JPH0439664A - Method for forming gold-plated pattern - Google Patents

Abstract

PURPOSE:To enable a good pattern to be formed under severe conditions by using a dry film resist composed essentially of a specified photosensitive composition and forming a photosensitive resin interlayer to further reinforce the gold plating resistance of the resist. CONSTITUTION:This photosensitive resin interlayer has an acid value of 10 - 100, and the dry film resist is composed essentially of a monomer having at least one ethylenically unsaturated group and a photopolymerization initiator and as a binder resin a thermoplastic copolymer of styrene or its derivative represented by formula I or its ring-substituted derivative, and a hydroxy-alkyl acrylate, a hydroxyalkyl methacylate, and a monomer having a 3 - 15 C alpha, beta-unsaturated carboxylic group. In formula I, R is H, halogen, or 1 - 6 C alkyl, thus permitting a good gold-plated pattern free from plating defects and the like to be effectively obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of forming a gold plating pattern using an alkaline developable dry film resist. More specifically, the present invention relates to a method for forming a gold plating pattern that can be used in manufacturing electronic components such as printed wiring boards and hybrid ICs, and in metal processing by electroforming.

[Prior art] From the viewpoint of workability and performance, resists used for pattern formation in ordinary copper-solder plating, etc., are flexible photosensitive resists with a structure in which a photopolymerizable resin layer is sandwiched between a support film and a protective film. A dry film resist layer is widely used. Among such resists, alkaline-developable dry film resists that can be developed with a dilute alkaline aqueous solution are often used, particularly in view of work environment, environmental pollution, and cost.

On the other hand, in recent years, in order to improve the reliability of electronic components such as printed wiring boards and hybrid ICs, gold plating has been increasingly applied to the surfaces of conductors. This gold plating is generally performed by forming a resist pattern on the metal substrate before forming the conductor pattern, and electrically applying gold plating to the metal surface not covered by the resist. .

If an alkali-developable dry film resist is used to form this gold plating pattern, the above-mentioned advantages can be expected, but in reality various problems arise. In other words, in the general gold plating process, the current efficiency is low and various side reactions usually occur, which causes the film resist to partially peel off from the substrate, and the gold plating solution seeps into the peeled part, causing the conductor to Increasing the width or shortening the gap between conductors will cause serious problems.

Therefore, the present applicant previously filed an application for a photosensitive resin composition capable of solving this problem (Japanese Patent Application No. 107810 (1983) and Japanese Patent Application No. 26677 (1989)). If you use a dry film resist whose main component is this photosensitive resin composition,
Under industrial conditions, it is possible to obtain a good gold plating pattern without plating spots. however,
If this photosensitive resin composition is used alone, it will not be possible to increase the current density of gold plating to shorten the gold plating time to improve productivity, or to increase the current density of gold plating to improve electrical reliability. If the gold plating time is increased in order to increase the coating thickness, plating bleed may still occur.

In addition, as a method of improving the adhesion between the dry film resist and the base material, Japanese Patent Application Laid-open No. 154363/1983,
JP-A-59-226346, JP-A-60-984
No. 32, etc., discloses a method of providing an adhesive layer between a dry film resist and a substrate. However, even if a general alkaline-developable dry film resist is used based on these descriptions and an adhesive layer is provided between it and the substrate, it will not work under milder conditions, not to mention general industrial conditions. Even under certain conditions (low current density, short time), plating bleed occurs.

[Problems to be Solved by the Invention] The purpose of the present invention is to use an alkali-developable dry film resist that is excellent in various aspects such as workability and environmental protection.
Another object of the present invention is to provide a method that can efficiently form a good gold plating pattern on a metal substrate without plating spots even when gold plating is performed under harsh conditions at high current density or for a long time.

