KR20180075697A - Method for forming solder resist pattern - Google Patents

Abstract

A step of forming a solder resist layer on a surface of a circuit board having a connection pad, and a step of thinning the solder resist layer until the thickness of the solder resist layer becomes equal to or less than the thickness of the connection pad by an alkaline aqueous solution. There is no electrical short circuit due to solder between adjacent semiconductor connection pads and the solder resist pattern is not left on the connection pads.

Description

METHOD FOR FORMING SOLDER RESIST PATTERN [0002]

And a method of forming a solder resist pattern.

The solder resist pattern on the circuit board inside the electric apparatuses is formed so as to cover the entire surface except for the portion to be soldered in order to prevent the solder from adhering to the wiring pattern which does not require brazing, And protection from the external environment.

In a semiconductor package in which an electronic component such as a semiconductor chip is mounted on a circuit board, mounting by flip chip bonding is an effective means for achieving high speed and high density. In the flip chip connection, a part of the conductor wiring of the circuit board is used as a connection pad for flip chip connection, for example, solder bumps arranged on the connection pads and the electrode terminals of the semiconductor chip are bonded.

Figs. 1 to 5 are schematic cross-sectional structural diagrams of a solder resist pattern covered with a solder resist layer other than a soldering portion (for example, a connection pad) on a circuit board. FIG. 1 is a schematic cross-sectional view of a structure of a solder mask defined (SMD) structure in which an opening of a solder resist layer 3 is smaller than a connection pad 6. FIG. FIGS. 2 to 5 are schematic cross-sectional structural views of a Non-Solder Mask Defined (NSMD) structure, wherein the openings of the solder resist layer 3 are not less than the connection pads 6.

As a method of forming a solder resist pattern, a photolithography method is generally known. In the photolithography method, the solder resist layer 3 is formed on the circuit board having the connection pads 6 and the conductor wirings 2 on the insulating substrate 1, The peripheral solder resist layer 3 is completely removed to form an opening. This photolithography method has heretofore been impossible to fabricate only the structures shown in Figs. 1, 2, and 3.

If there is no solder resist layer between the connection pads 6 as shown in Fig. 2, if the pitch between the connection pads is narrowed, a plating short circuit occurs between the connection pads during electroless nickel / (Short-circuit) occurs. Even when the solder resist layer 3 exists between the connection pads 6, when the solder resist layer 3 is thick as shown in Figs. 1 and 3, they are damaged and the electronic parts can not be mounted correctly There is a problem. In addition, with the recent miniaturization and multifunctionalization of electronic apparatuses, when the distance between the connection pads is less than 50 占 퐉, it is very difficult to manufacture the structures of Figs. 1 and 3 by photolithography in terms of positional shift of exposure Respectively. For this reason, a structure in which the thickness of the solder resist layer 3 between the connection pads 6 is equal to or less than the thickness of the connection pads 6 as shown in Figs. 4 and 5 is required.

4, a solder resist pattern having slit-shaped openings is formed by a wet blast method, and a plurality of connection pads 6 formed side by side are exposed, and the connection pads 6 adjacent to each other exposed in the slit- 6 are filled with a solder resist layer 3 having the same height as that of the connection pads 6. This structure is obtained by coating a solder resist layer 3 on a circuit board having a connection pad 6 and a conductor wiring 2 on an insulating substrate 1 and then forming a solder resist layer 3, a wet-blast mask for a pattern is formed, followed by wet blasting to form openings on the slit-like layer in the solder resist layer , And removing the wet blast mask (see, for example, Patent Document 1).

The connection pads are exposed to the circuit board having the conductor wirings lower than the connection pads and the connection pads. The conductor wirings are covered with the solder resist layer. A solder resist layer (See, for example, Patent Document 2). This structure is formed by coating a solder resist layer on a circuit board having conductor wirings having a height lower than that of the connection pads and the connection pads, and then polishing the upper surface of the connection pads until they are exposed. As a polishing method, a mechanical polishing method or a laser scribing method can be employed.

5, the solder resist layer 3 exists between the connection pads 6, but the outer peripheral surface of the connection pad 6 is exposed. 5, the entire connection pad 6 is coated with electroless nickel and covered with a nickel layer, the solder resist layer 3 is coated on the conductor wiring, and then the wiring is subjected to ultraviolet curing and heat curing, The layer 3 is subjected to blast polishing to expose the upper surface of the nickel layer, and then the nickel layer is removed by etching (see, for example, Patent Document 3).

In the methods of Patent Documents 1 to 3, a polishing method such as wet blast, mechanical polishing, or the like is used to form the openings of the solder resist layer. However, this method makes it difficult to uniformly grind the surface, It is very difficult to perform a highly accurate process of completely exposing the upper surface of the solder resist layer without leaving any residue on the pad. It is easy to make the height of the solder resist layer and the connection pad the same, but if it is tried to make the height of the solder resist layer lower than that of the connection pad, scratches or other defects occur in other parts including the connection pad in the polishing process Sometimes there was a problem.

As a method of removing the solder resist layer, there is a method of decomposing an unnecessary solder resist by laser irradiation. However, there is a problem that the process is troublesome and productivity is low (see, for example, Patent Documents 2 and 4).

Japanese Laid-Open Patent Publication No. 2008-300691 Japanese Laid-Open Patent Publication No. 2006-344664 JP-A-2009-253118 Japanese Laid-Open Patent Publication No. 2010-034414

A problem to be solved by the present invention is to provide a method of forming a solder resist pattern which does not cause electrical short circuit by solder between adjacent semiconductor connection pads and does not leave solder resist residues on the connection pads.

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that the above problems can be solved by the following invention.

(1) a step of (A1) forming a solder resist layer on a surface of a circuit board having a connection pad,

(B1) a step of thinning the solder resist layer until the thickness of the solder resist layer becomes equal to or less than the thickness of the connection pad by an aqueous alkali solution

Wherein the solder resist pattern is formed on the substrate.

(2) (A2) a step of forming a solder resist layer on a surface of a circuit board having a connection pad and conductor wiring,

(C) a step of exposing a portion other than the region to be thinned until the thickness of the solder resist layer becomes equal to or less than the thickness of the connection pad,

(B2) a step of making the solder resist layer thinner until the thickness of the solder resist layer of the non-visible portion becomes less than or equal to the thickness of the connection pad by an aqueous alkali solution

And forming a solder resist pattern on the substrate.

(3) Between the step (A2) and the step (C)

(D) a step of thinning the entire surface of the solder resist layer with an aqueous alkali solution

(2). ≪ / RTI >

(4) a step of (A3) forming a solder resist layer on a surface of a circuit board having a conductor wiring having a height lower than that of the connection pads and the connection pads,

(B3) a step of thinning the solder resist layer until the thickness of the solder resist layer is equal to or less than the thickness of the connection pad and becomes thicker than the thickness of the conductor wiring by an aqueous alkali solution

Wherein the solder resist pattern is formed on the substrate.

(5) The method for forming a solder resist pattern according to any one of (1) to (4), wherein the aqueous alkaline solution contains an inorganic alkaline compound and the content of the inorganic alkaline compound is 3 to 25 mass%.

(6) The method for forming a solder resist pattern according to (5), wherein the inorganic alkaline compound is at least one selected from an alkali metal carbonate, an alkali metal phosphate, an alkali metal hydroxide, and an alkali metal silicate.

(7) The method for forming a solder resist pattern according to (5), wherein the inorganic alkaline compound is an alkali metal silicate.

(8) The method for forming a solder resist pattern according to (7), wherein the alkali metal silicate is sodium metasilicate.

(9) The method for forming a solder resist pattern according to (5), wherein the inorganic alkaline compound is an alkali metal phosphate.

(10) The method for forming a solder resist pattern according to (9), wherein the alkali metal phosphate is at least one selected from trisodium phosphate and tripotassium phosphate.

(11) The method for forming a solder resist pattern according to (5), wherein the inorganic alkaline compound is potassium carbonate.

(12) The method for forming a solder resist pattern according to any one of (1) to (4), wherein the alkaline aqueous solution contains an organic alkaline compound.

(13) The method for forming a solder resist pattern according to (12), wherein the content of the organic alkaline compound is 5 to 25 mass%.

(14) The method for forming a solder resist pattern according to any one of (1) to (13), wherein the alkaline aqueous solution has a pH of 12.5 or more.

(15) After the step of thinning the solder resist layer with an aqueous alkali solution,

(E) a step of treating with an aqueous solution containing an alkaline compound, the content of the alkaline compound being less than that of the alkali aqueous solution, and having a pH of 5.0 to 10.0 and a temperature of 22 to 50 ° C

The solder resist pattern forming method according to any one of (1) to (14)

(16) A method of forming a solder resist layer by thinning an alkali aqueous solution according to any one of (1) to (15), wherein the solder resist layer is subjected to an immersion treatment.

In the method (1) to (4) of forming the solder resist pattern according to the present invention, there is no electrical short circuit due to the solder between the adjacent connection pads for semiconductor connection, The effect of not leaving residues can be achieved.

