JPH0561791B2 - - Google Patents

Description

[Detailed description of the invention]

(Technical Field of the Invention) The present invention relates to a method for manufacturing a printed wiring board,
More specifically, in the partial plating method in which electrical circuits are formed by electroless copper plating, the accuracy of the plated parts is improved and the photosensitive resist film used during plating is used as a permanent insulation mask. The present invention relates to a method for manufacturing a printed wiring board. (Prior Art) One embodiment of the subtractive method (etched foil method), which is a typical method for manufacturing conventional printed wiring boards, involves drilling holes in a copper-clad laminate, chemical cleaning, and activating the inside of the holes. A thin copper film is formed by plating, and then the entire surface is electrolytically plated so that the inner wall of the hole has the specified copper plating thickness. After plating, a circuit is formed with a resist. This method removes unnecessary copper by etching. On the other hand, recently, insulating plates are used as starting materials,
The fully additive method of forming circuits using only electroless copper plating is attracting attention and being put into practice, but this method generally consists of the following steps. A laminate with a catalyst-containing adhesive is drilled or punched to create through holes, then coated with resist ink to form a pattern using a screen printing method, and after curing is placed in an electroless copper plating solution. , the circuit is completed by depositing a plating film on the areas other than the resist ink to form a circuit. This fully additive method differs from the conventional subtractive method in that it forms a conductor pattern of any thickness only in the necessary areas, and is advantageous in terms of process simplification, resource saving, and low cost. However, one of the major problems with this method is the accuracy of the pattern, and it is difficult to obtain a sharp pattern. The reason for this is that fully additive plating resists are conventionally printed by screen printing, but there is a limit to the accuracy of screen printing.Generally, the dimensional accuracy is ±0.15mm/50cm, and the pattern width resolution is
It is said to be 0.25mm. In addition, in the fully additive method, the solvent contained in the resist ink causes "bleeding" of several tens of microns, which reduces the adhesion of the deposited copper, and the ink that occurs when hardened by heat treatment after printing. It is also desired to improve the drawbacks such as the fact that accuracy deteriorates further due to sagging. Furthermore, photosensitive resist films must withstand temperatures of around 260°C during the soldering process, or organic solvents such as isopropyl alcohol, trichloroethylene, and methylene chloride used to clean the flux used during soldering. etc. are also required. (Objective of the Invention) The first object of the present invention is to sufficiently withstand the electroless copper plating solution of the full additive method, and to have significantly improved pattern accuracy through the photographic method, and to be able to be used in the final product without removing it. An object of the present invention is to provide a method for manufacturing a printed wiring board having a permanent insulation mask. A second object of the present invention is to provide a method for manufacturing a printed wiring board having a heat-resistant permanent insulation mask that can withstand temperatures of around 260° C. during the soldering process. The final objective of the invention is to
It is an object of the present invention to provide a method for manufacturing a printed wiring board having a permanent insulating mask that is sufficiently resistant to organic solvents for cleaning flux used during soldering. (Structure of the Invention) The present invention comprises (i) a diallylphthalate prepolymer having a molecular weight within the range of about 3,000 to about 20,000, (ii) a photopolymerizable monomer, and (iii) a photopolymerization initiator. A photosensitive resist film contained as a main component is bonded to a laminate with a catalyst-containing adhesive, (b) a transparent negative is placed on the photosensitive resist film, and (c) the photosensitive resist film is passed through the transparent negative. (d) developing the exposed patterned resist film without heat treatment or after heat treatment; (e) heat-treating and/or irradiating the developed resist film with ultraviolet light; (f) This is a method for manufacturing a printed wiring board, which is characterized by electroless copper plating, and finally (g) ultraviolet irradiation and/or heat treatment. The components of the present invention will be explained in detail below. (Diallyl phthalate prepolymer) The name diallyl phthalate in the claims section of this specification is a generic name that includes not only diallyl phthalate itself but also diallyl isophthalate and diallyl terephthalate. The diallyl phthalate prepolymer used in the present invention is a prepolymer of diallyl phthalate, diallyl isophthalate, or diallyl terephthalate and has a molecular weight in the range of about 3,000 to about 20,000.
If the molecular weight is less than about 3000, the softening point will be low, and when used as a resist film, the film will be sticky and unsuitable for practical use. In addition, when the molecular weight is about 20,000 or more,
It has poor solubility in solvents and is not practical. Diallyl phthalate or diallyl isophthalate can be easily synthesized from phthalic anhydride or isophthalic anhydride and allyl alcohol, or from sodium phthalate or sodium isophthalate and allyl chloride. Diallyl terephthalate has a low yield when synthesized by direct esterification, so it can be synthesized by transesterification between dimethyl terephthalate and allyl acetate, or by converting terephthalic acid into an acid chloride with phosphorus pentachloride and reacting this with allyl alcohol. However, the synthesis method is complicated and the cost is high. Considering this point and the fact that a diallyl phthalate prepolymer has slightly inferior heat resistance than a diallyl isophthalate prepolymer, it is preferable to use diallyl isophthalate. ,
There are no limitations. It is also possible to use a mixture of isomers. (Photopolymerizable monomer) As the photopolymerizable monomer of the present invention, ethylenically unsaturated compounds such as polyfunctional acrylic compounds, and compounds having allyl groups, vinyl ether groups, and vinyl amino groups are also used. can. For example, polyethylene glycol diacrylate (polymerization degree is 2 to 200) represented by diethylene glycol diacrylate, triethylene glycol diacrylate, and tetraethylene glycol diacrylate.
and the corresponding methacrylates;
Polyalkylene glycol diacrylates (polymerization degree is 4 to 11); various acrylates represented by pentaerythritol triacrylate, trimethylolpropane triacrylate, 2,2-dimethylpropane diacrylate; Methacrylates corresponding to diallylphthalate monomers and diacrylates of alkylene oxide derivatives represented by the following general formula (),
and the corresponding dimethacrylates can also be used. (However, R ₁ is a hydrogen atom or a bromine atom, R ₂ and
R ₃ is a hydrogen atom or a methyl group, R ₄ is -
CH ₂ −,

