JP4599956B2 - Photosensitive resin composition, method for forming solder resist, and printed wiring board - Google Patents

Description

  The present invention relates to a photosensitive resin composition, a method for forming a solder resist, and a printed wiring board.

  A printed circuit board with a photosensitive solder resist is formed with a heat-resistant photosensitive resin composition layer on an insulating substrate on which a conductor circuit pattern is formed. It is manufactured by performing exposure through a photomask so as to be shielded, and selectively removing the shielded portion of the photosensitive resin composition layer with an alkaline developer, followed by light or thermosetting treatment. .

  As a method for forming a photosensitive resin composition layer on an insulating substrate on which a conductor circuit pattern is formed, a liquid photosensitive resin composition is screen-printed, roll-coated or curtain-coated, or a photosensitive resin composition is previously prepared. There is a method in which an object is applied onto a heat resistant resin film to form a film, and the film is laminated and bonded.

  In terms of productivity of the printed circuit board, the method of laminating a film rather than the method of directly applying a liquid material to the substrate can form both sides of the photosensitive resin composition layer at the same time. It is advantageous in that it does not contain foreign matter, and there is no contamination of the workplace with organic solvents, but it can be applied to different thicknesses depending on the application, the material cost is low, and the coating film properties are excellent. The material (liquid solder resist) is used more often.

  Solder resist has been conventionally used as a solder protective film formed on the outermost layer of a printed circuit board. However, with the recent increase in functionality of electronic devices, importance has been placed on the function as an insulating film in addition to the solder protective film. It is becoming.

  On the other hand, information terminal devices such as mobile phones and personal computers have rapidly become highly functional since the 1990s. Recently, as a mounting method of electronic components, flip chip, COF, or the like that directly mounts a semiconductor chip on a printed circuit board is used. Although the density mounting method has already begun to be put into practical use, the required quality for the printed circuit board (semiconductor package substrate) and the substrate constituent material used for such high density mounting is approaching the required quality for the semiconductor chip. Typical examples include crack resistance (TCT resistance), moisture insulation reliability (HAST resistance), moisture absorption reflow resistance, appearance, etc. during temperature cycling tests, all of which are higher than conventional printed circuit boards. Is required.

  Among these, in particular, the requirements for the appearance specifications of the solder resist, which is a substrate constituent material formed at the outermost layer of the semiconductor package substrate, that is, at the interface between the substrate and the semiconductor chip, have become stricter.

Further, according to Non-Patent Document 1, the solder resist formation process is ranked first among the processes requiring improvement (processes with low yield) in the printed wiring board manufacturing process, and the solder resist coating film appearance is improved. However, there is a fact that this is a big technical problem for each board manufacturer. This is no exception in the semiconductor package substrate.
Electronics packaging technology, September 2002 issue

  Until now, it has been said that the cause of solder resist coating film defects is dominated by foreign matter such as dust, dust, and fiber scraps mixed in the production of printed wiring boards. It is in an environment where the cleanliness of the semiconductor level is maintained, and the occurrence of coating film defects due to foreign matters is extremely small. Therefore, improvement of the solder resist itself is desired.

  Therefore, an object of the present invention is to provide a photosensitive resin composition that can stably produce a semiconductor package substrate that sufficiently satisfies the appearance specifications of a solder resist coating film, that is, a coating film defect can be reduced and a coating film defect. The object is to provide a photosensitive resin composition capable of reducing the number.

  In order to achieve the above object, the present inventors have studied in detail, paying attention to the relationship between raw materials and coating film defects. As a result, the particle size and particle size distribution of fillers (organic filler type adhesion promoters, etc.) used to impart adhesion and prevent discoloration due to oxidation of the coating are closely related to the occurrence of coating film defects. As a result, the present invention has been completed.