1 is a schematic cross-sectional structural view of a solder resist pattern.
2 is a schematic cross-sectional structural view of a solder resist pattern.
3 is a schematic cross-sectional structural view of a solder resist pattern.
4 is a schematic sectional structural view of a solder resist pattern.
5 is a schematic cross-sectional structural view of a solder resist pattern.
6 is a cross-sectional process diagram showing an example of a method (1) of forming a solder resist pattern of the present invention.
7 is a cross-sectional process diagram showing an example of a method (2) for forming a solder resist pattern of the present invention.
8 is a cross-sectional process diagram showing an example of a method (3) of forming a solder resist pattern of the present invention.
9 is a cross-sectional process diagram showing an example of a solder resist pattern forming method (4) of the present invention.
10 is a three-dimensional explanatory view schematically showing a vicinity of a connection pad of a circuit board manufactured by the method (1) for forming a solder resist pattern of the present invention.
11 is a three-dimensional explanatory view schematically showing the vicinity of a connection pad of a circuit board manufactured by the method (2) for forming a solder resist pattern of the present invention.
12 is a three-dimensional explanatory view schematically showing a vicinity of a connection pad of a circuit board manufactured by the method (3) for forming a solder resist pattern of the present invention.
13 is a three-dimensional explanatory view schematically showing the vicinity of a connection pad of a circuit board manufactured by the method (4) of forming a solder resist pattern of the present invention.
14 is a three-dimensional explanatory view schematically showing the vicinity of a connection pad of a circuit board manufactured by the method (4) for forming a solder resist pattern of the present invention.
Fig. 15 is a three-dimensional explanatory view schematically showing a vicinity of a connection pad of a circuit board manufactured by a conventional technique; Fig.
16 is a three-dimensional explanatory view schematically showing a vicinity of a connection pad of a circuit board manufactured by a conventional technique.

Hereinafter, the method of forming the solder resist pattern of the present invention will be described in detail.

6 is a cross-sectional process drawing showing an example of a solder resist pattern forming method (1) of the present invention. A circuit board on which a connection pad 6 is formed on an insulating substrate 1 is prepared. The connection pad 6 may be formed by a subtractive method, a semi-additive method, an additive method, or the like. In the step (A1), the solder resist layer (3) is formed so as to cover the entire surface of the substrate. In the step (B1), the solder resist layer 3 is thinned by an aqueous alkali solution. 10 is a three-dimensional explanatory view schematically showing the vicinity of the connection pad of the circuit board manufactured by the method (1) for forming a solder resist pattern of the present invention. In this connection, the connection pad 6 is exposed from the solder resist layer 3 Shaped resist pattern is formed. The thickness of the solder resist layer 3 in the present invention is a value obtained by measuring the thickness to the surface of the solder resist layer from the surface of the insulating substrate 1 as a starting point.

7 is a cross-sectional process drawing showing an example of a solder resist pattern forming method (2) of the present invention. A circuit board on which a connection pad 6 and a conductor wiring 2 are formed on an insulating substrate 1 is prepared. In the step (A2), the solder resist layer (3) is formed so as to cover the entire surface of the substrate. In the step (C), a portion other than the region to be thinned is exposed by the actinic ray 5 until the thickness of the solder resist layer becomes less than the thickness of the connection pad. In Fig. 7, although the exposure is performed via the photomask 4, the exposure may be performed by a direct drawing method. In the step (B2), the solder resist layer (3) of the non-visible portion is made thin by an alkaline aqueous solution. 11 is a three-dimensional explanatory diagram schematically showing the vicinity of the connection pad of the circuit board manufactured by the method (2) for forming a solder resist pattern of the present invention. The connection pad 6 is exposed from the solder resist layer 3 Shaped solder resist pattern is formed.

8 is a cross-sectional process drawing showing an example of a solder resist pattern forming method (3) of the present invention. A circuit board on which a connection pad 6 and a conductor wiring 2 are formed on an insulating substrate 1 is prepared. In the step (A2), the solder resist layer (3) is formed so as to cover the entire surface of the substrate. In the step (D), the solder resist layer 3 is thinned to a desired thickness within a range that is thicker than the thickness of the connection pad 6 by an aqueous alkaline solution. Since the solder resist layer 3 is thinned to a desired thickness and then exposed, the light scattering at the time of exposure is reduced, and higher-precision patterning becomes possible. In the step (C), a portion other than the region to be thinned is exposed by the actinic ray 5 until the thickness of the solder resist layer becomes less than the thickness of the connection pad. In the step (B2), the solder resist layer (3) of the non-visible portion is made thin by an alkaline aqueous solution. 12 is a three-dimensional explanatory view schematically showing the neighborhood of the connection pad of the circuit board manufactured by the method (3) for forming a solder resist pattern of the present invention. The conductor wiring 2 is covered with the solder resist layer 3, A solder resist pattern in which the connection pad 6 is exposed from the solder resist layer 3 is formed.

9 is a cross-sectional process diagram showing an example of a solder resist pattern forming method (4) of the present invention. First, a circuit board on which a connection pad 6 and a conductor wiring 2 having a height lower than that of the connection pad 6 are formed on the insulating substrate 1 is prepared. In the step (A3), the solder resist layer (3) is formed so as to cover the entire surface of the substrate. In the step B3, the solder resist layer 3 is thinned to a point where the thickness of the solder resist layer 3 is equal to or less than the thickness of the connection pad 6 and becomes thicker than the thickness of the conductor wiring 2 by the alkali aqueous solution . 13 and 14 are three-dimensional explanatory views schematically showing the vicinity of the connection pads of the circuit board manufactured by the method (4) for forming a solder resist pattern of the present invention. The conductor wirings 2 are covered with the solder resist layer 3 so that the solder resist pattern in which the connection pad 6 is exposed from the solder resist layer 3 is formed.

The circuit board having the connection pad in the present invention is a circuit board on which a connection pad for connecting electronic components such as a semiconductor chip made of metal such as copper is formed on an insulating substrate. A circuit board having a connection pad and a conductor wiring on a substrate in the present invention is a circuit board on which a connection pad and a conductor wiring are formed for connecting electronic components such as a semiconductor chip made of metal such as copper onto an insulating substrate. Examples of a method for producing a substrate on which a connection pad or a conductor wiring is formed on a substrate include a subtractive method, a semi-additive method, and an additive method. In the subtractive method, for example, a through-hole called a through hole is drilled in a copper-clad laminated board coated with a copper foil on a glass-base epoxy resin, and plating copper on the surface including the through-hole inner wall by electrolytic copper plating Precipitation. Then, an etching resist layer is formed in the circuit portion, and copper in the non-circuit portion is removed by an etching process. Thereafter, the circuit board is manufactured by removing the etching resist layer of the circuit portion. Further, in the semi-additive method, for example, an electroless copper plating layer is formed on the surface including the inner wall of the through hole by punching a through hole in a copper clad laminate having a very thin copper foil on a glass base epoxy resin. Subsequently, a plating resist layer is formed on the non-circuit portion, and an electrolytic copper plating layer is formed on the surface of the portion where the electroless copper plating layer is exposed by the electrolytic copper plating treatment. Thereafter, the plating resist layer in the non-circuit portion is removed, and the electroless copper plating layer under the plating resist layer is removed by flash etching to produce a circuit board.

The circuit board according to the present invention having the connection pads and the conductor wirings lower in height than the connection pads on the substrate is provided with a connection pad for connecting electronic components such as a semiconductor chip made of metal such as copper on an insulating substrate, And a conductor wiring having a height lower than that of the pad. Examples of a method for manufacturing a substrate having a conductor wiring on the substrate that is lower than the connection pads and the connection pads include a semi-additive method and an additive method. In the semi-additive method, for example, a copper-plated copper-plated layer is formed on the surface including the through-hole inner wall by drilling a through-hole called a through hole in a copper-clad laminate coated with a glass base epoxy resin. Subsequently, a plating resist layer is formed on the non-circuit portion, and an electrolytic copper plating layer (connection pad precursor and conductor wiring) is formed on the surface of the portion where the electroless copper plating layer is exposed by the electrolytic copper plating treatment. Subsequently, the plating resist layer is formed again so as to expose the connection pad precursor portion, and an electrolytic copper plating layer is formed on the surface of the connection pad precursor portion exposed by the electrolytic copper plating treatment. Thereafter, the plating resist layer is removed, and the electroless copper plating layer under the plating resist layer is subjected to flash etching to remove the circuit board.

The circuit board may be a single-sided board, a double-sided board or a multilayer board, and the solder resist pattern forming method of the present invention can be applied to any circuit board as long as it is necessary to form a solder resist pattern.

Any solder resist related to the present invention may be used as long as it can dissolve or swell the surface of the solder resist layer with an aqueous alkali solution to remove the solder resist layer. In addition, the resist may be a one-liquid, two-liquid, any liquid resist, or a dry film-based resist. The solder resist contains, for example, an alkali-soluble resin, a polyfunctional acrylic monomer, a photopolymerization initiator, an epoxy resin, an inorganic filler and the like. Examples of the alkali-soluble resin include alkali-soluble resins having both photocurable properties and thermosetting properties. For example, an acrylic acid is added to a novolak-type epoxy resin to form an epoxy acrylate, and an acid anhydride Is added. Examples of polyfunctional acrylic monomers include trimethylolpropane triacrylate, dipentaerythritol hexaacrylate, and pentaerythritol triacrylate. Examples of the photopolymerization initiator include 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropane-1-one. The epoxy resin is used as a curing agent. The reaction with the carboxylic acid of the alkali-soluble resin enables crosslinking to improve the properties of heat resistance and chemical resistance. Since the carboxylic acid and epoxy react even at room temperature, the storage stability is deteriorated. And often takes a form of a two-liquid mixture. Examples of the inorganic filler include talc, silica, barium sulfate, titanium oxide, and zinc oxide.