[Formula] or

[Formula] n is an integer. ) These photopolymerizable monomers can be used alone or as a mixture of two or more. The amount added is in the range of 5 to 50% by weight based on the diallylphthalate prepolymer. (Photopolymerization initiator) Examples of the photopolymerization initiator include benzophenones, benzoin, benzoin alkyl ethers such as benzoin ethyl ether and benzoin isopropyl ether, alkylanthraquinones such as ethyl anthraquinone and butyl anthraquinone,
2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, benzophenone, 4,4'-bisdimethylaminobenzophenone, 4,4'-bisdiethylaminobenzophenone, etc. I can give it to you. These may be used alone or as a mixture of two or more. The amount of the photopolymerization initiator added is 0.01 to 10% by weight based on the diallylphthalate prepolymer.
Preferably, it is sufficient to use it in a range of 0.05 to 5% by weight. (Other Additives) A thermal polymerization inhibitor, a plasticizer, and an ultraviolet inhibitor may be added to the resist film of the present invention, if necessary, in order to improve storage stability. Examples of the polymerization inhibitor include radical polymerization inhibitors such as hydroquinone monomethyl ether and methylhydroquinone. Examples of plasticizers include phthalate esters such as diethyl phthalate, dibutyl phthalate, and n-octyl phthalate, and dibasic acid esters such as di-2-ethylhexyl adipate and di-isodecyl adipate, and fatty acid esters. Butyl stearate based on epoxy, epoxidized soybean oil based on epoxy, and triphenyl phosphate and tricresyl phosphate based on phosphate ester can be used. These plasticizers are used in an amount ranging from 20 to 100% by weight, based on the diallylphthalate prepolymer. As a UV absorber, 2-hydroxy-4-
Methoxybenzophenone, 2-hydroxy-4-
Benzophenones such as octyloxybenzophenone and 2,4-dihydroxybenzophenone,
Benzotriazole series represented by 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 4-tert-butylphenyl salicylate,
Examples include salicylates such as p-octylphenyl salicylate. The amount of these added is usually 0.1 to 3% by weight. In addition, coloring agents such as dyes and pigments can be added as necessary. (Formation of Photosensitive Resist Film) A photosensitive resist film containing the above-mentioned components is prepared by dissolving it in a common organic solvent, coating it on a suitable substrate, and drying it. If necessary, it can be protected by appropriately laminating a protective film. Further, the thickness after coating is appropriately selected within the range of about 5 to 500 μm. The organic solvents used are benzene, toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, dioxane, ethyl acetate, butyl acetate, tetrahydrofuran, trichloroethane, trichloroethylene,
It is a single solvent such as dichloroethane or a mixed solvent. Application methods include spray method, dip method, fountain method, roll coater method, and bar coater method. Substrates can be used for metals such as non-rusting copper, plated chrome, polyester, and polyethylene. , boards, sheets or films made of single or composite materials such as paper or cloth impregnated with resins such as polyvinyl chloride, phenolic resins, melamine resins, etc.
The protective film may be cellulose-based, polyolefin-based, polyester-based, polyvinyl-based, etc., and the lamination method may include a press method, roll method, laminator method, etc. (Laminated board with catalyst-containing adhesive) The first step of the present invention is a step of bonding a photosensitive resist film to a laminate with catalyst-containing adhesive. The laminate with a catalyst-containing adhesive may be a commercially available product used in the full additive method, and prior to bonding the photosensitive resist film, it is cut to a specified size and holes are punched with a drill or punch. (Bonding of Photosensitive Resist Film) Bonding of the photosensitive resist film to the laminate with catalyst-containing adhesive is carried out at appropriate temperature and pressure using a lamination press, roll or laminator. (Exposure and Development) The next step of the present invention is an exposure and development step to form a circuit pattern by photography. Since the photosensitive resist film of the present invention is a negative type photosensitive resin, a negative film for patterns prepared in advance can be used for carbon arc lamps, xenon lamps, high pressure mercury lamps, ultra-high pressure mercury lamps, chemical lamps, metal halide lamps, etc. Print using a light source. After that, heat treatment is preferably performed, but the conditions are: temperature 100-200℃, time 5
~120 minutes is appropriate, and if necessary, pretreatment is performed at around 50°C for 30 minutes or more. Development is carried out using an organic solvent by a spray method, dip method, brush method, or the like.