That is, the present invention provides (A) a photosensitive resin, (B) a photopolymerization initiator, and (C) an organic filler such as triaminotriazine, hexamethoxymelamine, hexabutoxylated melamine, melamine polyphosphate, aminomercaptothiadiazole, and mercapto. a photosensitive resin composition comprising at least one selected from Toriazo Le or Ranaru group, not more than 30μm maximum particle size of (C) an organic filler, and, (C) an organic filler The integral area in the range of 20 μm to 100 μm in the particle size distribution curve is less than 2.0% of the integrated area in the range of 0.1 μm to 100 μm. The resin composition is provided.

  When the photosensitive resin composition having such a configuration is used as a solder resist, coating film defects can be reduced and the number of coating film defects can be reduced. In the photosensitive resin composition used for the conventional liquid solder resist, such characteristics cannot be obtained. This is because the maximum particle size of the filler is as large as 30 to 50 μm, or the particle size of 0.1 to 100 μm. This is probably because the integrated area of the particle size distribution of 20 to 100 μm with respect to the integrated area of the diameter distribution was about 2 to 5%.

  In recent years, the size of solder resist coating film defects has been required to be at a level of 30 μm or less, but the conventional liquid solder resist does not satisfy such requirements because the maximum particle size of the organic filler is If it exceeds 30 μm, it is considered that 1 to 1.5 times the coating film defect occurs with respect to the maximum particle size of the organic filler after the solder resist thermosetting step.

  Conventionally, the size of the filler to be used in the liquid resist is determined based on the average particle size, and a method of determining the filler based on the maximum particle size and the particle size distribution has not been adopted. This time, the present inventors adopt such a method, and even when the maximum particle size of the filler is 30 μm or less, the integrated area in the range of the particle size distribution of 20 to 100 μm is 0.1 to 0.1 μm. It has been found that the required characteristics are not satisfied when it exceeds 2% for an integrated area of less than 100 μm.

  The cause of the solder resist coating film defect occurring after the thermosetting process is not yet known, but is thought to be due to the effect of curing shrinkage due to the thermal reaction between the filler itself or the filler and other components during the thermosetting process. . Also, even if the filler large particles are removed by reducing the diameter of the pressure filtration filter, the filler large particles are particularly soft and plastically deformable when they are organic fillers, and the large particles cannot be completely captured. Have difficulty. Therefore, it is preferable to control the filler particle diameter in the above range in advance.

(A) Photosensitive resin, (B) photopolymerization initiator, and (C) organic filler as triaminotriazine, hexamethoxymelamine, hexabutoxylated melamine, melamine polyphosphate, aminomercaptothiadiazole, and mercaptotriazole according to the present invention solder resist photosensitive resin composition comprising at least one selected from the Le or Ranaru group, maximum particle diameter of (C) an organic filler is not more 30μm or less, and, in (C) an organic filler In the particle size distribution curve, the integrated area in the range of 0.1 to 10 μm and the integrated area in the range of 20 to 100 μm are both integrated areas in the range of 0.1 to 100 μm. It is preferable that it is less than 2.0%.

  With such a configuration, the thickening of the photosensitive resin composition can be prevented, so that the workability is further improved, and defects in the solder resist can be more reliably reduced.

  Using the photosensitive resin composition of the present invention, it is possible to provide a method for forming a solder resist pattern and a printed wiring board on which the solder resist is formed.

  That is, forming a resin layer made of the photosensitive resin composition of the present invention so as to cover the conductor layer on the insulating substrate of the laminated substrate in which the conductor layer having a circuit pattern is formed on the insulating substrate, A solder resist pattern can be formed by irradiating a predetermined portion of the resin layer with actinic rays to form an exposed portion and removing the resin layer other than the exposed portion.

  Further, a printed wiring board in which a conductor layer having a circuit pattern is formed on an insulating substrate, and further a solder resist layer is formed on the insulating substrate so as to cover the conductor layer, the solder resist layer is claimed. It consists of hardened | cured material of the photosensitive resin composition as described in any one of claim | item 1-3, The said soldering resist layer has an opening part so that a part of said conductor layer may be exposed. A printed wiring board is provided.

