JPH03220281A - Base adhesive for electroless plating, printed circuit board using the adhesive, and manufacturing method thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a base adhesive for electroless plating of printed circuit boards;
The present invention relates to an adhesive film in which a base film is coated with the adhesive, and a printed circuit board using the same.

[Prior Art] In a printed circuit board in which a circuit is formed on the surface of an insulating base material by electroless plating, an adhesive layer is formed on the base for adhesion of the electroless plating film.

The adhesive for the adhesive layer is an epoxy resin.

Those whose main components are synthetic rubber and phenolic resin (Japanese Patent Publication Nos. 45-9843, 58-57776, 59-62683, 62-248291, 63-277772) ), or one whose main components are synthetic rubber and phenolic resin (Special Publication Publication No. 1988-3
No. 0760.

Japanese Patent Publication Nos. 60-5079, 63-213676, and 63-213677) are known.

These adhesives contain imidazoles, amines, acid anhydrides, novolak-type phenolic resins, etc. as curing agents for epoxy resins, and resol-type phenolic resins, sulfur compounds, etc. as vulcanizing agents for synthetic rubber. , those containing metal oxide vulcanization aids such as zinc oxide and magnesium oxide are used.

These adhesive layers are etched with a chromium sulfuric acid mixture to roughen the surface and provide an anchor effect in order to improve the beer strength and solder heat resistance of the electroless plating film. Also, calcium carbonate, calcium silicate, silicon oxide, zirconium silicate to enhance the anchoring effect.

Some contain inorganic fillers such as titanium oxide.

The adhesive layer is formed by adding a solvent to the adhesive and applying a dip method,
It is formed by applying it to the surface of an insulating substrate by a roll coating method, curtain coating method, etc., drying it, and then heating and curing it.

[Problems to be Solved by the Invention] Conventionally, the curing of the adhesive has been performed using the method disclosed in Japanese Patent Application Laid-Open No. 62-24.
As described in No. 8291, heating at 150 to 200°C for 30 to 120 minutes is required.

However, in reality, although epoxy resin can be cured at 150°C for 30 minutes, it is insufficient for the reaction between synthetic rubber and its vulcanizing agent, phenolic resin or sulfur compound. There are problems in that the insulation resistance of the adhesive layer is low, the adhesive layer swells due to the stress deposited in the plating film during electroless plating, and the beer strength and solder heat resistance of the plating film are low. For this reason, the above-mentioned Japanese Patent Application Laid-Open No. 62-2482
As described in the example of No. 91, - 16 for boat fishing.
The reality is that curing is performed at 0° C. or higher for 60 minutes or longer.

Incidentally, printed circuit boards are becoming thinner year by year, and when the insulating base material is a paper phenol board, it is required to have a thickness of 0.8 to 1 mm, and in the case of a glass epoxy board, a thickness of 0.5 to 1 mm is required. Further, there is a demand for a fine circuit with a conductor circuit width or an interval between conductor circuits formed thereon of 0.1 mm or less. If an adhesive layer is formed on such a thin insulating base material and cured at 160°C or higher for 60 minutes or more, the insulating base material will warp or twist, causing the plating resist coating process, which is a pre-process of electroless plating. However, there are problems such as printing of resist ink and pasting of dry film resist cannot be performed properly due to warping or twisting of the substrate.

In addition, with paper phenol as a base material, the paper in the base material deteriorates due to heat, and cracks may appear between adjacent through holes or between perforations during press die cutting after circuit formation. However, there are problems such as the cut end surface of the substrate becomes moth-eaten.

On the other hand, high insulation resistance is required between conductor circuits formed by electroless plating, but with conventional adhesives, the insulation resistance value of the adhesive layer after curing is about 1011 to 1013 Ω, and the circuit spacing is 0.1 mm. It cannot be said that the insulation resistance of the adhesive layer on which the following microcircuits are provided is sufficient.

The purpose of the present invention is to prevent warping or twisting of the insulating base material, and to operate it at a relatively low temperature (around 150°C) in a short period of time (within 30 minutes).
An object of the present invention is to provide a base adhesive for electroless plating that cures with water and provides an adhesive layer with high insulation resistance after curing, and a printed circuit board using the adhesive.

Another object of the present invention is to provide an adhesive film that provides a base adhesive layer for electroless plating by coating a base film with the adhesive.

[Means for Solving the Problems] The gist of the present invention to achieve the above object is to contain an epoxy resin, a two-metal synthetic rubber, and a phenol resin as main components, a curing agent for the epoxy resin, and a combination of the synthetic rubber and the phenol resin. The adhesive is characterized by containing an inorganic filler having a hydroxyl group as a reaction accelerator.