[Means for Solving the Problem] As a result of repeated studies to achieve the above object, the present inventors have completed the present invention. That is, the present invention includes (D) forming an alkali-developable photosensitive resin intermediate layer on a metal substrate; (ii) laminating an alkali-developable dry film resist on the photosensitive resin intermediate layer; and (iii)
(iv) forming a pattern by partially exposing and curing the photosensitive resin intermediate layer and the dry film resist, and then removing the unexposed areas with an alkaline developer; (iv) electrically gold plating the pattern; A method for forming a gold plating pattern comprising a step of plating, wherein the photosensitive resin intermediate layer has an acid value of 10 to 100, and the dry film resist contains the following components (A) to (C) ( A) - selected from the group consisting of styrenic compounds of the formula (1) (wherein R represents hydrogen, an alkyl group having 1 to 6 carbon atoms or a halogen atom) and their substituted derivatives; 3 to 30% by weight of one or more compounds, and one selected from the group consisting of alkyl acrylates in which the alkyl group has 1 to 6 carbon atoms, and hydroxyalkyl acrylates in which the hydroxyalkyl group has 2 to 6 carbon atoms. The above compounds 15-45% by weight
and alkyl methacrylates in which the alkyl group has 1 to 6 carbon atoms, and hydroxyalkyl groups in which the alkyl group has 2 to 6 carbon atoms.
one or more compounds selected from the group consisting of hydroxyalkyl methacrylates having 25 carbon atoms
60% by weight and α, β- with 3 to 15 carbon atoms
15 to 3 types of unsaturated lupoxyl group-containing polymers
A polymer obtained by copolymerizing a total amount of 100% by weight with 5% by weight,
Glass transition temperature measured by differential scanning calorimeter is 60-10
Thermoplastic polymer for binder in the range of 0°C 40~
70 parts by weight: (B) Containing 5% by weight or more of a monomer having one or more hydroxyl groups and two or more ethylenically unsaturated groups in one molecule, one or more ethylenically unsaturated groups in one molecule Group-containing monomer 25 to 50 parts by weight; (C) photopolymerization initiator
This is a method for forming a gold plating pattern, characterized in that the dry film resist is mainly composed of a photosensitive composition consisting of 0 to 10 parts by weight.

[Function] In the present invention, a dry film resist containing the above-mentioned specific photosensitive composition as a main component, which has particularly excellent gold plating resistance, is used, and a photosensitive resin intermediate layer is provided for the purpose of preventing peeling. This further strengthens the gold plating resistance of the resist, so these act synergistically, resulting in a dramatic improvement in the resist's gold plating resistance, allowing for the formation of good patterns even under harsh conditions. It becomes possible. Even without providing this photosensitive resin intermediate layer, it is possible to form a suitable gold plating pattern under normal industrial conditions by using the above-mentioned specific dry film resist, but it is possible to form a suitable gold plating pattern under normal industrial conditions. Under these conditions, good results as in the present invention cannot be obtained.

Below, the photosensitive composition [thermoplastic polymer for binder (A), monomer (B), photoinitiator (C), etc.] for constituting the alkali-developable dry film resist used in the present invention will be described. I will explain in detail.

The thermoplastic polymer for binder (A) needs to be contained in the photosensitive composition in an amount of 40 to 70 parts by weight, preferably 45 to 65 parts by weight. If the content is less than 40 parts by weight, the film forming properties of the resulting alkali-developable dry film resist will be impaired, sufficient film strength will not be obtained, and the composition of the resist will deteriorate when stored in a roll. So-called cold flow, which oozes out from between the support films over time, is likely to occur. On the other hand, if the content exceeds 70 parts by weight, the photocured film becomes brittle, and even when an alkali-developable photosensitive resin intermediate layer is used, the adhesion to the base material is impaired, resulting in insufficient metal resistance. It becomes impossible to obtain good glazing properties.

Moreover, the weight average molecular weight of the thermoplastic polymer (A) for binder is preferably in the range of 40,000 to 200,000. If the weight average molecular weight is less than 40,000, a cold flow phenomenon will occur when used as an alkali-developable dry film resist, and if the weight average molecular weight exceeds 200,000, the unexposed areas will not dissolve and development will not be possible. Otherwise, the development time is extremely long, resulting in a decrease in resolution.

Furthermore, the thermoplastic polymer (A) for the binder must have a glass transition temperature (Tg) of 60 to 100°C, more preferably 70 to 95°C, as measured by a differential scanning calorimeter (DSC). be.

If the Tg exceeds 100°C, a sufficiently flexible alkali-developable dry film resist cannot be obtained, and adhesion will be insufficient even with an alkali-developable photosensitive resin intermediate layer, resulting in poor gold plating resistance. decreases. On the other hand, if the temperature is lower than 60° C., the resin composition itself is too soft, causing a cold flow phenomenon when used as an alkali-developable dry film resist.

In order to obtain this thermoplastic polymer (A) for a binder, predetermined amounts of the following first to fourth polymerizable substances may be copolymerized.