In step (A1), a solder resist layer is formed on the surface of a circuit board having a connection pad. In step (A2), a solder resist layer is formed on the surface of the circuit board having the connection pads and the conductor wiring. In the step (A3), the solder resist layer is formed on the surface of the circuit board having the conductor wirings lower than the connection pads and the connection pads. The formation of the solder resist layer may be carried out by any method known in the art such as screen printing, roll coating, spraying, dipping, curtain coating, bar coating, air knife coating, hot melt coating, gravure coating, , Offset printing method can be used. In the case of a dry film, a lamination method or a vacuum lamination method is used.

In the step (C), the solder resist layer in a portion other than the thinned region is selectively irradiated with an actinic ray to be cured. Examples of the exposure method include a reflective image exposure method using a xenon lamp, a high-pressure mercury lamp, a low-pressure mercury lamp, an ultra-high-pressure mercury lamp, or a UV fluorescent light as a light source, a one- or two- And the like. The " area to be thinned " is an area around the connection pad including, for example, between the connection pad and the connection pad. The term " region other than the region to be thinned " is, for example, a region around a conductor wiring including a conductor wiring or between conductor wirings.

In the steps (B1), (B2), and (B3), the thinning treatment of the solder resist layer is performed until the thickness of the connection pad is equal to or less than the thickness of the connection pad. In the step (D), the thinning treatment of the solder resist layer is carried out in a range of thickness that is thicker than the thickness of the connection pad 6 by the alkaline aqueous solution. Specifically, the surface of the solder resist layer is dissolved or swelled by an aqueous alkali solution to remove the surface of the solder resist layer of the non-visible portion. In the case of the dry film shape and the support layer film is formed on the solder resist layer, the support layer film is peeled off and thinning treatment is performed.

In the method for forming a solder resist pattern of the present invention, the thickness of the solder resist layer around the connection pad is determined by the thickness after formation of the solder resist layer and the amount of the solder resist layer of the non-visible portion thinned by the alkali aqueous solution treatment. In the method of forming a solder resist pattern of the present invention, the amount of thinning can be appropriately adjusted in the range of 0.01 to 500 탆. The height from the surface of the solder resist layer after thinning to the surface of the connection pad is appropriately adjusted according to the amount of solder required later.

In the steps (B1), (B2) and (B3), the thinning treatment is carried out until the thickness of the solder resist layer after the thinning treatment becomes equal to or thinner than the thickness of the connection pad. The thickness of the solder resist layer If it is too thin, the electrical insulation between the connection pads becomes insufficient, short-circuiting of the electroless nickel / gold plating occurs, and short-circuit due to solder may occur between the connection pads. Therefore, the thickness of the solder resist layer after thinning is preferably two-thirds or more of the thickness of the connection pad, and more preferably three-thirds or more.

In the thinning treatment with the alkaline aqueous solution, the pretreatment may be performed with water washing treatment. The hydrophilic groups such as the carboxyl groups in the solder resist layer are redirected by the pretreatment water washing, and the hydrophilic property of the surface of the layer is made uniform. Furthermore, it is possible to remove contaminants and foreign substances present on the solder resist layer. Examples of the water used for the pretreatment water washing include industrial water, tap water, ion exchange water, and distilled water. Examples of the pretreatment flushing method include an immersion treatment, a paddle treatment, a spraying treatment, a brushing, a scraping, and the like, and spray treatment is preferable considering the removal of contaminants and foreign substances on the solder resist layer. The spray conditions (temperature, spray pressure, time) can be suitably adjusted. Specifically, the temperature is preferably 15 to 30 占 폚, more preferably 20 to 25 占 폚. The spray pressure is preferably 0.02 to 0.5 MPa, and more preferably 0.05 to 0.3 MPa.

In addition, a surfactant may be contained in the pretreated water. The surface of the solder resist layer can be more rapidly and stably hydrophilized by the use of the surfactant. Examples of the surfactant include anionic surfactants such as alkyl sulfuric acid ester salts, polyoxyethylene alkyl ether sulfuric acid ester salts, alkyl benzene sulfonic acid salts and fatty acid salts; Polyoxyethylene alkyl ethers, polyoxyalkylene derivatives, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, glycerin fatty acid esters, polyoxyethylene fatty acid esters, polyoxyethylene hydrogenated castor oil, poly Based surfactants such as polyoxyethylene alkylphenyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene-polyoxypropylene block copolymers (so-called pluronic surfactants), fatty acid pentaerythritol esters, and acetylene glycols, An activator; Cationic surfactants such as alkylamine salts and quaternary ammonium salts; Amphoteric surfactants such as alkyl betaines can be used. The pretreatment water washing treatment does not cause any problem if any kind of surfactant is used so long as it does not impair the quality of the solder resist layer. However, when the anionic, cationic and amphoteric surfactants are specifically adsorbed to the resist surface, Therefore, since the surface of the resist may be partially destroyed, it is preferable to use a nonionic surfactant. More specific examples of the nonionic surfactant include acetylene glycol and surfactants such as Surfynol (registered trademark) 465, Surfynol (registered trademark) 485, Surfynol (registered trademark) 82 manufactured by Nissin Chemical Industry Co., Can be used.

The amount of the surfactant to be added to the pretreated water is changed depending on the characteristics of various surfactants. In addition to the hydrophilization of the surface of the solder resist layer, the amount of the surfactant to be added to the pre- Is preferably in the range of 0.001 to 0.1 mass%, more preferably in the range of 0.001 to 0.05 mass%, and still more preferably in the range of 0.01 to 0.05 mass%.

The aqueous alkali solution according to the present invention is an aqueous solution of an inorganic alkaline compound such as an alkali metal silicate, an alkali metal hydroxide, an alkali metal phosphate, an alkali metal carbonate, an ammonium phosphate or an ammonium carbonate; But are not limited to, monoethanolamine, diethanolamine, triethanolamine, methylamine, dimethylamine, ethylamine, diethylamine, triethylamine, cyclohexylamine, tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, -2-hydroxyethyl ammonium hydroxide (choline), and the like can be given as an aqueous solution of an organic alkaline compound. Examples of the alkali metal include lithium, sodium, potassium and the like. The inorganic alkaline compound and the organic alkaline compound may be used alone or in combination. The inorganic alkaline compound and the organic alkaline compound may be used in combination.

When the sodium salt is used as the alkali metal of the inorganic alkaline compound, it is preferable to mix the potassium salt. For example, when sodium carbonate or sodium metasilicate is used, carbonic acid ions or silicate ions in the component may form an insoluble salt with calcium or magnesium contained in water, and may be coagulated and separated in an aqueous alkali solution. Potassium is more soluble in water than sodium and has high reactivity with other compounds, so that carbonate or silicate ions react preferentially with potassium rather than react with calcium or magnesium, thereby interfering with insoluble salt formation I think.

In order to make the surface of the solder resist layer more uniformly thin, a sulfate and a sulfite may be added to the alkali aqueous solution. Examples of the sulfates or sulfites include alkali metal sulfates such as lithium, sodium or potassium or alkaline earth metal sulfates or sulfites such as sulfites, magnesium and calcium.

When the aqueous alkali solution is an aqueous solution containing an inorganic alkaline compound, it is preferable that the inorganic alkaline compound is at least one selected from alkali metal carbonate, alkali metal phosphate, alkali metal hydroxide and alkali metal silicate. The content of the inorganic alkaline compound is preferably 3 to 25% by mass. The alkaline aqueous solution having a content of the inorganic alkaline compound of less than 3% by mass is effective for completely removing the unexposed solder resist layer, which is used for development after exposure by the conventional photolithography method. However, There is a case that the thickness irregularity tends to occur easily in the process of making the thin film into a uniform thickness in the plane without completely removing it. On the other hand, if it exceeds 25% by mass, precipitation of the inorganic alkaline compound tends to occur, and the stability and workability of the liquid over time may deteriorate. The content of the inorganic alkaline compound is more preferably 5 to 20% by mass, and further preferably 7 to 15% by mass. Further, a surfactant, defoaming agent, solvent and the like may be appropriately added.

In the thinning treatment of the solder resist layer, the presence of the inorganic filler insoluble in the aqueous alkaline solution contained in the solder resist layer can not be ignored. Although the size of the inorganic filler varies depending on the kind thereof, it is present in a content of 30 to 70 mass% in the layer with a certain particle size distribution ranging from a submicron order called a nanopillar to a tens of micron in size . The thinning process proceeds by dissolving and diffusing the alkaline compound after penetrating into the solder resist layer. In some cases, the penetration of the alkaline compound is inhibited by the presence of the insoluble inorganic filler, and the thinning rate is slowed down in some cases.

The pH of the aqueous alkaline solution is preferably 12.5 or more, and more preferably 13.0 or more, in order to suppress penetration by the inorganic filler. The higher the pH of the alkaline aqueous solution is, the larger the swelling of the solder resist layer when the alkaline compound is infiltrated, so that the influence of the inhibition of penetration by the inorganic filler is not satisfied.

