JP2010180346A - Emulsion particle and method for producing mask for screen printing by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide emulsion particles for forming a resin layer which is hardly peeled even when it is subjected to scuffing using waste cloth impregnated with a solvent, and to provide a method for producing a mask for screen printing obtained by forming a resin layer by using the emulsion particles. <P>SOLUTION: The emulsion particles are composed of a dispersant and a core polymer which are dispersed in a highly insulative medium. The core polymer contains a hydroxy group and a blocked isocyanate group and further contains at least one group selected from a carboxyl group and a methoxy ethyl group. The method for producing the mask for screen printing comprises electrodepositing the emulsion particles on an opening part of the mask for screen printing to form a film, and cross-linking the film. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an emulsion particle and a method for producing a mask for screen printing in which a resin layer is formed on the inner wall of an opening using the emulsion particle.

  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. Generally, in screen printing, a screen printing mask with a patterned opening is set on the top surface of the substrate to be printed, and paste material such as cream solder is supplied to the squeegee surface of the screen printing mask. Then, the paste material is transferred and printed in a 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 deteriorated, causing defects such as protrusions, chips, cracks, and disconnection of the solder terminals, which was 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, a fluororesin, a silicon resin, etc.) having good repellent property or slipperiness with cream solder on the inner wall of the opening, the cream solder can be easily removed. As a means for forming the resin layer on the inner wall, a dipping method, a spray method, a spin coating, or the like can be considered. In these methods, the coating liquid accumulates at the edge of the opening due to surface tension, the coating liquid accumulates at the acute angle portion of the opening, the problem of dripping of the coating liquid and uneven drying, and a uniform thin film is formed. It is difficult. For this reason, as shown in FIG. 17, defects such as protrusions 9, partition walls 10, fillings 11, etc. of the resin layer may occur in the screen printing mask 1, causing a problem that the resin layer becomes non-uniform.

  On the other hand, a method of forming a resin layer by electrodeposition of resin particles dispersed in a highly insulating medium has been proposed (see, for example, Patent Documents 1 and 2). In this method, first, as shown in FIG. 9, a protective sheet 7 is attached to one side of a screen printing mask 1 having an opening 5. After that, as shown in FIG. 10, when the electrode 12 is placed so as to face the screen printing mask 1 and the screen printing mask 1 is grounded and an appropriate bias voltage is applied, the emulsion particles 13 charged in accordance with the electric field are applied. Electrophorese in the direction of the screen printing mask 1. The emulsion particles 13 approaching in the direction of the screen printing mask 1 by electrophoresis adhere from where the electric potential is close to 0. Therefore, the emulsion particles 13 are uniformly formed so as to cover the surface of the grounded screen printing mask 1. Adhere. Therefore, in the electrodeposition method, as shown in FIG. 11, even on the inner wall of the opening 5, defects such as the protrusions 9, the partition walls 10, and the filling 11 of the resin layer do not occur, and the uniform resin layer 2 It can be formed on the inner wall of the opening 5.

  Further, by repeatedly using the screen printing mask, a residue of cream solder is generated at the opening of the screen printing mask or the printed substrate contact surface. At this time, it is necessary to perform ultrasonic cleaning with an organic solvent such as alcohols or glycols, or to wipe off with a waste impregnated with an organic solvent. Therefore, it is necessary to form a resin layer that does not swell in an organic solvent and can withstand rubbing of the waste. As a method for forming such a resin layer by an electrodeposition method, a method has been proposed in which emulsion particles containing at least an isocyanate group and an active hydrogen group are crosslinked by heating. However, in the emulsion particles, the resin layer may be peeled off due to strong rubbing by the waste impregnated with the solvent, and further improvement has been desired (for example, see Patent Document 3).

JP 2008-155554 A JP 2008-246738 A JP 2008-201850 A

  An object of the present invention is to provide emulsion particles for forming a resin layer that hardly causes the resin layer to be peeled off even when rubbed with an organic solvent, and for screen printing formed using the emulsion layer. It is to provide a method for manufacturing a mask.

  In an emulsion particle comprising a dispersant and a core polymer dispersed in a highly insulating medium, the core polymer contains a hydroxy group and a blocked isocyanate group, and is selected from a carboxyl group and an alkoxyalkyl group. It has been found that the above problems can be solved by emulsion particles containing at least one group.

  It has been found that the acid value of the emulsion particles is preferably 60 mgKOH / g or less.

