JPH03120782A - Manufacture of printed-wiring board - Google Patents

Abstract

PURPOSE:To obtain a printed-wiring board with improved resolution without being affected by the width of development conditions by performing a process for irradiating a small amount of activation energy rays onto the entire coated surface of resist on the printed-wiring board before the development process for making a light decomposition resin within an electrodeposition paint to be alkali-resistant against reaction at the part between light-sensitive base parts due to semi-light-exposure. CONSTITUTION:A positive type light-sensitive resist film is formed onto a printed-circuit board with a conductive film by the electrodeposition painting method. A small amount of activation energy rays are irradiated uniformly onto a positive-type light-sensitive resist film and activation energy rays are irradiated onto the positive type light-sensitive resist film through a photo mask screening the part for forming a conductor from the activation energy rays. A resist film where the activation energy rays are irradiated is developed, the exposed copper-plated part is eliminated by etching, and then a resist film on the remaining conductor forming part is eliminated. The positive type electrodeposition paint to be used mainly consists of an acryl resin with a light- sensitive base and a carrier base which ionizes by neutralization.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for manufacturing a printed circuit board, and more specifically, to a method for manufacturing a printed circuit board with excellent developability using a positive type photosensitive electrodeposition paint. It relates to a manufacturing method.

(Prior art and its problems) In recent years, printed circuit boards have been frequently manufactured using photosensitive electrodeposition paints. Recently, as printed circuits have become more dense and highly integrated, there has been a demand for a method for efficiently (and highly reliable) manufacturing of printed circuit boards with fine patterns and small through-holes with a hole diameter of 0.4 mm or less. As a means for this, various methods have been proposed for manufacturing printed circuit boards using positive-type photosensitive electrodeposition paints (for example, Japanese Patent Laid-Open No. 602071
No. 39, JP-A-61-206293, JP-A-62-1
No. 57841, Japanese Unexamined Patent Publication No. 63-6070, etc.).

The industrial advantage of manufacturing printed circuit boards using positive-type photosensitive electrodeposition paints (hereinafter sometimes abbreviated as "positive-type electrodeposition paints") is that the resist coating is applied inside the through-holes by electrodeposition coating. It is possible to form small-diameter conductive holes (through-holes) that are difficult to expose to light because there is no need to harden the resist film with active energy rays and make it insoluble in the developing solution as in the case of negative-tone resist films. It is possible to easily manufacture a circuit board having holes (holes).

However, while positive electrodeposition paints have the above-mentioned advantages, on the other hand, when developing a resist film, the difference in solubility in an alkaline developer between exposed and unexposed areas is small, so the developing conditions (concentration, temperature, Developability is easily affected by changes in time (time, etc.), and reproduces printed wiring boards with good resolution (
It has the disadvantage that it cannot be obtained.

(Means for Solving the Problem) As a result of intensive studies aimed at solving the above-mentioned problems, the present inventors found that the photodegradable resin is partially activated by a small amount of active energy rays and becomes decomposed. Previously, it was discovered that the reaction between the photosensitive group sites of the resin increases the alkali resistance, that is, the resin becomes less soluble in a developer, and the present invention was completed.

That is, the present invention provides the following steps: 1. (I) Forming a positive photosensitive resist film on a circuit board having a conductive film by electrodeposition; (II) Applying a small amount on the positive photosensitive resist film. The alkali resistance is improved by uniformly irradiating the active energy rays, and then the active energy rays are irradiated through a photomask that blocks the part where the conductive wire is to be formed on the positive photosensitive resist film from the active energy rays. (III) developing the resist film irradiated with active energy rays; and (IV) etching away the exposed copper plating,
and further removing the resist film on the remaining conductive wire forming portion.

2. In the (TI) step, active energy rays are irradiated through a photomask that blocks active energy rays from the portion on which the conductive wire is to be formed on the positive photosensitive resist film, and then the positive photosensitive resist film is exposed to active energy rays. 2. The method of manufacturing a printed circuit board according to claim 1, further comprising: improving the alkali 5-J resistance by uniformly irradiating a small amount of active energy rays on the substrate.

