JP5113401B2 - Emulsion particles and method for producing mask for screen printing using the same - Google Patents

Description

  The present invention relates to emulsion particles having excellent solvent resistance and a method for producing a screen printing mask formed by forming a resin layer on the inner wall of an opening using the emulsion particles.

  With recent miniaturization and multi-functionalization of electronic devices, the density of printed wiring boards and the miniaturization of wiring patterns have been promoted, and high-density mounting of electronic components on printed wiring boards has been widely performed. Yes. In high density mounting of electronic components on this printed wiring board, cream solder is printed to mount the electronic components on the surface of the printed wiring board, and the electronic components are mounted on the solder terminals, and then heated in a reflow furnace for soldering. To do. As the cream solder printing method, a screen printing process is widely used. In general, screen printing is performed by setting a screen printing mask having a pattern-shaped opening formed on the upper surface of a substrate to be printed and supplying paste material such as cream solder to the squeegee surface of the screen printing mask. In this method, the paste material is transferred and printed onto the pattern through the opening by scraping with a squeegee.

  However, when cream solder is printed using a screen printing mask, if the pattern becomes high density and high definition, the ability of the cream solder to be removed from the screen printing mask deteriorates. In recent years, the trend of lead-free cream solder materials has been increasing due to environmental problems, and as part of the countermeasures, lead-free solders that do not contain lead have been used as cream solder materials. . Lead-free cream solder tends to be inferior in transferability compared to conventional cream solder. Deterioration of the cream solder from the screen printing mask deteriorates, causing defects such as protrusions, chips, cracks, and disconnection of the solder terminals, which is a major cause of yield reduction.

  In order to solve such a problem, a screen printing mask in which a resin layer is formed on at least the inner wall of the opening of the screen printing mask has been proposed. According to this, a resin layer is formed on the inner wall of the opening by applying a resin, and the unevenness of the inner wall is smoothed, thereby reducing the friction between the cream solder and the inner wall and improving the cream solder removability. ing. In addition, by forming a compound (for example, polysiloxane, fluorine resin, silicon resin, etc.) having good repellent or slipperiness with cream solder on the inner wall of the opening, the cream solder can be removed easily. However, as a means for forming the resin layer on the inner wall, dipping, spraying, brushing, spin coating, etc. are adopted, and in these methods, the resin layer can be uniformly formed on the inner wall of the opening. It is difficult, and defects such as protrusions 9, partition walls 10, fillings 11, etc. of the resin layer as shown in FIG. (For example, patent documents 1-6).

Further, by repeatedly using the screen printing mask, cream solder remaining on the opening of the screen printing mask is generated. At this time, it is necessary to wash with a solvent such as alcohols or propylene glycols. Therefore, it is necessary to form a resin layer that can withstand a solvent such as a cleaning agent.
Japanese Utility Model Publication No. 63-37256 JP-A-1-299088 Japanese Patent Laid-Open No. 4-357093 JP-A-6-219070 JP-A-8-290686 JP 2002-192850 A

  An object of the present invention is to provide emulsion printing for forming a resin layer having excellent solvent resistance, and screen printing for forming a uniform resin layer free from defects such as protrusions, partition walls, and filling of the resin layer on the inner wall of the opening. It is to provide a method for manufacturing a mask for use.

As a result of the study by the present inventors, it was dispersed in a highly insulating medium selected from linear or branched aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons and their halogen substitution products . An emulsion particle, wherein the emulsion particle comprises a dispersant and a core polymer, wherein the core polymer contains blocked isocyanate groups and active hydrogen groups. I found that the problem was solved.

  More preferably, the active hydrogen group is a hydroxyl group and the core polymer contains a tertiary amino group.

  In addition, in a method for producing a screen printing mask in which a resin layer is formed on at least the inner wall of the opening, the emulsion particles of the present invention are electrodeposited on the screen printing mask having the opening, and then blocked by heating. The above problem is solved by a method for producing a mask for screen printing, wherein an isocyanate group is generated from the formed isocyanate group and the resin layer is formed by reacting the isocyanate group with an active hydrogen group. I found.

  Further, in a method for manufacturing a mask for screen printing in which a resin layer is formed on at least the inner wall of the opening, a step of attaching a protective sheet to the squeegee surface of the screen printing mask having the opening, the inner wall of the opening, and the covering The step of electrodepositing the emulsion particles of the present invention on the printed substrate contact surface, the step of forming the emulsion particles by heating, the step of removing the protective sheet, and generating isocyanate groups from the isocyanate groups blocked by heating It has been found that the above-mentioned problems can be solved by a method for producing a mask for screen printing, which includes a step of reacting a hydrogen atom with an active hydrogen group.