Note that the organic solvent for development may be the same as the solvent used for producing the photosensitive resist film of the present invention. (Ultraviolet irradiation, heat treatment, and copper plating) The subsequent process of the present invention is the step of curing or strengthening the photosensitive resist pattern after exposure and development by heat treatment and/or ultraviolet irradiation to complete the permanent insulation mask. and immersing the masked laminate in an electroless copper plating solution to form a conductor circuit, and the heat treatment and/or ultraviolet irradiation steps are performed twice before and after the electroless copper plating step. Heat treatment method and conditions are temperature 100-200℃
What is necessary is just to process for 5 to 60 minutes inside. The method and conditions for ultraviolet irradiation may be carried out in accordance with those used for exposure. Further, the method and conditions for electroless copper plating may be the standard methods used in the fully additive method. (Effects of the Present Invention) The greatest advantage of the method of the present invention is, firstly, that the precision of the single pattern of the printed wiring board has been dramatically improved. This accuracy is determined by the resolution of the photosensitive resist film, but unlike conventional resist inks, it does not contain organic solvents, so phenomena such as "bleeding" caused by ink do not occur at all. The second advantage of the present invention is that the insulating mask formed by the method of the present invention only slightly discolors even if left in an atmosphere of 300°C for 3 minutes, does not show any film peeling phenomenon, and has excellent heat resistance. Because it is extremely excellent,
It should be able to sufficiently withstand a soldering process (soldering temperature: 260°C, soldering time: 4 to 5 seconds) on a conductor circuit plated with electroless copper. Furthermore, the insulating mask formed by the method of the present invention has excellent solvent resistance and can withstand organic solvents such as isopropyl alcohol, trichloroethylene, and methylene chloride without swelling or peeling. It is now possible to wash and remove it as it is. (Embodiments) The present invention will be described in more detail below with reference to Examples, but the present invention is not limited thereto. Example 1 After dissolving 100 parts by weight of diallyl isophthalate prepolymer (trade name: Daiso Isodap, manufactured by Osaka Soda Co., Ltd.) in 100 parts by weight of methyl ethyl ketone, trimethylolpropane trimethacrylate was dissolved.
30 parts by weight and 5 parts by weight of 2-ethyl anthraquinone were added to prepare a photosensitive resist composition. This composition was applied to a 30 μm thick film on a 25 μm thick polyester film.
It was coated in an amount of m and dried by irradiating it with infrared rays. Further, a 30 μm thick polyethylene film was press-bonded on top of this as a protective film to prepare a photosensitive resist film. Paper coated with additive adhesive (manufactured by Hyuson) and dried.
A phenolic resin laminate was treated with a surface treatment agent consisting of chromic acid and sulfuric acid, washed with water, and then a photosensitive resist film from which the polyethylene film had been peeled was thermocompression bonded to both surfaces whose surfaces had been activated with an activation treatment solution. A predetermined pattern was applied to this laminate and exposed to light using a 2kW ultra-high pressure mercury lamp with a radiation dose of 200mJ/ ^cm2 .
Developed with 1,1,1-trichloroethane. This was first heat treated at 50°C for 30 minutes and then at 120°C for 30 minutes. This was plated by immersing it in an electroless copper plating solution with the following composition for 10 hours (this is referred to as the A-treated product. Copper sulfate 12g/formalin 6ml/sodium hydroxide 12g/sodium ethylenediaminetetraacetate 35g/ polyethylene glycol stearylamine
50mg/dipyridyl 20mg/silver sulfide 0.0026ppm After plating, it was washed with water and then heat treated at 150°C for 30 minutes. Although it was immersed in a 260°C solder bath for 30 seconds, no change was observed in the resist film, and the heat resistance was good. Also, in trichlorethylene for 1 minute,
After soaking for 10 minutes, take it out and immediately (with the surface wet with liquid) soak it with tissue paper for 10 minutes.
The solvent resistance was determined by rubbing strongly twice and observing the degree of scratches using a loupe with a magnification of 50 times. Separately, it was immersed in a methylene chloride solution for 1 minute, 3 minutes, and 5 minutes and tested in the same manner as above to evaluate solvent resistance. These results are shown in Table 1. Example 2 The A-treated product shown in Example 1 was washed with water, air-dried, and then irradiated with ultraviolet rays. The conditions were: 6 kW x 3 ultra-high pressure mercury lamps, irradiation distance of 70 cm, and conveyor speed of 3 m/min. Heat resistance and solvent resistance were evaluated in the same manner as in Example 1. The results are shown in Table 1. Examples 3 to 6 The A-treated products shown in Example 1 were washed with water and air-dried, and then the heat resistance and solvent resistance were evaluated by changing the post-treatment process. The results are shown in Table 1.