  Further, in a method for producing a screen printing mask formed by forming a resin layer on at least the inner wall of the opening, a step of electrodepositing the emulsion particles on at least the inner wall of the opening of the screen printing mask made of a metal material, emulsion It has been found that the above problems can be solved by a method for producing a mask for screen printing, which comprises a step of forming particles into a film and a step of crosslinking a filmed layer by heating.

  The emulsion particles of the present invention contain hydroxy groups and blocked isocyanate groups. The emulsion particles are electrodeposited on at least the inner wall of the opening portion of the screen printing mask made of a metal material, formed into a film by low-temperature heating, and further processed under high temperature conditions to generate isocyanate groups. By the reaction between the isocyanate group and the hydroxy group, the resin layer is cross-linked, and the solvent resistance is remarkably improved. The emulsion particles of the present invention further contain at least one group selected from a carboxyl group and an alkoxyalkyl group, and the carboxyl group crosslinks with an isocyanate group in the same manner as the hydroxy group, and the hydroxy group and isocyanate. Since the reaction with the group is promoted, the crosslink density of the resin layer is improved and the solvent resistance is further improved. If a carboxyl group is introduced so that the acid value of the emulsion particles is 60 mgKOH / g or less, an effect of preventing the emulsion particles from aggregating with a highly insulating medium can be obtained. The alkoxyalkyl group has the effect of improving the dispersibility of the particles and improving the solvent resistance after crosslinking. Therefore, the method for producing a screen printing mask in which a resin layer is formed using the emulsion particles of the present invention provides a screen printing mask in which peeling of the resin layer hardly occurs even when rubbed with an organic solvent. It is done.

It is sectional drawing of the metal mask which formed the resin layer only in the inner wall of an opening part. It is sectional drawing of the metal mask which formed the resin layer in the inner wall of an opening part, and a to-be-printed substrate contact surface. It is sectional drawing of the metal mask which formed the resin layer in the whole surface. It is sectional drawing of the solid mask which formed the resin layer only in the inner wall of the opening part. It is sectional drawing of the solid mask which formed the resin layer in the inner wall of an opening part, and a to-be-printed substrate contact surface. It is sectional drawing of the solid mask which formed the resin layer in the whole surface. It is sectional drawing of the suspend mask which formed the resin layer in the whole surface. It is sectional drawing of a metal mask. It is sectional drawing of the metal mask which affixed the protection sheet. It is a conceptual diagram of an electrodeposition apparatus. It is one process figure of the preparation methods of the mask for screen printing of the present invention. It is sectional drawing of the metal mask which formed the resin layer in the inner wall of an opening part, and a to-be-printed substrate contact surface. It is sectional drawing of the mask for screen printing in which the resin layer and the thick film resin layer were laminated | stacked in this order. It is sectional drawing of the mask for screen printing in which the thick film resin layer and the resin layer were laminated | stacked in this order. It is sectional drawing of the mask for screen printing in which the resin layer and the thick film resin layer were laminated | stacked in this order. It is sectional drawing of the mask for screen printing in which the thick film resin layer and the resin layer were laminated | stacked in this order. It is a conceptual diagram of the protrusion of a resin layer, a partition, and filling. It is one process figure of the preparation methods of the mask for screen printing of the present invention. It is one process figure of the preparation methods of the mask for screen printing of the present invention.

  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. Product names include Isopar E, Isopar G, Isopar H, Isopar L (manufactured by EXXON), IP1620 (trade name, manufactured by Idemitsu Kosan 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 a long-chain monomer. The weight average molecular weight of the dispersant is preferably 1000 or more. If the molecular weight is less than this, the dispersion stability of the emulsion particles is lowered, and the emulsion particles may easily aggregate and settle. The upper limit of the molecular weight of the dispersant is not particularly defined. However, when the molecular weight exceeds 1,000,000, the viscosity of the polymer solution may increase and it may be difficult to handle. The long-chain monomer preferably contains at least 50% by mass to 100% by mass of a compound represented by the general formula 1 or 2. As other polymerization components, an appropriate monomer can be contained in a range that does not impair the solubility of the produced dispersant in the highly insulating medium.

(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 of the emulsion particles of the present invention contains 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, a monomer having a blocked isocyanate group is used as one component of the monomer of the core polymer, or a monomer having an isocyanate group. There is a method of reacting with a blocking agent after forming a polymer having an isocyanate group in the side chain by polymerizing.