  A photosensitive resin composition that can stably produce a semiconductor package substrate that sufficiently satisfies the appearance specifications of a solder resist coating film, that is, a photosensitive resin that can reduce coating film defects and reduce the number of coating film defects. A composition is provided.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. In addition, the same code | symbol shall be used for the same element and the overlapping description is abbreviate | omitted.

(Photosensitive resin composition)
The photosensitive resin composition of the present invention contains (A) a photosensitive resin, (B) a photopolymerization initiator, and (C) a filler. In a preferred embodiment, the photopolymerizable monomer and the thermosetting resin are used. In addition, at least one of additive components such as a colorant, a polymerization inhibitor, an antifoaming agent, a silane coupling agent, and an organic solvent can be contained.

  The photosensitive resin composition is preferably liquid at normal temperature (25 ° C.), but may be pasty or solid at normal temperature as long as it can be applied to the laminated substrate by means such as heating. When it is solid, it may have a film shape so that lamination on the laminated substrate is easy. The photosensitive resin composition may also be a mixture of liquid components or a mixture of solids and liquid components.

  (A) As the photosensitive resin, various epoxy resins such as bisphenol A type, bisphenol F type, phenol novolak type, cresol novolak type and the like are modified with monocarboxylic acid containing an unsaturated group, and then saturated or unsaturated group. A compound (acid-modified epoxy acrylate) modified with an acid containing polybasic acid anhydride can be used. It is preferable to use a resin having an acid value of 60 to 110 mgKOH / g and a weight average molecular weight of 10,000 or less in consideration of the solubility of the resin in the developer during the formation of the resist pattern and the photocurability of the coating film.

  Examples of monocarboxylic acids containing unsaturated groups are acrylic acid, dimer of acrylic acid, methacrylic acid, β-furfurylacrylic acid, β-styrylacrylic acid, cinnamic acid, crotonic acid, α-cyanocinnamic acid Etc. Examples of saturated or unsaturated group-containing polybasic acid anhydrides include succinic anhydride, maleic anhydride, tetrahydrophthalic anhydride, phthalic anhydride, methyltetrahydrophthalic anhydride, ethyltetrahydrophthalic anhydride, hexahydrophthalic anhydride. Methylhexahydrophthalic anhydride, ethylhexahydrophthalic anhydride, itaconic anhydride and the like. These can be used alone or in combination of two or more.

  The blending amount of the photosensitive resin is preferably 20 to 70% by weight, more preferably 30 to 60% by weight, based on the total solid content of the photosensitive resin composition. When the blending amount is less than 20% by weight, the exposure sensitivity is significantly lowered, and the photocurability of the photosensitive resin composition becomes insufficient, which may cause a problem in the developer resistance of the exposed portion. On the other hand, if the blending amount exceeds 70% by weight, there may be a problem in the flexibility and heat resistance of the solder resist coating film.

  (B) As a photoinitiator, the thing of the type which generate | occur | produces a radical when it irradiates with an ultraviolet-ray from the general purpose exposure machine for printed wiring board manufacture can be used. For example, benzoins such as benzoin, benzoin methyl ether, benzoin isopropyl ether, acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxy Acetophenones such as cyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2,2-diethoxyacetophenone, N, N-dimethylaminoacetophenone, 2 -Anthraquinones such as methyl anthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2-amylanthraquinone, 2-aminoanthraquinone, 2,4-dimethylthioki Thioxanthones such as nitrophenone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2,4-diisopropylthioxanthone, ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal, benzophenone, methyl benzophenone, 4,4'-dichlorobenzophenone, 4,4'-bis (diethylamino) benzophenone, Michler's ketone, benzophenones such as 4-benzoyl-4'-methyldiphenyl sulfide, acridi such as 9-phenylacridine, 1,7-bis (9,9'-acridinyl) heptane Derivatives, 2,4,6-trimethylbenzoyldiphenylphosphine oxide and the like. These can be used alone or in combination of two or more.

