JPH0457866A - Hole-filling ink for manufacturing copper through-hole printed wiring board - Google Patents

Abstract

PURPOSE:To obtain the title ink which can achieve flattening of through-hole areas to a high degree and is not corroded by an etchant by using, as constituents, a resin resistant to a weakly alkaline aqueous solution and removable with a strongly alkaline aqueous solution, a solvent, and a powdery foaming agent combined with resin. CONSTITUTION:The title ink contains a resin resistant to a weakly alkaline aqueous solution and removable through dissolution with a strongly alkaline aqueous solution (e.g. a phenol/aldehyde addition condensate or a p- hydroxystyrene resin), a solvent, and a powdery foaming agent combined with resin, and if necessary, an inert solid powder. By using this ink for filling the through-holes of a copper through-hole printed wiring board, flattening of the through-hole areas can be achieved to a high degree simply and easily, a mask film scarcely gets out of position on exposure for forming an etching resist layer and, even if it gets out of position and the through-hole areas are exposed, the copper-plated layer is protected from corrosion by an etchant, so that the reliability of the through-holes can be raised and the productivity and quality of a high-density, copper through-hole printed wiring board can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention has resistance to development with a weak alkaline aqueous solution used when forming an etching resist layer in the manufacturing process of copper through-hole printed wiring boards. High-precision, high-density copper through-hole printed wiring board with small diameter through-holes and landless through-holes.
The present invention relates to a hole-filling ink for manufacturing copper through-hole printed wiring boards, which makes it possible to connect wiring on both sides at low cost and with high reliability, and which can be dissolved and removed with a strong alkaline aqueous solution.

(Prior Art) A copper through-hole printed wiring board is usually manufactured by the following method (see FIG. 1).

In other words, through-holes are drilled and cleaned in an insulating board made of epoxy resin, polyimide resin, polyester resin, etc., or a copper-clad laminate with copper foil coated on both sides of the insulating board, and then electroless copper plating is applied. Alternatively, a copper plating layer forming a circuit is formed on the inner wall of the through hole and the surface of the substrate by using electroless copper plating and electrolytic copper plating in combination.

Next, hole-filling ink is filled into the through-hole to protect the inner wall of the through-hole from the etching solution, and the hole-filling ink is heated and dried or cured with ultraviolet light, and the hole-filling ink adhering to the copper plating layer on the surface of the board is removed by surface mechanical polishing. Remove by.

Thereafter, an etching resist layer corresponding to the wiring pattern is formed on the surface of the copper plating layer including on the through holes. Next, using this etching resist layer as a mask, the copper foil containing the copper plating layer is etched to form the desired wiring pattern, and then the etching resist layer and hole-filling ink are removed using a caustic soda aqueous solution to form the desired copper foil. Obtain a through-hole printed wiring board. In the above manufacturing process, heat-dried or ultraviolet-curable screen printing etching resist inks and dry films are generally used as the etching resist layer.

(Problems to be Solved by the Invention) FIGS. 2A and 2B show cases in which a heat-drying type hole-filling ink and a solvent-free ultraviolet curing type hole-filling ink, which are conventionally commonly used as hole-filling inks, are used. It shows the state around the through hole before etching.

A copper plating layer 2 is provided on both the front and back surfaces of the insulating substrate 1 and on the inner wall surface of the through-hole hole 10, and the inside of the through-hole hole 10 is filled with hole-filling ink 4. On this copper plating layer 2, an etching pattern is formed by an etching resist layer 3 corresponding to a desired circuit pattern.

Conventional hole-filling inks for manufacturing copper through-hole printed wiring boards mainly contain alkali-soluble resins such as rosin or rosin-modified resins, and therefore can be easily dissolved in alkaline aqueous solutions with a pH of 7 or higher.

For this reason, in the recent manufacturing of high-density copper through-hole printed wiring boards in which fine-line and small-diameter through-holes such as landless through-holes are being made, several problems have arisen that cannot be solved by conventional techniques.

1) When wiring patterns are formed using etching resist ink for screen printing, it is difficult to accurately reproduce and mass-produce fine patterns of 200t11n or less.