  In order to form the resin layer on the inner wall of the opening of the screen printing mask, the emulsion particles of the present invention are used. The emulsion particles are positively or negatively charged. Since the screen printing mask is formed of a metal material such as stainless steel, it has conductivity and the surface has the same potential. As shown in FIG. 11, when the electrode 12 is placed so as to face the screen printing mask 1, the screen printing mask 1 is grounded and an appropriate bias voltage is applied, the emulsion particles 13 charged according to the electric field are screened. Electrophoresis in the direction of the printing mask 1. Since the emulsion particles approaching in the screen printing mask direction by electrophoresis adhere from a place where the electric potential is close to 0, the emulsion particles adhere to cover the surface of the grounded screen printing mask. Therefore, defects such as protrusions, partition walls, and embedding of the resin layer do not occur due to the adhesion of the emulsion particles by the electrodeposition method. On the other hand, in the conventional resin layer forming method (for example, dip, spray method), there is a problem that the coating liquid accumulates at the edge portion of the opening due to surface tension, or a problem that the coating liquid accumulates at an acute angle portion where the opening has a sharp angle. In addition, problems such as dripping of the coating solution and uneven drying occur, and it is difficult to form a uniform thin film. The method of forming the resin layer by the water-based electrodeposition method has a problem that air is mixed into the inside of the opening, and consumption for forming a predetermined film thickness as compared with the case of using a highly insulating medium. There are many currents, and there are problems in terms of productivity and energy saving.

  The emulsion particles of the present invention have a particle shape when electrodeposited on a screen printing mask, and need to change into a film after electrodeposition. In order to transform the emulsion particles into a film, it is performed by means such as heating. For this reason, the emulsion particles need to have the characteristics that the particle shape can be stably maintained under storage conditions, can be easily formed into a film after electrodeposition, and the resin layer does not dissolve in the solvent. The emulsion particles of the present invention can be set in a temperature range in which the molecular weight of the resin can be lowered and the glass transition temperature can be lowered by blocking the isocyanate group. Therefore, it can be easily formed into a film at a low temperature. Furthermore, after forming into a film, an isocyanate group is generated by treatment under conditions higher than the glass transition temperature, and the generated isocyanate group reacts with the active hydrogen group to cause crosslinking of the resin layer. Solvent property is remarkably improved.

  Examples of the highly insulating medium according to the present invention include linear or branched aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, and halogen-substituted products thereof. Examples include octane, isooctane, decane, isodecane, decalin, nonane, dodecane, isododecane, cyclohexane, cyclooctane, cyclodecane, benzene, toluene, xylene, mesitylene and the like. The trade names include Isopar E, Isopar G, Isopar H, Isopar L (EXXON), IP1620 (trade name, Idemitsu Petrochemical Co., Ltd.) and the like. These highly insulating media can be used alone or in combination.

  The dispersant according to the present invention is a polymer soluble in a highly insulating medium obtained by polymerizing the monomer (M1). The mass average molecular weight of the dispersant is preferably 1000 or more. When the molecular weight is less than this, the dispersion stability of the emulsion particles is lowered, and the emulsion particles are likely to aggregate and settle. The upper limit of the molecular weight of the dispersant is not particularly defined, but when the molecular weight exceeds 1,000,000, the viscosity of the polymer solution increases and it becomes difficult to handle. The monomer (M1) preferably contains at least 50% by mass and 100% by mass of a compound represented by the general formula 1 or 2. As other polymerization components, the following monomer (M2), a monomer having a blocked isocyanate group or a monomer having an active hydrogen group, the solubility of the dispersing agent to be generated in a highly insulating medium is adjusted. It can contain in the range which does not impair.

(In Chemical Formula 1, R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkyl group having 8 to 30 carbon atoms, and the linking group T represents a —COO— group or a —CONH— group).

(In Chemical Formula 2, R ³ represents an alkyl group having 8 to 30 carbon atoms).

  The core polymer according to the present invention is a polymer of a monomer (M2) that is soluble in a highly insulating medium, and becomes insoluble in the highly insulating medium by polymerization. Examples of such a monomer (M2) include vinyl esters of aliphatic carboxylic acids having 1 to 6 carbon atoms, such as vinyl acetate, vinyl propionate, vinyl chloroacetate, vinyl benzoate, or acrylic. C1-C6 alkyl esters or amides such as acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, ethylene glycol di (meth) acrylate, methylenebisacrylamide, styrene and its derivatives, divinylbenzene, or N-vinyl-2-pyrrolidone, N-vinylpyridine, N-vinylimidazole and the like. As other polymerization components, a monomer having a blocked isocyanate group or a monomer having an active hydrogen group is contained.

  The emulsion particles of the present invention contain blocked isocyanate groups. The blocked isocyanate group is a functional group obtained by reacting an isocyanate group with a blocking agent and cleaving the blocking agent by heating to generate an isocyanate group. In order to contain a blocked isocyanate group in the core polymer, the monomer (M3) having a blocked isocyanate group is used as one component of the monomer of the core polymer, or the polymer side There is a method of reacting with a blocking agent after forming an isocyanate group in the chain. Blocking agents include phenols such as phenol, cresol, p-ethylphenol, p-tert-butylphenol, alcohols such as ethanol, butanol, ethylene glycol, methyl cellosolve, benzyl alcohol, diethyl malonate, ethyl acetoacetate, etc. Active methylenes, acid amides such as acetanilide, acetamide, other imides, amines, imidazoles, pyrazoles, ureas, carbamic acids, imines, holadaldoxime, acetoaldoxime, cyclohexanone oxime, etc. There are oxime, mercaptan, sodium bisulfite, sulfites such as potassium bisulfite, and lactams.

