JPS6350389B2 - - Google Patents

Description

[Detailed Description of the Invention] Compared to the conventional subtractive method, the additive method greatly contributes to improvements in printed wiring board manufacturing methods such as resource saving, pollution-free production, process automation, and fine patterning. It is well known that this is the case. Additive methods can be broadly classified into full additive methods and semi-additive methods, but in either case, a circuit is formed by depositing plating on the surface of an insulating substrate or an insulated metal substrate. In order to bring the deposited plating into close contact with these substrate surfaces, a method is generally used in which a resin layer to which electroless plating can easily adhere is formed in advance on the portion where the plating is to be deposited. Regarding the composition of this resin layer, many combinations of substances have already been studied, but among them, 1 part by weight of thermosetting resin is mixed with 0.1 to 10 parts of diene rubber.
Compositions containing parts by weight are useful. These compositions are dissolved in a suitable solvent and applied directly to the surface of the substrate.
Dry and cure or dip the substrate into this solution.
The resin layer can be formed by pulling it up and drying it, or by coating it on a suitable film and drying it, and then integrating it when laminating the substrate. However, in order to obtain a substrate for additive plating, a coating machine with high processing precision must be used to form a resin layer of uniform thickness, which is inconvenient. If this resin layer can be formed with good printability by screen printing, it should be possible to easily form the resin layer by the screen printing method normally used by general printed board processing manufacturers. .

However, this resin layer contains 0.1 to 10 parts by weight of diene rubber per 1 part by weight of thermosetting resin in order to easily adhere to the resin layer by electroless plating. Conventionally, it has not been possible to prepare a solution of a mixture having such a composition that is suitable for screen printing. That is, there were problems such as poor plate release properties, inclusion of air bubbles, and lack of continuous printing workability, and it was completely unusable for practical use. As a result of studying the unsuitability of such conventional solutions for screen printing, we found that if the type of solvent is selected and mixed in a specific ratio, for example, 0.1 to 10 parts of diene rubber can be mixed for 1 part by weight of thermosetting resin.
It has been found that an ink having good screen printability can be obtained even if the solution contains a mixture containing 100% by weight.

That is, according to the present invention, the diene rubber is contained in 0.1 to 10 parts by weight per 1 part by weight of the thermosetting resin, and the composition of the solvent is a good solvent for both the resin and the rubber. a first solvent that acts as a solvent and a second solvent that is a good solvent for the resins but a poor solvent for the rubbers;
It is characterized in that the amount of the second solvent is 0.1 to 2 parts by weight per part by weight.

That is, by using the first solvent that is a good solvent for both the resin and the rubber, a coating film is formed with long chain rubber molecules uniformly dispersed in the resin composition. , a second solvent that is capable of forming a uniform active surface in the subsequent electrolytic plating process and is a good solvent for the resins and a poor solvent for the rubbers. By using these together, it is possible to control the aggregation of long-chain rubber molecules and control the spinnability, thereby making it possible to maintain suitability for screen printing.

The details of the present invention will be described below.

The thermosetting resins used in the present invention are generally three-dimensional thermosetting resins such as phenolic resins, epoxy resins, alkyd resins, unsaturated polyester resins, urethane resins, polyimide resins, and polyamideimide resins, Used alone or in combination. In particular, phenol resin is a desirable resin because it can form a strong coating film by performing a crosslinking reaction with diene rubbers. Further, even if the resin is a fine powder that cannot be dissolved in a solvent, it can be used by uniformly dispersing it together with a resin that has good solubility in the solvent.

Next, the diene rubber components include natural rubber, butadiene/acrylonitrile copolymer, butadiene/styrene copolymer, polybutadiene, chloroprene rubber, isoprene rubber, butadiene/styrene anion copolymer rubber, liquid rubber (terminal OH
or a diene compound having an unsaturated double bond, such as COOH polybutadiene, butadiene acrylonitrile copolymer, etc.). The weight mixing ratio of the resin component and the rubber component is preferably in the range of 0.1 to 10 parts by weight of the rubber component per 1 part by weight of the resin component. No active surface is obtained. If it exceeds 10 parts by weight, printability will not be lost, and the physical properties of the coating film, especially the adhesion strength and scratch strength under heat, will be significantly reduced. As for the addition method, it is desirable to completely dissolve it in a good solvent for rubber and then mix it with the resin component.

The solvents used in the present invention include ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, acetate esters such as ethyl acetate and butyl acetate, and amides such as NN'-dimethylformamide, NN'-dimethylformamide, and NN'-dimethylacetamide. , N-methylpyrrolidone, γ-butyl lactone, and other lactones; benzyl alcohol, diphenyl ether, isophorone, and cyclohexanone; a first solvent that is a good solvent for both the resin component and the rubber component; Or the weight of a mixture of two or more types of glycols, cellosolves such as ethylene glycol monomethyl ether, ethylene glycol monomethyl ether, and ethylene glycol monobutyl ether, carbitols such as methyl carbitol, ethyl carbitol, butyl carbitol, and carbitol acetate. It is essential that the mixed solvent consists of one type or a mixture of two or more second solvents that are good solvents for the resin component selected from the following and are poor solvents for the rubber component.