The preferred blending amount of the epoxy resin/synthetic rubber/phenol resin, which is the main component of the adhesive, is based on a weight ratio of 15 to 4.
0)/(40-60)/(20-40), and the required amount of the curing agent for the epoxy resin, especially the photosensitive aromatic onium salt, is 0.2 parts by weight per 100 parts by weight of the resin components.
It is preferable to mix up to 5 parts by weight. Further, the amount of the inorganic filler having a hydroxyl group is preferably 3 to 20 parts by weight.

The adhesive of the present invention is formed by coating on the surface of an insulating base material and then cured by heating. However, the adhesive using a photosensitive aromatic onium salt as a curing agent for an epoxy resin can be cured by ultraviolet irradiation. It is hardened by post-heating.

The irradiation amount of the above ultraviolet rays is 365 nm wavelength O, 5 to 3 J.
/cm" is sufficient. Upon irradiation with ultraviolet rays, the photosensitive aromatic onium salt decomposes and releases a Lewis acid, which is a curing species of the epoxy resin, and a certain degree of curing can be performed at a relatively low temperature. Therefore, it has the effect of less thermal deformation during curing than general curing agents, and less deformation of the substrate etc. when forming the adhesive layer.However, epoxy resin cannot be completely cured by UV irradiation alone.Epoxy Thermal energy is also required for complete curing of the resin.

The epoxy resin can be completely cured if the ultraviolet irradiation device can simultaneously emit infrared rays and heat the adhesive layer to a temperature of 135 to 150°C. Note that the heat source may be an infrared lamp or a normal heating furnace.

As the epoxy resin, a known epoxy resin is used, and the epoxy equivalent is 450 to 2100 g /
A q bisphenol A type epoxy resin is preferred.

The inorganic filler having hydroxyl groups promotes the reaction between the synthetic rubber and the phenolic resin at 135-150°C.

It is sufficiently cured by heating for 20 to 30 minutes, and an adhesive layer with high insulation resistance can be obtained. If an inorganic filler having a hydroxyl group is not blended, heating at 160° C. or higher for 60 minutes or longer is required.

The synthetic rubber includes acrylonitrile butadiene rubber, isoprene-containing acrylonitrile butadiene rubber,
Carboxyl-containing acrylonitrile butadiene rubber, styrene butadiene rubber, etc. can be used.6 In addition, as a phenol resin, resol type phenol resin has good reactivity with synthetic rubber, and the resol type phenol resin is alkyl-modified or cashew-modified phenol. Resins and the like are particularly preferred since they have excellent reactivity.

The blending ratio of epoxy resin/synthetic rubber/phenolic resin is
Weight ratio: (15-40)/(40-60)/(20-4
0) is because if the epoxy resin is less than 15 parts by weight, the a-edge resistance of the adhesive layer after curing will be 1013Ω or less, and 40
If it exceeds 1 part by weight, it will be difficult to cause chemical roughening (described later), and the plating film may swell during electroless plating, and the beer strength may become 1.3 kg/Qm or less.

If the amount of synthetic rubber is less than 40 parts by weight, chemical roughening becomes difficult, causing swelling of the 5-plated film and a decrease in beer strength. 6
If the amount exceeds 0 parts by weight, the insulation resistance of the cured adhesive layer tends to be lower than 10''iΩ, especially in the case of synthetic rubber containing acrylonitrile.

Furthermore, if the phenol resin is less than 20 parts by weight, the reactivity with the synthetic rubber will be insufficient, and the adhesive layer will likely swell during electroless plating. If it exceeds 40 parts by weight, the reaction with the synthetic rubber will proceed too much, making it difficult to chemically roughen it.

As the photosensitive aromatic onium salt,
Aromatic onium salt of group ■a element described in No. 14277,
Aromatic onium salts of Vla group elements described in Japanese Patent Publication No. 52-14278 and aromatic onium salts of Va group elements described in Japanese Patent Publication No. 52-14279 are known, and any of these can be used. Specifically, triphenylphenacylphosnium tetrafluoroborate, triphenylsulfonium hexafluoroantimonate, diphenyliodonium tetrafluoroborate, etc. can be used. It is preferable that one or more of these photosensitive aromatic onium salts be blended in an amount of 0.2 to 5 parts by weight based on a total of 100 parts by weight of the resin component.

If it is less than 0.2 parts by weight, the epoxy resin will not be sufficiently cured, and the insulation resistance of the adhesive layer will be lower than 1011Ω.
Even if the amount is more than 5 parts by weight, no further effect will be obtained.

Inorganic fillers with hydroxyl groups include zinc hydroxide, aluminum hydroxide, antimony hydroxide, cadmium hydroxide, calcium hydroxide, chromium hydroxide, cobalt hydroxide, tin hydroxide, strontium hydroxide, iron hydroxide, water Copper oxide, lead hydroxide, nickel hydroxide, barium hydroxide, bismuth hydroxide.