  Examples of the monomer (M3) having a blocked isocyanate group include (meth) acrylic acid 2- (O- [1′-methylpropylideneamino] carboxyamino) ethyl, (meth) acrylic acid 2- (O- [1'-ethylpropylideneamino] carboxyamino) ethyl, 2- (O- [1'-butylpropylideneamino] carboxyamino) ethyl (meth) acrylate, (meth) acrylic acid O- [1 '-Methylpropylideneamino] carboxyaminomethyl, (meth) acrylic acid 3- (O- [1'-methylpropylideneamino] carboxyamino) propyl, (meth) acrylic acid O- (1'-methylideneamino) carboxyamino Methyl, (meth) acrylic acid 2- (O- [1'-methylideneamino] carboxyamino) ethyl, (meth) 3- (O- [1'-methylideneamino] carboxyamino) propyl crylate, O- (1'-ethylideneamino] carboxyaminomethyl (meth) acrylic acid, 2- (O- [1 '-(meth) acrylic acid) Ethylideneamino] carboxyamino) ethyl, 3- (O- [1′-ethylideneamino] carboxyamino) propyl (meth) acrylate, O- (1′-propylideneamino) carboxyaminomethyl (meth) acrylate, ( 2- (O- [1′-propylideneamino] carboxyamino) ethyl (meth) acrylate, 3- (O- [1′-propylideneamino] carboxyamino) propyl (meth) acrylate, (meth) acrylic acid 2-[(3,5-dimethylpyrazolyl) carbonylamino] ethyl and the like.

  The compounding ratio of the monomer (M3) when synthesizing the core polymer can be contained within a range in which particle aggregation or the like does not occur, and is 0 with respect to 100 parts by mass of all monomers of the core polymer. It is preferable to use within the range of 1-50 mass parts, and it is more preferable to use within the range of 1-30 mass parts. When the amount is less than 1 part by mass, the solvent resistance of the resin layer may be insufficient. When the amount is more than 30 parts by mass, aggregation of emulsion particles tends to occur. Moreover, it is also possible to mix | blend a monomer (M3) as a monomer of a dispersing agent. In this case, it can be blended within a range that does not impair the solubility of the dispersant in the highly insulating medium, and is used within a range of 0.01 to 20 parts by mass with respect to 100 parts by mass of the total monomer of the core polymer. It is preferable to do.

  The emulsion particles of the present invention contain active hydrogen groups. The active hydrogen group is not particularly limited as long as it can react with isocyanate, and examples thereof include a hydroxyl group, a primary amino group, a secondary amino group, a carboxyl group, a mercapto group, and a silanol group. In order to contain the active hydrogen group in the dispersant or / and the core polymer, the monomer (M4) having an active hydrogen group is used as a component of the dispersant or / and the core polymer monomer. As the monomer (M4) containing active hydrogen, (meth) acrylic acid-2-hydroxyethyl, (meth) acrylic acid-3-hydroxypropyl, (meth) acrylic acid-2-hydroxypropyl, (meth) 4-hydroxybutyl acrylate, (meth) acrylic acid-cyclohexanedimethanol, (meth) acrylic acid-trimethylolpropane, (meth) acrylic acid-glycerin, (meth) acrylic acid-pentaerythritol, (meth) acrylic acid , Itaconic acid, fumaric acid, maleic acid, (meth) acrylamide, diacetone (meth) acrylamide, N-methylol (meth) acrylamide, N-butoxymethyl (meth) acrylamide and the like. The blending ratio of the monomer (M4) to the dispersant or / and the core polymer can be included within a range in which particle aggregation does not occur, and the monomer having a blocked isocyanate group (M3 ) Is preferably used within a range of 0.1 to 10 mol per mol of the compounding amount.

  The core polymer according to the present invention preferably contains a tertiary amino group. By containing a tertiary amino group, the dispersion state of the emulsion particles becomes good, and an excellent effect is obtained that the reaction between the isocyanate group cleaved during heating and the active hydrogen group proceeds smoothly. A low molecular compound having a tertiary amino group such as triethylamine may be added to the core polymer, or a monomer having a tertiary amino group (M5) is used as a component of the monomer of the core polymer. Also good. Examples of the monomer (M5) include compounds represented by general formula 3. When mix | blending a monomer (M5) with a core polymer, it is preferable to use within the range of 0.01-50 mass parts with respect to 100 mass parts of all the monomers of a core polymer.