The first polymerizable substance is a styrene-type compound represented by the following formula (I) (wherein R represents hydrogen, an alkyl group having 1 to 6 carbon atoms, or a halogen atom) and a ring-substituted compound thereof. It is one or more compounds selected from the group consisting of derivatives. In the ring-substituted derivative, the benzene ring may be substituted with a functional group such as a nitro group, an alkoxyl group, an acyl group, a carboxyl group, a sulfone group, a hydroxyl group, or a halogen. Among these substituents, single alkyl groups such as methyl and t-butyl are preferred. Moreover, 1 to 5 of these substituents may be substituted on the benzene ring.

The first polymerizable substance needs to be used in an amount of 3 to 30% by weight, preferably 5 to 25% by weight, based on the total amount of 100% by weight of the first to fourth polymerizable substances. If this amount is less than 3% by weight, sufficient chemical resistance and gold plating resistance cannot be obtained even if a photosensitive resin intermediate layer is used in combination.
On the other hand, if it exceeds 30% by weight, the dry film resist becomes too hard, and resist peeling is likely to occur even if a photosensitive resin intermediate layer is used in combination.

The second polymerizable substance is one or more compounds selected from the group consisting of alkyl acrylates in which the alkyl group has 1 to 6 carbon atoms and hydroxyalkyl acrylates in which the hydroxyalkyl group has 2 to 6 carbon atoms. be. Such compounds include methyl acrylate, ethyl acrylate, n-propyl acrylate,
is.

-propyl acrylate, n-butyl acrylate, 5
Examples include ee-butyl acrylate, tert-butyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and the like.

This second polymerizable substance needs to be used in an amount of 15 to 45% by weight, preferably 20 to 40% by weight based on the total amount of 100% by weight of the first to fourth polymerizable substances. used in If it is less than 15% by weight, a sufficiently flexible alkali-developable dry film resist will not be obtained, and even if a photosensitive resin intermediate layer is used in combination, adhesion to the substrate will be insufficient and the resistance to gold-plating will decrease. . On the other hand, if it exceeds 45% by weight, the resist resin will be too soft and will cause a cold flow phenomenon when used as a dry film resist.

The third polymerizable substance is one or more compounds selected from the group consisting of alkyl methacrylates in which the alkyl group has 1 to 6 carbon atoms, and hydroxyalkyl methacrylates in which the hydroxyalkyl group has 2 to 6 carbon atoms. It is. Such compounds include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, 1so-propyl methacrylate, n-
Examples include butyl methacrylate, 5ec-butyl methacrylate, tert-butyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and the like. This third polymerizable substance
It is necessary to use it in a range of 25 to 60% by weight out of 100% by weight of the total amount of the fourth polymerizable substance, preferably 30 to 55% by weight.

The fourth polymerizable material is one or more monomers containing α,β-unsaturated hydroxyl groups having 3 to 15 (preferably 3 to 6) carbon atoms. Acrylic acid and methacrylic acid are particularly preferred as the unsaturated carboxyl group-containing acid, and other examples include cinnamic acid, crotonic acid, sorbic acid, itaconic acid, propiolic acid, maleic acid and fumaric acid. It is also possible to use half esters or anhydrides thereof.

This fourth polymerizable substance needs to be used in an amount of 15 to 35% by weight, preferably 18 to 30% by weight, based on the total amount of 100% by weight of the first to fourth polymerizable substances. It will be done. If this amount is less than 15% by weight, development with an alkaline aqueous solution may not be possible, or the development time may be too long, resulting in a decrease in resolution. On the other hand, this amount is 35
If the weight percentage is exceeded, the development time becomes extremely short, development control becomes complicated and difficult to obtain a high-resolution pattern, and the water resistance of the cured part also decreases.

The photosensitive composition for a dry film resist used in the present invention includes a thermoplastic polymer (A) for a binder obtained by copolymerizing predetermined amounts of the first to fourth polymerizable substances as described above; This is a composition containing monomer (B) as a main component, which will be described in detail below.

This monomer (B) has one or more hydroxyl groups and two
5% by weight of monomers having at least 5 ethylenically unsaturated groups
or more (preferably 10% by weight or more), containing 1 per molecule
It is a monomer having one or more ethylenically unsaturated groups.