2) When forming an etching resist layer using a dry film, when aligning the pattern mask film (hereinafter referred to as mask film), particularly advanced alignment techniques are required for landless through holes, small diameter through holes, etc. If the mask film is misaligned or stretched due to the number of exposures, the mask film position will shift and after the dry film is exposed, a developer such as an inorganic weakly alkaline aqueous solution will enter the through holes and dissolve the hole-filling ink. For this reason, when etching is performed, the copper plating layer in this area is etched away, causing problems such as disconnection due to missing through holes (see FIGS. 2C and 2D).

Furthermore, when through-holes are filled using conventional heat-drying hole-filling ink, even if the surface is flat immediately after filling with hole-filling ink 4 (Fig. 3 C-1), When heated and dried, the solvent in the hole-filling ink 4 evaporates and the volume shrinks by 20 to 50%, so the filled hole-filling ink 4
becomes concave (Fig. 3 C-1). After this, when forming an etching resist layer 3 with a pattern corresponding to the wiring pattern on the copper foil 2' and the copper plating layer 2, since the surface of the hole-filling ink 4 is concave, the hole-filling ink 4 must be filled after laminating the dry film. There is a problem in that an air layer 9 remains between the ink and the dry film, causing rupture and peeling during the subsequent exposure, development, and etching processes, resulting in a lack of reliability (Fig. 3C-
1, C-2).

In addition, when screen printing etching resist ink, the film thickness of the resist ink on the edge of the copper through-hole becomes thin (see Figure 3), or the copper plating layer is exposed due to insufficient coverage (Figure 3C). -1). In this case, the copper plating layer 2 and the copper through hole edge portion 2' are etched by the subsequent etching process, causing problems such as disconnection.

Therefore, in order to compensate for the volumetric shrinkage of the heat-drying hole-filling ink 4 that forms these concave shapes, there is a method in which a foaming agent or expansion agent whose volume increases with heat is mixed into the hole-filling ink as it is or in the form of microcapsules. are known (for example, JP-A-54-139065, JP-A-61-
No. 212092 and JP-A-63-226992). However, in either case, the volume change rate of the hole-filling ink during the heating and drying process is extremely large, ranging from several tens of times to several hundreds of times, and it is difficult to control the volume change rate due to heating. For this reason, after filling the copper through holes with hole-filling ink and heating and drying, the hole-filling ink may expand beyond the thickness of the printed circuit board (Figure 3 C-1), or the hole-filling ink may expand too much. The hole-filling ink 4' on the copper plating layer 2 ruptures (Fig. 3 C-1).
When mechanically polishing, a large load is placed on the polishing machine, and there are problems such as the hole-filling ink is not completely removed by polishing and remains on the copper plating layer.

In addition, when passing through the polisher several times to flatten the excessively expanded hole-filling ink, the hole-filling ink at the through-hole edge portion 2' may be chipped due to excessive polishing (see Figure 3 H). There is a problem that the thickness of the copper in the copper plating layer 2 and the through-hole edge portion 2' is reduced, and the subsequent etching process causes wire breakage and a reduction in pattern width, resulting in a decrease in reliability.

Therefore, an object of the present invention is to provide a hole-filling ink for producing the above-mentioned high-density copper through-hole printed wiring board, which preferably has a filling rate of 90 to 100 after heating and drying.
% and through-holes are highly flattened, and by preventing elution into the inorganic weakly alkaline developer,
An object of the present invention is to provide a hole-filling ink for manufacturing a copper through-hole printed wiring board that can improve the reliability of through-holes such as landless through-holes and small-diameter through-holes.

(Means for Solving the Problems) The present inventors used weak alkaline development to replace an alkali-soluble resin in conventional hole-filling ink as a hole-filling ink to fill through-holes in the production of copper through-hole printed wiring boards. By using a resin that is liquid resistant and removable with a strong alkaline aqueous solution, and further including a powdered foaming agent resin composite having a low volume change rate, the above problems were solved and scales were discovered, resulting in the present invention. did.

That is, the present invention has resistance to weakly alkaline aqueous solutions,
The present invention relates to a hole-filling ink for producing copper through-hole printed wiring boards, which includes a resin composite of a resin, a solvent, and a powdered blowing agent that can be dissolved and removed in a strongly alkaline aqueous solution, and optionally an inert solid powder. This pore-filling ink forms a dry coating that is resolvable.