[In Formula 3, R ⁴ represents a hydrogen atom or a methyl group, A represents an —O— or —NH— group, R ⁵ represents an alkylene group having 1 to 6 carbon atoms, and R ⁶ and R ⁷ each independently represent Represents an alkyl group having 1 to 6 carbon atoms. ]

  The emulsion particles of the present invention are preferably composed of a dispersant and a core polymer, and the dispersant and the core polymer are preferably bonded by a urethane bond. The method of bonding the dispersant and the core polymer with a urethane bond involves adding a hydroxyl group to the dispersant and then chemically bonding the isocyanate group of the monomer having an isocyanate group and a polymerizable double bond group to the hydroxyl group of the dispersant. A urethane bond is formed, and the dispersant contains an unreacted polymerizable double bond group, and then polymerizes with the monomer component of the core polymer, and the dispersant contains an isocyanate group. Then, the hydroxyl group of the monomer having a hydroxyl group and a polymerizable double bond group is chemically bonded to the isocyanate group of the dispersant to form a urethane bond, and the dispersant contains an unreacted polymerizable double bond group, Next, a method of polymerizing with the monomer component of the core polymer is exemplified. When the dispersant and the core polymer are bonded with a urethane bond, the stability over time of the emulsion particles can be improved.

  The blending ratio of the dispersant for the emulsion particles and the core polymer of the present invention is such that the core polymer is in the range of 50 to 5000 parts by mass with respect to 100 parts by mass of the dispersant from the viewpoint of maintaining the dispersed state. It is preferable to use in the range of 100 to 2000 parts by mass. The average particle diameter of the emulsion particles measured by the Coulter counter method is preferably in the range of 0.05 to 1.0 μm from the viewpoint of securing the thickness as the resin layer and maintaining the dispersed state, and more preferably 0. It is preferably in the range of 1 to 0.6 μm.

  The emulsion particles of the present invention can be produced by a conventionally known polymerization method. For example, an ion polymerization method such as anionic polymerization or cationic polymerization, a radical polymerization method obtained by radical polymerization using a polymerization initiator and / or a chain transfer agent, and a method by polyaddition or polycondensation reaction may be mentioned. .

  The emulsion particles according to the present invention can form a resin layer by electrodeposition. In this case, the particles are made positive or negative charged particles, and the emulsion particles are electrodeposited while applying an appropriate electric field. Therefore, an electric charge is imparted to the emulsion particles by adding an appropriate charge control agent to the emulsion particle liquid. As the charge control agent, for example, a compound shown in JP-A-6-51567 or a polycarboxylic acid type polymer surfactant such as homogenol L18 (trade name, manufactured by Kao Corporation) can be used. . Further, an additive such as a colorant may be contained within a range that does not adversely affect the electrodeposition characteristics.

  The mask for screen printing having an opening according to the present invention can transfer a paste material such as cream solder onto a substrate to be printed by placing the paste material on the squeegee surface and scraping it with the squeegee. For example, a screen printing mask produced by any method can be used. For example, any of a solid mask, a suspend mask, a metal mask (etching method, laser method, additive method, machining method) or the like can be used. The material is preferably a conductive material because it can be electrodeposited. Specifically, general materials such as stainless steel and nickel can be applied. Also, there is no particular limitation on the opening pattern of the mask for screen printing, for example, a circle, an ellipse, a square, a rectangle, a diamond, a square such as a trapezoid, a polygon such as a hexagon and an octagon, a gourd, a dumbbell, etc. Examples include irregular shapes such as shapes.

  Examples of a mask for screen printing in which a resin layer is formed on at least the inner wall of the opening according to the present invention are shown in FIGS. 1-3 are examples in which a metal mask is applied as a mask for screen printing. In FIG. 1, the resin layer 2 is formed only on the inner wall of the opening 5. FIG. 2 is formed on the inner wall of the opening 5 and the printed substrate contact surface 4. FIG. 3 shows the resin layer 2 formed on the entire surface. When the resin layer 2 is not formed on the squeegee surface 3 as shown in FIGS. 1 and 2, when the squeegee is contacted many times with a high indentation pressure, the resin layer 2 is peeled off if the durability of the resin layer 2 is insufficient. Sometimes. Since the peeled resin layer 2 is mixed with the paste material, the squeegee surface 3 preferably has no resin layer 2. 4 to 7 are examples of screen printing plate masks in which a mesh 6 is formed on the squeegee surface 3 such as a solid mask and a suspend mask. FIG. 4 shows the resin layer 2 formed around the inner wall of the opening 5 and the mesh 6 of the opening. FIG. 5 shows the resin layer 2 formed on the entire surface of the mesh 6 other than the squeegee surface 3. 6 and 7 show the resin layer 2 formed on the entire surface. In order to reduce the difference in opening area of the opening 5 before and after forming the resin layer 2, the thickness of the resin layer 2 is preferably 0.1 μm to 5 μm. When the thickness of the resin layer is less than 0.1 μm, the adhesion between the screen printing mask 1 and the resin layer 2 may be lowered. On the other hand, if the thickness exceeds 5 μm, it may be difficult to form a uniform film.

