JPS5844709B2 - Resin composition for printed wiring boards - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an adhesive for electroless plating, and more specifically, an adhesive used between a board and a circuit conductor in the production of printed wiring boards using electroless plating. This is related to drugs.

Conventionally, the main method for manufacturing printed wiring boards has been the etched foil method, which involves etching out unnecessary copper foil parts of copper-clad laminates. In addition, with the aim of rationalizing the through-hole connection technology between the front and back conductors, an additive method has been developed in which a printed wiring board is created by adding only the necessary conductor circuit parts mainly by electroless copper plating.

This additive method involves drilling holes in the board, activating the entire surface (if a catalyst-containing board is used, the activation process is omitted), printing a Menki resist, and then forming the necessary conductor circuits using only electroless copper plating. Complete electroless copper plating is added, or after the substrate is drilled and the entire surface is activated (if a catalyst-containing substrate is used, the activation treatment is omitted).

), the main method is to perform electroless plating on the entire surface, print a metal resist, and form the necessary conductor circuits by electroplating, and then use a combined method of electrolytic copper plating, which removes the metal resist and the electroless plating other than the conductor circuit parts. ing.

The additive method of forming circuits using electroless plating has the disadvantage that there is no established method to stably obtain sufficient adhesion and mechanical strength of the deposited copper, and the line precision is low. .

The present invention was made in view of these points, and relates to an adhesive for electroless plating that improves adhesion to an electroless plating layer and mechanical strength.

The present invention provides a component (4) that can be eluted by etching and forms a continuous phase, and a component (4) that is incompatible with component (4), is not etched, and has a diameter of 0.
．． It consists of a thermosetting resin component (b) that becomes spherical particles of 5 to 15μ and is dispersed in the continuous phase of component (4), and the component (B) is the sum of components (4) and (B). The present invention relates to an adhesive for electroless plating that occupies 20 to 85 volumes.

The component (4) which can be eluted by etching and forms a continuous phase used in the present invention is acrylonitrile butadiene copolymer with various nitrile contents, butadiene com, chloroprene rubber, styrene butadiene copolymer, polyamide. ,
There is polyethylene terephthalate.

In this case, for etching, a chromic acid-sulfuric acid solution, a potassium dichromate-concentrated sulfuric acid solution, a potassium dichromate-concentrated sulfuric acid solution, or the like is used.

The thermosetting resin component (6) dispersed in particulate form in the continuous phase of component (4) includes bisphenol A epoxy resin, epoxidized phenol resin, epoxidized cresol novolak resin, alicyclic oxirane, and alicyclic glycidyl. One or more of ether, phenolic resin, urea resin, melamine resin, polyester resin, etc. are used.

In the adhesive of the present invention, in the component (4) that can be eluted by etching and forms a continuous phase, the thermosetting resin component (B) that remains without being etched contains spherical particles with a diameter of 0.5 to 15 μm. It has become dispersed.

In order to obtain such a resin layer, component (4) and component () must be incompatible.

If component (4) and component (6) are incompatible, they will separate into two layers or become dispersed even if three good solvents are used.

The compatibility of these two types of polymer solutions is determined by the solubility parameter (SP value, a measure of cohesive energy per unit volume).
When considered using , substances with similar SP values are easy to dissolve into each other, and when the difference in SP value becomes large, it becomes difficult to dissolve, resulting in a dispersed state.

That is, a component with a large SP value becomes particulate and is dispersed in a continuous phase consisting of a component with a small SP value and a solvent.

In the present invention, the SP value of component (4) is smaller than that of component (4).

Furthermore, if this difference becomes large, the solutions will not match and will immediately separate into two phases even if they are mixed.

Now, if we increase the mutually incompatible component (4), @, the component with a large SP value in a mixed system of both with a good solvent,
Since it is essentially an incompatible and unstable system, as the particle concentration of the components increases, particles collide with each other (particle coalescence) and the particle size increases.

That is, an increase in the relative occupied volume of component (6) particles and an increase in particle diameter occur in parallel.

According to this knowledge, the selection of the solvent, the modification of the component (4) that will become the continuous phase (for example, varying the nitrile group content of the acryloni-t-1) butadiene copolymer), and the component that will become the dispersoid ( B) modification (e.g. modification of epoxy resin,
It is easy to control the SP value or the dispersion state depending on the degree of polymerization, and the desired dispersion state can generally be obtained when the SP value difference is in the range of 1 to 4.