  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 having an isocyanate group include (meth) acryloyl isocyanate, (meth) acryloyloxyethyl isocyanate, (meth) acryloyloxypropyl isocyanate, p-isopropenyl-α, α-dimethylbenzyl isocyanate, m- An example is isopropenyl-α, α-dimethylbenzyl isocyanate. In addition, a 1: 1 adduct of a (meth) acrylic acid hydroxyalkyl ester and a bifunctional isocyanate compound such as 2,4-tolylene diisocyanate or isophorone diisocyanate is also included.

  Examples of the monomer 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, O- [1'-methyl (meth) acrylate Propylideneamino] carboxyaminomethyl, (meth) acrylic acid 3- (O- [1′-methylpropylideneamino] carboxyamino) propyl, (meth) acrylic acid O- (1′-methylideneamino) carboxyaminomethyl, ( 2- (O- [1'-methylideneamino] carboxyamino) ethyl, (meth) acrylic acid, (meth) acrylic 3- (O- [1'-methylideneamino] carboxyamino) propyl, (meth) acrylic acid O- (1'-ethylideneamino) carboxyaminomethyl, (meth) acrylic acid 2- (O- [1'-ethylideneamino) ] Carboxyamino) ethyl, (meth) acrylic acid 3- (O- [1'-ethylideneamino] carboxyamino) propyl, (meth) acrylic acid O- (1'-propylideneamino) carboxyaminomethyl, (meth) 2- (O- [1'-propylideneamino] carboxyamino) ethyl acrylate, 3- (O- [1'-propylideneamino] carboxyamino) propyl (meth) acrylate, 2- (meth) acrylic acid 2- [(3,5-dimethylpyrazolyl) carbonylamino] ethyl and the like.

  The blending ratio of the monomer having a blocked isocyanate group when synthesizing the core polymer can be adjusted within a range in which particle aggregation or the like does not occur. It is preferable to use within the range of 10-70 mass parts with respect to a part, 20-60 mass parts is more preferable, 30-50 mass parts is further more preferable. When the amount is less than 10 parts by mass, the solvent resistance of the resin layer may be insufficient. When the amount is more than 70 parts by mass, aggregation of emulsion particles tends to occur.

  The core polymer of the emulsion particles of the present invention contains a hydroxy group. In order to contain a hydroxy group, a monomer having a hydroxy group is used as one component of the monomer of the core polymer. Examples of the monomer having a hydroxy group include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, Examples include (meth) acrylic acid cyclohexanedimethanol, (meth) acrylic acid trimethylolpropane, (meth) acrylic acid glycerin, (meth) acrylic acid pentaerythritol, and the like. The mixing ratio of the monomer having a hydroxy group can be adjusted within a range in which particle aggregation or the like does not occur, and within a range of 0.1 to 10 mol with respect to 1 mol of the blocked isocyanate group. It is preferable to use, 0.2-4 mol is more preferable, and 0.3-1.5 mol is further more preferable.

  The emulsion particles of the present invention have a particle shape during storage and electrodeposition, and need to be formed into a film after electrodeposition. Filming is by means such as heating. If there is an unblocked isocyanate group, the emulsion particle undergoes a crosslinking reaction during storage, but the emulsion particle of the present invention can block the progress of the crosslinking reaction during storage due to the isocyanate group being blocked. . And since the emulsion particle | grains of this invention in which bridge | crosslinking has not progressed have low melting | fusing point or a softening point, it can be easily formed into a film at low temperature. After forming into a film, an isocyanate group is generated by further processing at a temperature higher than the melting point or softening point, and the generated isocyanate group reacts with the hydroxy group to cause crosslinking of the resin layer, resulting in solvent resistance. Is significantly improved.

  The core polymer of the emulsion particles of the present invention contains at least one group selected from a carboxyl group and an alkoxyalkyl group. In order to contain a carboxyl group, a monomer having a carboxyl group is used as one component of the monomer of the core polymer. Examples of the monomer having a carboxyl group include (meth) acrylic acid, itaconic acid, fumaric acid, maleic acid and the like. In addition to cross-linking with the isocyanate group, the carboxyl group promotes the reaction with the hydroxy group, the cross-linking density is improved, and the solvent resistance is improved. The mixing ratio of the monomer having a carboxyl group is preferably such that the acid value of the emulsion particles is in the range of 60 mgKOH / g or less. When the acid value is 60 mgKOH / g or less, an effect that aggregation during storage hardly occurs can be obtained. The acid value according to the present invention is the number of mg of KOH required to neutralize 1 g of emulsion particles.