In steps (B1), (B2), and (B3), the surface of the connection pad is exposed by thinning treatment. Generally, when a solder resist layer is formed on a circuit board having a connection pad and a conductor wiring, the connection pad surface is roughened by various polishing treatments in the same manner as the conductor wiring in consideration of the adhesion between the conductor wiring and the solder resist layer. The adhesion between the conductor wiring and the solder resist layer is improved by the anchor effect by roughening, and high insulation reliability is maintained for a long time. Conventionally, when removing the solder resist layer to expose the surface of the connection pad, it is common to use a low-concentration sodium carbonate aqueous solution having excellent dispersing ability as a developing solution, and residual residue of the solder resist on the surface of the connection pad hardly occurs. However, when the thinning treatment is performed using a sodium carbonate aqueous solution of a low concentration, the surface of the solder resist layer can not be treated uniformly, and in-plane unevenness occurs.

Therefore, an alkali aqueous solution containing an alkali metal silicate may be used as an alkaline aqueous solution which does not leave a solder resist residue on the roughened surface of the connection pad while being uniformly thinned in the plane. The alkali metal silicate is superior in dissolving and diffusing ability of the solder resist layer as compared with other inorganic alkaline compounds, and residue residue on the surface of the connection pad is not generated well. The general formula of the alkali metal silicate is shown in the following formula (i). Alkali metal silicate is a generic name of a chemical substance in which three kinds of components are continuously changed in various ratios. The mass ratio (mass ratio in the case of sodium salt = molar ratio x 1.032, mass ratio in the case of potassium salt = mole ratio x 1.568) The name changes accordingly. For example, in the case of a sodium salt, sodium orthosilicate having a mass ratio of 0.5, sodium metasilicate having a mass ratio of 1.0, and sodium silicate having a mass ratio of 1.3 to 4 are generally referred to as sodium silicate. When the mass ratio is 1 or less, it is called crystalline sodium silicate. When the mass ratio is larger than 1, it is amorphous and the mass ratio can be continuously changed. In addition, the viscosity of the solution of sodium silicate varies depending on the mass ratio, concentration, temperature, and the like. That is, as the mass ratio is increased, the concentration is increased, or the temperature is lowered, the viscosity of the solution becomes higher. The solution of sodium silicate contains silicate ion monomer, polysilicate ion, colloidal silicate ion micelle, etc. and takes various forms according to the mass ratio and concentration. In the case where the mass ratio is 1 or less, silicate ion monomers are mainly present, and in a solution having a high mass ratio, besides silicate ion monomers, dimer and polysilicate ion micelles are contained, and polysilane ion micelle concentration increases with an increase in the mass ratio. As the polysilicate ion micelle increases, the mass average molecular weight of the solution increases and the viscosity increases. Generally, when the mass ratio is larger than 2, attention should be paid to an increase in viscosity. In this respect, in the case of a sodium salt, sodium metasilicate is most preferably used in terms of stability of an aqueous solution and workability. In addition, since the potassium salt has higher solubility in water than the sodium salt, the aqueous solution can not be easily solidified and separated, so that various kinds of potassium salts can be used. The content of the alkali metal silicate is more preferably from 5 to 25 mass%, and still more preferably from 7 to 20 mass%.

M ₂ O.nSiO ₂ .xH ₂ O (i)

[M: sodium or potassium, n: molar ratio (SiO ₂ / M ₂ O)]

An alkaline aqueous solution containing an alkali metal phosphate is an inorganic alkaline compound having a dissolving and diffusing ability of a solder resist layer which is equivalent to an alkali metal silicate. As the alkali metal phosphate, trisodium phosphate or tripotassium phosphate strong in alkalinity in which an alkali metal is three-atom coordinated is preferably used. The content of the alkali metal phosphate is more preferably 5 to 20 mass%, and still more preferably 7 to 15 mass%.

In addition, an aqueous solution containing potassium carbonate as an inorganic alkaline compound can dissolve and diffuse the solder resist layer properly. Although the carbonate has a higher hydration power than the silicate or phosphate, potassium as an alkali metal tends to ionize in an aqueous solution more than sodium, and thus dissolves and diffuses favorably in the solder resist layer. The content of potassium carbonate is more preferably 3 to 15 mass%, and still more preferably 5 to 10 mass%.

When the aqueous alkali solution is an aqueous solution containing an inorganic alkaline compound, examples of the organic alkaline compound contained in the aqueous alkali solution include tetramethylammonium hydroxide (TMAH), trimethyl-2-hydroxyethylammonium hydroxide (choline) It is preferable to include at least one kind selected. An alkaline aqueous solution having an organic alkaline compound content of 5 to 25 mass% can be preferably used. If it is less than 5% by mass, in-plane unevenness may easily occur in the thinning treatment. On the other hand, if it exceeds 25 mass%, the thinning rate may be slowed down. The content of the organic alkaline compound is more preferably 7 to 20% by mass, and still more preferably 10 to 20% by mass. Further, a surfactant, defoaming agent, solvent and the like may be appropriately added. When an alkali aqueous solution containing an alkali metal salt is used, depending on the composition of the solder resist to be used, alkali metal ions may flow into the solder resist layer to lower the insulation reliability, but an alkali aqueous solution containing an organic alkaline compound It is possible to obtain an effect of suppressing deterioration in insulation reliability.

The temperature of the aqueous alkali solution is preferably 15 to 35 占 폚, more preferably 20 to 30 占 폚. If the temperature is too low, the penetration rate of the alkaline compound into the solder resist layer may be slowed down, and it takes a long time to thin the desired thickness. On the other hand, if the temperature is excessively high, dissolution and diffusion proceed simultaneously with the penetration of the alkaline compound into the solder resist layer, so that the film thickness irregularity may easily occur in the surface.

In the thinning treatment of the solder resist layer, it is preferable to use a neutralization titration method as a solution management method of an aqueous alkaline solution. That is, in order to keep the ability of the alkali aqueous solution to be thinned at a constant level, it is preferable to conduct the concentration-based management as an index of the liquid management. As an index of the liquid management, management by pH may be considered, but an alkali-soluble resin having an acid terminal end such as a carboxylic acid group contained in the solder resist layer contacts and reacts with a high-concentration aqueous alkaline solution to measure pH at an actual concentration , It is difficult to strictly control the pH of the solution. In the concentration control by the neutralization titration method, it is preferable to replenish an alkaline aqueous solution having the same concentration as the initial concentration as the replenishment liquid. Generally, in a development treatment with a low-concentration alkaline aqueous solution in the formation of a solder resist pattern by a photolithography method, it is common to replenish a treatment solution at a higher concentration than the initial concentration. In the thinning of the solder resist layer according to the present invention, The influence of the change in the concentration of the aqueous solution on the thinning is large, and more strict concentration control is required. Specifically, in the case of developing treatment with a low-concentration alkaline aqueous solution in forming a solder resist pattern by a photolithography method, the developing treatment is performed at a time of about 1.5 to 2.0 times longer than the time at which all the solder resist layer is eluted , In the case of thinning the solder resist layer according to the present invention, it becomes important to form a thin film uniformly in a plane by a desired amount. Therefore, more strict concentration control is required. In order to replenish a high-concentration alkali aqueous solution, it is common to carry out an operation such as mechanical stirring so that the concentration of the liquid in the tank is instantaneously aimed at. However, when the alkali aqueous solution is foamed to cause film thickness unevenness The alkaline aqueous solution having the same concentration as the initial concentration is preferably replenished.

As a method of concentration control by the neutralization titration method, specifically, a predetermined amount of alkali aqueous solution is taken from a continuously operating thinning apparatus, hydrochloric acid or sulfuric acid is dropped while measuring pH, and acid The concentration of the alkaline compound is obtained. The concentration of the alkaline compound is calculated from the obtained titration curve. In the acid region, the titration curve is shifted due to the acid group contained in the solder resist layer, so that the accurate concentration can not be predicted in some cases. Therefore, it is necessary to calculate the concentration in the alkali region. When this concentration is out of the predetermined range of the aqueous alkaline solution, an aqueous alkaline solution having the same concentration as the initial concentration is added and replenished. The " predetermined range " refers to a concentration range of -5% to + 5% with respect to the initial concentration, hereinafter also referred to as " target concentration ". Measurement of the alkaline compound concentration by the neutralization titration and addition and replenishment of the alkaline aqueous solution are carried out every predetermined time, so that the thinning ability can be maintained within a certain range.

From the neutralization titration to the addition and replenishment of the aqueous alkaline solution, it is also possible to carry out automatically. Examples of the automatic system include a function (sampling pump, metering tube, and the like) for sampling at least the alkaline aqueous solution at least automatically at predetermined time intervals, a pH meter, a function of stirring the liquid (such as a magnetic stirrer) (A pulse motor driven pump, etc.), a function of setting the estimated neutralization point pH, a function of stopping the dropping of the titrant when the pH is reached, a function of calculating the dropping amount of the titrant, The function of calculating the concentration of the alkaline compound, the function of setting the target concentration, the function of supplying the aqueous alkali solution having the same concentration as the initial concentration of the amount calculated by [(target concentration-measurement concentration) x alkali aqueous solution tank volume / target concentration] (Such as a metering pump), and a function of cleaning a titration container after a series of appropriate measurements are completed. Although the calculation formula for supplementing the liquid is based on the above, it is desirable to perform various corrections while observing the actual process.

In the above example, the estimated neutralization point pH was set and the concentration of the alkaline compound was calculated from the amount of the acid dropped until the pH was reached. However, in order to increase the measurement accuracy, and when the pH is 8, it is set to about 7 to 6), and an acid drop amount at which the rate of pH change is greatest from the start of acid drop to the end of drop is determined. The acid drop amount is taken as a neutralization point, It is preferable to calculate the concentration of the compound.

