JPH0453187A - Manufacture of printed board - Google Patents

Abstract

PURPOSE:To prevent deterioration in physical properties by emitting a UV light except a specific short wavelength component or less to a desired part, developing it, forming a photosensitive solder resist film, and precipitating copper in a through hole and on a desired part with chemical copper plating solution. CONSTITUTION:A through hole is formed at a desired position of a copper-plated laminated board, activated therein, and a part to become a rotary pattern is covered with resist. Then, a circuit is formed by etching, the resist is removed, the board formed with a circuit is coated with solder resist having plating resistance, preliminarily dried, and a UV light except a short wavelength component of at least 300nm or less is emitted to a desired part. The light is emitted to the desired part in vacuum of 10Torr or less of partial oxygen pressure of the resist surface and inert gas atmosphere, and copper is precipitated in the hole and on the desired part with chemical copper plating solution. Thus, dissolving of the resist in the solution can be prevented, and deterioration of the physical properties of the copper due to dissolving of the resist is prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a printed circuit board, and in particular to a method of forming a plating-resistant solder resist on desired parts and then connecting through-hole parts with chemical copper plating. This invention relates to improvements in the manufacturing method of high-density printed circuit boards.

[Conventional technology]

An example of a conventional printed circuit board manufacturing method is Japanese Patent Application Laid-Open No. 62-2
It is as described in Publication No. 95487, and
As shown in the figure, holes are drilled in predetermined parts of the copper-clad laminate, the inside of the through-hole is then activated with a catalyst, and the circuit pattern is then etched to form a photosensitive solder resist layer on the desired part including the copper foil circuit. , this substrate was immersed in a chemical copper plating solution, and chemical copper plating was deposited only on the through-hole portions.

It is well known that this manufacturing method is suitable for mass manufacturing inexpensive, reliable, and high-density printed boards, but it requires harsh chemical conditions to realize this method. It is also well known that it is essential to use a resist that does not cause problems during the process of immersing the substrate in a chemical steel plating solution for a long time.

[Problem to be solved by the invention]

The main problems that occur in the plating process are, firstly, that the chemical copper plating causes the circuit fJR foil and the resist to peel off, making it no longer function as a solder resist. JP-A-62-295487 states that a resist with a special composition that has plating resistance should be used.

The second problem is that the resist itself dissolves into the chemical copper plating, degrading the physical properties of the plating film and reducing the connection reliability of the through holes. This problem does not become apparent when the number of substrates put into the plating solution is small, and its effects tend to become more pronounced as the number of substrates increases.In mass production of substrates, it is a serious problem that deteriorates the performance of the substrates. Ta.

The above-mentioned conventional technology has not solved this second problem.

An object of the present invention is to provide the ability to manufacture printed circuit boards without deteriorating physical properties due to dissolution in a chemical copper plating solution.

Another object of the present invention is to provide an inexpensive and highly reliable printed circuit board.

[Means to solve the problem]

The structure of the printed circuit board manufacturing method of the present invention to solve the above problems is to form a through hole at a desired position in a copper-clad laminate, activate the inside of the through hole, and form a circuit pattern with a resist. A circuit is formed by etching, the resist is removed, a plating-resistant solder resist is applied to the circuit-formed circuit board, pre-dried, and UV ( UV) light is irradiated to the desired area, and/or UV light is irradiated to the desired area under a vacuum with an oxygen partial pressure of 10 Torr or less and an inert gas atmosphere, and the through-hole area and the desired area are removed using a chemical copper plating solution. This is because copper is deposited on top of the parts.

[Effect]

We investigated measures to prevent the photosensitive solder resist from eluting into the chemical copper plating solution during the plating process during the manufacturing process of printed circuit boards.

First, it is essential to select the composition of the resist material to be used, but we devised the following as an improvement to the manufacturing method.

That is, in the step of exposing the resist surface using UV (ultraviolet) light before the chemical copper plating step, (1) UV light is used excluding UV components with short wavelengths of 300 nm or less.