In order to contain an alkoxyalkyl group, a monomer having an alkoxyalkyl group is used as one component of the monomer of the core polymer. Examples of the monomer having an alkoxyalkyl group include compounds represented by general formula 3. The monomer having an alkoxyalkyl group improves the dispersibility of the particles and brings about an effect of improving the solvent resistance after crosslinking. When the carbon number of R ⁵ and R ⁶ is 1 or more and 2 or less, This is preferable because the effect of the above increases. The blending ratio is preferably used within a range of 10 to 70 parts by mass with respect to 100 parts by mass of all monomers of the polymer, more preferably 20 to 60 parts by mass, and even more preferably 30 to 50 parts by mass. When the amount is less than 10 parts by mass, the solvent resistance of the resin layer may be insufficient. When the amount is more than 70 parts by mass, aggregation of emulsion particles tends to occur.

In (Formula 3, ^{R 4} represents a hydrogen atom or a methyl group, ^{R 5} is an alkylene group having 1 to 3 carbon atoms, ^{R 6} is a ^.R 5, ^{R 6} representing one or more 3 preferably an alkyl group having a carbon number When the number of carbon atoms is 3, it may be linear or branched.)

  In addition to the above monomers, the core polymer of emulsion particles of the present invention can be copolymerized with a monomer that is soluble in a highly insulating medium and insoluble in the highly insulating medium upon polymerization. Examples of such monomers include vinyl esters of aliphatic carboxylic acids having 1 to 6 carbon atoms, such as vinyl acetate, vinyl propionate, and vinyl chloroacetate, vinyl esters of benzoic acid, acrylic acid, methacrylic acid, C1-C6 alkyl esters or amides such as crotonic acid, maleic acid, itaconic acid, ethylene glycol di (meth) acrylate, methylenebisacrylamide, styrene and its derivatives, divinylbenzene, N-vinyl-2- Examples include pyrrolidone, N-vinyl pyridine, N-vinyl imidazole, and the like.

  In the emulsion particles of the present invention, the dispersant and the core polymer are preferably bonded by a urethane bond. In the method of bonding the dispersant and the core polymer with a urethane bond, after adding a hydroxy group to the dispersant, the isocyanate group of the monomer having an isocyanate group and a polymerizable double bond group and the hydroxy group of the dispersant are combined. A urethane bond is formed by chemical bonding, an unreacted polymerizable double bond group is contained in the dispersant, and then a method of polymerizing with the monomer component of the core polymer, and an isocyanate group is contained in the dispersant. Later, 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. And then polymerizing with the monomer component of the core polymer. 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 size 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. Preferably it is 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 of 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 polymer containing a carboxyl group as disclosed in JP-A-6-51567 and the like, and polycarboxylic acid type polymer surfactants such as homogenol L18 (trade name, manufactured by Kao Corporation) are used. It is possible. 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 made of a metal material according to the present invention is a mask that can transfer 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. A screen printing mask produced by either method can also 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. As the material, a metal mainly composed of nickel, copper, chromium, zinc, iron or the like, an alloy, stainless steel, or the like can be applied. Also, there is no particular limitation on the opening pattern of the screen printing mask, for example, a circle such as a regular circle or an ellipse, a square such as a square, rectangle, rhombus, trapezoid, a polygon such as a hexagon, an octagon, etc. Examples include an indeterminate shape such as a gourd shape and a dumbbell shape. The thickness of the screen printing mask made of a metal material is usually 30 to 500 μm, and the thickness is determined by the transfer amount of the paste material. The size of the opening is several hundred μm to several tens of mm in general surface mounting, and the size is 50 to 300 μm and the pitch interval is 50 to 500 μm in high-density mounting. Furthermore, the cross-sectional shape of the opening of the screen printing mask may have a taper.