3. The method for producing a printed circuit board according to claim 1, wherein the printed circuit board used in the step (I) has a through hole, and the small amount of active energy ray used in the step (TI) is in the form of scattered light. There are no particular limitations on the resist as long as it can form a positive resist film on the conductive substrate (any resist can be used, but particularly preferred in the present invention are those having the following formula in the molecule). Quinonediazide sulfonic acids, R2 represents a hydrogen atom, an alkyl group, a cycloalkyl group or a 6-alkyl ether group, and R3 represents an alkylene group, a cycloalkylene group or an alkylene ether group.

) is an electrodeposition coating mainly composed of an acrylic resin having a photosensitive group represented by
279288 etc.). This positive-type electrodeposition paint has a high pattern resolution of the resist film formed therefrom, and also has excellent long-term running stability because the stability of the electrodeposition bath is excellent.

Each step of the present invention will be explained below using an anionic electrodeposition paint as an example, depending on the type of carrier group in the resin component of the electrodeposition bath. The substrate to be electrodeposited may be any copper-plated printed circuit board substrate having ordinary conductive holes and non-conductive holes, without any limitations on thickness, shape, etc.

Electrodeposition coating on a circuit board can be performed in the same manner as in the formation of a conventional positive photosensitive resist film. That is, the circuit board is immersed in an electrodeposition paint bath as an anode, and a direct current of 20 to 400 V is applied between it and a counter electrode. Generally, the current application time is about 30 to 300 seconds. The thickness of the resist film formed on the circuit board is 2 to 1
00 μm, preferably in the range of 2 to 20 μm.

After energization, the circuit board is lifted out of the electrodeposition bath, washed with water, and then moisture contained in the resist film is removed using hot air, an air knife, or the like.

Next, the exposure process will be explained. This process consists of the following (1)
) or (2).

(1) A small amount of active energy rays is uniformly irradiated onto a circuit board on which a resist film is formed by electrodeposition, and in the case of a board with through holes, the inside of the through hole is also irradiated; (2) Active energy rays are irradiated onto the resist film through a photomask that effectively blocks the active energy rays from the portion where the conducting wire is to be formed.

In this step, conductive wires of the circuit board are formed in the above step, and the solubility of exposed areas and semi-exposed areas in a developer is differentiated. Although the reason for the half-exposed state has not yet been elucidated, it is presumed that some kind of reaction occurred between the photosensitive groups. For example, considering a resin having a quinonediazide sulfonic acid in the photosensitive group site, the following conclusions can be made.

When this resin is irradiated with active energy rays in a certain amount or more, the quinone diazide part, which is a photosensitive group part, changes to carboxylic acid through ketene, and can be easily developed with a weak alkaline solution. However, if the active energy dose is small, the azo group (N=) portion of the photosensitive group portion may be activated while remaining, causing azo coupling or trimerization, resulting in an increase in the molecular weight of the resin. It is thought that this resulted in a resin form that did not dissolve in weakly alkaline developing solutions.

If a specific amount or more of active energy rays are further irradiated in this state, the bonding portion of the photosensitive group portion is decomposed and development becomes possible. Furthermore, once photodecomposition has been completed, the polymer will not undergo trimerization or other polymerization. A series of changes in the resin depending on the active energy dose was confirmed by thin layer chromatography.

The amount of active energy ray irradiation to bring the film into a semi-exposed state in step (1) is suitably in the range of 2 to 150 mj/cm2, more preferably 10 to 100 mj/cm2. If the active energy dose is less than 2 mj/cm2, there will be no change to an alkali-resistant form (the effect of this process will not appear during development, and if it exceeds 150 mj/cm2, photodecomposition will proceed and the entire surface will be destroyed during development. This is not preferable since it may lead to dissolution.

In addition, in (2), the irradiation amount for complete exposure is 200 mj/cm
2 or more is appropriate, and photodecomposition is complete with this irradiation amount.

In step (1), especially in the case of a circuit board having through holes, it is preferable to use scattered light as the active energy ray. This facilitates semi-exposure of the inside of the through hole and improves the alkali resistance inside the through hole.

In (2), if the through hole part is a through hole with a land, use a photomask that can block the inside of the circle (or area) corresponding to the land diameter from active energy rays, and if the through hole part is a landless through hole, also use a photomask that can block the through hole part from active energy rays. A photomask that blocks active energy rays is used. The active energy rays used for exposing the positive resist film are preferably light rays having a wavelength of 250 to 450 nm. These light sources include sunlight, mercury lamps, xenon lamps, arc lamps, and the like. Irradiation is usually carried out for a period of 1 to 20 seconds.