Thinning treatment with an alkali aqueous solution can be carried out by an immersion treatment, a paddle treatment, a spraying treatment, a brushing, a scraping or the like, but immersion treatment is preferred. Bubbles tend to be generated in the aqueous alkaline solution and the resulting bubbles adhere to the surface of the solder resist layer during the thinning process, resulting in non-uniform film thickness. In the case of using a spraying process or the like, it is preferable to make the spraying pressure as small as possible so as not to generate bubbles.

After the steps (B1), (B2), (B3) and (D), it is preferable to thoroughly clean the circuit board with water. The solder resist layer to be removed is completely dissolved and removed by the circuit board cleaning with the water. As the method of the water washing treatment, immersion treatment, paddle treatment, spray treatment and the like are available, and spray treatment is most suitable in terms of the dissolution diffusion speed of the solder resist layer and uniformity of liquid supply. The temperature of the wash water is more preferably 25 to 45 캜, and further preferably 27 to 40 캜.

(E) an alkaline compound after the step (B1), (B2), (B3) or (D) of making the solder resist layer thin as in the method of forming the solder resist pattern of the present invention, Alkali aqueous solution and an aqueous solution having a pH of 5.0 to 10.0 and a temperature of 22 to 50 ° C. Step (E) is carried out before cleaning with water. In the step (E), the aqueous solution containing the alkaline compound has a buffering ability in the alkaline region, so that it is possible to prevent the rapid increase in the pH and to maintain the excellent in-plane uniformity. In addition, by using an aqueous solution having a pH of 5.0 to 10.0, the dissolution diffusion property of the solder resist layer can be maintained constant, and stable continuous thinning treatment becomes possible. Further, by setting the temperature of the aqueous solution at 22 to 50 캜, it is possible to obtain an effect that the surface of the roughened connection pad can be processed without leaving the residue of the solder resist.

Examples of the alkaline compound in the aqueous solution of the step (E) include inorganic alkaline compounds such as alkali metal carbonates, alkali metal phosphates, alkali metal hydroxides and alkali metal silicates, tetramethylammonium hydroxide (TMAH), trimethyl- And organic alkaline compounds such as hydroxyethyl ammonium hydroxide (choline). The alkaline compound in the alkaline aqueous solution used in the step (B1), (B2), (B3) or (D) and the alkaline compound used in the step (E) may be the same or different from each other, However, in general, it is general that the same alkaline compound is contained in consideration of the presence of an alkaline compound in the transition from the previous step to the subsequent step, in which two steps are usually carried out continuously.

The content of the alkaline compound in the aqueous solution of the step (E) is lower than that of the alkali aqueous solution used in the step (B1), (B2), (B3) or (D). That is, an aqueous solution which is thinner than the alkali aqueous solution used in the step (B1), (B2), (B3) or (D) is used in the step (E). When the aqueous solution of the step (E) is thicker than the alkali aqueous solution used in the step (B1), (B2), (B3) or (D), there arises a problem that control of the thinning amount of the solder resist layer becomes difficult.

When the pH of the aqueous solution of the step (E) is less than 5.0, the solder resist components dissolved in the aqueous solution aggregate and become insoluble sludge, which may adhere to the surface of the solder resist layer after thinning. On the other hand, if the pH of the aqueous solution of the step (E) exceeds 10.0, the dissolution diffusion of the solder resist layer is promoted and the film thickness irregularity may easily occur in the surface. The pH of the aqueous solution can be adjusted by using sulfuric acid, phosphoric acid, hydrochloric acid, or the like.

The pH of the aqueous solution of the alkali solution and the aqueous solution of the step (E) is temperature-dependent, and the pH according to the present invention indicates the value at a liquid temperature of 22 ° C. pH The function of temperature compensation corresponding to the temperature characteristic of the glass electrode (the function of correcting the property change by the temperature of the pH glass electrode) and the temperature conversion function corresponding to the temperature characteristic of the aqueous solution (the function of converting into the pH value at a constant temperature ) To measure the pH value of the aqueous solution at 22 占 폚.

In the step (E), the temperature of the aqueous solution is more preferably 25 to 45 占 폚, and still more preferably 27 to 40 占 폚. The temperature of the aqueous solution in the step (E) affects the dissolution diffusion efficiency of the solder resist layer. When the temperature is less than 22 캜, the solder resist layer component fails to dissolve and the solder resist residue remains on the roughened surface There is an easy case. On the other hand, if it exceeds 50 캜, there is a problem that temperature control during evaporation of an aqueous solution, continuous operation, and restrictions on apparatus design may occur.

Further, an antifoaming agent which is effective for vesicles (permeation, spreading) can be added to the aqueous solution of the step (E). When the solder resist layer is continuously thinned to dissolve a large amount of the solder resist component in the aqueous solution, the foaming becomes violent and the continuous operation can not be performed. Antifoaming agents inhibit such foaming, and there are two types of silicone antifoaming agent and organic antifoaming agent.

Silicone antifoaming agents are excellent in the short-term effectiveness of parcels, but they are prone to cause defects such as lumps and craters because they are deteriorated in terms of perspiration ability, compatibility and wettability. On the other hand, the organic antifoaming agent has a surfactant system, a paraffin system, a mineral oil system and the like, and exhibits excellent persistence in the water-based foamed liquid as compared with the silicone-based antifoaming agent. Surfactant-based antifoaming agent is often emulsion-dispersed with a surfactant having a low HLB by using an emulsifier. Although this type of antifoaming agent is relatively persistent, the antifoaming effect is much smaller than the others. Among them, the surfactant represented by the following formula 1 or formula 2 having a very stable molecular structure symmetrically with the acetylene group at the center has a small molecular weight and an effect of greatly lowering the surface tension, and has not only functions such as defoaming property and dispersibility Excellent wettability and compatibility are exhibited.

[Chemical Formula 1]

In the formulas (1) and (2), m and n are 0 or an integer of 1 or more, and 0? M + n?

Examples of such surfactants include Surfynol (registered trademark) 104, Surfynol (registered trademark) DF110D, Surfinol (registered trademark) MD-20, Surfynol (registered trademark) 420 manufactured by Nissin Chemical Industry Co., NOLOL (registered trademark) 440, SURFINOL (registered trademark) 465, SURFYNOL (registered trademark) 485, ORPIN (registered trademark) AF-103 and ORPIN (registered trademark) E1004. Particularly, Surfynol (registered trademark) 104 and Orpin (registered trademark) AF-103 are preferable in the foaming property and Surfynol (registered trademark) 465, Surfynol (registered trademark) ) E1004. In addition to these, the use of Surfynol (registered trademark) MD-20 is most preferable in view of the compatibility, the persistence of the bubble effect and the dispersibility of the oil scum accompanied by the increase of the amount of dissolution .

These surfactants are preferably added in an amount of 0.01 to 5.0 g per 1 g of the solder resist to be dissolved and dispersed, and more preferably 0.05 to 2.0 g. If it is less than 0.01 g, the effect of foaming on foaming may be insufficient. If it exceeds 5.0 g, there is a possibility that layer separation of the surfactant occurs. Further, when the surfactant is added in a state of being dispersed in an aqueous solution, it spreads quickly and exhibits a bubble effect.

The paraffin-based antifoaming agent is obtained by emulsion-dispersing paraffin wax or its modified product using an emulsifier, and is preferably used as a defoaming agent containing mineral oil as a component. The content of mineral oil and other components can make it possible to combine the defoaming effect and the durability. Examples of the mineral oil used include petroleum crude oil and saturated or unsaturated hydrocarbons such as liquid paraffin, lubricating oil, gasoline, kerosene, diesel oil, heavy oil, and machine oils, which are mainly obtained from petroleum crude oil or its products. Mineral oil defoaming agents are made up of mineral oil as a major defoaming agent. In order to increase the defoaming effect, metal soap and silicon dioxide are mixed. The antifoaming agent containing mineral oil as a main vesicle component has a problem that the dispersibility of water to water is very poor and the separated oil particles float on the water surface and the separated oil adheres to the surface of the solder resist layer and further, .

The antifoaming agent containing mineral oil preferably has a mineral oil content of 20 mass% or less. Mineral oil is generally considered to have a great effect but has no persistence. It contains both mineral oil and less than 20% by mass, and replenishes the sustainability with other ingredients. The content of the mineral oil contained in the antifoaming agent is more preferably 10 to 20 mass%, and still more preferably 15 to 20 mass%. Commercially available antifoaming agents having a mineral oil content of 20% by mass or less may be used. Specific examples thereof include Crilles (registered trademark) 505, 514 and 521 manufactured by Kurita Kogyo K.K. The amount of the antifoaming agent to be added is not particularly limited, but the concentration is preferably 1 to 10000 ppm, more preferably 10 to 1000 ppm.

In the thinning treatment of the solder resist layer related to the present invention, the concentration of the solder resist component removed by thinning into the aqueous solution of the step (E) in the aqueous solution is preferably 0.5 mass% or less, more preferably 0.3 mass% or less , More preferably 0.2 mass% or less. If the dissolution amount of the solder resist component into the aqueous solution of the step (E) is increased by the continuous thinning treatment, haze unevenness may occur on the surface of the thinned solder resist, and film thickness unevenness may occur at that portion. The haze unevenness is considered to be caused by the poor dispersion of the solder resist layer in the thinning treatment process, resulting in poor solubility and hence the precipitation of insoluble components, but the details are unclear. The solder resist component dissolved in the aqueous solution of step (E) can be removed at any time by circulating the filter. The type of the filter can be used without any particular limitation. For example, a depth cartridge filter or a wound cartridge filter manufactured by Advanetto Co., Ltd. can be used. The number of the filters to be used, the hole diameter, and the like can be freely selected as needed.

