DDAC”) polymer is used. Is most preferred. DDAC forms a cyclic structure when taking a polymer structure, and a part of the cyclic structure is composed of a quaternary ammonium nitrogen atom. The DDAC polymer has a plurality of forms such as those in which the cyclic structure is a 5-membered ring or a 6-membered ring, and the actual polymer is considered to be any one or a mixture depending on the synthesis conditions. Here, among these polymers, compounds having a five-membered ring structure are representative, for example, chloride ion is used as a counter ion, and DDAC polymer has a polymer structure in which DDAC is a dimer or more. It is what.

  Here, the degree of polymerization of the DDAC polymer is preferably 300 to 10000, preferably 1000 to 3000, and more preferably about 1200 as the number average molecular weight in order to flatten the surface of the cross section of the wiring.

  It is also preferable to use a mixture of DDACs having different molecular weights. In particular, by mixing a number average molecular weight of 900 to 3,000 and a number average molecular weight of 5,000 to 9000, the surface can be stably planarized.

  The number average molecular weight of the DDAC polymer is a value obtained by the following measuring method. That is, the sample was dissolved in a solvent and measured by gel permeation chromatography (GPC) under the following conditions. A multi-angle laser light scattering photometer (MALS) was used as the detector. The value of “second virial coefficient × concentration” was assumed to be 0 mol / g, and polyethylene oxide (SRM1924); NIST was used as a standard sample for calculating refractive index concentration change (dn / dc).

[GPC measurement conditions]
Column: TSKgel α-4000, α-2500 (φ7.8 mm × 30 cm); Tosoh Corporation solvent: water system: methanol = 50: 50 (volume ratio)
Flow rate: 0.504 mL / min
Temperature: 23 ° C ± 2 ° C
Detector: MALS (DAWN-EOS type); Wyatt Technology
Wavelength: 690nm

  And the density | concentration of this DDAC polymer is 35-85 mg / L, Preferably it is 40-80 mg / L. If the concentration of the DDAC polymer in the sulfuric acid-based copper electrolyte is smaller than the above range, the current density tends to decrease. On the other hand, if the concentration is larger than the above range, it is difficult to obtain a wiring with a flat surface, which is not preferable.

  The chlorine concentration in the semi-additive sulfuric acid-based copper plating solution is 30 to 55 mg / L, preferably 35 to 50 mg / L. If the chlorine concentration is out of the above range, any current density tends to decrease, which is not preferable. Here, the chlorine concentration includes chlorine derived from DDAC.

  As described above, the component balance of MPS or SPS, DDAC polymer, and chlorine in the sulfuric acid-based copper plating solution for semi-additives is the most important. If these quantitative balances deviate from the above range, the surface becomes the result. It becomes impossible to manufacture a flat wiring efficiently.

And when forming a wiring by a semi-additive method using this sulfuric acid-based copper plating solution for semi-additive, the solution temperature is room temperature, for example, 15 to 30 ° C., preferably 15 to 25 ° C., and the current density is 10 A / dm ² or less, preferably to form a wiring by electroless with 5A / dm ² or less. Needless to say, the electrolysis process may be made into a plurality of steps, or pulse electrolysis or PR electrolysis may be employed as necessary.

  In this way, when the wiring is formed using the sulfuric acid copper plating solution for semi-additive of the present invention, the wiring can be formed with high efficiency, and there is no burning or shape abnormality of the wiring, and the surface of the wiring cross section is flat. The effect that it is. In particular, when a semi-additive sulfuric acid copper plating solution having a predetermined composition is used, it is possible to obtain a wiring having excellent folding resistance.

  EXAMPLES Next, the present invention will be described in more detail with reference to examples of the present invention, but the present invention is not limited thereto.