In addition, the diameter of the particles is 0.5 to 0.5, which is required in the present invention.
The formation of spherical particles of 15 μm can also be controlled by controlling the relative concentration of the component (4) with a high SP value to the component (4) with a low SP value, or by the degree of dilution of the solvent.

Furthermore, the initial dispersion state is determined by the method of applying dispersion energy.
It is also controlled by the mixing method and the molecular weight of the component that becomes the dispersoid.

For example, when stirring with a propeller in an acrylonitrile butadiene copolymer-methyl ethyl ketone solution having a l) content of 18% to 45%, the average molecular weight (weight) is 50%.
When a bisphenol A type epoxy resin having a molecular weight of 0 to 1500 is used, epoxy resin particles having a diameter of 1 to 10 μm are preferably dispersed.

As described above, the present invention focuses on the mutual incompatibility between the components of a polymer solution, which was originally unresolved, and creates a solution containing a relatively large amount of the component with higher cohesive energy (component with a higher SP value). This was made based on the knowledge that by using the above method, it is possible to obtain a resin layer having large particle size and densely dispersed particles and excellent adhesion to the electroless plating layer.

When the adhesive for electroless plating according to the present invention is roughened by etching,
The roughened surface has irregularities with a depth of about 20 microns and has spherical particles made of thermosetting resin with a diameter of 0.5 to 15 microns.

For this reason, the contact area with the conductor layer increases and the anchor effect seems to increase beer strength.

Similarly, in the present invention, component (B) has a volume φ of 20 to 85 with respect to the sum of component (4) and @, because if it is 20% or less, sufficient adhesion with the electroless plating layer is achieved. This is because it is difficult to obtain a resin layer with a volume occupancy of 85% or more.

Next, the present invention will be specifically explained using an example in which an acrylonitrile butadiene copolymer is used as the component (4) and a bisphenol A type epoxy resin is used as the component (B).

1) Add 40 to 100 parts by weight of an acrylonitrile butadiene copolymer as a roughening eluent component to 100 parts by weight of bisphenol A-type engineered resin as a thermosetting resin.

2) Furthermore, 10 to 20 parts by weight of zinc oxide is added as a filler.

3) Using dicyandiamide as an epoxy resin curing agent
Add 4 parts by weight.

The solvent used for preparing this resin composition is methyl ethyl ketone, which is a good solvent for both, and has a total nonvolatile content of 20 to 40% by weight.
Preferably, the solution is over 30% by weight.

4) Place this resin assembly paraboloid on a glass epoxy resin board with a thickness of 5
Apply to 0 to 60μ and heat cure at 160°C for 60 minutes.

The SP values of bisphenol-A epoxy resin and acryloni-H-rubutadiene copolymer are approximately 11 and 9.5, respectively.
The difference is about 1.5.

Therefore, the two are essentially incompatible. Therefore, the epoxy resin is dispersed in the methyl ethyl ketone-acrylonitrile copolymer continuous phase (generally referred to as a sea) in the form of particles (generally referred to as islands) having a diameter of 0.8 to 5 microns.

When this material is applied to a substrate and methyl ethyl ketone is evaporated, a coating film can be obtained in which the epoxy resin is dispersed in the form of fine particles in the acrylonitrile butadiene copolymer.

5) The substrate coated with the resin composition was treated with a chromic acid-sulfuric acid solution (CrO3100g/!, concentrated H28043) at 45°C.
001rtl/t) for 10 minutes for etching roughening.

In this case, some of the epoxy resin particles are also removed into the liquid together with the acrylonitrile butadiene copolymer, but fine convex portions are formed by the epoxy resin particles on the surface of the substrate.

6) After the activation treatment, a circuit conductor is formed by a known additif method to obtain a printed wiring board.

It goes without saying that if the catalyst is mixed into the resin composition in advance, there is no need to carry out the activation treatment.

As component (4), the rubber may be vulcanized using sulfur as a vulcanizing agent and a common vulcanizing agent such as benzothiazoles as a vulcanization accelerator.

Appropriate resin vulcanization can also be carried out.