A monomer contained in this monomer (B) in an amount of 5% by weight or more,
That is, as compounds having one or more hydroxyl groups and two ethylenically unsaturated groups in one molecule (hydroxyl group-containing crosslinkable monomer), glycerin di(meth)acrylate, trimethylolethane di(meth) acrylate, trimethylolbroban di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta( Examples include meth)acrylate, inocyanuric acid triethylol di(meth)acrylate, and (meth)acrylic acid addition compounds with a concentration of 2 mm per epoxy resin molecule, and one or more of them may be used in combination.

This monomer (B) contains at least 5% by weight of the above-mentioned hydroxyl group-containing crosslinkable monomer, and also contains one ethylenically unsaturated group per molecule. It contains one or more of the following monomers. Examples of the lt form having one or more ethylenically unsaturated groups in one molecule include n-butoxymethylacrylamide, 1so-butoxymethylacrylamide, phenoxyjethoxy(meth)acrylate, and polyethylene glycol oxy(meth)acrylate. , polypropylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, 1,6-hexanethiol di(meth)acrylate, neobentyl glycol di(meth)acrylate, trimethylolpropane tri (meth)acrylate, 2.2-bis[4-
(meth)acroxypolyethoxyphenyl]propane,
2.2-bis[4-(meth)acroxypolypropyleneoxyphenyl]propane, acryloxypivalyl acryloxybiparate, trimethylolpropane tris[
Polyethoxy(meth)acrylate], trimethylolpropane tris[polypropyleneoxy(meth)acrylate], triethyloltri(meth)isocyanurate
Examples include acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and urethane(meth)acrylate.

In the monomer (B), the content of the hydroxyl group-containing crosslinkable monomer is 5
If it is less than % by weight, sufficient gold plating resistance cannot be obtained. The detailed mechanism has not been fully elucidated, but because this compound has one or more hydroxyl groups and two or more ethylenically unsaturated groups in one molecule, gold plating occurs when the resist is cured. The photosensitive resin intermediate layer is sufficiently cross-linked to prevent penetration of the coating liquid, and the hydroxyl groups in the molecules have an appropriate acid value (10 to 100). It is assumed that the gold plating resistance is improved.

Monomer (B) needs to be contained in the photosensitive composition in an amount of 25 to 50 parts by weight, preferably 30 to 45 parts by weight. If the amount is less than 25 parts by weight, it will not cure sufficiently, resulting in poor chemical resistance and gold plating resistance, while if it exceeds 50 parts by weight, cold flow will occur when used as an alkali-developable dry film resist. Moreover, the cured product becomes hard and brittle, and even if a photosensitive resin intermediate layer is used in combination, it becomes easy to peel off from the substrate.

In the method of the present invention, when the dry film resist is partially exposed to ultraviolet irradiation, the photosensitive composition constituting the dry film resist is further added with a photopolymerization initiator (
It is desirable to contain C). The content thereof is preferably o, i to 10 parts by weight in the photosensitive composition. This amount is 0.
If it is less than 1 part by weight, sufficient photocuring may not occur, and if it exceeds 10 parts by weight, it may become thermally unstable. However, when partial exposure is performed by electron beam irradiation,
The photopolymerization initiator (C) may not be included.

Examples of the photopolymerization initiator (C) include benzophenone, Michler's ketone, 4.4°-bis(diethylamino)benzophenone, t-butylanthraquinone,
-Ethylanthraquinone, thioxanthone, hendiyne alkyl ethers, pencil ketals, etc. These can be used alone or in combination of two or more.

In addition to the above, components such as adhesion promoters, thermal polymerization inhibitors, dyes, plasticizers, and fillers may be added to the photosensitive composition constituting the alkaline-developable dry film resist detailed above. You can also.

Next, the alkali-developable photosensitive resin intermediate layer used in the present invention will be described in detail. The acid value of this photosensitive resin intermediate layer must be within the range of 10 to 100 (preferably 15 to 95). When the acid value is less than 10, it becomes difficult to develop with an alkaline aqueous solution, and when it exceeds 100, the water resistance of the cured portion of the intermediate layer decreases.