The hole-filling ink of the present invention uses a resin that has resistance to a weakly alkaline aqueous solution and can be dissolved and removed in a strongly alkaline aqueous solution, and this resin must have resistance to an etching solution described below. The weak alkaline aqueous solution referred to herein is an aqueous solution with a pH of more than 7 and 12 or less, preferably 11-12, and the strong alkaline aqueous solution is an aqueous solution with a pH of more than 12 and 14 or less, preferably 13-14. As the resin which has resistance to weakly alkaline aqueous solution and can be dissolved and removed in strongly alkaline aqueous solution, it is preferable to use phenol, cresol, resorcinol, xylenol, pt-butylphenol, ethylphenol, butylphenol,
Phenylphenol, chlorophenol, bromophenol, catechol, a mixture of two or more of phenols such as hydroquinone, formaldehyde, paraformaldehyde, acetaldehyde, butyraldehyde, trioxane, acrolein, benzaldehyde, salicylaldehyde, glyoxal, glutaraldehyde, acetaldehyde , addition condensates with aldehydes such as sebacinaldehyde, terephthalaldehyde, isophthalaldehyde, and 5-formylsalicylaldehyde alone or with a mixture of two or more, and with the above phenols alone or with a mixture of two or more. dichloroethane, 1
．． Examples include adducts of dihaloalkanes such as 3-dichloropropane, 1,4-dichlorobutane, or dienes such as butadiene and 1,4-pentadiene, alone or in a mixture of two or more, and rose hydroxythrene resins. Particularly preferred are addition condensates or para-hydroxy of the above-mentioned phenols alone or in mixtures of two or more thereof and formaldehyde, paraformaldehyde, acetaldehyde, butyraldehyde, trioxane, acrolein, benzaldehyde, salicylaldehyde, etc. alone or in mixtures of two or more thereof. Styrene resin can be used.

The solvent used to make the ink must be such that the temperature during the heating and drying process to volatilize it does not exceed the heat resistance limit of the copper through-hole printed circuit board, and that the ink surface quickly forms when filling the hole-filling ink. It is desirable to use an organic solvent with a boiling point of 140°C to 220°C to prevent drying.

Examples include esters such as cellosolve acetate, butyl cellosolve acetate, and propylene glycol monomethyl ether acetate, ethers such as butyl cellosolve, methyl carpitol, and ethyl carpitol, and petroleum solvents such as petroleum ether, petroleum naphtha, and solvent naphtha.

The resin composite of the powdered foaming agent used in the pore-filling ink of the present invention is one in which the powdered foaming agent is uniformly dispersed in a resin. Powdered blowing agents used here include, for example, dinitrosopentamethylenetetramine, azodicarbonamide, 4,4'-oxinebenzenesulfonyl hydrazide, para-toluenesulfonyl hydrazide, para-toluenesulfonylacetone hydrazone, hydrazodicarbonamide, N N '-Dimethyl-N N'-dinitrosoterephthalamide, dimethyldinitroterephthalamide, azobisisobutyronitrile, diazoaminobenzene, barium azodicarboxylate, 3,3-disulfonehydrazide diphenylsulfone, sodium bicarbonate, ammonium carbonate, bicarbonate Examples include ammonium, calcium azide, and mixtures thereof.

The average particle size of the blowing agent is preferably 0.1 to 10 μs, more preferably 0.5 to 5 p. In addition, the resin for dispersing the foaming agent may be a thermoplastic resin or a thermosetting resin, but
A mesh thermosetting resin is effective.

Examples include epoxy resin, phenol resin, polyamide resin, polyester resin, and polyurethane resin.

The content of the blowing agent in the resin composite is 1 to 95% by weight,
In particular, it is preferably 5 to 60% by weight.

The method of dispersing the blowing agent is not particularly limited;
Any known method may be used. For example, the resin composite can be obtained by kneading a foaming agent at a temperature at which the resin softens, or by dispersing the foaming agent into a prepolymer and curing it. Further, the resin composite is preferably in the form of fine particles, and the particle size thereof is preferably 100 μs or less, particularly preferably 5 to 801 J. Atomization is achieved by pulverizing the obtained resin composite by a known method, or by dispersing the composite in water to make it fine before curing. When the obtained composite is heated, it expands according to the decomposition temperature of the blowing agent, and it is preferable that the rate of volume change upon heating is 10 times or less, particularly 1.5 to 2 times.