The method of measuring the concentration of the solder resist component in the aqueous solution of the step (E) can be measured as the difference from the absolute dry mass. Specifically, for example, 10 g of an aqueous solution in which a solder resist component is dissolved is taken in a chalet, and the resultant is placed in a drier at a temperature of 100 캜 to completely evaporate water. Then, by measuring the mass after evaporation, the amount (mass%) of the solder resist component dissolved in 10 g of the solution can be calculated.

As the liquid supply method in the step (E), the spray treatment is most preferable in terms of the dissolution diffusion speed of the solder resist layer and the uniformity of the liquid supply. The spray pressure is preferably 0.01 to 0.5 MPa, and more preferably 0.02 to 0.3 MPa. The spraying method is preferably sprayed in a direction tilted with respect to the direction perpendicular to the surface of the solder resist layer in order to efficiently flow the liquid on the surface of the solder resist layer.

The time from the end of steps (B1), (B2), (B3) or (D) to the start of cleaning with water and the end of steps (B1), (B2), (B3) ) Is preferably 6 seconds or less, and more preferably 4 seconds or less. The thinning amount of the solder resist layer is determined according to the total time from the start of the steps (B1), (B2), (B3) or (D) to the time of washing with water or just before the start of the step (E). In short, the time from the end of the steps (B1), (B2), (B3), or (D) to the start of the cleaning with water or the start of the step (E) also affects the amount of thinning. Here, when the thinning treatment is carried out by using the thinning treatment apparatus, the time from the step (B1), (B2), (B3) or (D) to the step (E) is made zero by considering the conveying speed Is practically impossible. If the time from the end of the steps (B1), (B2), (B3), or (D) to the start of the step (E) becomes long, the degree of swelling and penetration of the alkali aqueous solution into the solder resist layer becomes uneven, The film thickness unevenness may occur in some cases.

Example

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

(Example 1)

≪ Process (A1) >

A circuit board having connection pads having a wiring width of 50 mu m and a wiring width of 50 mu m was fabricated on a copper-clad laminate (area: 170 mm x 200 mm, copper foil thickness: 18 mu m, substrate thickness: 0.4 mm) using the subtractive method. Then, a solder resist film (trade name: PFR-800 AUS410, manufactured by TAIYO INK MFG. CO., LTD.) Having a thickness of 30 占 퐉 was vacuum-pressed onto the circuit board using a vacuum laminator (laminate temperature: 75 占 폚, Sec, press time 10 seconds). As a result, a solder resist layer having a thickness of 38 mu m from the surface of the insulating substrate to the surface of the solder resist layer was formed.

≪ Process (B1)

The thinning treatment was carried out in the time described in Table 1 by an immersion method so that the thickness of the solder resist layer from the surface of the insulating substrate was 12 占 퐉 on average using the aqueous alkali solution (liquid temperature 25 占 폚) shown in Table 1, Treated (liquid temperature 25 캜), and dried under a cold air to obtain a thin solder resist layer. After the thinning treatment, the thickness of the thinned solder resist layer was measured at 10 points, and the maximum and minimum values were measured. The results are shown in Table 1. The difference between the film thickness maximum value and the film thickness minimum value was sufficiently small, and good in-plane uniformity was obtained.

Next, in order to cure the solder resist layer, the entire surface was exposed at an exposure amount of 500 mJ / cm 2, and then subjected to a thermal curing treatment at 150 캜 for 60 minutes to form a solder resist pattern. The solder resist pattern formed was of the structure shown in Fig. 10 and observed with an optical microscope. As a result, the connection pad 6 having a thickness of 18 탆 had its metal surface exposed, and a thickness of 12 탆 Of the solder resist layer 3 is buried.

(Example 2)

≪ Process (A2) >

A circuit board having conductor wirings having a wiring width of 50 mu m and a wiring width of 50 mu m was fabricated on a copper-clad laminate (area 170 mm x 200 mm, copper foil thickness 18 mu m, substrate thickness 0.4 mm) using the subtractive method. Then, a solder resist film (trade name: PFR-800 AUS410, manufactured by TAIYO INK MFG. CO., LTD.) Having a thickness of 30 占 퐉 was vacuum-pressed onto the circuit board using a vacuum laminator (laminate temperature: 75 占 폚, Sec, press time 10 seconds). As a result, a solder resist layer having a thickness of 38 mu m from the surface of the insulating substrate to the surface of the solder resist layer was formed.

≪ Process (C) >

A portion of the conductor wiring was used as a connection pad, and contact exposure with a photomask was performed at an exposure amount of 300 mJ / cm 2 in order to cure the solder resist layer in an area other than 50 탆 from the end of the connection pad.

≪ Process (B2)

The thinning treatment was carried out in the time described in Table 1 by the immersion method so that the average thickness of the solder resist layer from the surface of the insulating substrate of the non-exposed portion was 12 mu m using the aqueous alkaline solution (liquid temperature 25 DEG C) shown in Table 1 , A sufficient water washing treatment (liquid temperature 25 캜), and a cold air drying to obtain a thin solder resist layer. After the thinning treatment, the thickness of the thinned solder resist layer was measured at 10 points, and the maximum and minimum values were measured. The results are shown in Table 1. The difference between the film thickness maximum value and the film thickness minimum value was sufficiently small, and good in-plane uniformity was obtained.

Next, in order to cure the solder resist layer, the entire surface was exposed at an exposure dose of 500 mJ / cm 2, followed by thermal curing treatment at 150 캜 for 60 minutes. The solder resist pattern formed was of the structure shown in Fig. 11 and observed with an optical microscope. As a result, the conductor wiring 2 having a thickness of 18 mu m was covered with the solder resist layer 3 having a thickness of 38 mu m, The metal surface of the pad 6 was exposed, and a solder resist layer 3 having a thickness of 12 占 퐉 was buried between the adjacent connection pads 6. [

(Example 3)

≪ Process (A2) >

A circuit board having conductor wirings having a wiring width of 50 mu m and a wiring width of 50 mu m was fabricated on a copper-clad laminate (area 170 mm x 200 mm, copper foil thickness 18 mu m, substrate thickness 0.4 mm) using the subtractive method. Then, a solder resist film (trade name: PFR-800 AUS410, manufactured by TAIYO INK MFG. CO., LTD.) Having a thickness of 30 占 퐉 was vacuum-pressed onto the circuit board using a vacuum laminator (laminate temperature: 75 占 폚, Sec, press time 10 seconds). As a result, a solder resist layer having a thickness of 38 mu m from the surface of the insulating substrate to the surface of the solder resist layer was formed.

≪ Process (D) >

The thinning treatment was carried out by an immersion method until the thickness of the solder resist layer from the surface of the insulating substrate became 28 mu m on average using the aqueous alkaline solution (liquid temperature 25 DEG C) shown in Table 1, Lt; 0 > C), followed by cooling and drying to obtain a thin solder resist layer.

≪ Process (C) >

A portion of the conductor wiring was used as a connection pad, and contact exposure with a photomask was performed at an exposure amount of 300 mJ / cm 2 in order to cure the solder resist layer in an area other than 50 탆 from the end of the connection pad.

≪ Process (B2)

The thinning treatment was carried out in the time described in Table 1 by the immersion method so that the average thickness of the solder resist layer from the surface of the insulating substrate of the non-exposed portion was 12 mu m using the aqueous alkaline solution (liquid temperature 25 DEG C) shown in Table 1 , A sufficient water washing treatment (liquid temperature 25 ° C), and a cold air drying to obtain a thin solder resist layer. After the thinning treatment, the thickness of the thinned solder resist layer was measured at 10 points, and the maximum and minimum values were measured. The results are shown in Table 1. The difference between the film thickness maximum value and the film thickness minimum value was sufficiently small, and good in-plane uniformity was obtained.

Next, in order to cure the solder resist layer, the entire surface was exposed at an exposure dose of 500 mJ / cm 2, followed by thermal curing treatment at 150 캜 for 60 minutes. The solder resist pattern formed was of the structure shown in Fig. 12 and observed with an optical microscope. As a result, the conductor wiring 2 having a thickness of 18 mu m was covered with the solder resist layer 3 having a thickness of 28 mu m, The metal surface of the pad 6 was exposed, and a solder resist layer 3 having a thickness of 12 占 퐉 was buried between the adjacent connection pads 6. [

(Example 4)

≪ Process (A3) >

A connection pad having a thickness of 25 占 퐉, a wiring width of 50 占 퐉 and a wiring width of 50 占 퐉 and a connection pad of thickness 15 占 퐉 and wiring width of 50 占 퐉 (area: 170 mm 占 200 mm, substrate thickness 0.4 mm) , And a conductor wiring having a wiring width of 50 mu m. Then, a solder resist film (trade name: PFR-800 AUS410, manufactured by TAIYO INK MFG. CO., LTD.) Having a thickness of 30 占 퐉 was vacuum-pressed onto the circuit board using a vacuum laminator (laminate temperature: 75 占 폚, Sec, press time 10 seconds). As a result, a solder resist layer having a thickness of 38 mu m from the surface of the insulating substrate to the surface of the solder resist layer was formed.