The mixing weight ratio of the solvents should be 0.1 to 2 parts by weight of the second solvent to 1 part of the first solvent.
Here, the second solvent is
If the amount is less than 0.1 part by weight, the chain rubber molecules will be sufficiently dispersed, but the rubber molecules will be in a sufficiently elongated state, resulting in a significantly high viscosity and poor stringability during the screen printing process. It becomes significantly larger, resulting in decreased plate separation, inclusion of bubbles, decreased continuous printability, etc., and becomes virtually impossible to use for printing.

On the other hand, if the amount is 2 parts by weight or more, long-chain rubber molecules become entangled and aggregate to form lumpy particles, which will not lose screen printing suitability, and furthermore, even after the resin composition is cured, these rubber particles will remain as islands in the cured coating film. Therefore, good plating properties cannot be obtained.

In the ink of the present invention, the concentration of the mixture of the resin and the rubber is preferably in the range of 20 to 90% by weight;
If it is less than % by weight, the viscosity of the resin composition increases,
High stringiness is observed, printing workability is markedly reduced, and when it is 90% by weight or more, the thickness of the cured coating film becomes thin and sufficient scratch strength and adhesion cannot be obtained. In addition, if the drying conditions of the ink coating film after screen printing are poor, the rubber components in the coating film tend to aggregate and become coarse particles due to moisture absorption, changes in the composition of the mixed solvent, and the like. It is desirable that the second solvent among the components of the mixed solvent has a higher boiling point than the first solvent, since this prevents the formed coating film from deteriorating.

Antifoaming agents such as silicone resins and fluororesins, spreading agents, plasticizers, colorants, liquid flame retardants, and the like can be added to the resin composition of the present invention, if necessary. In addition, ultrafine colloidal silica powder can be added to improve printing workability, especially to impart thixotropy, and furthermore, fine powder of resins that cannot be dissolved in the solvent used in the present invention can be uniformly dispersed. When dispersing such powders or additives in a solution, use a three-roll roll, a so-called ink roll, or a device with similar capabilities to completely disperse the powder or additives. is essential.

This will be explained in more detail below with reference to Examples.

Example 1 Butadiene rubber (manufactured by Japan Synthetic Rubber, JSR-N-
220SH) Cut 120g into small pieces and add benzyl alcohol.
A 20% rubber solution was obtained by heating and dissolving 480 g of the product at 80°C.

The rubber solution was blended with a thermosetting resin and various additives in the following blending ratios, and thoroughly stirred and mixed using three rolls to obtain a paste-like resin composition.

JSR-N-220SH/benzyl alcohol (20% by weight solution) 100 parts by weight EP-1001 (Epicote, manufactured by Shell Chemical Co., Ltd.)/butyl carbitol (75% by weight solution) 10.6 parts by weight Diaminodiphenylmethane/butyl carbitol (50 parts by weight) % solution) 1.6 parts by weight PR-51833 (phenolic resin manufactured by Sumitomo Durez)
30 parts by weight R-972 (manufactured by Nippon Aerosil, fine powder silica)
3 parts by weight SC-5540 (manufactured by Toray Silicone, antifoaming agent) 2 parts by weight Benzyl alcohol 20 parts by weight Butyl carbitol 15 parts by weight The composition ratios (% by weight) of the main components of this resin composition are as follows: .

Thermosetting resin component 15.5% Diene rubber component 11.0% Solvent that is a good solvent for both the resin component and diene rubber component 54.9% Solvent that is a good solvent for the resin component and a poor solvent for the diene rubber component 15.9% Others 2.7% When screen printing was performed on a phenolic resin laminate using the above resin composition, the plate releasability was extremely good, there was no entrapment of bubbles, and the screen printing was continuous.
It was possible to print 90 sheets.

Next, the resin composition was cured by heating at 150°C for 1 hour, and the surface of the cured product was treated with an aqueous solution of chlorosulfuric acid for 3 hours.
After chemical roughening for 25 minutes, electroless copper plating was performed using the ship play process.
Copper was deposited to a thickness of m. Next, electrolytic copper plating was performed using a copper pyrophosphate bath to form a copper plating film with a thickness of 38 μm, and an adhesion test by peeling was performed and the result was 1.8 Kgf/cm, indicating good plating adhesion. had.

Example 2 Using the rubber solution obtained in Example 1, a thermosetting resin and additives were blended in the following blending ratio, and kneaded with three rolls to obtain a paste-like resin composition.