Note that the volume change rate means a value obtained by dividing the volume of the resin composite after heating by the volume before heating, and the heating temperature is the temperature range in the heating drying process of the hole-filling ink.

The inert solid powder included as necessary is a commonly used powder that is used to adjust the flow characteristics and viscosity of the hole-filling ink and to color the hole-filling ink in an easily distinguishable color tone, such as: These include fine particles of inorganic compounds such as talc, silica, alumina, titanium oxide, and barium sulfate, and organic polymers such as polyethylene, nylon, and polyester. Coloring agents such as dyes and organic pigments having characteristics such as acid resistance, weather resistance, and heat resistance are also used as appropriate.

The blending ratio of the pore-filling ink of the present invention containing the above four components is as follows:
The resin is preferably 5 to 90% by weight, more preferably 10 to 60% by weight, more preferably 10 to 60% by weight, and the solvent is preferably 5 to 5% by weight.
0% by weight, more preferably 10-40% by weight, powdered blowing agent resin composite preferably 01-20% by weight, more preferably 1-10% by weight, inert solid powder preferably 0-80% by weight. %, more preferably in the range of 20 to 70% by weight.

The hole-filling ink for manufacturing copper through-hole printed wiring boards of the present invention is prepared by adding, for example, a resin that has resistance to weakly alkaline aqueous solutions and can be removed by dissolving in strongly alkaline aqueous solutions, an appropriate amount of solvent, and, if necessary, a conventional additive. It can be prepared by adding an active solid powder or the like to obtain a viscous liquid or paste, and then adding and mixing a powdered blowing agent resin complex.

The hole-filling ink of the present invention obtained in this way can form a dry coating film that can be redissolved, and can be easily applied by simply heating and drying after filling the through-holes of a copper through-hole printed wiring board. plays a volume regulating function.

This hole-filling ink uses a resin composite of powdered foaming agent with a low volume change rate, so the volume change rate after heating and drying can be easily adjusted.
The hole-filling ink can be filled up to 0 to 1 (10%), and therefore the hole-filling portion can be highly flattened.

A specific example of how to use the hole-filling ink of the present invention will be described below with reference to the drawings. FIG. 1 is a process flowchart showing a method of manufacturing a copper through-hole printed wiring board using hole-filling ink, and the process will be sequentially explained according to this process flowchart. Also the fourth
The figure shows a cross-sectional view of the vicinity of the through-hole in the middle of the process, and the same reference numerals are given to structural parts similar to those of the conventional example in the drawing.

Insulating board 1 made of epoxy resin, polyimide resin, polyester resin, etc., copper-clad laminate with copper foil 2' coated on both sides of insulating board 1, metal such as aluminum or iron insulated with epoxy resin, etc. After drilling through-holes 10 in an insulating board 1 made of a material used for ordinary printed wiring boards, such as a system insulating board or a ceramic board, electroless copper plating or electroless copper plating and electrolytic copper plating are applied. In combination with copper plating, a copper plating layer 2 that becomes a circuit is formed on the inner wall of the through-hole hole 10 and on the surface of the substrate. Next, in order to protect the inner walls of the through holes from the etching solution, the through holes 10 are filled with hole-filling ink 4 and dried by heating at a temperature of about 80 DEG C. to 125 DEG C. for 30 minutes to 4 hours. At this time, the hole-filling ink 4 in the through-hole after filling and drying using the hole-filling ink according to the present invention has a filling rate of 90 to 100% of the internal volume of the through-hole without exceeding the thickness of the printed wiring board. Become (4th
(See Figures A and B). Therefore, in the next mechanical polishing for removing the hole-filling ink 4' on the surface of the copper plating layer 2, it can be easily removed with low polishing pressure. Therefore, the copper plating layer 2 and the through hole edge portion 2' are not polished excessively.
There is no chipping of the filling ink at the edge part 2' of the through hole, and even after polishing the surface of the copper plating layer, the filling rate of the filling ink in the through hole can be maintained at 90 to 100% ( (See Figure 4C).

Next, as a method for forming an etching resist layer, there are the following methods.