As the curing agent for the epoxy resin (component), aliphatic amines, aromatic amines, secondary amines, tertiary amines, acid anhydrides, etc. can be used.

Furthermore, a suitable curing accelerator can also be used.

In addition to zinc oxide, silica powder titanium oxide, zinc sulfide, zirconium oxide, calcium carbonate, magnesium carbonate, etc. may be added as a filler.As the substrate, phenol resin, epoxy resin, allyl phthalate resin, furan resin, melamine Synthetic resin laminates, iron, A substrate made of an inorganic material such as aluminum or mica, or a composite thereof can be used.

Example 1 ■) Bisphenol A epoxy resin (Epicote 10
01 (manufactured by Ciel Chemical Co.) 100 parts, nitrile rubber (N
1032, Nippon Zeon Engineering Co., Ltd.) 70 parts, 0 sulfur powder
．． 7 parts, 0.07 parts of 2-mercaptobenzothiazole, 10 parts of lead oxide, 0.03 parts of palladium chloride, 3 parts of dicyandiamide, Curazole C, Z-AZINE (20.3 parts manufactured by Shikoku Kasei, dissolved in 400 parts of methyl ethyl ketone) to make a homogeneous solution.

2) The above resin composition was applied to a catalyst-containing glass Epokin substrate (L
E-161, manufactured by Hitachi Chemical Co., Ltd.) to a thickness of 40 to 60 microns and dried in a hot air dryer at 130°C for 5 minutes.
Cure in air at 60°C for 60 minutes.

3) After drilling the hole, clean the surface and inside of the hole, use a screen printer to apply epoxy max (HPR-404V, manufactured by Hitachi Chemical Co., Ltd.) in areas other than the areas that will become the printed wiring pattern,
Heat and cure at 130°C for 30 minutes.

4) Chromic acid-concentrated sulfuric acid solution heated to 45°C < CrO31o g/1% concentrated sulfuric acid 3001111
/l) for 10 minutes to roughen the resin composition.

5) Add this to electroless copper plating solution (copper sulfate 0.03 mol/11 caustic soda 0.125 mol/1. sodium cyanide 0.0004 mol/4. formalin 0.08 mol/
11 ethylenediaminetetraacetate (0.036 mol/1) for 30 to 40 hours to obtain a printed wiring board.

The beer strength of the conductor and resin layer of the obtained printed wiring board was 2.3 Ky/cm, and no blistering occurred even when immersed in a 260° C. solder bath for 3 minutes.

The epoxy resin in the adhesive layer is in the form of spherical particles with a diameter of 0.5 to 4μ, and the SP of the epoxy resin component and rubber component is
The difference in values was 1.9.

Example 2 ■) Bisphenol A epoxy resin (Epicor) 10
02, manufactured by Shell Chemical Company) 75 parts, novolac type epoxy resin (Epicote 154, manufactured by Shell Chemical Company) 2
5 parts, nitrile comb (N100I, manufactured by Nippon Zeon Kogyo ■) 80 parts, sulfur powder 0.8 part, 2-mercaptobenzothiazole 0.08 part, palladium chloride 0.03 part, dicyandiamide 3 parts, Curazole C,,Z- AZINE
(manufactured by Shikoku Kasei) and 10 parts of Zr5i04 (Micropax A-20, manufactured by Hakusui Kagaku Kogyo ■) were dissolved in 400 parts of methyl ethyl ketone to form a uniform solution.

2) The above resin composition was applied to a catalyst-containing glass Epokin substrate (L
E-161, manufactured by Hitachi Chemical Co., Ltd.) to a thickness of 40 to 60 microns, dried at 130°C for 5 minutes, and then heated to 60°C at 160°C.
Allow to air cure for a minute.

3) After drilling, clean the inside of the surface hole and apply a Menki mask (Riston film, manufactured by DuPont) to areas other than the areas that will become the printed wiring pattern.

4) After heating this product at 130°C for 40 minutes, Example 1
．． Perform steps 4) and 5).

5) A printed wiring board can be obtained by peeling off the plating mask with methylene chloride.

The beer strength of the conductor and resin layer of the obtained printed wiring board was 2.1 KFI/IZ771, and no blistering occurred even when immersed in a 260° C. solder bath for 3 minutes.