In addition, in the case of a circuit board consisting only of through holes with land and non-conducting holes, parallel light and scattered light can be used as the light source, but in the case of landless through holes, it is necessary to use parallel light or a similar light source. be.

The exposed board is then developed with a weak alkaline developer of about 1 to 3%, such as soda carbonate, sodium metasilicate, or amine, and then the copper plated parts (non-circuit parts) exposed on the board are treated with chloride, for example. It is removed by treatment with an etching solution such as a cupric aqueous solution. Next, the resist film (unexposed area) on the circuit pattern is removed by treatment with a strong alkaline stripping solution such as about 3 to 10% caustic soda or a solvent capable of dissolving the unexposed resist film. Thus,
A circuit board is formed when an anionic type is used as the positive type electrodeposition paint.

When using a cationic type of positive electrocoating paint, use the circuit board as the cathode, use an alkaline etching solution such as a mixture of ammonium hydroxide and ammonium chloride, and use unexposed etching solutions. It can be carried out in the same manner as in the anionic type except that an acid or a solvent is used to remove the resist film.

(Effects of the Invention) According to the present invention, by performing the step of irradiating the entire surface of the resist film on the circuit board with a small amount of active energy rays before the development step, the photodegradable resin in the electrodeposition paint becomes sensitized by half-exposure. It becomes alkali resistant due to the reaction between the chemical groups, and when a photomask is placed on the film and exposed and developed, the difference in solubility in an alkaline developer between the exposed and semi-exposed areas widens, allowing for a wide range of development conditions. A printed wiring board with good resolution could be obtained with good reproducibility without being affected.

(Examples) Hereinafter, the present invention will be explained in more detail with reference to Examples. Parts and percentages refer to parts and percentages by weight.

Production example of positive type photosensitive electrodeposition paint-1 1.2-naphthoquinonediazide-5-
269 parts of sulfonic acid chloride and 1345 parts of dioxane
150 parts of N-methylethanolamine was added thereto over 1 hour while stirring at room temperature. After the dropwise addition was completed, stirring was continued for about 3 hours, and after confirming that the absorption of amino groups around 3300 crn-' in the infrared spectrum disappeared, the reaction was terminated.

Next, this solution was poured into deionized water to remove the quaternary ammonium salt that trapped the hydrochloric acid generated during the reaction. Next, the product was extracted with isobutyl acetate, the solvent was distilled off, and the product was dried in a vacuum dryer to obtain a hydroxyl group-containing orthoquinonediazide compound (a).

Next, a solution of 309 parts of the above compound (a) dissolved in 1,500 parts of dioxane was added dropwise over 1 hour to 0.5 parts of dibutyltin dilaurate and 174 parts of tolylene diisocyanate heated to 60°C. The temperature was maintained for 4 hours to obtain a compound (b) solution. The compound (b) solution 2
, a solution of 77 parts of 2.3.4-trihydroxybenzophenone dissolved in 300 parts of dioxane was added to 157 parts of
After further reacting at 60°C until the absorption of isocyanate around 2250 cm-' in the IR spectrum disappears,
The reaction mixture was poured into a large amount of deionized water for 14 hours, the precipitated solids were filtered out, and washed thoroughly with water.
The photosensitive agent A was obtained by drying under reduced pressure at °C.

1000 methyl isobutyl ketone in another 4 flasks
A mixture of 500 parts of n-butyl acrylate, 90 parts of acrylic acid, 300 parts of methyl methacrylate, 110 parts of styrene and 3 parts of azobisisobutyronitrile was added dropwise to the mixture heated to 100°C over 3 hours. After adding a solution of 300 parts of photosensitizer A dissolved in 900 parts of dimethyl diglyme to the fat solution for 3 hours at that temperature and mixing well,
After neutralizing by adding 63 parts of l-ethylamine and 100 parts of butyl cellosolve, the mixture was heated at 1000 to 1500 rpm.
While stirring at a speed of 10,150 parts of deionized water was gradually added to obtain a stable water dispersion.