1) Screen printing method 2) Dry film method 3) Electrodeposition method 4) Liquid resist method 1) In the screen printing method, when the hole-filling ink of the present invention is used, the flatness of the hole-filling ink in the through hole is excellent. Therefore, it is possible to uniformly and accurately print the etching resist ink in the hole and its surrounding area in a desired wiring pattern.

2) In the dry film method, the through holes are filled with hole-filling ink, dried, the hole-filling ink on the surface of the copper plating layer is mechanically polished, the dry film is laminated, the mask film is aligned, and then exposed to ultraviolet rays under vacuum. Develop with a weakly alkaline aqueous solution to form an etching resist layer. In this case, if the through-hole filling ink is resistant to a weakly alkaline developer like the hole-filling ink of the present invention and can be highly flattened, it can be used even if the mask film shifts as in the past. The hole-filling ink will not be eluted by the developer, and the mask film will not be misaligned when vacuumed after the mask film is assembled, making it possible to form an etching resist layer with a high-precision, high-density wiring pattern. .

3) In the electrodeposition method, the through-holes are filled with hole-filling ink, dried, the hole-filling ink on the surface of the copper plating layer is mechanically polished, and the electrodeposition liquid bath is filled with the hole-filling ink to create a copper through-hole printed circuit board. A photo-developable electrodeposited resist is electrodeposited on the copper plating layer, the water and solvent in the electrodeposited resist are evaporated, the electrodeposited resist is dried, and a mask film is brought into direct contact as in the dry film method. After UV exposure,
Develop with a weakly alkaline aqueous solution to form an etching resist layer. In this case, a negative electrodeposited resist is used.

At this time, when the hole-filling ink of the present invention is used, the shift of the mask film is extremely small as in the dry film method, and even if the mask film shifts, the hole-filling ink does not dissolve into the developer, resulting in high It is possible to form an etching resist layer with an accurate and high-density wiring pattern.

4) In the liquid resist method, instead of a dry film, a photo-developable liquid resist is coated by a spray method, a roll coater method, etc. After drying, the mask film is aligned, and after exposure to ultraviolet rays, it is coated with a weak alkaline aqueous solution. Develop to form an etching resist layer. In this case as well, if the hole-filling ink of the present invention is used, it is possible to form an etching resist layer with a high-precision, high-density wiring pattern, as in 2) and 3) above.

Next, it is subjected to an etching process. As the etching solution, an acidic etching solution such as a ferric chloride solution or a cupric chloride solution is used, but it is also possible to use an alkaline etching solution with a pH of 8 to 9.

In this case, it is necessary to form an etching resist layer that is resistant to the above pH.

Finally, an aqueous solution of an inorganic strong alkaline substance such as caustic soda, caustic potash, or sodium metasilicate (herein also simply referred to as a strong alkaline aqueous solution)
4), the etching resist layer and the hole-filling ink of the present invention are dissolved and removed to obtain the intended copper through-hole printed wiring board.

(Function) In this way, a pore-filling ink containing a powdered blowing agent resin composite with a low volume change rate, a resin that is resistant to weakly alkaline aqueous solutions and can be dissolved and removed in strongly alkaline aqueous solutions is used. By using this method, it has become possible to manufacture high-density copper through-hole printed wiring boards with higher precision, lower cost, and higher reliability than conventional ones.

The hole-filling ink is resistant to weak alkaline developers,
If it can be removed with a strong alkaline aqueous solution and is highly flattened after heating and drying, even if the mask film shifts during exposure of the dry film and electrodeposited resist and there is no etching resist layer on the through hole, the etching process will remove the through hole. The holes will not be disconnected (and the ink can be removed at the same time as the resist layer is removed after etching).

(Example) Hereinafter, the present invention will be explained in more detail with reference to Production Examples, Examples, and Comparative Examples.

Production Example 1 (Production of resin composite of powdered blowing agent) l! Polyoxyethylene nonylphenol ether 15 in the reaction pot
5 [lfl g] of water in which 5 g of water was dissolved was charged.