  The method for producing a mask for screen printing according to the present invention will be described in detail with reference to FIGS. 9 to 12 in the order of steps, taking as an example a metal mask in which the resin layer 2 is formed on the inner wall of the opening 5 and the printed substrate contact surface 4. First, a protective sheet 7 is attached to a screen printing mask (FIG. 9) having an opening 5 (FIG. 10). Next, the electrode 12 was placed so as to face the printed substrate contact surface 4 in a liquid in which the emulsion particles 13 used for the resin layer 2 were dispersed in a highly insulating medium (FIG. 11). Next, an appropriate potential difference is generated between the screen printing mask 1 and the electrode 12, and the emulsion particles 13 are electrophoresed in the direction of the screen printing mask 1 to the inner wall of the opening 5 and the printed substrate contact surface 4. Emulsion particles 13 are deposited. Next, the screen printing mask 1 is taken out of the liquid, and the highly insulating medium is evaporated. Next, the emulsion particles 13 adhered by the electrodeposition method are formed into a film by heating, pressure, light, water, solvent, etc. and fixed (FIG. 12). Subsequently, the protective sheet 7 is peeled off. Next, an isocyanate group is generated from the blocked isocyanate group by heating, and the isocyanate group and the active hydrogen group are reacted to form the resin layer 2 on the inner wall of the opening and the printed substrate contact surface 4. A fabricated metal mask can be produced (FIG. 2).

  Next, a method for producing a mask for screen printing when a protective sheet having the property of dissolving in an alkaline aqueous solution is used will be described. First, an alkali-soluble protective sheet is attached to a screen printing mask having an opening. Next, an electrode is placed so as to face the printed substrate contact surface in a liquid in which emulsion particles used for the resin layer are dispersed in a highly insulating medium. Next, an appropriate potential difference is generated between the screen printing mask and the electrode, and the emulsion particles are electrophoresed in the direction of the screen printing mask to adhere the emulsion particles to the inner wall of the opening and the printed substrate contact surface. Subsequently, the screen printing mask is taken out of the liquid, and the highly insulating medium is evaporated. The emulsion particles adhered by the electrodeposition method are fixed by forming a film by heating, pressure, light, water, solvent, etc., and then the alkali-soluble protective sheet is dissolved and removed with an aqueous alkali solution. Next, an isocyanate group is generated from the blocked isocyanate group by heating, and the isocyanate group and the active hydrogen group are reacted to form the resin layer 2 on the inner wall of the opening and the printed substrate contact surface 4. A fabricated metal mask can be produced (FIG. 2).

  In the emulsion particles of the present invention, the active hydrogen group is preferably a hydroxyl group. That is, in the method for producing a screen printing mask of the present invention, when applied to a method for producing a screen printing mask using a protective sheet having a property of being dissolved in an alkaline aqueous solution, the filmed emulsion particles are converted into an alkaline aqueous solution. It must be insoluble. At this time, by using a hydroxyl group as an active hydrogen group, the solubility of the film-formed emulsion particles in an aqueous alkaline solution can be made very low as compared with other active hydrogen groups (for example, a carboxyl group).

  In the method for producing a screen printing mask of the present invention, in the method for producing a screen printing mask (FIG. 1) in which the resin layer 2 is formed only on the inner wall of the opening 5, as shown in FIG. A protective sheet (hereinafter referred to as a non-opening protective layer 8) having an opening at the same position is formed on the printed substrate contact surface 4 of the screen printing mask 1, and then the emulsion particles are formed by electrodeposition in the same manner as described above. Can be made by attaching. Such a method for forming the non-opening protective layer 8 includes a method of forming an opening with a laser, a non-opening protective layer having photosensitivity, and using a photomass having the same pattern as a screen printing mask to form a pattern of the opening. A non-opening protective layer having an opening at the same position as the opening of the mask for the screen printing plate can be applied. Any one can be applied (for example, Japanese Patent Application Laid-Open No. 2004-311867, Japanese Patent Application Laid-Open No. 3-57697, Japanese Patent Application Laid-Open No. 2006-173597).

  Further, in the method for producing a screen printing mask of the present invention, the method for producing the screen printing mask (FIGS. 3, 6, and 7) in which the resin layer 2 is formed on the entire surface does not attach a protective sheet. This is achieved by performing the electrodeposition process. When electrodeposition is performed, the electrode facing the screen printing mask may be disposed only on the printed substrate contact surface side, or may be disposed on both the printed substrate contact surface side and the squeegee surface side.

  In the method of electrodepositing emulsion particles, an appropriate bias voltage is applied between the screen printing mask and the electrode as shown in FIG. For example, a horizontal / horizontal transfer device (for example, a special technique) that is inserted between electrodes arranged in parallel so as to face the screen printing mask and supplies the liquid onto both sides of the screen printing mask from the upper and lower sides of the electrode for electrodeposition. (Kaihei 6-224541, JP-A 2004-163605, etc.) and a screen printing mask held substantially vertically and immersed in a bath containing liquid, and then substantially vertically on both sides of the screen printing mask. An apparatus (for example, Japanese Patent Application Laid-Open No. 2002-132049) or the like that performs electrodeposition processing by fixing the screen printing mask substantially vertically with electrodes arranged opposite to each other is applicable as the electrodeposition apparatus.