[Test Example A]
A semi-additive sulfuric acid copper plating solution having a composition in which the SPS concentration is 10 mg / L, the DDAC concentration is 40 mg / L, and the sulfuric acid concentration and the copper concentration are changed as shown in Table 1 below, the liquid temperature is 20 ° C., the current is Plating was performed at a density of 5 A / dm ² for 7.7 minutes to form a copper plating layer having a thickness of 8 μm. Here, the chlorine concentration is 38 mg / L. Further, as the anode, an insoluble anode in which a Ti material was coated with iridium oxide was used, and a cation exchange membrane was used in order to prevent the additive from being decomposed by the generated oxygen. Note that bis (3-sulfopropyl) disulfide (manufactured by Asahi Chemical Industry Co., Ltd.) was used as the SPS, and a DDAC polymer having a number average molecular weight of 1220 was used as the DDAC.

  The plating target is a polyimide film (Kapton EN-C: manufactured by Toray DuPont), a 250-thickness Ni—Cr film and a 0.3 μm-thick Cu film are formed by sputtering, and then a resist film with a thickness of 8 μm. In addition, a wiring pattern with a 30 μm pitch and a wiring width of 15 μm was formed. As a result, a test printed wiring board having a wiring pattern with a 30 μm pitch and a wiring width of 15 ± 1 μm was manufactured by a semi-additive method.

  The current efficiency of the wiring of each test example was calculated and the cross-sectional shape was observed, and the results are shown in Table 1. The current efficiency was calculated by (measured film thickness / theoretical film thickness) × 100 (%) and is shown in the middle of Table 1. In addition, the cross-sectional shape was obtained by calculating the thickness (height) of a rounded portion in cross-sectional observation by the difference between the height of the central portion of the cross section and the height of the end portion, and the results are shown in the lower part of Table 1. In addition, when a cross-sectional convex part is 0 micrometer, it means that the surface was flat and roundness was not observable. In addition, no plating is performed for those that are poorly dissolved and are unsuitable as a plating solution, and those that have burned as a result of plating are regarded as defective and no subsequent measurement is performed.

  From the results in Table 1, it was found that the compositions of Test Examples A3, A4, and A8 are not suitable as a plating solution because copper is not completely dissolved. Moreover, it turned out that test example A1, A5, A9, and A13 have the remarkable discoloration and shape abnormality of the copper plating surface, and cannot form favorable copper plating. In addition, it was found that Test Examples A12, A2, and A6 were not preferable as the wiring because the cross-sectional surface of the wiring was rounded. On the other hand, in Test Examples A16, A17, A18, A19, and A20, it was found that the cross-sectional shape of the wiring was good, but the current efficiency was lowered and efficient plating was not possible.

  As a result, the current efficiency is good at 90% or more, and the thickness of the rounded portion is as small as 1 μm or less in Test Examples A7, A10, A11, A14, and A15, and the copper concentration is 25 to 40 g. It was found that the sulfuric acid concentration is preferably 80 to 220 g / L.

[Test Example B]
For semi-additives in which the sulfuric acid concentration was 100 g / L, the copper concentration was 150 g / L (Cu: 38.2 g / L), and the SPS concentration and DDAC concentration were changed as shown in Table 2 below. The test was performed in the same manner as in Test Example A except that a sulfuric acid-based copper plating solution was used.

  From the results of Table 2, in the compositions of Test Examples B3, B6, B9, B12, and B15 with an SPS concentration of 20 mg / L, the shape of the surface of the wiring cross section is rounded, and a wiring with a flat surface cannot be formed. In Test Examples B1, B4, B7, B10, and B13 with an SPS concentration of 5 mg / L, the wiring shape is relatively good, but the current efficiency is reduced, and efficient copper plating cannot be performed, and the SPS concentration is high. In Test Examples B8 and B11 at 10 mg / L, it was found that there was no decrease in current efficiency and wiring with a flat surface could be formed. Thereby, it was found that the SPS concentration is preferably in the range of 8 to 12 mg / L.