  (B) The compounding quantity of a photoinitiator is 0.5-20 weight% with respect to solid content of the photosensitive resin, Furthermore, 1-10 weight% is preferable. If the blending amount is less than 0.5% by weight, the amount of radicals generated by ultraviolet rays is insufficient, so that the photocurability of the photosensitive resin composition becomes insufficient, and a problem may occur in the developer resistance of the exposed portion. On the other hand, if the blending amount exceeds 20% by weight, light may not be sufficiently transmitted to the lower part of the photosensitive resin layer, and problems such as undercutting may occur.

  As the filler (C), an organic filler capable of imparting adhesion and prevention of discoloration of the solder resist coating film by oxidation to the solder resist coating film can be used, but the maximum particle size is 30 μm or less. It is essential to use one having an integrated area of 20-100 μm particle size distribution of less than 2.0%, more preferably less than 1.0% relative to an integrated area of particle size distribution of 1-100 μm. Maximum particle size and particle size distribution are controlled by existing classification methods such as gravity field classification using thickeners, wind shears, multistage fluidized bed classifiers, and centrifugal field classification using cyclones, vortex flow classifiers, etc. It can be carried out. The maximum particle size and particle size distribution can be measured by using an existing apparatus such as a microtrack method.

  Examples of the organic filler include triaminotriazine, hexamethoxymelamine, hexabutoxylated melamine, melamine polyphosphate, aminomercaptothiadiazole, mercaptotriazole, piperidine and the like. These can be used alone or in combination of two or more. Moreover, the compounding quantity is 0.1 to 10 weight% with respect to the total solid of the photosensitive resin composition, Furthermore, 0.5 to 5 weight% is preferable. When the blending amount is less than 0.1% by weight, the adhesion of the coating film is lowered, and the problem of discoloration of the resist coating film due to oxidation tends to occur.

  In addition to the organic filler, an inorganic filler can also be used for the purpose of improving the mechanical strength of the coating film as necessary. Examples of the inorganic filler that can be used include barium sulfate, silicon oxide, magnesium oxide, calcium carbonate, zirconium silicate, zirconium oxide, calcium silicate, talc, clay, silica, bentonite, and kaolin zirconium silicate. These can be used alone or in combination of two or more.

  In the photosensitive resin composition of the present invention, a photopolymerizable monomer can be used for the purpose of improving photosensitivity and developer resistance as required. Examples of the photopolymerizable monomer include 2-hydroxyethyl (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, N, N-dimethyl ( (Meth) acrylate, N-methylol (meth) acrylamide, polyethylene glycol, polypropylene glycol, polyethylene glycol or propylene glycol of bisphenol A, mono- or polyfunctional (meth) acrylates of tris (2-hydroxyethyl) isocyanuric acid, triglycidyl Photopolymerizable monomers such as (meth) acrylates of glycidyl ether such as isocyanurate and diallyl phthalate can be used. These can be used alone or in combination of two or more.

  As for the compounding quantity of a photopolymerizable monomer, 0.5 to 30 weight% is preferable with respect to the photosensitive resin composition total solid. If the blending amount is less than 0.5% by weight, the exposure sensitivity is low, so that it is necessary to spend a lot of time in the exposure process, and the productivity of the substrate tends to be lowered. On the other hand, if the blending amount exceeds 30% by weight, the flexibility and heat resistance tend to decrease.

  In the photosensitive resin composition of the present invention, a thermosetting resin can be used for the purpose of improving heat resistance, chemical resistance and insulation reliability, if necessary. Examples of the thermosetting resin include epoxy compounds, amide or imide compounds, urea compounds, and the like. Examples of the epoxy compound include bisphenol A type epoxy resins, bisphenol F type epoxy resins, novolac type epoxy resins, bisphenol S type epoxy resins, biphenyl type epoxy resins, and heterocyclic epoxy resins such as triglycidyl isocyanurate. Examples of the amide or imide compound include bismaleimide resin, amideimide resin, etherimide resin, and amide epoxy resin. Examples of the urea compound include dimethylol urea.