Production example of positive-type photosensitive electrodeposition paint-2 1.030 parts of dimethyl diglyme was charged into a four-bottle flask and heated to 100°C, and 500 parts of n-butyl acrylate, 90 parts of acrylic acid, and 2-hydroxyethyl acrylate were added. 130 parts, methyl methacrylate 280
A mixture of 1 part and 3 parts of azobisisobutyronitrile was added dropwise over 3 hours, maintained at that temperature for 3 hours, and then cooled to 60°C to form a solution of compound (b) obtained in Production Example-1.
1 part and 1.0 part of dibutyltin dilaurate were added, and the mixture was reacted at 60°C until the absorption of incyanate around 2250 cm-' in the infrared spectrum disappeared, and then concentrated under reduced pressure until the solid content became 60%. After neutralizing the resin solution by adding 63 parts of triethylamine and 100 parts of butyl cellosolve, 10,650 parts of deionized water was gradually added to the mixture while stirring at a speed of 1,000 to 1.50 Orpm to achieve stable water dispersion. I got a body.

Example-1 Plate thickness 1.6 mm, hole diameter 0.8 mm, copper plating thickness 35 μm
The plated substrate was immersed in a bath paint obtained from the aqueous dispersion of Production Example-1 kept at 25°C, and after being energized at 100V for 90 seconds, it was washed with water and dried to obtain a resist film with a thickness of 10μm. Ta. The substrate covered with the resist film was exposed to 50 mj using a scanning type exposure machine (ultra high pressure mercury lamp 80 W/cm).
/cm2 of light was applied to the entire surface. Then, the same exposure machine was used to irradiate the film with a light amount of 300 mj/cm2 through a photomask that shielded the part where the conducting wire was to be formed from active energy rays.

The resulting exposed substrate was sprayed with a 2% sodium metasilicate aqueous solution at 30° C. for 2 minutes, washed with water, and developed. Next, etching was performed using a cupric chloride aqueous solution, and the resist film remaining on the conductive wire portions was peeled off using methylene chloride to obtain a circuit board. During the development process, the developer temperature is ± the set temperature/degree.
Even with a 5°C fluctuation, all 300 circuit boards produced using the above process had a line/space ratio of 100/100 to 2.
The plating in the holes was completely protected in the 00/200 (μm/μm) pattern, and the resolution was good.

Example-2 Using a bath paint obtained from the aqueous dispersion of Production Example-2, and
Except for the case where a 3% metasilicic acid sorg 7-aqueous solution at 35°C was used as the developer, the same procedure as in Example-1 was carried out.
A circuit board was obtained. The condition of the pattern and the plating in the holes were all good.

Example 3 A substrate covered with a resist film obtained in the same manner as Example 1 was exposed to a scanning exposure machine (8
A light intensity of 2 SOmj/cm2 was irradiated using an ultra-high pressure mercury lamp (0 W/cm). Then, the entire surface of the film was irradiated with a light amount of 60 mj/cm2 using the same exposure machine. The resulting exposed substrate was sprayed with a 1% sodium metasilicate aqueous solution at 30°C for 2 minutes, washed with water, and developed. The exposed copper plated portion was etched away with a cupric chloride aqueous solution, and the remaining copper plated portion was removed with a 3% caustic soda aqueous solution. The resist film on the conductive wire portion was peeled off. During the development process, the developer temperature is ±5℃ relative to the set temperature.
Even if there is a variation in the line/space = 150/150 (μm/
The fine pattern (μm) had no defects and had good resolution.

18- Comparative Example-1 300 circuit boards were obtained in the same manner as in Example-1 except for the amount of vehicles in which the entire surface exposure step was not performed in Example-1.

A circuit board where there were cuts and pattern burrs in some of the line/space patterns, and where touches occurred from film residue because the developer temperature fluctuated by ±5°C from the set temperature during the development process. There were many.

Claims (3)

[Claims] 1. (I) Forming a positive photosensitive resist film on a circuit board having a conductive film by electrodeposition coating; (II) Uniformly applying a small amount of active energy rays onto the positive photosensitive resist film. (III ) developing the resist film irradiated with active energy rays; and (IV) etching away the exposed copper plated portion and further removing the resist film on the remaining conductor forming portion; Production method. 2. In the step (II), active energy rays are irradiated through a photomask that blocks active energy rays from the portion on which the conductive wire is to be formed on the positive photosensitive resist film, and then active energy rays are irradiated on the positive photosensitive resist film. 2. The method of manufacturing a printed circuit board according to claim 1, further comprising: uniformly irradiating a small amount of active energy rays to improve alkali resistance. 3. 2. The method of manufacturing a printed circuit board according to claim 1, wherein the printed circuit board used in the step (I) has a through hole, and the small amount of active energy rays used in the step (II) are in the form of scattered light.