Examples include arsenic hydroxide, magnesium hydroxide, manganese hydroxide, and lanthanum hydroxide.

However, considering the insulation properties and ease of roughening of the adhesive layer after curing, the beer strength of the plating film, and the solder heat resistance, zinc hydroxide, hydroxide Antimony.

Calcium hydroxide, cobalt hydroxide, barium hydroxide,
Magnesium hydroxide and manganese hydroxide are preferred. One or more of these is used in an amount of 3 to 20 parts by weight based on a total of 100 parts by weight of the resin components.

If it is less than 3 parts by weight, low temperature (135 to 150°C) curing of the synthetic rubber and phenolic resin cannot be sufficiently promoted. Further, even if the amount exceeds 20 parts by weight, further curing will not be promoted.

In the present invention, zinc oxide is further used as a vulcanization aid for synthetic rubber.
Magnesium oxide, cobalt oxide, etc. can be used. In addition, silicon oxide powder with a large surface area is used as a thixotropic agent to prevent spillage during coating, or fine powder fillers such as calcium carbonate, calcium silicate, and zirconium silicate are used to facilitate chemical roughening. can do.

The adhesive of the present invention is prepared by kneading using a known two-roll, three-roll, kneader, ball mill, sand mill, or the like.

In the case of roll-mixing, first the synthetic rubber, an inorganic filler having a hydroxyl group, a vulcanization aid, and other additives are kneaded with a roll, and this is diluted with an appropriate solvent. It can be obtained by blending an epoxy resin curing agent such as a photosensitive aromatic onium salt and a phenol resin. In the case of kneading with a kneader, it can be produced in the same manner as the above-mentioned roll kneading.

When kneading in a ball mill or sand mill, add epoxy resin, synthetic rubber, or phenol resin to the solvent in advance.

A photosensitive aromatic onium salt is dissolved, and an inorganic filler having a hydroxyl group, a vulcanization aid, and other additives are added and kneaded.

The solvent may be selected from ketones, cellosolves, and others depending on the purpose, and is preferably adjusted to have a solid content of 10 to 50% by weight.

As a method for applying the adhesive to the surface of the insulating substrate, known methods such as a roll printing method, a curtain coating method, a dip method, and a screen printing method can be used. At this time, the coating thickness can be adjusted by adjusting the concentration of the adhesive solution and the coating method, but the thickness of the adhesive layer after drying is preferably 10 to 1100 AL.

If it is thinner than 10ILm, the beer strength and soldering heat resistance of the electroless plating film formed thereon will be insufficient.
If the adhesive layer is thicker than m, the irradiated ultraviolet rays may not be sufficiently transmitted to the lower layer of the adhesive layer.

An adhesive film for forming a base adhesive layer for electroless plating (hereinafter referred to as an adhesive film) can be prepared by applying the adhesive onto a base film that has been subjected to a mold release treatment. This adhesive film is used to attach the adhesive-coated side to an insulating substrate along with the base film, and then peel off the base film after a curing process. Demonstrates workability. This adhesive film can be created as follows.

After thoroughly kneading the resin components, the photosensitive aromatic onium salt is dissolved and dispersed in an organic solvent while being added, and filtered to prepare an adhesive having a solid content of 10 to 40% by weight. A transparent base film (thickness 10 to 10
0μm) using the knife coating method or applicator method so that the dried coating film has the desired thickness, and then drying it at 60 to 110°C for 5 to 20 minutes to form an adhesive film. can be created. The adhesive layer of the adhesive film contains 0.0 of the organic solvent.
It is preferable that 01 to 0.5% by weight remain. The reason why the organic solvent is left behind is that tacking is necessary in the process of automatically bonding the adhesive film onto the insulating substrate. Note that if the content of the solvent is too small, the temporary adhesion will be poor, and if it is too large, it will cause foaming of the adhesive layer, so it is preferably within the above range.

As the base film of the adhesive film, a known transparent film can be used. In particular, polyester films have excellent transparency and smoothness, and can be effectively treated with a mold release agent to facilitate peeling off of unnecessary base films after forming an adhesive layer on an insulating substrate. In addition, since it has excellent heat resistance, it has excellent workability in adhesive coating. Note that the thickness of the polyester film is 10 to 100 μm depending on the film tension during coating work, the efficiency of ultraviolet ray irradiation for curing the adhesive, etc.
m is preferred.

A known mold release agent is used for the mold release treatment of the base film. However, it is important to use UV light that does not cause interference fringes. Silicone mold release agents are generally well known as mold release agents.
This is undesirable because it tends to cause interference fringes, and when interference fringes occur, parts of the adhesive layer are cured to different degrees, resulting in non-uniform quality of the adhesive layer.