  The protective sheet according to the present invention can be attached to a screen printing mask and does not dissolve even if it touches a highly insulating medium in which emulsion particles are dispersed. Electrodeposition treatment and fixing of emulsion particles Even if it can be easily peeled off from the screen printing mask even after being exposed to heat treatment, pressure, light, water, etc. by the treatment, and the adhesive does not remain in the screen printing mask even after peeling, Any one is acceptable. For example, ELEP Masking N-380 (trade name, Nitto Denko Corporation), Paint Ace 720A (trade name, Nitto Denko Corporation), SPV-K100 (trade name, Nitto Denko Corporation), Scotch plating masking tape 851A (Product name, Sumitomo 3M Co., Ltd.), Scotch heat resistant masking tape 214-3MNE (Product name, Sumitomo 3M Co., Ltd.), Masking tape No 2311 (Product name, Nichiban Co., Ltd.), etc. Absent. Further, the protective sheet may have a property of being dissolved in an alkaline aqueous solution. As a component of such an alkali-soluble protective sheet, a monomer having a carboxylic acid group, a carboxylic acid amide group, a phenolic hydroxyl group, a sulfonic acid group, a sulfonamide group, a sulfonimide group, or a phosphonic acid group is polymerized. And a copolymer, a phenol resin, a xylene resin, and the like. Copolymers of monomers having carboxylic acid groups include copolymers of styrene and maleic acid monoesters, and copolymers of two or more of acrylic acid or methacrylic acid and their alkyl esters, aryl esters or aralkyl esters. A polymer is mentioned. In addition, a copolymer of vinyl acetate or vinyl benzoate and crotonic acid can be used. Particularly preferred among the phenolic resins are phenol, o-cresol, m-cresol, or novolak resin obtained by condensing p-cresol and formaldehyde or acetaldehyde under acidic conditions. In addition, these may contain a plasticizer, a colorant and the like. By laminating these components on a carrier film to form a sheet, it becomes easy to attach using a laminator or the like. Examples of the carrier film include polypropylene, polyethylene, polyester, and polyvinyl alcohol. Also, a negative dry film photoresist for manufacturing a circuit board can be applied. Specifically, for example, Liston from DuPont MRC Dry Film Co., Ltd., Fotec from Hitachi Chemical Co., Ltd., Sunfort from Asahi Kasei Electronics Co., Ltd. can be used.

  When an alkali-soluble protective sheet is used, a method such as spraying or dipping can be applied as a method for removing the resin sheet with an alkaline aqueous solution. Examples of the alkaline aqueous solution include aqueous solutions of inorganic basic compounds such as alkali metal silicates, alkali metal hydroxides, phosphoric acid and alkali metal carbonates, phosphoric acid and ammonium carbonates, ethanolamines, ethylenediamine, and propanediamine. And organic basic compounds such as triethylenetetramine and morpholine diluted in water.

  As a method for attaching the protective sheet to the screen printing mask, any method may be used as long as it does not cause unevenness and undulations on the attachment surface and does not include air or dust. For example, an apparatus is used in which a hot rubber roll for a printed circuit board is pressed with pressure to perform thermocompression bonding.

  The heating temperature for generating an isocyanate group from the blocked isocyanate group and causing the isocyanate group to react with the active hydrogen group is equal to or higher than the temperature at which the blocked isocyanate group to be used is cleaved by 90 mol% or more. It is preferable that the temperature be lower than that which can be tolerated by the screen printing mask. Although it depends on the components used, it is preferably in the range of 80 to 400 ° C. When it is 80 ° C. or lower, the storage stability of the emulsion particles may be deteriorated.

  Hereinafter, the present invention will be described in more detail by way of examples. However, the present invention is not limited to these examples.

(1) shown in Table 1 was placed in a four-necked flask equipped with an emulsion particle synthesis stirrer, thermometer, and reflux condenser, purged with nitrogen, heated to 80 ° C., and 2,2′-azobis (2 -Methylbutyronitrile) 4.8 parts by mass was added. The temperature was kept at 80 ° C. and reacted for 7 hours. Next, the temperature is lowered to 65 ° C., (2) shown in Table 1 is added, the temperature is kept at 65 ° C., and the reaction is performed for 3 hours. Obtained.

  Next, in a four-necked flask equipped with a stirrer, a thermometer, and a reflux condenser, the amount of the dispersant, monomer, and solvent shown in Table 2 was added and purged with nitrogen, and then heated to 70 ° C., 0.4 parts by mass of 2'-azobis (4-methoxy-2,4-dimethylvaleronitrile) was added. The emulsion particles of Examples 1 to 7 and Comparative Examples 1 to 3 were synthesized by keeping the temperature at 70 ° C. and reacting for 8 hours.