(2) UV light irradiation is carried out under a vacuum with an oxygen partial pressure of 10 Torr or less and in an inert gas atmosphere at the resist surface.

This will be explained in detail below, divided into (1) and (2).

(1) The photodecomposition effect of short-wavelength UV components is presumed to be due to the fact that high-energy UV light is absorbed by the resist and the resist skeleton is radically cut. Such photocleavage is thought to be caused by Norrish type photocleavage involving carbonyl groups.

Exposure to UV light excluding such short wavelength components should be performed in each step of exposing to UV light in the resist forming process.

To remove short wavelength components of 300 nm or less from UV light during exposure, technical means well known to those skilled in the art can be used. Specifically, it is the selection of the UV light source and filter. For example, a UV light source including a wide wavelength component from about 250 nm to visible light, such as a high-pressure mercury lamp or a metal halide lamp, may be used, and a filter that cuts components of 300 nm or less may be used. Economically available U
Although the V light source contains a large amount of short wavelength components of about 250 nm, it is obvious that if a special light source that does not contain such short wavelength components is used, there is no need to use a filter. The acid component has a short wavelength of 300 nm or less, and as described above, cuts the chemical bonds on the resist surface, so the degree of crosslinking on the resist surface decreases. As a result, the resist becomes significantly more soluble in the alkaline chemical steel plating solution.

Chemical steel plating is an autocatalytic reaction whose main reactions are the oxidation reaction of formaldehyde and the reduction reaction of copper (II) ions using the catalytic activity of the copper surface. Such reactions tend to be significantly affected by the adsorption of trace amounts of organic matter contained in the plating solution onto the copper plating surface.

Therefore, when the resist is dissolved in the plating solution, the decomposition products of the resist due to photo-cutting and the unreacted organic matter in the resist become trapped in the plating solution, which adversely affects the deposition of chemical copper plating, which involves delicate catalytic reactions. It is estimated that the physical properties of copper will be significantly deteriorated.

In the present invention, since the resist is formed using UV light that does not contain components of 300 nm or less, dissolution of the resist in the plating solution can be prevented, and the problem of deterioration of physical properties of copper due to resist dissolution, that is, through-holes, can be prevented. This solves the reliability problem.

(2) If the area of the resist immersed in the plating solution is large, the connection reliability of the through holes will decrease, making mass production of substrates impossible. This is a mechanism in which when forming a photosensitive solder resist film, only desired areas are irradiated with UV light, and only the irradiated areas are cured by radicals generated by the photopolymerization initiator in the resist components. However, the generated radicals are extremely likely to react with oxygen, and as a result, the radicals disappear without initiating polymerization. That is, the higher the oxygen concentration on the resist surface when exposing the photosensitive resist, the more uncured the resist becomes. Furthermore, since the surface of the resist comes into contact with a high oxygen concentration, the resist becomes uncured, and even in the UV light irradiated area, the resist bleeds out from the surface into the developer during the next development step. Furthermore, a semi-hardened portion of the resist that is difficult to dissolve with a developer is exposed on the surface. Particularly, semi-hardened resists are likely to undergo hydrolysis during subsequent immersion into the plating solution, and as a result, it is thought that the resist dissolves into the plating solution.

Chemical steel plating is an autocatalytic reaction that utilizes the catalytic activity of the copper surface to perform an oxidation reaction of formaldehyde and a reduction reaction of (n) ions. Such reactions tend to be significantly affected by the adsorption of minute amounts of organic matter contained in the plating solution onto the copper surface. Therefore, when the amount of resist dissolution at this time increases, it inhibits the plating reaction and causes deterioration of the plating film. In other words, this leads to a decrease in through-hole connection reliability. Therefore, we newly discovered that reducing the amount of resist dissolution in an alkaline plating solution can be achieved by reducing the oxygen concentration on the resist surface during exposure, and the oxygen partial pressure on the resist surface was reduced to 10 Torr.
Mass production is fully possible under the following high vacuum and inert gas atmosphere.

