JPS5945237B2 - Method for forming circuit elements using photoetching method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves applying a resin composition that can be cured by irradiating ultraviolet rays onto the surface of a metal plate, irradiating it with ultraviolet rays to form a cured film in a desired shape, and then applying the resin composition to the surface of the metal plate. The present invention relates to a method for forming a circuit element, which comprises plating the exposed surface of a plate to form a circuit element, and after removing a hardened film, etching the metal plate layer in this area.

The present inventors are currently investigating a method of applying a resin that can be crosslinked and cured by ultraviolet light in a conventional method of forming circuit elements using a photoetching method. The present invention was completed based on the discovery that the object could be achieved by using the following method.

The gist of the present invention is that the metal plate has a molecular weight of 200 to 2000, one or more acryloyl group or methacryloyl group per molecule, and an acid value of 30 to 300.
A resin composition consisting of 85 to 75% by weight of an unsaturated acid of KOH ~ number/V, 95 to 25% by weight of another crosslinking polymerizable unsaturated compound (B), and a photosensitizer is applied and irradiated with ultraviolet rays. After forming a hardened film in the desired shape, the exposed surface of the metal plate is plated to form a circuit element, and after the hardened film is removed, this portion of the metal plate layer is etched. The main feature lies in the method for forming circuit elements.

The unsaturated acid (2), which is a component of the resin composition used in carrying out the present invention, must have a molecular weight in the range of 200 to 2,000, and the resin containing an unsaturated acid with a molecular weight of less than 200 A cured film formed using a method similar to that of the present invention has insufficient adhesion to the metal plate, and the cured film may peel off during plating, or it may not be possible to form a circuit element by plating with a clear image. On the other hand, a resin composition containing an unsaturated acid with a molecular weight of more than 2000 has an extremely high viscosity, which impedes workability and makes it difficult to form a cured film in the desired shape. A cured film formed using such a resin composition is not preferable because the removability of the cured film with an alkaline solution required for forming a circuit element is reduced.

In addition, the acid value of the unsaturated acid must be 30 to 300, 0H to several f7, and the cured film formed using a resin composition containing an unsaturated acid with an acid value of less than 30 is It cannot be used in the present invention because the adhesion to the board and the film removability with an alkaline solution deteriorate, while a resin composition containing an unsaturated acid with an acid value greater than 300 has poor storage stability. Yes, it's not good.

It is necessary that the unsaturated acid used in the present invention contains at least one acryloyl group or methacryloyl group, and if such a compound is not used, good image forming properties will not be obtained in the formation of circuit elements by the method of the present invention. It is not possible to form a cured film with

Specific examples of unsaturated acids used in carrying out the present invention include the general formula [wherein R1 is H or CH3, R2 is a C1-10 alkylene group, or a polyethylene glycol residue or polypropylene glycol residue having 10 or less repeating units] , R3 is -
CH2CH2- -CH=CH represents a group selected from 1-'.

], and these compounds are co-formed with hydroxyalkyl acrylate or methacrylate.
- Can be produced by reacting with citric acid, fumaric acid, itaconic acid, maleic acid, phthalic acid, tetrahydrophthalic acid, trimellitic acid, or anhydrides thereof.

Other types of unsaturated acids (4) are contained in di- or triacryloyl or methacryloyl compounds obtained by addition-reacting acrylic acid or methacrylic acid with an epoxy compound that is a condensate of bisphenol A and epichlorohydrin. Compounds produced by addition reaction of an acid anhydride represented by (R3 is the same as above) to 1 mole of hydroxyl group, or addition of hydroxyalkyl acrylate or methacrylate with phosphoric anhydride or polyphosphoric acid. The reactant is acryloyloxyalkyl phosphate or methacryloyloxyalkyl phosphate.

Other crosslinking polymerizable unsaturated compounds used together with the unsaturated acid (4) in carrying out the present invention are compounds that form a dry film that is crosslinked and cured by ultraviolet irradiation, and in particular, at least one compound in the molecule. These are compounds having an acryloyl group or a methacryloyl group, and specific examples thereof include the following. (1) (meth)acrylic acid addition reaction products of polyepoxy compounds (10 polyfunctional polyester acrylates (4) polyfunctional monomers and monoacrylates such as polyethylene glycol di(meth)acrylate, polypropylene glycol di(
meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)
These include acrylate, trimethylolpropane tri(meth)acrylate, 2-hydroxypropyl(meth)acrylate, carbitol(meth)acrylate, and tetrahydrofurfuryl(meth)acrylate.

When carrying out the present invention, the unsaturated acid (A) 5 to 7
5% by weight and the crosslinked polymerizable unsaturated compound (8) 95-2
A resin composition containing 5% by weight or less of an unsaturated acid is used, and a cured film formed using a resin composition containing 5% by weight or less of an unsaturated acid has insufficient adhesion to the metal plate and has poor plating properties. This is undesirable because it reduces the film resistance, and it is also undesirable because the film cannot be easily removed with an alkaline solution.

When carrying out the present invention, a photosensitizer such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzophenone, Michler's ketone, diethoxyacetophene, etc. is added to the resin composition in an amount of 1 to 10% by weight. The wavelength is 200-800 nm, preferably 250-45 nm.
It is sufficient to irradiate near ultraviolet rays of 0 nm.

Furthermore, the resin composition of the present invention can be used as it is, but
Other suitable additives such as pigments and dyes may be added and used as necessary, but in order to more efficiently achieve the purpose of the present invention, especially to form circuits efficiently by screen printing, it is necessary to Pigments such as barite powder, precipitated barium sulfate, barium carbonate, clay, silica powder, fine silicic acid, talc, etc. are preferably added to the resin composition in a proportion of 70% by weight or less.