Next, 70g of polymethylene polyphenylisocyanate
1 polytetramethylene glycol 30 g 1 azodicarbonamide (average particle size 11 J) I [1 g, methylene chloride
Pour 100 ml of homogeneous mixture and stir at 6 rotations.
Stirred at 00 rpm for 10 minutes. After that, the stirring rotation speed was set to 20 Orpm, the temperature was 40°C for 2 hours, and the stirring speed was increased to 70°C.
While the resin was cured for 3 hours at 0.degree. C., methylene chloride was distilled off. The obtained aqueous dispersion of fine particles was centrifuged and further dried to obtain particles of a resin composite of a powdered foaming agent.

The average particle size was 25 μs. In addition, the volume change rate when this resin composite was heated to 120°C was 151.6.
%Met.

Production Example 2 (Production of resin composite of powdered blowing agent) Mirex X L-2252 (manufactured by Mitsui Toatsu) 90g and 4.4'
- Oxybisbenzenesulfonyl hydrazide (average particle size 1 μs).
The mixture was kneaded while adding the toluene diisocyanate adduct to form a homogeneous mixture. Here, the prepolymer reacted and became insoluble in the solvent. The resulting foaming agent resin composite was then cooled to room temperature and pulverized using a pulverizer and a mill. A foaming agent resin composite having an average particle size of 36 IJA was obtained. Further, the volume change rate when this resin composite was heated to 120°C was 163.0%.

Examples 1 to 4, Comparative Examples 1 to 5 Resins, solvents, and inert solid powders that have resistance to weakly alkaline aqueous solutions and can be dissolved and removed in strongly alkaline aqueous solutions are shown in Table 1 below.
The mixture was mixed into a paste-like ink using a three-roll mill. Next, the powdered blowing agent resin composite prepared in Production Example 1.2 was blended into the resulting paste and uniformly dispersed in the paste to obtain a hole-filling ink. Hole-filling ink containing a resin composite of powdered foaming agent with such a composition was filled into the holes of a copper through-hole board, and heated at a temperature of 120°C.
Dry for 90 minutes in a box oven with forced exhaust air.

In addition, hole-filling inks of Comparative Examples 1 to 5 were prepared in the same manner as above by blending in the proportions shown in Table 2 below.

Each of the prepared pore-filling inks was evaluated for filling rate, abrasiveness, etching resist layer forming property, developer resistance, etching resistance, dissolution removability, and presence or absence of dissolution and removal residue, and the results are summarized in Table 3 below. .

The evaluation method and conditions for each test item are as follows.

1) Filling rate and condition The condition of the ink filling the copper through hole after heating and drying.
It was observed with a microscope and the filling rate was measured from the cross-sectional photograph.

2) The surface of the copper through-hole board is filled with abrasive hole-filling ink, heated and dried, and the surface of the copper through-hole board is polished using a 4-axis double-sided polishing machine with an oscillation mechanism (manufactured by Hoben notation). The presence or absence of chips in the filling ink and the residue on the copper plating layer were measured.

3) Formation of etching resist layer Dry film Liston 3 as etching resist layer
1H (manufactured by Du Pon1 Japan Lid) and Electrodeposition Resist Sonne EDUV (manufactured by Kansai Paint ■) were used.

4) Developer Resistance The etching resist layer was developed using an aqueous solution containing 1% by weight of sodium carbonate at a temperature of 25° C. and a spray pressure of 2 kg 1 for 60 seconds, and its resistance was evaluated. At this time, the mask film was adjusted so that the etching resist layer on the hole-filling ink was developed, and the hole-filling ink was exposed in a developer to evaluate its resistance at the same time.

5) Using an etching-resistant cupric chloride solution at a temperature of 40°C and a spray pressure of 2 kg/
The copper foil and copper plating layer were etched under conditions of , J, 3 minutes, and their resistance was evaluated.

6) Dissolution and removal The etching resist layer and hole-filling ink were dissolved and removed using a 5% by weight aqueous solution of caustic soda at a temperature of 40° C. and a spray pressure of 2 kg/ail for 60 seconds, and their solubility was evaluated.

7) Presence of dissolution and removal residue If hole-filling ink remains in the copper through-hole, there will be a problem that the solder will not adhere when electronic components are mounted and soldered. Therefore, we soldered using a jet solder layer.
The adhesion of solder inside the through-hole was observed, and the presence or absence of dissolution and removal residue was evaluated.

As is clear from the results in Table 3 above, the hole-filling ink of the present invention has better characteristics than conventional hole-filling inks.