Hereinafter, the materials used in the present invention will be explained in detail.

The photosensitive solder resist composition used in the present invention is ortho,
It comprises a prepolymer of diallyl ester of iso or terephthalic acid. Such prepolymers are
It is also called a β-polymer, and its detailed properties and manufacturing method are described, for example, in "Diallyl Phthalate Resin" by Naoyoshi Yoshimi, Nikkan Kogyo Shimbun Sha Series (1972). It can also be obtained as a prepolymer, for example from Osaka Soda KK.

The molecular weight of the prepolymer essential to the photosensitive solder resist used in the present invention is preferably about 3,000 to 30,000, but is not limited thereto. Furthermore, the statement that a prepolymer is included does not preclude the inclusion of a small amount of a diallyl phthalate monomer or a three-dimensional network structure γ-polymer that remains or is produced during the synthesis of the prepolymer.

Furthermore, the photosensitive solder resist composition used in the present invention is
It contains a polyfunctional unsaturated compound having at least two or more ethylene bonds in its molecule. Such a compound can be obtained, for example, by an esterification reaction between an unsaturated carboxylic acid and a divalent or higher polyhydroxy compound. Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, etc., and examples of divalent or higher polyhydroxy compounds include ethylene glycol, propylene glycol, triethylene glycol, hydroquinone, pyrogallol, etc. Can be mentioned. Compounds obtained by the esterification reaction between such unsaturated carboxylic acids and polyhydroxy compounds include diethylene glycol diacrylate and polyethylene glycol diacrylate.

Neopentyl glycol diacrylate, 1.5bentanediol diacrylate, 1.6 hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, diethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, 1.3 butanediol dimethacrylate Diacrylate, dimethacrylate compounds represented by tri, tetra, dipentaerythritol, etc.
Polyhydric acrylates and methacrylate compounds such as pentaacrylate or methacrylate, sorbitol tri, tetra, penta, hexaagelylate or methacrylate, oligoester acrylate, oligoester methacrylate, etc., and epoxy resins and acrylic acid and methacrylic acid. Examples include epoxy (meth)acrylate produced by the reaction of

The above examples do not limit the addition of monofunctional unsaturated compounds, and mixtures of polyfunctional unsaturated compounds can also be used if necessary.

Furthermore, the photosensitive solder resist composition used in the present invention is
It contains a photopolymerization initiator.

Examples of the photopolymerization initiator include acetophenone, acetophenone derivatives, benzophenone, benzophenone derivatives, Michler's ketone, and benzyl.

Benzoin, benzoin alkyl ether, benzyl alkyl ketal, thioxanthone, thioxanthone derivative, anthraquinone, anthraquinone derivative, tetramethylthiuram monosulfide, l-hydroxycyclohexylphenyl ketone, 2-methyl-1-(4-
Examples include α-aminoketone compounds represented by (methylthio)phenylcou 2-morpholino-propene-1. If desired, mixtures of photoinitiators can be used. Furthermore, if necessary, it is also possible to use an amine compound or the like that sensitizes the action of the photopolymerization initiator.

Further, the photosensitive solder resist used in the present invention may contain an appropriate amount of an epoxy resin and a curing agent in order to prevent the solder resist from peeling off on the copper foil in an alkaline plating solution.

Epoxy resins have an average of two or more epoxy groups per molecule, such as bisphenol A,
Polyglycidyl ether or polyglycidyl ester, novolag-type phenol obtained by reacting a polyhydric phenol such as halogenated bisphenol A, catechol, resorcinol, or a polyhydric alcohol such as glycerin with epichlorohydrin in the presence of a basic catalyst. Examples include epoxy novolak obtained by condensing a resin and epichlorohydrin, epoxidized polyolefin epoxidized by a peroxidation method, epoxidized polybutadiene, dicyclopentagenated oxide, and epoxidized vegetable oil.