The epoxy resin in the adhesive layer was in the form of spherical particles with a diameter of 2 to 6 μm, and the difference in SP value between the epoxy resin component and the rubber component was 1.0.

Example 3 1) The same resin composition as in Example 1 except that it did not contain palladium chloride was coated on a paper epoxy substrate (LE-47, manufactured by Hitachi Chemical Co., Ltd.) to a thickness of 40 to 60 microns.
After drying for 5 minutes at 160°C, it is cured in air for 60 minutes.

2) After drilling, clean the surface and inside of the hole, Example 1.4)
The above resin composition is roughened by performing the steps of.

3) This material was immersed in H8-101B (palladium-containing sensitizing solution, manufactured by Hitachi Chemical Co., Ltd.) for 10 minutes to roughen the surface,
Provides catalytic properties for electroless copper plating on the inner wall of the hole.

4) Immerse in an electroless copper plating solution (liquid composition is the same as Example 1.5) for 1 to 2 hours to form a 1 to 2 micron copper layer on the roughened surface and inner wall of the hole.

5) Provide a plating mask (Riston film, Dupont "f3") in areas other than the part that will become the printed wiring pattern, and
Heat at 0°C for 40 minutes.

6) Add this electrolytic copper plating solution (copper pyrophosphate 85 g
/l, potassium pyrophosphate 310 g/l.

Ammonia water 3rlll/l, brightener (Pyrolite PY
-61, manufactured by Uezai Kogyo ■) for 40 minutes at 3 Ttl/l, temperature 55°C, cathode current density 3 A/d m2).

7) Peel off the plating mask with methylene chloride.

8) Ammonium persulfate solution ((NHJ2820510
A printed wiring board can be obtained by immersing the copper layer at 0g/4, 40°C) and removing the copper layer other than the printed wiring pattern.

The beer strength of the conductor and resin layer of the obtained printed wiring board was 2.1 KfI/CrIL, and no blistering occurred even when immersed in a 260° C. solder bath for 3 minutes.

The epoxy resin in the adhesive layer is spherical particles with a diameter of 0.5 to 4μ, and the SP of the epoxy resin component and rubber component
The difference in values was 1.9.

Example 4 1) The same resin composition as in Example 2 except that it did not contain palladium chloride was coated on a paper Tsubonol substrate (LP-414F, manufactured by Hitachi Chemical Co., Ltd.) to a thickness of 40 to 60 microns and heated at 130°C. After drying for 5 minutes, it is cured in air at 160°C for 60 minutes.

2) The steps of Example 1.4) and Example 3.3) are carried out to impart catalytic properties for electroless copper plating to the roughened surface and inner wall of the hole.

3) Immerse it in an electroless copper plating solution (Cust 101, manufactured by Hitachi Chemical Co., Ltd.) for 1 to 2 hours, and apply 1 to 1 on the roughened surface and inner wall of the hole.
Form a ~2 micron copper layer.

4) After carrying out the process of Example 3.5), this product was added to an electroless copper plating solution (liquid composition is the same as Example 1.5) for 30 minutes.
Soak for ~40 hours.

5) A printed wiring board can be obtained by carrying out the steps of Example 3, 7) and 8).

The beer strength of the conductor and resin layer of the obtained printed wiring board was 2.3 Ky/cm, and no blistering occurred even when immersed in a bank bath at 260° C. for 3 minutes.

Similarly, the epoxy resin in the adhesive layer was in the form of spherical particles with a diameter of 2 to 6 μm, and the difference in SP value between the epoxy resin component and the rubber component was 1.0.

Comparative example 1 1) Hisphenol A type epoxy resin (Epicote 1o
oi, manufactured by Shell Chemical Co., Ltd.) 100 parts, polybutadiene (N-BR-1220, manufactured by Nippon Zeon Industries) 500 parts, sulfur powder 5.0 parts, zinc oxide 40 parts, 2-mercaptobenzothiazole 0.5 parts, dicyandiamide 6 Department,
Curesol C1□ Z-AZINE (manufactured by Shikoku Kasei) 0
．． 6 parts were dissolved in 1130 parts of methyl ethyl ketone and 60 parts of methyl cellosolve to form a homogeneous solution.