1 IP1620; IP solvent 1620 (trade name, manufactured by Idemitsu Petrochemical Co., Ltd.)
・ 2 Karenz MOI; (trade name, manufactured by Showa Denko KK), methacryloyloxyethyl isocyanate 3 DBU; 1,8-diazabicyclo [5.4.0] undec-7-ene 4 Karenz MOI-BM; Trade name, manufactured by Showa Denko KK), 2- (O- [1'-methylpropylideneamino] carboxyamino) ethyl methacrylate,
5 Karenz MOI-BP; (trade name, manufactured by Showa Denko KK), 2-[(3,5-dimethylpyrazolyl) carbonylamino] ethyl methacrylate

  The emulsion particles of Examples 1 to 5 and Comparative Examples 1 and 2 were successfully synthesized. When the monomer having an unblocked isocyanate group shown in Comparative Example 3 (Karenz MOI, trade name, manufactured by Showa Denko KK) is used as the monomer for the core polymer, a large amount of precipitation is caused. As a result, a good emulsion particle could not be synthesized. In the obtained emulsion particles of Examples 1 to 5 and Comparative Examples 1 and 2, the charge control agent (octadecyl vinyl ether / maleic anhydride copolymer; mass composition ratio) with respect to 1 part by mass of the solid content 3/1, maleic anhydride hydrolysis rate 45%, mass average molecular weight 13,000), and diluted with IP1620 (trade name, manufactured by Idemitsu Petrochemical Co., Ltd.) so that the solid content concentration becomes 1% by mass Then, a positive charge was imparted to the particles. The emulsion particles of Examples 1 to 5 and Comparative Examples 1 and 2 were allowed to stand for 30 days after the charge control agent was added, but they did not precipitate and were in a good dispersion state.

Formation of Resin Layer on Screen Printing Mask A number of openings were formed with a YAG laser on a stainless steel plate (SUS304) having a thickness of 80 μm to produce a screen printing mask. Next, using the electrodeposition apparatus having the structure shown in FIG. 11, using the emulsion particles of Examples 1 to 5 and Comparative Examples 1 and 2 prepared above on the entire surface of the screen printing mask, Electrodeposition was performed under the conditions of an applied voltage of 120 V and 20 seconds. Next, IP1620 (trade name, manufactured by Idemitsu Petrochemical Co., Ltd.) was dried with cold air. Next, the emulsion particles were fixed as a film under conditions of 80 ° C. for 3 minutes. Next, what was produced in Examples 1-5 was exposed to the conditions of 180 degreeC for 2 hours, the isocyanate group was generated from the blocked isocyanate group, and the isocyanate group and the active hydrogen group were made to react. On the other hand, those prepared in Comparative Examples 1 and 2 were also exposed to the conditions of 180 ° C. for 2 hours. When the opening was observed with a microscope, it was possible to produce a screen printing mask in which the resin layer was formed on the entire surface without protrusions, partition walls, and filling of the resin layer.

  Using the screen printing mask produced using the emulsion particles of Examples 1 to 5, when screen printing was repeated 100 times as cream paste as a paste material with a squeegee, no omission of cream solder occurred, and good Shaped solder terminal pattern was formed. Moreover, when the solder paste was ultrasonically cleaned with a 1/1 mixed solvent of propylene glycol monomethyl ether and 2-propanol, the resin layer did not swell. On the other hand, when the screen solder was repeatedly screen-printed as a paste material with a squeegee using the screen printing mask prepared using the emulsion particles of Comparative Examples 1 and 2, the cream solder could not be removed if it was repeated 20 times. The solder terminal pattern having a good shape could be formed, but in the 30th time, peeling due to swelling of the resin occurred. Further, when the solder paste was ultrasonically cleaned with a 1/1 mixed solvent of propylene glycol and 2-propanol, the resin layer swelled in 2 minutes, and good printing could not be performed.