Further, as the curing agent, a mixture of a diaminotriazine-modified imidazole compound and dicyandiamide is suitable for preventing peeling of the solder resist.

As the diaminotriazine-modified imidazole compound used in the present invention, a compound represented by the following general formula and having latent curability with respect to an epoxide compound can be used.

H,N\2N/H,N (R is an imidazole compound.) For example, 2,4-diamino-6(2'-methylimidazole-(1'))ethyl-s-triazine, 2,4- Diamino-6(2'-ethyl-4'-methylimidazole-(1'))ethyl-3-triazine, 2,4-diamino-6(2'-undecylimidazole=(1'))ethyl-s- triazine or 2,4-diamino-6(
Examples include 2'-methylimidazole (1'))ethyl-3-triazine/isocyanuric acid adduct.

Furthermore, the resist composition used in the present invention contains an organic solvent as a diluent, a coloring agent, an antifoaming agent, a filler,
A thixotropic agent may also be included.

Suitable examples of organic solvents include cellosolve, cellosolve acetate, methyl cellosolve, butyl cellosolve, calpitol, methyl carpitol butyl carpitol,
High boiling point solvents such as terpineol are preferred, but acetone,
Methyl ether ketone.

This does not mean that ethanol etc. cannot be used.

As the colorant, a coloring material such as phthalocyanine green or phthalocyanine blue may be used as appropriate.

As the antifoaming agent, an organosilicon compound containing a siloxane bond, typified by silicone oil, is preferably used.

The filler is added to the resist composition as an inorganic filler, and fine powders of silica, alumina, talc, etc. are preferably used.

As the thixotropic agent, ultrafine powdered silica is preferably used as it contributes to improving the viscosity of the resist composition, particularly the thixotropy.

Preferred composition ratios for constituting the photosensitive solder resist used in the present invention are: 1 to 30 parts by weight of a polyfunctional unsaturated compound, 0.5 to 20 parts by weight of a photopolymerization initiator, to 100 parts by weight of diallyl phthalate resin; The amount of the epoxy resin is 5 to 30 parts by weight, the amount of the diaminotriazine-modified imidazole compound is 1 to 20 parts by weight, and the amount of dicyandiamide is 0.5 to 15 parts by weight per 100 parts by weight of the epoxy resin.

The lower limit of the composition is determined so that the exposure sensitivity of the resist is not insufficient, and the upper limit is determined so that the contact exposure, plating resistance, and heat resistance of the resist described below can be ensured.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 4.

FIGS. 1(a) to 1(f) are process diagrams of a printed circuit board manufacturing method. In FIG. 1, 1 is a glass epoxy double-sided copper-clad laminate, 2' is copper foil, 2 is a circuit and land, and 3
4 is a through hole, 4 is a photosensitive solder resist layer, 5 is an activated catalyst, 6 is a through-hole copper plating, and 7 is an etching resist.

The manufacturing process will be explained in detail below.

As shown in FIG. 1(b), through-holes 3 are drilled in a glass epoxy double-sided copper-clad laminate l coated with a 35 μm copper foil 2' as shown in FIG. 1(a), and the Sn/Pd catalyst is The activated catalyst 5 was applied by immersing it in a liquid. Next, as shown in FIG. 1(C), a dry film 7 is laminated on the substrate by a conventional method, and a land and a circuit 2 are formed on the substrate by a tenting method consisting of steps of exposure, development, etching, and peeling. The procedure was as shown in FIG. 1(d).

Next, as a pre-printing treatment of the photosensitive solder resist,
The substrate was immersed in an aqueous IN hydrochloric acid solution for 30 seconds, and then the entire surface of the substrate was puff-polished, washed with water, and dried. The following photosensitive solder resist composition was used.