  As for the compounding quantity of the said thermosetting resin, 10 to 60 weight% is preferable with respect to solid content of the photosensitive resin. If the amount is less than 10 parts by weight, the heat resistance, chemical resistance and insulation reliability of the resist coating film tend to decrease. If the amount exceeds 60% by weight, the photocurability of the photosensitive resin composition decreases, and the developer resistance Tend to decrease.

  The photosensitive resin composition of the present invention includes, as necessary, known colorants such as phthalocyanine blue, phthalocyanine green, iodine green, disazo yellow, kustal violet, titanium oxide, carbon black, naphthalene black, hydroquinone, and the like. Various known and conventional additives such as polymerization inhibitors such as methyl hydroquinone, hydroquinone monomethyl ether, catechol and pyrogallol, silicone-based, fluorine-based and vinyl resin-based antifoaming agents, and silane coupling agents can be used.

  The photosensitive resin composition of the present invention may contain an organic solvent. Examples of the organic solvent that can be contained include ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene and tetramethylbenzene; methyl cellosolve, butyl cellosolve, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, di Glycol ethers such as propylene glycol monoethyl ether, dipropylene glycol diethyl ether and triethylene glycol monoethyl ether; esters such as ethyl acetate, butyl acetate, butyl cellosolve acetate and carbitol acetate; aliphatic hydrocarbons such as octane and decane And petroleum solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha.

  As described above, the photosensitive resin composition may have a film shape. The photosensitive resin composition having a film shape is preferably used as a photosensitive film sandwiched between a support and a cover form.

  FIG. 1 is a cross-sectional view showing an embodiment of such a photosensitive film. A photosensitive film 1 shown in FIG. 1 includes a support 11, a resin layer 12 made of the photosensitive resin composition formed on the support, and a cover film 13 laminated on the resin layer 12. It is to be prepared.

  As the support 11, a plastic film is good, and it is preferable to use a plastic film such as a polyester film such as polyethylene terephthalate, a polyimide film, a polyamideimide film, a polypropylene film, or a polystyrene film. Here, the thickness of the support is appropriately selected within a range of 10 to 150 μm.

  There is no restriction | limiting in particular about the thickness of the resin layer 12, For example, it selects suitably in the range of 10-150 micrometers. For example, the resin layer 12 is formed by applying a photosensitive resin composition containing an organic solvent to the support 11 with a uniform thickness using a comma coater, blade coater, lip coater, rod coater, squeeze coater, reverse coater, transfer roll coater, or the like. The organic solvent can be volatilized by heating and drying.

  Examples of the cover film 13 include a polyethylene film, a polypropylene film, a Teflon (registered trademark) film, and a surface-treated paper. The cover film 13 only needs to have a smaller adhesive force between the resin layer 12 and the cover film 13 than the adhesive force between the resin layer 12 and the support 11. As a modification of the photosensitive film 1 shown in FIG. 1, an embodiment without the cover film 13 is possible. However, when the photosensitive film 1 is wound and stored, the resin layer 12 is used for the purpose of protecting the resin layer 12. It is preferable to laminate the cover film 13 thereon.

(Method for forming resist pattern)
Formation of the resist pattern using the photosensitive resin composition can be performed by the following method. That is, first, a laminated substrate in which a conductor layer having a circuit pattern is formed on an insulating substrate is prepared. And the photosensitive resin composition mentioned above is apply | coated so that a conductor layer may be covered on the insulated substrate of this laminated substrate, and the resin layer which consists of a photosensitive resin composition is formed. Next, an exposed portion is formed by irradiating a predetermined portion of the resin layer with actinic rays, and the resin layer other than the exposed portion is removed.

  Application of the photosensitive resin composition on the laminated substrate can be performed by spin coating, screen printing, curtain coating, etc., and as a light source of actinic rays irradiated to the applied resin layer, a known light source, for example, A carbon arc lamp, a mercury vapor arc lamp, an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a xenon lamp, or the like that emits ultraviolet rays effectively is used. Moreover, what emits visible light effectively, such as a photographic flood light bulb and a solar lamp, is also used.