(Effect of the invention) In the through-hole part of the copper through-hole printed wiring board,
By using the hole-filling ink of the present invention, it is possible to easily achieve a high degree of flattening of through-hole portions, and when forming an etching resist layer, there is little displacement of the mask film during exposure. Even if the through-hole part is exposed by etching, the copper plating layer is protected from being attacked by the etching solution, improving the reliability of through-holes such as landless through-holes and small-diameter through-holes, and improving the reliability of high-density copper through-hole printed wiring boards. It has advantages that greatly help improve productivity and quality.

[Brief Description of the Drawings] Figure 1 is a process flow diagram showing a method for manufacturing a copper through-hole printed wiring board using hole-filling ink, and Figures 2A-D are cross-sectional views after forming an etching resist layer and the through-hole portion. A plan view, FIGS. 3A-H are cross-sectional views of the through-hole portion before and after heating and drying when conventional hole-filling ink is used, and FIGS. 4A-C are cross-sectional views of the through-hole section when using hole-filling ink according to the present invention. FIG. 3 is a cross-sectional view of the through-hole portion after drying. 1...Insulating substrate 2...Copper plating layer 2'...Copper foil 2'...Through hole edge portion 3...
・Etching resist layer 4...Ink for filling the inner hole of the copper through hole 4'...Filling ink on the copper plating layer 4'...Ink for filling the edge of the through hole 9 Air layer 10 Hole diagram for through holes Diagram Ultraviolet curing type hole filling ink Dry film resist Diagram Heat drying type hole filling ink Heat drying type Elatin resist ink No. Figure Figure Figure Figure 3 C-2 Figure Figure Figure Figure C-2 Figure Figure Figure Figure C-2 Figure Figure Figure Figure C-2

Claims (7)

[Claims] (1) Manufacture of a copper through-hole printed wiring board containing a resin composite of a resin, a solvent, and a powdered foaming agent that is resistant to weakly alkaline aqueous solutions and can be dissolved and removed in strongly alkaline aqueous solutions, and if necessary, an inert solid powder. Hole-filling ink for. (2) The hole-filling ink for manufacturing copper through-hole printed wiring boards according to claim 1, wherein the rate of volume change due to heating of the resin composite of the powdered foaming agent is 10 times or less. (3) Resin 5-90% by weight that has resistance to weakly alkaline aqueous solutions and can be dissolved and removed in strongly alkaline aqueous solutions, solvent 5-5%
3. Hole filling for manufacturing copper through-hole printed wiring boards according to claim 1 or 2, comprising: 0% by weight, 0.1-20% by weight of a resin composite of powdered foaming agent, and 0-80% by weight of an inert solid powder. ink. (4) 10 to 60% by weight of resin that has resistance to weakly alkaline aqueous solutions and can be dissolved and removed in strongly alkaline aqueous solutions; 10% by weight of solvent;
40% by weight, 1-10% by weight of a resin composite of powdered blowing agent, and 20-70% by weight of an inert solid powder. (5) The resin that has resistance to weakly alkaline aqueous solutions and can be dissolved and removed in strongly alkaline aqueous solutions is selected from addition condensates of phenols and aldehydes, adducts with dihaloalkanes or dienes, or parahydroxystyrene resins. The hole-filling ink for manufacturing copper through-hole printed wiring boards according to any one of claims 1 to 4. (6) Powdered blowing agent is dinitrosopentamethylenetetramine, azodicarbonamide, 4,4'-oxybenzenesulfonylhydrazide, paratoluenesulfonylhydrazide, paratoluenesulfonylacetone hydrazone,
hydrazodicarbonamide, N,N'-dimethyl-N,
N'-Dinitrosoterephthalamide, dimethyldinitroterephthalamide, azobisisobutyronitrile, diazoaminobenzene, barium azodicarboxylate, 3,3
The hole for producing copper through-hole printed wiring boards according to any one of claims 1 to 5, which is selected from '-disulfone hydrazide diphenyl sulfone, sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, calcium azide and mixtures thereof. Filling ink. (7) Any one of claims 1 to 6, wherein the resin in the resin composite of the powdered blowing agent is a reticulated thermosetting resin selected from epoxy resin, phenol resin, polyamide resin, polyester resin, and polyurethane resin. Hole-filling ink for producing copper through-hole printed wiring boards as described.