(a) Diaryl phthalate resin...65
g (average molecular weight 7000, isotap. Osaka Soda KK
(B) Trimethylolpropane trimethacrylate...
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・2.6g (c) Epoxy resin (Epikoat 828. Ebisu type epoxy resin, manufactured by Yuka Shell Epoxy KK) ・・・・・・・・・10g (d) 2-Methyl- 1[4-(methyl)phenyl2
-morpholino-propane-1...1.3g (e)dicyandiamide......
...0.7g) 2.4-diamino-6 [2
' ~ Methylimidazole-(1'))ethyl-s-triazine 0.25 g (g) Ultrafine silicon powder Aerosil 200 200・・・
0.5g (manufactured by Nippon Aerosil KK) (chi) Silicone oil 5R-203...
...1.5g (manufactured by Toshi Silicone KK) (su) Phthalocyanine Green ......
... o, os g (nu) Ethylene glycol monobutyl ether ......44 g Among the above compositions, (a) to (d) were mixed and heated and stirred at about 80°C for 30 minutes. . Further, (E) to (N) were kneaded using a three-roll mill. After bringing (a) to (d) to room temperature, (
Appropriate amounts of (v) to (v) were added to obtain a photosensitive plating-resistant solder resist.

Next, the photosensitive solder resist composition was printed on the entire surface of the circuit-formed printed wiring board using a screen printing machine using a 180 mesh stainless steel screen plate, and heated at about 80°C.
Pre-drying was carried out for 30 minutes.

After drying, the resist surface was solidified and a negative mask could be attached to it.

Next, as a first exposure, the film was exposed to ultraviolet light through a negative mask for 0.5 to 2 minutes using a 400W high-pressure mercury lamp, and then spray-developed using 1.1.1-trichloroethane. At this time, components of 300 nm or less were removed by using an organic film material for the negative mask.

After development, a heat curing treatment was performed at 150° C. for 30 minutes, and then a second exposure was performed using a belt type exposure device using a metal halide lamp at 1 to 10 J/− to form a solder resist pattern 4.

During such exposure, a glass filter was used to
Exposure was performed with the following short wavelength components removed.

Next, apply a chemical copper plating solution (manufactured by Silapray) with the following composition:
The sample was immersed in the liquid for 2 minutes, and a chemical steel plating with a thickness of approximately 0.4 μm was applied.

Copper mix 328 A 125m Q Copper mix 328 L 125m Q Copper mix 328 C25m Q Distilled water The total amount is defined as IQ Thereafter, through-hole chemical copper plating layer 6 was formed by thickening with chemical copper plating. At this time, a chemical copper plating solution used for thickening through-holes was used as the chemical steel plating solution. The plating conditions were 15 hours of immersion in a strongly alkaline plating solution with a pH of 12.5 at approximately 70°C, and approximately 20 μm was applied to the designated area.
Copper plating of m.

The plating solution components in the plating tank were kept constant through automatic management.

The adhesion between the resist coating film of the printed circuit board thus manufactured and the circuit steel foil was evaluated by a cross-cut cellophane tape test, and it was found that the resist film did not peel off and had good adhesion. Furthermore, even when immersed in a 260° C. solder bath for 20 seconds, there was no deterioration such as blistering or peeling of the resist film, and it was found that the resist film had good solder heat resistance.

In addition, as a result of observing the through-hole portions and land portions immediately after plating, it was found that copper was deposited uniformly in the thick portions, and no abnormal copper deposits were observed on the resist other than in desired portions.

Further, as a result of measuring the insulation resistance between the circuits after being left in a constant temperature and humidity chamber at 60° C. and 95% RH for one week, no extreme insulation deterioration was observed.

Furthermore, the board was immersed in a solder bath at 260°C for 10 seconds,
After repeating the process of air cooling to room temperature five times, the cross section of the through hole was observed and the presence or absence of cracks in the copper plating was investigated. Table 1 summarizes the relationship between the resist area and the resist area immersed in the liquid.