  In Test Example B5 with a DDAC concentration of 10 mg / L, the wiring shape is relatively good, but the current efficiency is reduced and efficient copper plating is not possible. However, the DDAC concentration is 40 mg / L or 80 mg / L. In Test Examples B8 and B11, it was found that there was no decrease in current efficiency and wiring with a flat surface could be formed. Therefore, it was found that the DDAC concentration is preferably in the range of 40 to 80 mg / L. Note that when the DDAC concentration increases beyond 80 mg / L, the current efficiency tends to decrease.

  Furthermore, in Test Examples B1 and B2 with a chlorine concentration of 18 mg / L, and Test Examples B13 and B14 with 58 mg / L, the wiring shape is relatively good, but the current efficiency is reduced, and efficient copper plating can be performed. In Test Example B8 with a chlorine concentration of 38 mg / L and Test Example B11 with a chlorine concentration of 46 mg / L, it was found that current efficiency did not decrease and a wiring with a flat surface could be formed. Therefore, it was found that the chlorine concentration is preferably in the range of 35 to 50 mg / L.

[Examples 1 to 4]
Wirings formed in the same manner as in Test Examples A6, A7, A14, and A15 were designated as Examples 1 to 4, and the folding resistance was tested as follows.

  In the folding resistance test, an MIT folding resistance test (ASTM D2176) was performed at R0.8 mm and a load of 100 g, and the number of times that folding occurred was measured.

  For comparison, a fold resistance test was also performed on a sample in which wiring was formed by the subtractive method using a commercially available laminated film of caprolactone and a copper layer (esperflex: trade name, manufactured by Sumitomo Metal Mining Co., Ltd.). went.

[Example 1]
A seed layer was formed by sputtering Ni—Cr (20 wt%) at a thickness of 250 mm on the surface of the polyimide film having a thickness of 35 μm on the pretreatment side. Further, copper was plated on the surface of the seed layer to a thickness of 1.3 μm to form a copper thin film layer. Subsequently, a negative dry film resist (made by Asahi Kasei Co., Ltd.) having a thickness of 15 μm was bonded to the surface of the copper thin film layer side with a laminator.

Next, UV exposure was performed at 180 mJ / cm ² using an exposure apparatus (manufactured by Ushio Electric Co., Ltd.) in which a glass photomask on which a wiring pattern composed of wiring having a width of 10 to 230 μm was drawn in a pitch range of 20 μm to 460 μm was placed. .

  After the exposure, development was performed with a 1% sodium carbonate solution to dissolve unexposed portions, and a photoresist pattern with each pitch was formed.

In this way, a semi-additive sulfuric acid-based copper plating solution having the composition of Example 1 in Table 3 was used for the base tape on which the resist pattern with the photosensitive resin was formed, and the liquid temperature was 22 ° C. and the current density was 5 A / dm ² . . Plated for 7 minutes to form an 8 μm thick copper plating layer. As the anode, an insoluble anode in which a Ti material was coated with iridium oxide was used.

  Next, the sample on which the copper plating layer was formed was dipped in a 50 ° C. stripping solution containing 2-aminoethanol as a main component for 30 seconds to strip the resist pattern. Then, it processed with the sulfuric acid and hydrogen peroxide type etching liquid, and removed the 0.4 micrometer-thick copper thin film layer on a base material by whole surface etching. Next, it is treated with a 9% hydrochloric acid solution at 55 ° C. for 13 seconds, and is treated with a mixed solution of 13% sulfuric acid and 13% hydrochloric acid at 55 ° C. for 13 seconds without washing with water to dissolve the Ni—Cr layer, thereby wiring each pitch. A pattern was formed. The thickness of the wiring with a pitch of 20 μm was 8 μm.

[Examples 2 to 4]
A wiring pattern was formed in the same manner as in Example 1 except that the plating solution having the composition of Examples 2 to 4 in Table 3 was used.

  Table 3 shows the MIT resistance test results of the wirings of Examples 1 to 4 and Comparative Example 1 thus formed. As a result, it was found that the folding resistance was significantly improved when the sulfuric acid concentration was around 100 g / L and the copper concentration was around 38.2 g / L. Therefore, it was found that a bath composition having a sulfuric acid concentration of 90 to 110 g / L and a copper concentration of 35 to 45 g / L is particularly preferable in consideration of blending errors and bath composition changes.