  Examples of a screen printing mask according to the present invention formed by forming a resin layer on at least the inner wall of the opening 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 shows the resin layer 2 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. As shown in FIG. 3, when the resin layer 2 is formed on the squeegee surface 3, the resin layer may be peeled off when the squeegee is contacted many times with a high pushing pressure. Since the peeled resin layer 2 may be mixed with the paste material, it is preferable that the squeegee surface 3 does not have the 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. In FIG. 4, the resin layer 2 is 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. First, a protective sheet 7 is attached to a screen printing mask (metal mask) 1 (FIG. 8) having an opening 5 (FIG. 9). Next, the electrode 12 is installed 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 are dispersed in a highly insulating medium (FIG. 10). 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 attached by the electrodeposition method are fixed by forming a film by heating or the like (FIG. 11). Subsequently, the protective sheet 7 is peeled off. Next, the metal mask which formed the resin layer 2 in the inner wall of the opening part 5 and the to-be-printed substrate contact surface 4 can be produced by bridge | crosslinking by heating (FIG. 12).

  As a protective sheet, it can be attached to a mask for screen printing and does not dissolve even if it touches a highly insulating medium in which emulsion particles are dispersed. Electrodeposition treatment and film formation (fixing) of emulsion particles As long as it can be easily peeled off from the screen printing mask even after being exposed to heat, pressure, light, water, etc., and the sticking material does not remain in the screen printing mask even after peeling. May be good. For example, ELEP Masking N-380 (trade name, manufactured by Nitto Denko Corporation), Paint Ace 720A (trade name, manufactured by Nitto Denko Corporation), SPV-K100 (trade name, manufactured by Nitto Denko Corporation), masking tape 851A for Scotch plating (Trade name, manufactured by Sumitomo 3M), Scotch heat-resistant masking tape 214-3MNE (trade name, manufactured by Sumitomo 3M), masking tape No 2311 (trade name, manufactured by Nichiban), Rio Elm LE970 (trade name, manufactured by Toyo Ink Co., Ltd.) ) And the like, but is not limited thereto. As the adhesive layer of the protective sheet, an acrylic adhesive can be preferably used from the viewpoint of poor solubility in a highly insulating medium.

  Further, in the screen printing mask formed by forming a resin layer on at least the inner wall of the opening, the resin layer 2 is formed on the inner wall of the opening 5 of the screen printing mask 1 made of a metal material as shown in FIG. The screen printing mask may be formed by laminating the resin layer 2 and the thick film resin layer 16 in the non-opening portion of the printed substrate contact surface 4 of the screen printing mask 1. . In either order of the lamination of the resin layer and the thick resin layer, good printing characteristics are exhibited. After the resin layer 2 is formed on the inner wall of the opening 5 and the printed substrate contact surface 4, the thick film resin layer 16 is formed on the non-opened portion of the printed substrate contact surface 4. Can be made. After the thick resin layer 16 is formed on the printed substrate contact surface 4, the resin layer 2 is formed on the inner wall of the opening 5 and the non-opened portion of the printed substrate contact surface 4. Can be made. The thickness of the thick film resin layer 16 is preferably in the range of 5 to 200 μm. If it is less than 5 μm, sufficient cushioning properties cannot be obtained, and the paste material may ooze out. On the other hand, when the thickness exceeds 200 μm, when the volume expansion of the thick film resin layer 16 occurs, a change in the shape of the opening becomes large, which may cause a problem that the transfer amount of the paste material changes.

  As shown in FIG. 15, the screen printing mask having the thick film resin layer 16 has the width L2 of the opening 5 of the thick film resin layer 16 larger than the width L1 of the opening 5 of the screen printing mask 1. May be. Further, as shown in FIG. 16, the width L2 of the opening of the thick film resin layer 16 covered with the resin layer 2 may be made larger than the width L1 of the opening of the screen printing mask. The half value (d) of (L2−L1) is preferably 0 to 200 μm, more preferably 0 to 30 μm. When d is a negative value, that is, the width L2 of the opening of the thick film resin layer 16 is smaller than the width L1 of the opening of the screen printing mask, so that the thick film resin layer 16 is open like a ridge. In the protruding state, an appropriate amount of paste material cannot be transferred, or a sufficient effect may not be obtained with respect to the detachability between the paste material and the screen printing mask. On the other hand, when d is larger than 200 μm, not only is it difficult to form a high-definition transfer pattern, but the paste material particles enter and bleeding tends to occur.