That is, as shown in Table 1, in the case of the present invention in which components of 300 nm or less were removed and exposed in the resist forming process, the resist area in the plating solution was affected as shown in Test Nos. 1 to 4. Good quality copper plating can be obtained without warping, 5
Even after multiple solder immersion tests, no cracks occurred in the copper plating of the through-holes. This is the same characteristic as Test No. 10 in which there is no resist at all.

On the other hand, when the resist is exposed using a filter without removing wavelengths of 300 nm or less, good quality copper plating can be obtained if the resist area in the plating solution is small (Test No. 5).
6) However, when the resist area becomes large, the quality of the copper plating deteriorates significantly as shown in test number 7.8, and cracks occur after just one or two solder immersion tests, making it difficult to use through-holes for practical purposes. It turned out that reliability could not be ensured.

From this, it has been found that in the case of mass production where the resist area is large, the method of the present invention is an extremely excellent method for producing printed boards. This trend is
Test No. 9 was also found to be independent of the exposure position during the process.

FIG. 2 is a diagram showing the relationship between the amount of resist dissolution and the cut wavelength of the filter.

That is, the relationship between the amount of resist dissolved in the plating solution and the amount of resist dissolved in the plating solution was determined from the viewpoint of the type and presence or absence of a glass filter that cuts short wavelength components used during the second exposure. A resist is formed in the above-mentioned process, and then placed in a chemical copper plating solution at 70°C.
FIG. 2 shows the change in weight per unit area of the resist when immersed for 15 hours. The cut wavelength in the figure indicates that short wavelength components below that wavelength are not included.

From these results, it was found that 300
It has been found that removal of wavelength components of nm or less is necessary and sufficient.

Next, the manufacturing process of the second embodiment of the present invention will be explained in detail. However, the pre-process up to FIG. 1(d) is the same as in the first embodiment, and will therefore be omitted.

Stainless steel plate (80mm x 80mm x thickness 0.5
mm) is washed with 1.1.1-trichloroethane, and then a photosensitive solder resist is printed in a 60 mm x 60 mm area using a screen printing method. The following photosensitive solder resist composition was used.

(Photosensitive solder resist composition) (a) Diaryl phthalate resin...1
00g (average molecular weight 7000. Manufactured by Isodap, Osaka Soda Ni, K.) (b) Trimethylolpropane trimethacrylate・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・1og (c) Epoxy resin (
Epicor)-828, Epibis type epoxy resin, oil-based shell epoxy, manufactured by K,)...
・・・・・・・・・・・・・・・・・・20g(d)
2-Methyl-[4-(methylthio)phenyl]2-morpholinopropane-1...4g (e) Dicyandiamide...3g
(f) 2,4-diamino 6 [2'-methylimidazole (1')) ethyl-s-triazine 1 g (g) Ultrafine silicon powder Aerosil RK, -200...
・5g (manufactured by K, Nippon Aerosil) (chi) Silicone oil 5H-203...5
g (manufactured by Toshi Silicone, K) (su) Phthalocyanine green...
...1g (nu) Ethylene glycol monobutyl ether...40g Mix (a) to (d) and (n) of the above compositions and heat at about 80°C for 30 minutes Stirred. Next, (a) ~ (
(iv) and (nu) were brought to room temperature, and appropriate amounts of (e) to (phosphorus) were added and mixed using a three-roll roll to obtain a photosensitive solder resist having plating resistance.

Next, the photosensitive solder resist composition was printed all over the cleaned stainless steel plate using a screen printing machine using a 120 mesh stainless steel screen plate as described above.
Pre-drying was performed at about 80° C. for 30 minutes. After drying, the resist surface was solidified and a negative mask could be attached to it.

Next, in order to protect the resist surface from oxygen, the space between the resist surface and the negative mask was evacuated using a rotary pump (atmospheric pressure to a degree of vacuum of 0.5 Torr).