2) Thereafter, a printed wiring board was obtained in the same manner as in Example 3.

The beer strength of the conductor of the obtained printed wiring board is l, 7
Ky/Crn, and no blistering occurred even when immersed in a 260° C. solder bath for 3 minutes.

Note that the epoxy resin of the adhesive layer was in the form of spherical particles with diameters o, i~0.3μ.

The difference in SP value between the epoxy resin component and the rubber component was 2.8.

Comparative Example 2 1) Bisphenol A epoxy resin (Epicote 83
6, manufactured by Shell Chemical Company) 50 parts, bisphenol A type epoxy resin (Epicote 834, manufactured by Shell Chemical Company) 50 parts, nitrile rubber (N-1001, manufactured by Nippon Zeon Industries ■) 25 parts, sulfur powder 0.25 part, Zr5i04
(Micropax A-20. manufactured by Hakusui Kagaku Kogyo ■) 10 parts, 0.02 parts of 2-mercaptobenzothiazole, 6 parts of dicyandiamide, Curazole C, 0.6 parts of Z-AZINE (manufactured by Shikoku Kasei), 190 parts of methyl ethyl ketone, Dissolve in 60 parts of methylcellosolve to make a homogeneous solution.

2) Thereafter, a printed wiring board was obtained in the same manner as in Example 3.

The beer strength of the conductor of the obtained printed wiring board was 1.2
Kf/C11l, and blistering occurred when immersed in a 260°C solder bath for 2 minutes.

Note that the epoxy resin of the adhesive layer was uniformly mixed in the nitrile rubber.

The difference in SP value between the epoxy resin component and the rubber component was 0.5.

Comparative Example 3 1) 80 parts of bisphenol A type epoxy tree J]s (Epicoat 1O01, manufactured by Shell Chemical Company), 20 parts of novolac type epoxy resin (Epicoat 152, manufactured by Shell Chemical Company), polybutadiene (N-BR, -1220, Nippon Zeon Kogyo ■) 30 parts, sulfur powder 0.3 parts, zinc oxide 40 parts, 2-mercaptobenzothiazole 0.03 parts, dicyandiamide 6 parts, Curazole C, I Z-A
0.6 part of ZINE (manufactured by Shikoku Kasei) is dissolved in 250 parts of methyl ethyl ketone and 60 parts of methyl cellosolve to form a uniform solution.

2) Thereafter, a printed wiring board was obtained in the same manner as in Example 3.

The beer strength of the conductor of the obtained printed wiring board is l, 7K.
y/CrIL, and no blistering occurred even when immersed in a 260° C. solder bath for 3 minutes.

Note that the epoxy resin of the adhesive layer was in the form of spherical particles with a diameter of 18 to 20 μm.

The difference in SP value between the epoxy resin component and the rubber component was 2.3.

Comparative example 4 1) Novolac type phenolic resin (HP-607N).

Hitachi Chemical Co., Ltd.) 80 parts, alkylphenol resin (
H-2400, Hitachi Chemical Co., Ltd.) 20 parts, Nitrile Comb (N1032, Nippon Zeon Co., Ltd.) 10 parts, hexamethylenetetramine 8 parts, zinc oxide 5 parts, sulfur powder 0
．． 1 part of ZrSiO4 (Micropax A-20, manufactured by Hakusui Kagaku Kogyo ■) and 0.01 part of 2-mercaptobenzothiazole were dissolved in 245 parts of methyl ethyl ketone to form a homogeneous solution.

2) Thereafter, a printed wiring board was obtained in the same manner as in Example 3.

The beer strength of the conductor of the obtained printed wiring board is 1.5K.
y/cIn, and no blistering occurred even when immersed in a 260° C. solder bath for 3 minutes.

Note that the adhesive layer had a phenol resin component as a continuous phase.

The difference in SP value between the phenol resin component and the rubber component was 1.2.

Claims (1)

[Claims] 1 Component (4) that can be eluted by etching and forms a continuous phase
Component (4) has an SP value 1 to 4 higher than component (4), is not etched, and becomes spherical particles with a diameter of 0.5 to 15μ.
of a thermosetting resin component dispersed in a continuous phase of
) of the above components is 20 to 8 for the sum of component (4) and @
An adhesive for electroless plating that occupies 5 volumes.