After the exposure, an alkaline aqueous solution (alkaline developer) is used, and development is performed by removing portions other than the exposed portion by a known method such as spraying, rocking immersion, brushing, and scraping to form a resist pattern. It is preferable. Note that after the resist pattern is formed, post-curing may be further performed by exposure at 1 to 5 J / cm ² and / or heating (post-heating) at 100 to 200 ° C. for 30 minutes to 12 hours.

  A developer other than those described above may be used as long as it does not damage the exposed area and selectively elutes the unexposed area. As the developer, a semi-aqueous developer, a solvent developer, or the like can be used according to the development type of the resin composition. For example, an emulsion developer containing water and an organic solvent as described in JP-A-7-234524 can be used. Particularly useful emulsion developers include, for example, propylene glycol monomethyl ether acetate, ethylene glycol ethyl ether acetate, 2,2-butoxyethoxyethanol, butyl lactate, cyclohexyl lactate, ethyl benzoate, and 3-methyl-3 as organic solvent components. An emulsion developer containing 10 to 40% by weight of an organic solvent such as methoxybutyl acetate can be mentioned. When an alkali developer is used, an alkaline aqueous solution such as potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, 4-sodium borate, ammonia, amines, and the organic solvent are used. It is also possible to use an emulsion developer.

  By the above-described method, a resist pattern can be formed on the photosensitive resin composition layer on the conductor layer on which the circuit pattern is formed. The resin layer on which the resist pattern is formed is used as a solder resist that prevents the solder from adhering to unnecessary portions on the conductor layer when bonding the mounted components.

  In addition, when forming a resist pattern using the photosensitive film 1 shown in FIG. 1, first, the resin layer 12 is piled up on a laminated substrate, and a resin layer is laminated | stacked on a laminated substrate by sticking using a hot roll laminator etc. 12 is formed. There is no restriction | limiting in particular about the thickness of the resin layer 12 laminated | stacked, Usually, it selects suitably in the range of 10-150 micrometers.

  The formed resin layer 12 can be exposed through a photomask using, for example, an ultra-high pressure mercury lamp or a high pressure mercury lamp as a light source, and a resist pattern can be formed by removing the unexposed portion by the same method as described above. It becomes possible. As another method, a resist pattern can be formed by a laser drilling method using a printing method, a carbon dioxide gas laser, a Y 、 G laser, an excimer laser, or the like.

(Printed wiring board)
FIG. 2 is a schematic cross-sectional view showing an embodiment of the printed wiring board of the present invention. The printed wiring board 2 shown in FIG. 2 has an insulating substrate 22, a conductor layer 23 having a circuit pattern formed on one surface of the insulating substrate 22, and a circuit pattern formed on the other surface of the insulating substrate 22. And a solder resist layer 24 formed on the insulating substrate 22 so as to cover the conductor layer 23 having a circuit pattern. The solder resist layer 24 is made of a cured product of the above-described photosensitive resin composition, and the solder resist layer 24 has an opening 26 so that at least a part of the conductor layer 23 having a circuit pattern is exposed. Yes.

  Since the printed wiring board 2 has the opening 26, a mounting component such as CSP or BGA can be joined to the conductor layer 23 having a circuit pattern by solder or the like, and so-called surface mounting becomes possible. The solder resist layer 24 has a role as a solder resist for preventing solder from adhering to unnecessary portions of the conductor layer 23 during soldering for joining, and also for mounting component bonding. Later, it functions as a permanent mask for protecting the conductor layer 23.

  Hereinafter, an example of a method for manufacturing the printed wiring board 2 will be schematically described. FIG. 3 is a process diagram schematically showing a method of manufacturing the printed wiring board 2 shown in FIG. 3A is a printed wiring board 3 (comprising a conductor layer 23 having a circuit pattern on one side of the insulating substrate 22 and a conductor layer 21 having no circuit pattern on the other side), and FIG. 3 (c) and 3 (d) respectively show irradiation of actinic rays to the printed wiring board 4 and the resin layer 12 after laminating the resin layer 12 made of the photosensitive resin composition on the insulating substrate 22, respectively. The printed wiring board 2 after development is shown.