Next, the entire surface of the resist was exposed to UV light for 1 minute using an exposure machine using a 400W high-pressure mercury lamp, and spray development was performed for 1 minute using 1.1.1-trichloroethane. At this time, the difference in weight of the stainless steel substrate coated with the resist before and after development was measured, and the amount of the resist dissolved during development was determined. FIG. 3 is a relationship diagram showing the weight loss during development of the resist exposed at each degree of vacuum.

That is, from FIG. 3, it was found that the amount of resist dissolved during development is smaller as the degree of vacuum during exposure is higher.

Next, the developed substrate was subjected to heat curing treatment at 150° C. for 30 minutes, and then post-exposure was performed at 2 J/ad.

Thereafter, the substrate was immersed in a chemical copper plating solution for about 12 hours. At this time as well, the difference in weight of the stainless steel substrate coated with resist was measured before and after being immersed in the chemical steel plating solution, and this was determined as the amount of resist eluted into the plating solution.

FIG. 4 is a characteristic diagram showing the elution amount into the plating solution of the resist film formed by exposure at each degree of vacuum.

As can be seen from FIG. 4, the amount of resist dissolved into the plating solution was found to be smaller as the degree of vacuum during exposure was higher. This tendency was almost the same as the way the resist was dissolved during development. The composition of the chemical copper plating solution and plating conditions described above are as follows.

Composition: Cu5O,-5) 1.0 12
gEDTA-2Na 42gN
a0) I 12g surfactant 0.1g K, S
1mg distilled water Amount where the total amount is IQ Conditions: Plating solution temperature 70℃ pH 12,
3 hours The components of the plating solution in the plating tank were kept constant through automatic management for approximately 12 hours.

From the above results, it was found that in order to reduce the amount of resist dissolved into the plating solution, the higher the degree of vacuum during exposure, the more effective it is.

Next, a third embodiment of the present invention will be described.

From the results of the second example, it was found that the degree of vacuum during exposure is effective in reducing the amount of resist dissolved.In the third example, an actual printed circuit board was manufactured and through-holes were The connection reliability was evaluated.

Drill a through hole in a glass epoxy double-sided copper clad laminate covered with 35 μm copper foil, activate the inside of the through hole by immersing it in a Sn/Pd catalyst solution, and then apply a photosensitive etching dry film to the substrate using a conventional method. Laminate and
Lands and circuits were formed on the substrate by a tenting method consisting of steps of exposure, development, etching, and peeling.

Next, the circuit-formed board was immersed in an IN hydrochloric acid aqueous solution for 30 seconds as a pre-printing treatment, and then the entire surface of the board was puff-polished.
Washed with water and dried. Next, a resist was printed in the same manner as in the second example using a photosensitive solder resist having plating resistance similar to that in the second example, and pre-dried.

Next, in the same manner as in the second embodiment, in order to protect the resist surface from oxygen, a vacuum is drawn between the resist surface and the negative mask using a rotary pump (atmospheric pressure to vacuum degree 0.5 To
(up to rr).

Next, the resist was exposed to UV light for 1 minute as desired using an exposure machine using a 400W high-pressure mercury lamp.
Unnecessary resist was removed by spray development using trichloroethane for 1 minute.

Next, the developed substrate was subjected to heat curing treatment at 150° C. for 30 minutes, and then post-exposure was performed at 2 J/a1.

Thereafter, chemical copper plating was applied in the same manner as in the second example to produce a printed circuit board.

Table 2 shows the results of evaluating the through-hole connection reliability of the printed circuit board thus manufactured by a solder cycle test.

From the above results, if exposure is performed in a high vacuum with a degree of vacuum of 50 Torr or less, a resist area of 1 dm''/Q or more can be used. Therefore, mass production becomes possible.

Furthermore, plating resistance properties, resist heat resistance, JIS-C5
A cooling/heating cycle test was conducted on 012, but no abnormality was observed and excellent results were obtained.