This photosensitive resin intermediate layer is not particularly limited as long as it is a layer made of a photosensitive resin having an acid value of 10 to 100, but it may have the same structure as the alkali-developable dry film resist described in detail above. It is preferably a photosensitive composition (i.e., a composition comprising a thermoplastic polymer for binder (A), a monomer (B), a desired photopolymerization initiator (C), etc.); in that case, The acid value of the photosensitive resin intermediate layer is preferably 20 or more. In addition to these, a mixture comprising a crosslinkable oligomer having a carboxyl group, a crosslinkable monomer, and a photopolymerization initiator, as described in Japanese Patent Application No. 61-47889, can also be used.

In the method of the present invention, by using such an alkali-developable photosensitive resin intermediate layer and an alkali-developable dry film resist in combination, the gold plating resistance under severe conditions is significantly improved. It is desirable that this photosensitive resin intermediate layer contains one or more compounds selected from the group consisting of tetrazole, triazole, thiazole, imidazole and derivatives thereof, mainly for the purpose of acting as an adhesion promoter. When this adhesion promoter is included, the gold plating resistance is further improved.

The content of this adhesion promoter is as follows:
Desirably 0.005 to 5 parts by weight, 0.01 parts by weight
-1 part by weight is more preferred. If this amount is less than 0.005 parts by weight, the gold plating resistance may not be sufficient for long periods of time and at high current density. Dissolution may be difficult.

Examples of the adhesion promoter include 1-phenyltetrazole, 5-phenyltetrazole, 5-aminotetrazole, 5-amino-1-methyltetrazole, 5-amino-2-phenyltetrazole, 5-mercapto-1-phenyltetrazole, 5-mercapto-1-methyltetrazole, benzotriazole, 3-amino-1,2,
4-triazole, 4-amino-1,2,4-triazole, benzothiazole, 2-mercaptobenzothiazole, 2-aminothiazole, 2-phenylimidazole, 4-phenylimidazole, benzimidazole,
Examples include 2-aminoimidazole and 2-mercaptobenzothiazole. Particularly preferred are tetrazoles and their derivatives, such as 1-phenyltetrazole, 5-phenyltetrazole, 5-aminotetrazole, 5-amino-1-methyltetrazole, 5-
Amino-2-phenyltetrazole, 5-mercapto-
Examples include 1-phenyltetrazole and 5-mercapto-1-methyltetrazole. In addition, these may be used alone or in combination of two or more.

Next, aspects of the method of the present invention will be explained in detail along its steps.

In the present invention, first, an alkali-developable photosensitive resin intermediate layer is formed on a desired metal substrate [step (i)].

As detailed above, this photosensitive resin intermediate layer is preferably formed using a photosensitive composition having the same structure as the alkaline developable dry film resist. After diluting with an organic solvent to obtain a resin solution, it may be applied onto a metal substrate and dried or semi-dried to form an alkali-developable photosensitive resin intermediate layer. Alternatively, a solvent-free alkali-developable liquid photosensitive resin containing no ordinary organic solvent may be applied onto a metal substrate to form an alkali-developable photosensitive resin intermediate layer as it is without drying. Various methods can be used to apply these solvent-type or solvent-free photosensitive compositions onto a metal substrate, such as a roll coater method, a blade coater method, a lot coater method, a curtain coater method, Screen printing methods, dipping methods, etc. can be used. Various methods can be used to dry or semi-dry the alkali-developable photosensitive resin solution, such as hot air drying, vacuum drying, far infrared drying, and the like. Further, when drying, it may be completely dried or may be in a semi-dry state to the extent that it does not solidify.

Although there is no particular limitation on the thickness of the alkali-developable photosensitive resin intermediate layer, the preferred thickness is 1 to 10 μm. For this photosensitive resin intermediate layer, from the viewpoint of adhesion to the dry film resist, etc., it is preferable to use a solution prepared by diluting the same composition as the dry film resist described above with a common organic solvent. Further, when such a composition is used and the thickness of the intermediate layer is 5 μm or more, the intermediate layer also satisfactorily functions as a gold plating resist. In addition, when forming the photosensitive resin intermediate layer to a thickness of 5 μm or more, it is preferable to dry it sufficiently so that the amount of residual solvent is less than 5% by weight so that the gold plating resistance does not deteriorate.

Next, the alkali-developable dry film resist described above is laminated on the thus formed photosensitive resin intermediate layer [step (ii)]. Various methods can be used for this lamination method, such as normal pressure hot roll crimping, vacuum hot roll crimping, and vacuum hot press crimping, but the most common method is hot roll crimping under normal pressure. In addition, when using an alkali-developable photosensitive resin intermediate layer as in the present invention, the lamination should be performed at a lower temperature than the temperature when laminating the alkaline-developable dry film resist alone on the substrate. I can do it.