【table】

[Table] Example 7 After dissolving 100 parts by weight of diallylisophthalate prebolimer in 100 parts by weight of methyl ethyl ketone, diacrylate (trade name: BP-
4EA (manufactured by Kyoeisha Yushi), 4 parts by weight of benzophenone, and 0.3 parts by weight of 4,4'-bis(dimethylamino)benzophenone to prepare a photosensitive resin composition. A photosensitive resist film was prepared from this in the same manner as in Example 1. This photosensitive resist film was bonded to both sides of a catalyst-containing adhesive-coated laminate obtained in the same manner as in Example 1 by thermocompression bonding. This plate was exposed and developed in the same manner as in Example 1, heated at 150°C for 30 minutes, and then irradiated with ultraviolet rays. Next, plating was performed using an electroless copper plating solution having the composition shown in Example 1 (this is referred to as a B-treated product). After washing the B-treated product with water, it was heat-treated at 150°C for 30 minutes. This was immersed in a 260°C solder bath for 30 seconds, but no change was observed in the resist film. Table 2 shows the results of evaluating solvent resistance using the same method as in Example 1. Examples 8 to 12 The heat resistance and solvent resistance of the B-treated products shown in Example 7 were evaluated in the same manner as in Example 1, except that the post-treatment steps after plating and water washing were changed. The results are shown in Table 2.

[Table] Note Processing conditions and evaluations are the same as in Table 1. Example 13 After dissolving 100 parts by weight of diallylphthalate prepolymer (trade name: Daisodap A, manufactured by Osaka Soda Co., Ltd.) in 100 parts by weight of methyl ethyl ketone, tetraethylene glycol dia Kurirato (product name A)
-4G, manufactured by Shin Nakamura Chemical Co., Ltd.) and 5 parts by weight of benzoin isopropyl ether were added to prepare a photosensitive resin composition. A photosensitive resist film was prepared from this in the same manner as in Example 1, and was adhered to both sides of the catalyst-containing adhesive-coated laminate obtained in the same manner as in Example 1 by thermocompression bonding. This plate was exposed and developed in the same manner as in Example 1, then heat treated at 150°C for 30 minutes, and plated with an electroless copper plating solution having the composition shown in Example 1. After washing with water, heat treatment was performed at 160°C for 30 minutes, and no change was observed even when immersed in a 260°C solder bath for 30 seconds. Furthermore, as a result of evaluating the solvent resistance in the same manner as in Example 1, no abnormality was observed even after immersion in trichlorethylene for 1 minute, but some scratches were observed when rubbed strongly with tissue paper after immersion in trichlorethylene for 5 minutes. It was done.

Claims (1)

[Scope of Claims] 1 (a) Mainly comprising (i) a diallylphthalate prepolymer having a molecular weight within the range of about 3,000 to about 20,000, (ii) a photopolymerizable monomer, and (iii) a photopolymerization initiator. A photosensitive resist film contained as a component is bonded to a laminate with a catalyst-containing adhesive, (b) a transparent negative is placed on the photosensitive resist film, and (c) a transparent negative is placed on the photosensitive resist film through the transparent negative. (d) developing the exposed patterned resist film without heat treatment or after heat treatment; (e) heat-treating and/or irradiating the developed resist film with ultraviolet light; (f) A method for producing a printed wiring board, which comprises: then electroless copper plating, and finally (g) ultraviolet irradiation and/or heat treatment.