≪ Process (B3) >

Thinning treatment was carried out in the time described in Table 1 by an immersion method so that the thickness of the solder resist layer from the surface of the insulating substrate became 20 mu m on average using the alkali aqueous solution (liquid temperature 25 DEG C) shown in Table 1, Treated (liquid temperature 25 캜), and dried under a cold air to obtain a thin solder resist layer. After the thinning treatment, the thickness of the thinned solder resist layer was measured at 10 points, and the maximum and minimum values were measured. The results are shown in Table 1. The difference between the film thickness maximum value and the film thickness minimum value was sufficiently small, and good in-plane uniformity was obtained.

Next, in order to cure the solder resist layer, the entire surface was exposed at an exposure dose of 500 mJ / cm 2, followed by thermal curing treatment at 150 캜 for 60 minutes. 13, the conductor wirings 2 having a thickness of 15 占 퐉 are completely covered with the solder resist layer 3 having a thickness of 20 占 퐉 and the connection pads 6 having a thickness of 25 占 퐉 are covered with the metal surface And a solder resist layer 3 having a thickness of 20 占 퐉 was buried between the adjacent connection pads 6. [

(Example 5)

≪ Process (A3) >

A semi-additive method was used to form a copper-clad laminate (area: 170 mm x 200 mm, substrate thickness: 0.4 mm) having a wiring width of 50 mu m and a wiring width of 50 mu m, connecting pads each having a thickness of 25 mu m, A circuit board having conductor wirings formed in a stepped shape was produced. Then, a solder resist film (trade name: PFR-800 AUS410, manufactured by TAIYO INK MFG. CO., LTD.) Having a thickness of 30 占 퐉 was vacuum-pressed onto the circuit board using a vacuum laminator (laminate temperature: 75 占 폚, Sec, press time 10 seconds). As a result, a solder resist layer having a thickness of 38 mu m from the surface of the insulating substrate to the surface of the solder resist layer was formed.

≪ Process (B3) >

Thinning treatment was carried out in the time described in Table 1 by an immersion method so that the thickness of the solder resist layer from the surface of the insulating substrate became 20 mu m on average using the alkali aqueous solution (liquid temperature 25 DEG C) shown in Table 1, Treated (liquid temperature 25 캜), and dried under a cold air to obtain a thin solder resist layer. After the thinning treatment, the thickness of the thinned solder resist layer was measured at 10 points, and the maximum and minimum values were measured. The results are shown in Table 1. The difference between the film thickness maximum value and the film thickness minimum value was sufficiently small, and good in-plane uniformity was obtained.

Subsequently, in order to cure the solder resist layer, the entire surface was exposed at an exposure dose of 500 mJ / cm 2, and then heat cured at 150 캜 for 60 minutes. 14, the conductor wiring 2 having a thickness of 15 占 퐉 is completely covered with the solder resist layer 3 having a thickness of 20 占 퐉, and the connection pad 6 having a thickness of 25 占 퐉 is covered with the metal surface And a solder resist layer 3 having a thickness of 20 占 퐉 was buried between the adjacent connection pads 6. [

(Comparative Example 1)

A circuit board having conductor wirings having a wiring width of 50 mu m and a wiring width of 50 mu m was fabricated on a copper-clad laminate (area 170 mm x 200 mm, copper foil thickness 18 mu m, substrate thickness 0.4 mm) using the subtractive method. Then, a solder resist film (trade name: PFR-800 AUS410, manufactured by TAIYO INK MFG. CO., LTD.) Having a thickness of 30 占 퐉 was vacuum-pressed onto the circuit board using a vacuum laminator (laminate temperature: 75 占 폚, Sec, press time 10 seconds). As a result, a solder resist layer having a thickness of 38 mu m from the surface of the insulating substrate to the surface of the solder resist layer was formed.

A part of the conductor wiring was used as a connection pad and contact exposure with a photomask was performed at an exposure amount of 300 mJ / cm 2 in order to harden the solder resist layer in an area other than 50 탆 from the end of the connection pad.

Subsequently, the unexposed portion of the solder resist layer was removed by a developing treatment using a 1% by mass sodium carbonate aqueous solution (liquid temperature of 30 占 폚), and thermal curing treatment was performed at 150 占 폚 for 60 minutes. The formed solder resist pattern had a structure shown in Fig. 15, in which the conductor wiring 2 having a thickness of 18 mu m was covered with the solder resist layer 3 having a thickness of 38 mu m. In the structure shown in Fig. 15, since there is no solder resist layer 3 between the adjacent connection pads 6, connection failure due to the solder bridge occurred in the mounting process.

(Comparative Example 2)

A circuit board having conductor wirings having a wiring width of 50 mu m and a wiring width of 50 mu m was fabricated on a copper-clad laminate (area 170 mm x 200 mm, copper foil thickness 18 mu m, substrate thickness 0.4 mm) using the subtractive method. Then, a solder resist film (trade name: PFR-800 AUS410, manufactured by TAIYO INK MFG. CO., LTD.) Having a thickness of 30 占 퐉 was vacuum-pressed onto the circuit board using a vacuum laminator (laminate temperature: 75 占 폚, Sec, press time 10 seconds). As a result, a solder resist layer having a thickness of 38 mu m from the surface of the insulating substrate to the surface of the solder resist layer was formed.

A part of the conductor wiring was used as a connection pad and an exposure amount of 300 mJ / cm 2 was used to cure the solder resist layer in a region other than 50 탆 from the end of the connection pad and in a region of 20 탆 in width from the midpoint between adjacent connection pads, Cm < 2 > by a photomask.

Subsequently, the unexposed portion of the solder resist layer was removed by a developing treatment using a 1% by mass sodium carbonate aqueous solution (liquid temperature of 30 占 폚), and thermal curing treatment was performed at 150 占 폚 for 60 minutes. 16, a conductor wiring 2 having a thickness of 18 占 퐉 is covered with a solder resist layer 3 having a thickness of 38 占 퐉, and a solder resist layer 3 having a width There was a solder resist layer 3 having a thickness of 38 mu m at a portion of 20 mu m. However, depending on the observation point, the solder resist layer 3 on the insulating substrate 1 comes into contact with the connection pad 6 due to the positional deviation in the exposure process. Because of this state, the amount of solder for ensuring the electrical connection between the electrode terminals and the connection pads can not be ensured, resulting in a connection failure at the time of bonding, and the solder resist layer 3, which has been displaced, .

(Comparative Example 3)

A circuit board having conductor wirings having a wiring width of 50 mu m and a wiring width of 50 mu m was fabricated on a copper-clad laminate (area 170 mm x 200 mm, copper foil thickness 18 mu m, substrate thickness 0.4 mm) using the subtractive method. Then, a solder resist film (trade name: PFR-800 AUS410, manufactured by TAIYO INK MFG. CO., LTD.) Having a thickness of 30 占 퐉 was vacuum-pressed onto the circuit board using a vacuum laminator (laminate temperature: 75 占 폚, Sec, press time 10 seconds). As a result, a solder resist layer having a thickness of 38 mu m from the surface of the insulating substrate to the surface of the solder resist layer was formed.

The entire surface of the solder resist layer was exposed at an exposure dose of 1000 mJ / cm 2, and then thermally cured at 150 캜 for 60 minutes. A wet blast process was performed until a wet blast pattern was formed on the surface of the solder resist layer after the heat curing treatment and the connection pad surface was exposed using the wet blast pattern as a mask. Thereafter, the mask pattern was removed. The solder resist pattern formed was of the structure shown in Fig. 11 and observed with an optical microscope. As a result, the conductor wiring 2 having a thickness of 18 mu m was covered with the solder resist layer 3 having a thickness of 38 mu m, The metal surface of the pad 6 is exposed, and the solder resist layer 3 is buried between the adjacent connection pads 6. [ However, there was a variation in the thickness of the solder resist layer buried between the adjacent connection pads 6, so that the metal surface of the connection pad 6 was not completely exposed, and there was a portion where the solder resist layer remained. In addition, a number of scratches generated by the blast treatment were confirmed on the connection pad 6 whose surface was exposed.

(Examples 6 to 27)

A solder resist pattern was formed in the same manner as in Example 2 using the aqueous alkaline solution described in Table 1. [ After the thinning treatment, the thickness of the thinned solder resist layer was measured at 10 points, and the maximum and minimum values were measured. The results are shown in Table 1. In Examples 2 and 6 to 27, when an aqueous solution having an inorganic alkaline compound content of 3 to 25 mass% was used (Examples 2 and 7 to 27), the difference between the maximum film thickness value and the minimum film thickness was sufficiently small, A solder resist pattern with a very good in-plane uniformity in the surface was formed. In Example 6 in which the content of the inorganic alkaline compound was 1% by mass, it was confirmed that the difference between the maximum value of the film thickness and the minimum value of the film thickness was somewhat large, and the in-plane uniformity after thinning tended to deteriorate. As for the thinning rate, in the case of the concentration of 7 mass% in the comparison of Examples 2 and 6 to 12, in the case of the concentration of 20 mass% in the comparison of Examples 13 to 18, the thinning rate becomes maximum, and at the higher concentration, There was a tendency to decrease. In addition, the time required for the thinning treatment differs depending on the kind of the inorganic alkaline compound, and in particular, when sodium metasilicate is used, a very rapid thinning rate is obtained.