Furthermore, a fourth embodiment of the present invention will be described.

The photosensitive solder resist composition having plating resistance used in Example 2 was applied to a copper-clad laminate on which a circuit was formed in the same manner as in Example 3, followed by pre-drying, UV exposure, solvent development, The film was formed through heat curing and post-exposure steps. The process conditions for each were the same as in the third example. However, during exposure, the oxygen partial pressure at the resist surface is set to 0. Inert gas (nitrogen) to achieve ITorr (oxygen concentration 138 ppm)
I went with the atmosphere. Next, the substrate on which the film was formed was subjected to the same plating treatment as in the third example, and the connection reliability of the through holes was evaluated. The results are shown in Table 2. Degree of vacuum during exposure: 0, 5
Similar results were obtained when using Torr. In other words, it is shown that reducing the oxygen partial pressure on the resist surface during exposure is effective in reducing the amount of resist in the plating solution.

〔Effect of the invention〕

According to the present invention, since a photosensitive solder resist is used, there is an effect of improving pattern accuracy, and since this photosensitive resist can withstand alkaline plating, a resist is formed before the plating process, and only desired parts are can be plated. Furthermore, since the resist does not dissolve into the plating solution, high-quality plating can be obtained and highly reliable printed boards can be manufactured.

The present invention has immeasurable economic effects that allow mass production of highly reliable, high-density printed circuit boards at low cost.

[Brief explanation of drawings]

Figure 1 is a diagram of the printed circuit board manufacturing process of the present invention, Figure 2 is a diagram of the relationship between the cut wavelength of the filter and the amount of resist dissolution, and Figure 3 is a diagram of the relationship between the degree of vacuum during exposure and the amount of resist loss during development. FIG. 4 is a diagram showing the relationship between the degree of vacuum during exposure and the amount of resist elution. <Explanation of symbols> ■...Glass epoxy double-sided copper-clad laminate 2'...Copper foil...Circuit and land...Through hole...Photosensitive solder resist layer... Activated catalyst...Through-hole copper plating...Etching resist force Figure 1-11 Force Input Ebo + C inner surface @ Zhang O V# Kaya? --Ikkunhaku? --- Roji 8J Hiushi F 5-m-Through hole et al.・Sa7---Etsunashida Shijinto

Claims (5)

[Claims] 1. Through-holes at desired locations in copper-clad laminates
, activate the inside of the through hole, cover the part that will become the circuit pattern with resist, form the circuit by etching, remove the resist, apply a solder resist with plating resistance to the circuit board, Pre-dry, irradiate desired areas with UV (ultraviolet) light excluding short wavelength components of at least 300 nm or less, develop, form a photosensitive solder resist film, and coat through-hole areas and desired areas with chemical copper plating solution. A method for manufacturing a printed circuit board, characterized by depositing copper thereon. 2. Form slow holes in desired positions of copper-clad laminates,
Activate the inside of the through hole, cover the part that will become the circuit pattern with resist, form the circuit by etching, remove the resist, apply a plating-resistant solder resist to the circuit-formed board, pre-dry it, UV light is irradiated to the desired areas under a vacuum with an oxygen partial pressure of 10 Torr or less on the resist surface and in an inert gas atmosphere, developed, a photosensitive solder resist film is formed, and through-hole areas and desired areas are coated with a chemical copper plating solution. A method for manufacturing a printed circuit board, characterized by depositing copper on the board. 3. In the manufacturing method according to claims 1 and 2, the photosensitive solder resist having plating resistance comprises a diallyl phthalate prepolymer, a polyfunctional unsaturated compound, a photopolymerization initiator, an epoxy resin, and a dicyandiamide and diaminotriazine-modified imidazole compound. A method for manufacturing a printed circuit board, characterized in that it is made of a mixture. 4. A printed circuit board manufactured by the manufacturing method according to claim 1. 5. A printed circuit board manufactured by the manufacturing method according to claim 2.