JSR-N-220SH/Benzyl alcohol (20% by weight solution) 100 parts by weight Ep-828 (Epicoat manufactured by Shell Chemical Co., Ltd.) 11 parts by weight Diaminodiphenylmethane/Butyl carbitol (50% by weight solution) 1.2 parts by weight Kelimide #601 ( Polyimide resin powder manufactured by Lorne Poulenc) 15 parts by weight R-972 1.5 parts by weight SC-5540 2 parts by weight Butyl carbitol 25 parts by weight The composition ratios (% by weight) of the main constituent components of this resin composition are as follows. be.

Thermosetting resin component 17.1% Diene rubber component 12.8% Solvent that is a good solvent for both the resin component and diene rubber component 51.4% Solvent that is a good solvent for the resin component and a poor solvent for the diene rubber component 16.4 % Others 2.2% When screen printing was performed on a paper-based epoxy resin laminate using the above resin composition, the plate release properties were good and 120 sheets could be printed continuously without trapping bubbles. It was hot.

Next, the resin composition was heated and cured at 150°C for 1 hour, and the surface of the cured product was roughened by liquid honing, and then electroless nickel plating was performed using the Kanigen method at a bath temperature of 85°C for 2 hours. However, 31μm
A thick nickel plating film could be formed.
When we conducted an adhesion test by peeling, we found that
The plating adhesion was 0.9 kgf/cm and had good plating adhesion.

Example 3 100g of butadiene rubber (JSR-N-220SH) was cut into small pieces and mixed with 900g of a mixture of equal amounts of acetone, methyl ethyl ketone (MEK), and methyl isobutyl ketone (MIBK) at 90°C for 4 hours to form a rubber. was completely dissolved to obtain a 10% by weight rubber solution.

Next, the rubber solution was mixed with a thermosetting resin and a solvent at the following blending ratio to obtain a resin/rubber solvent mixture.

JSR-N-220SH (10% by weight solution) 200g PR-51833 35g Butyl carbitol acetate 40g Next, stir and heat at 60°C for 40 minutes under reduced pressure.
A part of the low boiling point rubber solvent was distilled off to obtain the following composition.

JSR-N-220SH 20g MEK/MIBK mixture
76g (partial distillation of acetone and MEK) PR-51833 35g butyl carbitol acetate 40g Next, add 3g of R-972 to these mixtures, SC-5540
Add 1.2g and knead uniformly using three rolls. The composition (weight %) of the obtained resin composition is as follows.

Thermosetting resin component 13.0% Diene rubber component 11.4% Solvent that is a good solvent for both the resin component and diene rubber component 43.4% Solvent that is a good solvent for the resin component and a poor solvent for the diene rubber component 29.8% Others 2.4% When screen printing was performed on a phenolic resin laminate using the above resin composition, the plate releasability was good, there was no entrapment of bubbles, and continuous 65%
It was possible to print multiple sheets.

Next, in the same manner as in Example 1, after pretreatment, electroless copper plating was performed by a ship play process, and copper was deposited to a thickness of about 0.5 μm in 20 minutes. Next, electrolytic copper plating was performed using a copper pyrophosphate bath to form a copper plating film with a thickness of 34 μm. When an adhesion test was performed by peeling, it was 1.6 Kgf/cm, indicating good plating adhesion. It had

Example 4 Heat drying at 150°C after screen printing in Example 1,
The copper plating film processed through the same process as in Example 1 except that it was air-dried for 10 hours at 20 to 30°C before the 1-hour drying, showed no results in the adhesion test by peeling.
The plating adhesion was 1.8 Kgf/cm and had good plating adhesion.

Comparative Example 1 When processed in the same manner as in Example 3 except that butyl carbitol acetate was replaced with benzyl alcohol in the formulation of Example 3, plate separation during the screen printing process was poor. Ink also tends to smudge. While the printability of Examples 1, 2, and 3 was good,
The reason why this comparative example is bad is that only the first solvent was used instead of a mixed solvent of the first solvent and the second solvent.

Claims (1)

[Claims] 1. In the ink composition, 0.1 to 10 parts by weight of a diene rubber is contained per 1 part by weight of a thermosetting resin as a solid component composition, and the resins are included as a solvent composition. and a first solvent that acts as a good solvent for both components of the rubbers, and a second solvent that is a good solvent for the resins but a poor solvent for the rubbers. The second solvent is blended at a mixing ratio of 0.1 to 2 parts by weight per 1 part by weight of the first solvent, and the resin is mixed with respect to the total amount of the mixture of the resin and the rubber and the first and second solvents. 1. An ink composition for screen printing for forming a resin layer that easily adheres to electroless plating, characterized in that the weight ratio of the mixture of the rubber and the rubber is in the range of 20 to 90%. 2. The screen printing ink composition according to claim 1, characterized in that the first solvent has a boiling point higher than that of the second solvent.