After this dry film resist is laminated, the photosensitive resin intermediate layer and the dry film resist are partially exposed and cured, and the unexposed parts are removed with an alkaline developer to form a pattern (step (iii)).

Various methods known in the art can be used for this partial exposure and alkali development. For example, for exposure, an ultraviolet exposure method, an electron beam exposure method, a laser exposure method, etc. can be used, and as a method for selectively performing exposure, a method using a photomask, a direct imaging method, etc. can be used. . As the alkaline developer, for example, a sodium carbonate aqueous solution, a sodium phosphate aqueous solution, a potassium carbonate aqueous solution, etc. can be used, and as a developing method, a dipping method, a spray method, a combination of both, etc. can be used. That is, this step (i ii) is a general step for forming a desired pattern on the resist, and is not particularly limited in the present invention.

Next, the resist pattern of the laminate thus obtained is electrically plated with gold [step (iV)].

In this gold plating step, various commercially available acidic gold plating solutions can be used. Commercially available products include, for example, Autoronex CI, Autoronex Nl, and Aurobond T manufactured by Nippon Electroplating Engineers.
N: Trade name Aurobrite H5 and Temperresist-7T manufactured by Nippon Kojundo Kagaku ■; and Japan Ronal ■
You can use the product name Ouro Glow P C171 manufactured by Manufacturer.

Furthermore, when performing gold plating, the laminate that has undergone step (iii) may be directly plated, or plating with various other metals may be performed prior to gold plating. for example,
- nickel plating as the next plating and gold plating as the second plating, - copper plating as the second plating,
Examples include a method in which nickel plating is performed as secondary plating and gold plating is performed as tertiary plating.

The gold-plated pattern obtained by the method of the present invention described above can be used as an electroformed product as it is, but it is also useful to further perform desired etching to form a pattern for a printed wiring board.

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples.

45 parts by weight of isopropyl alcohol and 105 parts of methyl ethyl ketone for alkaline dry film resist
A predetermined amount of the thermoplastic polymers A to H for binders shown in Table 1 were added to a mixed solution consisting of Ll parts, and the mixture was sufficiently stirred until dissolved.

Thereafter, predetermined amounts of crosslinkable monomers, photopolymerization initiators, and dyes shown in Table 1 were added and thoroughly stirred. The obtained composition was applied onto a polyester film having a thickness of 25 scales and a width of 360 mm using a blade coater in a coating width of 340 mo+. Next, hot air was fed as a free flow through a crat-type dryer having a width of 4000+111 mm, a height of 100 cm, and a length of 8 m to obtain a dry coating thickness of 50 mm. The coating speed at this time is 2
．． 5 m/min, and the hot air temperature was 90°C. Next, a 35-thick polyethylene protective film was laminated on the dried coating film to obtain an alkali-developable dry film resist I-■. Note that the resist that falls within the scope of the present invention is I
~■.

A mixture of a thermoplastic polymer for a binder, a crosslinkable monomer, and a photopolymerization initiator (and adhesion promoter) listed in Table 2 of an alkali liquid,
A predetermined amount of the mixture was mixed with a solvent consisting of 105 parts by weight of isopropyl alcohol and 845 parts by weight of methyl ethyl ketone, and thoroughly stirred to obtain a homogeneous solution, thereby obtaining alkali-developable photosensitive resin solutions a to g.

A crosslinkable oligomer having a carboxyl group, a crosslinkable monomer, and a photopolymerization initiator are mixed at the proportions shown in Table 3, stirred thoroughly until uniform, and subjected to solvent-free alkaline development. liquid photosensitive resin h
−j was obtained.

1-8, 1-10 Using a dip coating device, a rough-polished copper clad laminate was coated with the previously prepared alkali-developable photosensitive resin solution (Table 1).
2:axg) for a few seconds, then pulled up at a pulling speed of 2.5cn+/mm, dried at 80°C for 1 minute,
An alkali-developable photosensitive resin intermediate layer having a film thickness of 2 μm was formed. On top of this intermediate layer, the previously prepared alkali-developable dry film resist (Table 1: B to M) was laminated, partially exposed using a photomask, developed, washed with water, -
Next plating was performed (nickel plating), water washing, and secondary plating (gold plating). These conditions are shown in Table-4. After completing this gold plating, washing with water was performed, and then the alkali-developable dry film resist and the alkali-developable photosensitive resin intermediate layer were peeled off with a 3% by weight aqueous sodium hydroxide solution, and then
The copper was etched by immersion in a wt % ammonium persulfate aqueous solution. After this, the state of the plating was visually observed, and the results are shown in Table 5.