  The thick film resin layer 16 is a resin having a chemical strength and a mechanical strength, and any resin can be used as long as it does not swell in the solvent and cleaning agent of the paste material to be used. Also good. Specifically, polyimide, polyamide, polyester, epoxy, polycarbonate, polystyrene, polyethylene, polypropylene, polyacetal, fluororesin, silicon, acrylic, vinyl acetate, vinyl chloride, vinylidene chloride, phenol resin, polyvinyl butyral, gelatin, carboxymethylcellulose, etc. Is mentioned. In order to give durability and mechanical strength to the organic solvent for cleaning the paste material and the mask for screen printing, ultraviolet curable property, electron beam curable property, heat curable property and the like can be imparted.

  Among the methods for producing the screen printing mask having the thick resin layer 16, the resin layer 2 is formed on the inner wall of the opening 5 of the screen printing mask 1 made of the metal material illustrated in FIG. A method for producing a screen printing mask in which the resin layer 2 and the thick film resin layer 16 are laminated in this order on the non-opening portion of the printed substrate contact surface 4 of the screen printing mask will be described with reference to FIGS. Explain in detail. First, a screen printing mask (metal mask) 1 in which the resin layer 2 as shown in FIG. 12 is formed on the inner wall of the opening 5 and the printed substrate contact surface 4 is manufactured in the same manner as the above manufacturing method. Next, the thick film resin layer 16 and the carrier layer 15 are provided on the printed substrate contact surface by lamination so as to close the opening 5 (FIG. 18).

  As the carrier layer 15, polyimide, polyamide, polyester, epoxy, polycarbonate, polystyrene, polyethylene, polypropylene, polyacetal, fluororesin, silicon, acrylic, vinyl acetate, vinyl chloride, vinylidene chloride, polyphenol, polyvinyl butyral, gelatin, carboxymethylcellulose, etc. Metals such as resin, copper, nickel, stainless steel (SUS), and aluminum can be used. When the carrier layer 15 contains a resin, a resin that is insoluble in the thick film resin layer removing solution is used.

  Next, the thick film resin layer 16 is removed from the squeegee surface 3 by supplying the thick film resin layer removing solution by spraying or the like (FIG. 19). Next, the thick film resin layer removing liquid is removed by washing with water and dried with cold air, and then the carrier layer 15 is removed. The thick resin layer 16 may be cured by heating, ultraviolet light, electron beam, or the like. In this manner, the screen printing mask illustrated in FIG. 13 can be manufactured. Specifically, the technique disclosed in JP 2008-246738 can be applied.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to this Example.

<Synthesis of emulsion particles>
In a four-necked flask equipped with a stirrer, a thermometer, and a reflux condenser, 180 parts by mass of IP solvent 1620 (manufactured by Idemitsu Kosan Co., Ltd.), 114 parts by mass of dodecyl methacrylate and 6 parts by mass of 2-hydroxyethyl methacrylate were mixed. After substitution with nitrogen, the mixture was heated to 80 ° C., 1.1 parts by mass of 2,2′-azobis (2-methylbutyronitrile) was added, and radical polymerization was performed. Two hours later, 0.1 part by mass of 2,2′-azobis (2-methylbutyronitrile) and 0.1 part by mass of 1,1′-azobis (cyclohexane-1-carbonitrile) were added. Further, after 4 hours, 0.1 part by weight of 1,1′-azobis (cyclohexane-1-carbonitrile) was added, the temperature was set to 85 ° C., and the reaction was terminated by heating for 7 hours. A combined (O-1) mixture was obtained.

  10 parts by mass of the above polymer (O-1) mixture, 0.1 part by mass of methacryloyloxyethyl isocyanate, 0.001 part by mass of 1,8-diazabicyclo [5.4.0] undec-7-ene as a catalyst, IP solvent 2020 parts by mass of 1620 (manufactured by Idemitsu Kosan Co., Ltd.) was mixed and reacted at 60 ° C. for 4.5 hours to obtain a polymer (O-2) mixture.

  In a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a dropping funnel, 475 parts by mass of the IP solvent 1620, 30 parts by mass of the polymer (O-2) mixture, and the monomers described in Table 1 And heated to 70 ° C. under a nitrogen atmosphere. To this, 0.45 parts by mass of 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile) was added. The temperature was kept at 70 ° C. and reacted for 8 hours to synthesize emulsion particles of Examples 1 to 9 and Comparative Example.