  First, the pattern of the conductor layer 23 is formed on the insulating substrate 22 as shown in FIG. 3A by a known method of etching one side of a double-sided metal laminate (for example, double-sided copper-clad laminate). A wiring board 3 is obtained. Next, as shown in FIG. 3B, a resin layer 12 made of a photosensitive resin composition is formed on the printed wiring board 3 on which the conductor layer 23 is formed so as to cover the conductor layer 23. A printed wiring board 4 having 12 formed thereon is obtained. Next, as shown in FIG.3 (c), the predetermined part of the resin layer 12 is hardened by irradiating the laminated resin layer 12 with actinic light through the mask 5 which has a predetermined pattern. Finally, the printed wiring board 2 is obtained by removing the unexposed portion (for example, alkali development) to form the solder resist layer 24 having the opening 26 as shown in FIG. Note that the solder resist layer 24 may be further subjected to photocuring or thermosetting.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example at all.

Example 1
Composition A shown in Table 1 and Composition B shown in Table 2 were blended separately, and after blending, these were kneaded and dispersed using a three-roll mill to obtain a photosensitive resin composition.

(Example 2)
The maximum particle size of triaminotriazine in Example 1 (Composition B) is 25 μm, and the integrated area of the particle size distribution of 20 to 100 μm is changed to 0.3% with respect to the integrated area of the particle size distribution of 0.1 to 100 μm. A photosensitive resin composition was prepared in the same manner as in Example 1 except that was used.

(Example 3)
The maximum particle size of triaminotriazine in Example 1 (Composition B) is 30 μm, and the integrated area of the particle size distribution of 20 to 100 μm is changed to 0.5% with respect to the integrated area of the particle size distribution of 0.1 to 100 μm. A photosensitive resin composition was prepared in the same manner as in Example 1 except that was used.

(Comparative Example 1)
The maximum particle size of triaminotriazine in Example 1 (Composition B) is 40 μm, and the integrated area of the particle size distribution of 20 to 100 μm is changed to 3% with respect to the integrated area of the particle size distribution of 0.1 to 100 μm. A photosensitive resin composition was produced in the same manner as in Example 1 except that.

(Comparative Example 2)
The maximum particle size of triaminotriazine in Example 1 (Composition B) is 40 μm, and the integrated area of the particle size distribution of 20 to 100 μm is changed to 0.3% with respect to the integrated area of the particle size distribution of 0.1 to 100 μm. A photosensitive resin composition was prepared in the same manner as in Example 1 except that was used.

(Comparative Example 3)
The maximum particle size of triaminotriazine in Example 1 (Composition B) is 25 μm, and the integrated area of the particle size distribution of 20 to 100 μm is changed to 3% with respect to the integrated area of the particle size distribution of 0.1 to 100 μm. A photosensitive resin composition was produced in the same manner as in Example 1 except that.

(Comparative Example 4)
A photosensitive resin composition was prepared in the same manner as in Example 1 except that triaminotriazine was not blended in (Composition B) in Example 1.

  The characteristics of the photosensitive resin composition produced as described above were evaluated by the following items.

(Appearance of coating film)
Samples for coating film appearance test evaluation were prepared and evaluated by the following methods.
(1) After mixing composition A and composition B at a weight ratio of 70/30, the film thickness after drying the photosensitive resin composition on a polyimide film substrate on which a conductor circuit of L / S = 50/50 μm was formed was 20 μm. It was applied and dried (80 ° C./15 minutes).
(2) Ultraviolet rays were irradiated at an exposure amount of 200 to 1000 mJ through a photomask provided with a shielding portion at a location where a resist pattern was to be formed.
(3) The resist pattern was formed by dissolving and removing the unexposed portion by developing for 1 to 3 minutes with a predetermined alkaline developer kept at 30 to 40 ° C.
(4) A thermosetting treatment was performed at 150 ° C. for 60 minutes.