The circuit element of the present invention is formed by printing the resin composition on the metal plate surface of a metal laminate, which is a metal plate in which a metal thin film of copper, copper alloy, Kovar, permalloy, etc. is provided on an insulating substrate. Alternatively, print with a gravure printing machine, irradiate with ultraviolet rays, form a cured film negatively, that is, on areas where circuits should not be formed, and perform a treatment to prevent plating from being applied to those areas, and then apply a coating to the exposed areas of the metal plate. A positive plating process is performed to form a metal plating layer of copper, gold, silver, nickel, tin, etc. on the part where a circuit is to be formed, and then the unnecessary hardened film is removed with an alkaline solution with a pH of 9 or higher. For example, NaOH. KOH,
After dissolving and removing ammonia and primary to tertiary amines in water or a water-soluble organic solvent solution, the unnecessary portions of the metal plate layer are etched using an acid solution such as nitric acid, hydrochloric acid, or ferric chloride. By performing an etching process, a circuit element can be obtained.

Since the resin composition used in the present invention is solvent-free, there is no concern about air pollution during the process of forming a cured film.
In addition, since it is an ultraviolet irradiation method, there is no thermal deformation of the substrate, and it can be dried and cured quickly.The formed cured film has good adhesion to the metal plate, and there is no phenomenon such as peeling during the plating process. It has excellent plating properties, and it is easy to remove the hardened film that becomes unnecessary after the plating process, and it is possible to form such a hardened film, and its industrial value is extremely large.

The present invention will be explained in more detail below using examples.

Note that "Example Middle" means parts by weight.

Example 1 Unsaturated acid obtained by adding succinic anhydride to 2-hydroxyethyl acrylate (acid value 260K0Hη number/
t) 30 parts, 10 parts of acryloyloxyethyl phosphate (acid value 265K0Hη number/7), epoxy resin (
5 parts of benzoin methyl ether per 100 parts of a resin composition consisting of 40 parts of acrylic acid adduct of Syodyne 508 (manufactured by Showa Denko) and 20 parts of carbitol acrylate;
Printing ink (1) was obtained by kneading 30 parts of talc and 2 parts of phthalocyanine blue.

The printing ink (1) is printed on a copper foil laminate using a 250-mesh screen printer, and then irradiated with ultraviolet rays for 8 seconds using a high-pressure mercury lamp of 80 W/cm to form a cured film on areas where circuits should not be formed. was formed.

After that, silver plating is applied to the exposed parts of the copper plate to form a silver plating layer on the parts where the circuit will be formed, and then a hardened film is applied to the parts where the circuit will be formed.
The copper plate was dissolved and removed using a H9.5 NaOH solution, and the copper plate in this area was etched using ferric chloride to form a circuit element.

Incidentally, the characteristics of the cured film formed using the printing ink (1) obtained by the above method are shown in Attached Table 1.

Comparative Example 1 Among the constituent components of the resin composition of Example 1, an epoxy resin (Syodyne 508, Showa Denko company)
A printing ink () was obtained in the same manner as in Example 1, except that 70 parts of the acrylic acid adduct and 30 parts of carbitol acrylate were used.

The printing ink I [) was printed in the same manner as in Example 1, and UV rays were irradiated to form a cured film on areas where no circuit should be formed. Thereafter, in the same manner as in Example 1, a silver plating layer was formed on the exposed part of the copper plate, the hardened film was then removed, and this part of the copper plate was etched using ferric chloride to form a circuit element. .

The properties of the cured film formed using the printing ink (11) obtained by the above method are shown in Appendix Table 1.

Example 2 50 parts of unsaturated acid obtained by adding 100 parts of co-citric anhydride to 680 parts of acrylic acid adduct of epoxy resin (Syodyne 729, manufactured by Showa Denko), 10 parts of acryloyloxypropyl phosphate , 20 parts of tetrahydrofurfuryl acrylate, and 20 parts of carbitol acrylate were added with 6 parts of benzoin ethyl ether and 40 parts of talc to obtain a resin composition.

The resin composition was applied to the copper plating layer of the electroless copper plating laminate.
A desired pattern was applied to the portion where no circuit should be formed using a 50-mesh screen printer, and a cured film was formed by irradiating ultraviolet rays for 10 seconds. Next, electrolytic copper plating is applied to the exposed areas of the electroless copper plating, followed by electrolytic silver plating to form a positive silver plating layer on the areas where circuits are to be formed, and then the cured film is heated to pH 9.5. The electroless copper plating layer in unnecessary portions was etched using ferric chloride saturated water to form a circuit element.

The cured film formed using the resin composition (e) by the above method has good properties such as adhesion to the copper plating layer and alkaline solution removability, and forms an excellent circuit element. We were able to.

Claims (1)

[Scope of Claims] 1. An unsaturated acid having a molecular weight of 200 to 2000, having one or more acryloyl group or methacryloyl group in one molecule, and an acid value of 30 to 300 KOHmg/g on the surface of the metal plate. A resin composition consisting of 5 to 75% by weight of (A), 95 to 25% by weight of another cross-linked polymerizable unsaturated compound (B), and a photosensitizer is applied and irradiated with ultraviolet rays to form a cured film in the desired shape. After forming the metal plate, the exposed surface of the metal plate is plated to form a circuit element, and after the hardened film is removed, this portion of the metal plate layer is etched. Method. 2. The method for forming a circuit element according to claim 1, wherein a resin composition containing an extender pigment is used.