(Examples 28 to 41)

A circuit board having conductor wirings was produced on the copper-clad laminate by the subtractive method, then the surface of the conductor circuit was roughened by chemical polishing treatment, and the aqueous alkaline solution described in Table 2 was used as the aqueous alkaline solution. A solder resist pattern was formed in the same manner as in Example 2. In order to investigate the presence or absence of solder resist residues on the roughened surface of the connection pad exposed by the thinning treatment, the exposed copper surface was subjected to electroless nickel plating treatment. Further, plating pretreatment was carried out if necessary, and when the residue was present, the removability was also investigated. The evaluation criteria are as follows. The results are shown in Table 2. Particularly, when an alkali aqueous solution containing sodium metasilicate was used, residues of the solder resist component were not confirmed on the roughened surface.

○: No residue of solder resist component

[Delta]: A level remained at a very small amount but easily removed by pretreatment of plating

X: level at which there is a large amount of residue and is not easily removed by plating pretreatment

(Examples 42 to 55)

A solder resist pattern was formed in the same manner as in Example 2 except that the aqueous alkaline solution described in Table 3 was used. After the thinning treatment, the thickness of the thinned solder resist layer was measured at 10 points, and the maximum and minimum values were measured. The results are shown in Table 3. When an aqueous solution having an organic alkaline compound content of 5 to 25% by mass was used, the difference between the maximum film thickness value and the minimum film thickness was sufficiently small, so that a solder resist pattern with excellent in-plane uniformity after thinning was formed. In Examples 42 and 43 in which the content of the organic alkaline compound was 3 mass% or less, it was confirmed that the difference between the maximum value of the film thickness and the minimum value of the film thickness was somewhat large, and the in-plane uniformity after thinning tended to deteriorate.

(Examples 56 to 63)

A circuit board having conductor wiring was formed on the copper-clad laminate by the subtractive method, then the surface of the conductor circuit was roughened by a chemical polishing treatment, and an aqueous alkaline solution described in Table 4 was used as an aqueous alkaline solution. A solder resist pattern was formed in the same manner as in Example 2. In order to investigate the presence or absence of solder resist residues on the roughened surface of the connection pad exposed by the thinning treatment, the exposed copper surface was subjected to electroless nickel plating treatment. Further, plating pretreatment was carried out if necessary, and when the residue was present, the removability was also investigated. The evaluation criteria are as follows. The results are shown in Table 4. Even when an organic alkaline compound is used, the residue of the solder resist component on the roughened surface has a level that can be easily removed by the pretreatment of plating, and there is no practical problem.

<Measurement of sodium ion concentration>

The solder resist patterns prepared in Example 1, Example 2, Example 19, Example 47, Example 53, and Example 53 and Comparative Example 1 were each subjected to hot water ion extraction at 100 ° C, and sodium chloride The ion concentration was measured. The results are shown in Table 5. When an aqueous alkaline solution containing an organic alkaline compound was used, there was almost no incorporation of sodium ions into the solder resist layer. On the other hand, in the case of using an alkaline aqueous solution containing an inorganic alkaline compound, incorporation of sodium ions into the solder resist layer to the extent equivalent to the developing treatment in Comparative Example 1 was observed. However, in Example 1, when the entire surface of the solder resist layer was thinned using an inorganic alkaline compound, the amount of sodium ions mixed was small. From this point of view, it was found that the incorporation of sodium ions tends to increase mainly when the exposed portion of the solder resist layer is present.

(Examples 64 to 91)

Spray treatment (spray pressure 0.20 MPa) was carried out using the aqueous solution of step (E) shown in Table 7 before the water treatment, using the alkali aqueous solution (liquid temperature 25 ° C) shown in Table 6 in the thinning treatment of the solder resist layer A solder resist pattern was formed in the same manner as in Example 28, except for the following. The pH of the aqueous solution of the step (E) was adjusted by adding sulfuric acid having a lean concentration. After the thinning treatment, the thickness of the thinned solder resist layer was measured at 10 points, and the maximum and minimum values were measured. The results are shown in Table 7. When the pH of the aqueous solution of the step (E) was 5.0 to 10.0, the difference between the maximum film thickness and the minimum film thickness was small and the in-plane uniformity after thinning was good. In Example 67 in which the pH of the aqueous solution of the step (E) was 10.3, it was confirmed that the difference between the maximum value of the film thickness and the minimum value of the film thickness was somewhat large and the in-plane uniformity after thinning tended to deteriorate.

Further, in order to investigate the presence or absence of solder resist residues on the roughened surface of the connection pad exposed by the thinning treatment, the exposed copper surface was subjected to electroless nickel plating treatment. Further, plating pretreatment was carried out if necessary, and when the residue was present, the removability was also investigated. The results are shown in Table 7. When the solution temperature of the aqueous solution of the step (E) is 22 to 50 캜, residue residue of the solder resist component tends to be hardly generated together with the temperature rise. Residual residue at 27 캜 or higher was not observed. It was confirmed that the residue of the solder resist component tended to be easily left in Example 68, Example 76, and Example 86 in which the liquid temperature of the aqueous solution of the step (E) was 20 占 폚.

(Examples 92 to 93)

In order to investigate the stability of the continuous thinning treatment, in the thinning treatment of the solder resist layer, an aqueous alkaline solution (25 ° C) shown in Table 8 was used and an aqueous solution of the step (E) shown in Table 8 A solder resist pattern was formed in the same manner as in Example 2 except that spray treatment (spray pressure 0.20 MPa) was applied. During the continuous thinning treatment, the pH of the aqueous solution of the step (E) was not adjusted for every one treatment, and the thickness of the solder resist layer of the thinned portion was measured at 10 points in the first chapter and the tenth chapter of the thinning treatment The maximum and minimum values were examined. The results of the pH of the aqueous solution of the step (E) and the results are shown in Table 9. In Examples 2 and 20 in which thinning was carried out by washing with water after the treatment with an aqueous alkali solution, the difference between the maximum film thickness and the minimum film thickness became larger with the increase in the number of thinning treatments, . In Example 92 and Example 93 in which the step (E) was performed before the water washing treatment, since the aqueous solution of the step (E) had a buffering ability, the pH of the aqueous solution after 10 sheets of thinning treatment was less than 10, And the film thickness minimum value were small, and the in-plane uniformity after thinning was good.

(Example 94)

A solder resist pattern was formed in the same manner as in Example 2 except that the thinning treatment of the solder resist layer was carried out by spray treatment in which an aqueous alkaline solution was sprayed at a spray pressure of 0.1 MPa. And the spraying time was adjusted so that the thickness of the solder resist layer after thinning became an average of 12 占 퐉. When an aqueous alkali solution was supplied by spraying, bubbles generated in a large amount in the aqueous alkaline solution adhered to the surface of the solder resist layer to be thinned, and the thick film portion which was not thinned locally was confirmed to be uneven in film thickness. As a result, the spray pressure was lowered to 0.03 MPa so as not to generate bubbles, and the bubble trap filter was arranged in the recovery path of the liquid after spraying the alkaline aqueous solution. As a result, Respectively.

Industrial availability

The method of forming a solder resist pattern of the present invention can be applied to a case where a solder resist pattern is formed on a circuit board having a connection pad for flip chip connection, for example.

1 insulating substrate
2 conductor wiring
3 solder resist layer
4 Photomasks
5 active rays
6 connection pads

Claims (13)

(A1) a step of forming a solder resist layer on a surface of a circuit board having a connection pad,
(B1) a step of thinning the solder resist layer with an alkali aqueous solution until the thickness of the solder resist layer which is not cured becomes less than or equal to the thickness of the connection pad,
Wherein the solder resist pattern is formed on the substrate. The method according to claim 1,
Wherein the alkaline aqueous solution contains an inorganic alkaline compound and the content of the inorganic alkaline compound is 3 to 25 mass%. 3. The method of claim 2,
Wherein the inorganic alkaline compound is at least one selected from an alkali metal carbonate, an alkali metal phosphate, an alkali metal hydroxide, and an alkali metal silicate. 3. The method of claim 2,
Wherein the inorganic alkaline compound is an alkali metal silicate. 5. The method of claim 4,
Wherein the alkali metal silicate is sodium metasilicate. 3. The method of claim 2,
Wherein the inorganic alkaline compound is an alkali metal phosphate. The method according to claim 6,
Wherein the alkali metal phosphate is at least one selected from trisodium phosphate and tripotassium phosphate. 3. The method of claim 2,
Wherein the inorganic alkaline compound is potassium carbonate. The method according to claim 1,
Wherein the alkaline aqueous solution is an aqueous solution containing an organic alkaline compound. 10. The method of claim 9,
Wherein the content of the organic alkaline compound is 5 to 25 mass%. The method according to claim 1,
Wherein the alkaline aqueous solution has a pH of 12.5 or more. The method according to claim 1,
After the step of thinning the solder resist layer with an alkaline aqueous solution,
(E) a step of treating with an aqueous solution containing an alkaline compound, the content of the alkaline compound being less than that of the alkali aqueous solution, and having a pH of 5.0 to 10.0 and a temperature of 22 to 50 ° C
And forming a solder resist pattern on the substrate. The method according to claim 1,
Wherein the step of thinning the solder resist layer with an alkaline aqueous solution is an immersion treatment.

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