  After the thermosetting treatment, the occurrence state (defect size) of solder resist coating film defects was observed with a microscope. Evaluation was performed with n = 10, and the appearance was evaluated with the maximum defect diameter. A film having a maximum defect diameter of 30 μm or less was evaluated as “◯”, and a film having a maximum defect diameter exceeding 30 μm as “×”.

(Hue of coating film)
Samples for hue evaluation were prepared and evaluated by the following methods. An evaluation sample was prepared by the same method as the sample preparation method for coating film appearance evaluation. Evaluation was performed by visually observing the change in the hue of the coating film before and after the thermosetting treatment step. The case where no change was observed in the hue of the coating film was marked as ◯, and the case where a change was observed in the hue was marked as x.

(Adhesiveness of coating film)
Samples for evaluating adhesiveness were prepared and evaluated by the following methods. An evaluation sample was prepared by the same method as the sample preparation method for coating film appearance evaluation. The sample was floated in a solder bath at 260 ° C. for 30 seconds, and the adhesion of the coating film was evaluated by visually observing whether the coating film was peeled off. The case where peeling was not recognized by the coating film was set as (circle), and the case where peeling was not recognized was set as x.

The above evaluation results are summarized in Table 3.

It is a schematic cross section showing one embodiment of a photosensitive film. It is a schematic cross section showing one embodiment of a printed wiring board. It is process drawing which shows the manufacturing method of a printed wiring board, (a) is an insulated substrate, (b) is a printed wiring board which laminated | stacked the resin layer, (c) is irradiation of the active ray to a resin layer, (d) is Each printed wiring board after development is shown.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Photosensitive film, 2, 3, 4 ... Printed wiring board, 5 ... Photomask, 11 ... Support body, 12 ... Resin layer, 13 ... Cover film, 21 ... Conductor layer without a circuit pattern, 22 ... Insulating substrate , 23 ... a conductor layer having a circuit pattern, 24 ... a solder resist layer, 26 ... an opening.

Claims (4)

(A) a photosensitive resin, (B) a photopolymerization initiator and (C) triaminotriazine as organic fillers, hexamethoxymelamine, Hekisabutokishi melamine, melamine polyphosphate, amino mercaptothiadiazole, and mercapto thoria zone le or Ranaru a comprising at least one member selected from the group photosensitive resin composition,
(C) The organic filler has a maximum particle size of 30 μm or less, and
(C) In the particle size distribution curve of the organic filler, the integrated area in the range of 20 μm to 100 μm is less than 2.0% of the integrated area in the range of 0.1 μm to 100 μm. A photosensitive resin composition for solder resist. (A) a photosensitive resin, (B) a photopolymerization initiator and (C) triaminotriazine as organic fillers, hexamethoxymelamine, Hekisabutokishi melamine, melamine polyphosphate, amino mercaptothiadiazole, and mercapto thoria zone le or Ranaru a comprising at least one member selected from the group photosensitive resin composition,
(C) The organic filler has a maximum particle size of 30 μm or less, and
(C) In the particle size distribution curve of the organic filler, the integrated area in the range of 0.1 to 10 μm and the integrated area in the range of 20 to 100 μm are both in the range of 0.1 to 100 μm. The photosensitive resin composition for solder resists, wherein the integrated area is less than 2.0% of the integrated area.   3. A resin layer made of the photosensitive resin composition according to claim 1 or 2 is formed on a laminated substrate in which a conductor layer having a circuit pattern is formed on an insulating substrate so as to cover the conductor layer. And a predetermined portion of the resin layer is irradiated with actinic rays to form an exposed portion, and a resin layer other than the exposed portion is removed, and a method for forming a solder resist pattern is provided. A printed wiring board in which a conductor layer having a circuit pattern is formed on an insulating substrate, and further a solder resist layer is formed on the insulating substrate so as to cover the conductor layer,
The solder resist layer is made of a cured product of the photosensitive resin composition according to claim 1, and the solder resist layer has an opening so that a part of the conductor layer is exposed. Printed wiring board characterized by

Images