[Examples 5 to 8]
With the bath compositions of Test Examples B8 and B11, the bath temperature (liquid temperature) was set to 25 ° C., and the current efficiency and the cross-sectional shape of the wiring were the same when implemented in the same manner as in the above-described examples (referred to as Examples 5 and 6) Measured. The results are shown in Table 4.

  In addition, each of the test compositions B8 and B11 was further subjected to a bath composition in which 10 ppm of a DDAC polymer having a number average molecular weight of 7250 was added, respectively, at a bath temperature of 25 ° C. (referred to as Examples 7 and 8). The cross-sectional shape of the wiring was measured in the same manner. The results are also shown in Table 4.

  As a result, in Examples 5 and 6 in which the bath temperature was 25 ° C. in the bath compositions of Test Examples B8 and B11, the surface shape of the wiring cross section was somewhat rounded, but the DDAC polymer having a number average molecular weight of 7250 was obtained. In Examples 7 and 8 where 10 ppm was added, although the current efficiency was somewhat lowered, it was found that the cross-sectional shape was greatly improved and the surface of the wiring cross-section could be formed almost flat. That is, it was found that the addition of a small amount of the high molecular weight DDAC polymer has an effect of improving the wiring cross-sectional shape when the bath temperature is increased.

1 COF film carrier tape (printed circuit board)
2 Sprocket hole 3 Solder resist layer 10 Insulating substrate 11 Reinforcement material 20 Wiring pattern 21 Seed layer 22 Copper thin film layer 23 Underlayer 24 Copper plating layer 31 Photoresist layer 32 Photomask 33 Resist pattern

Claims (8)

A sulfuric acid-based copper plating solution for semi-additives,
It contains at least one selected from 3-mercapto-1-propanesulfonic acid or bis (3-sulfopropyl) disulfide, a quaternary ammonium salt polymer having a cyclic structure, and chlorine, with a copper concentration of 23 to 55 g / L. A sulfuric acid-based copper plating solution for semi-additives, wherein the sulfuric acid concentration is 50 to 250 g / L. 2. The semi-additive sulfuric acid-based copper plating solution according to claim 1, wherein the concentration of the 3-mercapto-1-propanesulfonic acid and / or bis (3-sulfopropyl) disulfide is 8 to 12 mg / L in total. The sulfuric acid-based copper plating solution for semi-additive according to claim 1 or 2, wherein the concentration of the quaternary ammonium salt polymer having a cyclic structure is 35 to 85 mg / L. The sulfuric acid-based copper plating solution for semi-additive according to any one of claims 1 to 3, wherein the quaternary ammonium salt polymer having a cyclic structure is a diallyldimethylammonium chloride polymer. The sulfuric acid-based copper plating solution for semi-additive according to claim 4, wherein the diallyldimethylammonium chloride polymer is a mixture of different molecular weights. The sulfuric acid-based copper plating solution for semi-additive according to any one of claims 1 to 5, wherein the chlorine concentration is 30 to 55 mg / L. A conductive underlayer is formed on the surface of the insulating substrate, a photoresist layer is formed on the surface of the underlayer, and a predetermined pattern is exposed and developed on the photoresist layer to pattern the underlayer. Form a recess to be exposed, form a copper plating layer on the underlying layer of this recess, and then peel off the patterned photoresist layer, and then remove the exposed underlying layer by stripping the photoresist layer. In the manufacturing method of the printed wiring board which forms a pattern, the formation of the said copper plating layer uses the sulfuric acid type copper plating solution for semiadditives in any one of Claims 1-6, and bath temperature is 15-30 degreeC. A method for producing a printed wiring board, wherein the current density is set to a plating condition of 10 A / dm ² or less. The method for manufacturing a printed wiring board according to claim 7, wherein the current density is 5 A / dm ² or less.

Images