Formation of Resin Layer on Screen Printing Mask Using Protective Sheet A large number of openings were formed with a YAG laser on a stainless steel plate (SUS304) having a thickness of 80 μm to produce a screen printing mask. Next, using a laminator, a commercially available dry film photoresist (Sunfort AQ2575, manufactured by Asahi Kasei Electronics Co., Ltd.) was attached at 80 ° C. and a pressure of 0.1 MPa. Next, using the electrodeposition apparatus having the structure shown in FIG. 11, Examples 1 to 5 and Comparative Examples 1 and 2 prepared above were formed on the inner wall of the opening of the screen printing mask and the printed substrate contact surface. Each was used for electrodeposition under conditions of an applied voltage of 120 V and 20 seconds. Next, after IP1620 (trade name, manufactured by Idemitsu Petrochemical Co., Ltd.) was dried with cold air, the particles were fixed as a film under conditions of 80 ° C. for 3 minutes. Next, after the polyethylene terephthalate layer of the dry film photoresist was peeled off by hand, the dry film photoresist was eluted and removed with 1 mass part of sodium carbonate aqueous solution (30 ° C.) under a spray pressure of 0.1 MPa. At this time, those prepared with the emulsion particles of Examples 4 and 5 and Comparative Example 2 contained a carboxyl group in the resin layer, and thus the resin layer on the printed substrate contact surface was partially peeled off. It was confirmed that the resin layer remained. Next, after washing with water, moisture was removed with cold air. Next, what was produced in Examples 1-5 was exposed to the conditions of 180 degreeC for 2 hours, the isocyanate group was generated from the blocked isocyanate group, and the isocyanate group and the active hydrogen group were made to react. On the other hand, those prepared in Comparative Examples 1 and 2 were also exposed to the conditions of 180 ° C. for 2 hours. When the opening was observed with a microscope, it was possible to produce a mask for screen printing in which the resin layer was formed on the inner wall of the opening and the contact surface of the substrate to be printed, without the protrusions, partition walls, and filling of the resin layer. .

  Using the screen printing mask produced using the emulsion particles of Examples 1 to 5, when screen printing was repeated 100 times as cream paste as a paste material with a squeegee, no omission of cream solder occurred, and good Shaped solder terminal pattern was formed. Moreover, when the solder paste was ultrasonically cleaned with a 1/1 mixed solvent of propylene glycol monomethyl ether and 2-propanol, the resin layer did not swell. On the other hand, when the screen solder was repeatedly screen-printed as a paste material with a squeegee using the screen printing mask prepared using the emulsion particles of Comparative Examples 1 and 2, the cream solder could not be removed if it was repeated 20 times. The solder terminal pattern having a good shape could be formed, but the resin peeled off at the 30th time. Further, when the solder paste was ultrasonically cleaned with a 1/1 mixed solvent of propylene glycol and 2-propanol, the resin layer swelled in 2 minutes, and good printing could not be performed.

  The method for producing the emulsion particles and the mask for screen printing of the present invention can be widely applied to screen printing applications. For example, as a paste material, a conductive material, an insulating material, a color material, a sealing material, an adhesive material , Resist materials, processing chemicals, and the like can be applied to applications in which a pattern is formed on an arbitrary substrate by screen printing.

Sectional drawing of the metal mask which formed the resin layer only in the inner wall of an opening part. Sectional drawing of the metal mask formed in the inner wall of an opening part, and a to-be-printed substrate contact surface. Sectional drawing of the metal mask which formed the resin layer in the whole surface. Sectional drawing of the solid mask which formed the resin layer only in the inner wall of an opening part. Sectional drawing of the solid mask formed in the inner wall of an opening part, and a to-be-printed substrate contact surface. Sectional drawing of the solid mask which formed the resin layer in the whole surface. Sectional drawing of the suspend mask which formed the resin layer in the whole surface. The conceptual diagram of the protrusion of a resin layer, a partition, and filling. Sectional drawing of the mask for screen printing which has an opening part. Sectional drawing of the mask for screen printing which affixed the masking sheet. The conceptual diagram of an electrodeposition apparatus. Sectional drawing showing 1 process in the preparation methods of the mask for screen printing of this invention. Sectional drawing which formed the non-opening protective layer in the to-be-printed substrate contact surface of the mask for screen printing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Screen printing mask 2 Resin layer 3 Squeegee surface 4 Printed substrate contact surface 5 Opening part 6 Mesh 7 Masking sheet 8 Non-opening protective layer 9 Protrusion of resin layer 10 Partition 11 Filled 12 Electrode 13 Emulsion particle

Claims (4)

Emulsion particles dispersed in a highly insulating medium selected from linear or branched aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, and halogen-substituted products thereof, wherein the emulsion particles are An emulsion particle comprising a dispersant and a core polymer, wherein the core polymer contains blocked isocyanate groups and active hydrogen groups.   The emulsion particles according to claim 1, wherein the active hydrogen group is a hydroxyl group, and the core polymer contains a tertiary amino group.   In a method for producing a mask for screen printing comprising forming a resin layer on at least the inner wall of the opening, the emulsion particles according to claim 1 or 2 are electrodeposited on the screen printing mask having the opening, and then heated. A method for producing a mask for screen printing, comprising generating an isocyanate group from an isocyanate group blocked by the step, and reacting the isocyanate group with an active hydrogen group to form the resin layer.   In a method for producing a screen printing mask formed by forming a resin layer on at least an inner wall of an opening, a step of attaching a protective sheet to a squeegee surface of the screen printing mask having an opening, an inner wall of the opening, and a substrate to be printed The step of electrodepositing the emulsion particles according to claim 1 or 2 on the contact surface, the step of forming the emulsion particles into a film by heating, the step of removing the protective sheet, and generating isocyanate groups from the isocyanate groups blocked by heating. A method for producing a mask for screen printing, comprising a step of reacting the isocyanate group with an active hydrogen group.

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