9-10, H" 11 The thickness of the previously prepared solvent-free alkali-developable liquid photosensitive resin (Table 3: h-j) was applied to the caulked and polished copper-clad laminate using a Baker applicator. was coated so as to have about two scales to form an alkali-developable photosensitive resin intermediate layer.Next, in the same manner as Examples 1 to 8 and Comparative Examples 1 to 10, the procedure shown in Table 4 was followed. , the alkali-developable dry film resist listed in Table 1 was laminated, exposed and
It was developed and gold plated. The evaluation results are shown in Table-5.

Directly laminate an alkali-developable dry film resist on a pre-polished copper clad laminate according to the procedure shown in Table 4 without forming an alkaline-developable photosensitive resin intermediate layer, Gold plating was performed by exposure and development. The evaluation results are shown in Table-5.

Table 3 (Solvent-free alkaline developable liquid photosensitive resin) (Numbers in the table indicate parts by weight or oxidation number) Table 4 Table 5 According to the method for forming the gold plating pattern, an alkaline developable dry film resist, which is excellent in various aspects such as workability and environmental protection, is used, and the gold plating pattern can be formed under harsh conditions such as high current density and long periods of time. Even when plating is performed, a good gold plating pattern without plating spots etc. can be formed extremely efficiently on a metal substrate.

Therefore, the method for forming a gold plating pattern of the present invention can be used in various applications such as manufacturing electronic components such as printed wiring boards and hybrid ICs, and metal processing by electroforming.
In particular, it is very useful in terms of improving productivity and electrical reliability.

Applicant: Mitsubishi Rayon Co., Ltd.

Claims (1)

[Claims] 1) (i) forming an alkali-developable photosensitive resin intermediate layer on a metal substrate; (ii) forming an alkali-developable dry film on the photosensitive resin intermediate layer; a step of laminating resist; (iii)
After partially exposing and curing the photosensitive resin intermediate layer and the dry film resist, removing the unexposed portions with an alkaline developer to form a pattern; (iv) electrically plating the pattern with gold; A method for forming a gold plating pattern, the photosensitive resin intermediate layer having an acid value of 10 to 100, and the dry film resist containing the following components (A) to (C) (A) General formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R represents hydrogen, an alkyl group having 1 to 6 carbon atoms, or a halogen atom) and its ring 3 to 30% by weight of one or more compounds selected from the group consisting of substituted derivatives; alkyl acrylates in which the alkyl group has 1 to 6 carbon atoms; and hydroxyalkyl in which the hydroxyalkyl group has 2 to 6 carbon atoms. 15 to 45% by weight of one or more compounds selected from the group consisting of acrylates, alkyl methacrylates in which the alkyl group has 1 to 6 carbon atoms, and hydroxyalkyl methacrylates in which the hydroxyalkyl group has 2 to 6 carbon atoms. 25 to 60% by weight of one or more compounds selected from the group consisting of 15 to 35% by weight of one or more α,β-unsaturated carboxyl group-containing monomers having 3 to 15 carbon atoms
A polymer obtained by copolymerizing a total amount of 100% by weight with % by weight,
Glass transition temperature measured by differential scanning calorimeter is 60-10
Thermoplastic polymer for binder in the range of 0°C 40-7
0 parts by weight: (B) Containing 5% by weight or more of a monomer having one or more hydroxyl groups and two or more ethylenically unsaturated groups in one molecule, one or more ethylenically unsaturated groups in one molecule Monomer 2 having a group
5 to 50 parts by weight; and (C) 0 to 10 parts by weight of a photopolymerization initiator. 2) The alkali-developable photosensitive resin intermediate layer contains one or more compounds selected from the group consisting of tetrazole, triazole, thiazole, imidazole, and derivatives thereof.
The method for forming a gold plating pattern according to claim 1, wherein the amount is 0.005 to 5 parts by weight in 100 parts by weight of the photosensitive resin intermediate layer.