  In the obtained emulsion particles of Examples 1 to 9 and Comparative Example, the charge control agent (octadecyl vinyl ether / maleic anhydride copolymer; mass composition ratio 3/1) with respect to 1 part by mass of the solid content , Maleic anhydride hydrolysis rate 45 mol%, mass average molecular weight 13,000), and diluted with IP1620 (trade name, manufactured by Idemitsu Kosan Co., Ltd.) so that the solid content concentration becomes 0.5 mass%. A dispersion of emulsion particles to which a positive charge was imparted was prepared.

<Formation of resin layer on screen printing mask>
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 mask for screen printing. Next, Rio Elm LE970 (trade name, manufactured by Toyo Ink Co., Ltd.) was attached to the squeegee surface side as a protective sheet. Next, using the electrodeposition apparatus having the structure shown in FIG. 10, dispersions of emulsion particles of Examples 1 to 9 and Comparative Example in which the positive charges produced above were applied to the entire surface of the screen printing mask. Were used for electrodeposition under an applied voltage of 120 V for 20 seconds. Next, IP1620 (trade name, manufactured by Idemitsu Kosan Co., Ltd.) was dried with cold air. Next, the protective sheet was peeled off. Next, the emulsion particles were formed into a film and fixed at 80 ° C. for 3 minutes. Next, the film-formed emulsion particles were cross-linked by exposure to 180 ° C. for 1 hour. 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 masks produced using the emulsion particles of Examples 1 to 9 and Comparative Example, cream solder was repeatedly screen-printed 100 times as a paste material with a squeegee, and no cream solder omission occurred. A solder terminal pattern having a good shape was formed. In addition, since it was necessary to scrape the residue of the cream solder generated on the printed substrate contact surface of the screen printing mask with a waste dipped in an organic solvent, the solvent was immersed in a solvent of isopropyl alcohol, propylene glycol monomethyl ether, or methyl ethyl ketone. The wiping test was conducted with various types of waste. In the wiping test, a waste cloth (trade name: Nanowiper, manufactured by Mitsubishi Paper Industries Co., Ltd.) was wrapped around 500 g of a cylindrical weight having a cross-sectional area of 78.5 cm ² and impregnated with an appropriate amount of each solvent. And rubbed 50 times. The evaluation was made visually and evaluated in the following three stages.
○: No scratches △: Scratches ×: The resin layer peels off

  It was found that the resin layers of the screen printing masks of Examples 1 to 9 were not scratched at all when impregnated with isopropyl alcohol and rubbed, and the resin layers were more resistant to rubbing than the comparative example. Moreover, when impregnated with propylene glycol monomethyl ether and rubbed, scratches were slightly generated in Examples 1, 6 and 7, but in the comparative example, peeling of the resin layer was observed, and the resin layers of Examples 1 to 9 It was confirmed that is stronger than the resin layer of the comparative example. When Examples 1-5 were compared and it rubbed by impregnating methyl ethyl ketone, it has confirmed that a thing with a large acid value became strong with respect to rubbing. The resin layer of the emulsion particles of Example 5 having an acid value larger than 60 mg / KOH was satisfactory in the result of the wiping test, but was dispersed in a high humidity environment at a temperature of 25 ° C. and a relative humidity of 50% or more. Aggregation of emulsion particles began to occur by repeating the above stirring.

  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, conductive materials, insulating materials, color materials, sealing materials, adhesive materials, resist materials, and processing. The present invention can be applied to applications in which a pattern is formed on an arbitrary substrate by screen printing using a paste material such as a medicine.

DESCRIPTION OF SYMBOLS 1 Screen printing mask 2 Resin layer 3 Squeegee surface 4 Printed board contact surface 5 Opening 6 Mesh 7 Protective sheet 9 Protrusion 10 of resin layer 11 Filled 11 Electrode 13 Emulsion particle 15 Carrier layer 16 Thick film resin layer

Claims (3)

  In an emulsion particle comprising a dispersant and a core polymer dispersed in a highly insulating medium, the core polymer contains a hydroxy group and a blocked isocyanate group, and is selected from a carboxyl group and an alkoxyalkyl group. An emulsion particle comprising at least one group.   An emulsion particle having an acid value of 60 mgKOH / g or less.   3. A method for producing a screen printing mask comprising a resin layer formed on at least an inner wall of an opening, wherein the emulsion particles according to claim 1 or 2 are electrodeposited on at least an inner wall of the opening of the screen printing mask made of a metal material. A method for producing a mask for screen printing, comprising: a step of forming a film, forming a film of emulsion particles, and a step of crosslinking the filmed layer by heating.

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