According to studies by the present inventors, a silyl isocyanate-based mold release agent is preferable as a mold release agent that is less likely to cause such interference fringes. The reason why these do not generate interference fringes is thought to be that they blend well with the surface of the base film and form an optically uniform thin mold release agent layer.

Further, in order to avoid as much as possible the transfer or migration of the release agent to the adhesive and the effects on the properties of the adhesive layer, the thickness of the release agent layer is desirably 0.1 μm or less.

The adhesive film obtained as described above must be easily peeled off at the time of application in order to prevent secondary adhesion to the back surface of the base film due to winding, or to prevent dust, etc. from adhering to the adhesive layer surface and preventing contamination. Preferably, the adhesive surface is provided with a thin protective coating with good releasability.

The adhesive coated or pasted on the insulating base material can be heated or irradiated with ultraviolet rays to give a 135 to 150
Cure in 20-30 minutes. In addition, in the method using an adhesive film, it is preferable to peel off the base film after the ultraviolet irradiation and then perform heat curing. If the base film is heated with the base film attached, there is a risk that the adhesive layer will foam due to reaction products (moisture, etc.) between the synthetic rubber and the phenolic resin.

The surface of the hardened adhesive layer is roughened using a well-known mixture of chromic acid, etc., and then a catalyst for electroless plating reaction is applied and activated, and areas other than the circuit pattern are covered with a plating resist. , plating is deposited on the circuit pattern portion by electroless plating to form a conductor circuit.

[Function] The reason why the adhesive of the present invention can be cured at a relatively low temperature of 135 to 150°C is due to the inorganic filler having a hydroxyl group.

The inorganic filler releases hydroxyl groups at relatively low temperatures (below 150°C), and the hydroxyl groups promote a crosslinking reaction between the α carbon adjacent to the double bond of the synthetic rubber and the methylol group of the phenolic resin. I think this is due to

In addition, when a photosensitive aromatic onium salt is used as a curing agent for epoxy resin, curing can proceed to some extent by UV irradiation, so dimensional changes during curing of the adhesive can be suppressed, and insulation It is considered that even a base material with a thickness of 1 mm or less is unlikely to warp or twist.

The low curing temperature means that there is little thermal deterioration even when a paper phenol base material is used, and cracks between through holes and perforations caused by press die cutting and moth-eaten defects on the cut end surface are less likely to occur.

[Example] The present invention will be explained in detail below.

[Examples 1 to 8] Table 1 shows the composition of the adhesive used in the examples.

The adhesive was kneaded using two rolls, and a solvent was added to adjust the solid content to about 30% by weight.

Each of these adhesives is 500mm x 500mm x thickness 0
, 8 mm paper phenol base material (LP-461F manufactured by Hitachi Chemical Co., Ltd.) and a 0.5 mm thick ultraviolet opaque glass epoxy base material (EL-37 manufactured by Juju Bakelite Co., Ltd.).
62) by a roll coating method so that the thickness of the adhesive layer after drying was about 30 μm, and dried at 80° C. for 20 minutes.

Next, we used an ultraviolet irradiator (HMW-514 model manufactured by Oak Manufacturing Co., Ltd.) equipped with two 80 W/cm high-pressure mercury lamps with parallel light irradiation type reflectors that can emit ultraviolet and infrared rays simultaneously, and used a 365 nm sensor to generate 1.27 J. /cm2 of ultraviolet light was irradiated. The surface temperature of the adhesive layer at this time was 135°C.

Next, after thermosetting at a predetermined temperature and cooling to room temperature, we examined the amount of warpage and twist of each base material, and the occurrence of moth-eaten defects on the cut end surface due to press die cutting of the paper phenol base material after plating. evaluated. The results are shown in Table 2.

The amount of twist is the amount of lift of the other end surface when one end surface of a 500 mm x 500 mm base material is brought into close contact with the end surface, expressed as the distance ('mm) from the end surface of the end surface.

The insulation resistance of the adhesive is determined based on Figure 2 of JIS Z3197. A 35 μm thick copper foil-coated glass epoxy board is used, the copper foil is etched to create a comb-shaped electrode, and the comb-shaped electrode is formed on the surface of the board. The adhesive of each example was applied to the adhesive, and dried, irradiated with ultraviolet rays and infrared rays, and cured by heating in the same manner as described above. Table 3 shows the initial value of the insulation resistance at 500 VDC for 1 minute and the value after moisture absorption (40° C., 95% RH, 240 hours).

On the other hand, each test piece used for the evaluation of warping and twisting was mixed with 65 g of chromic anhydride and 250 ml of concentrated sulfuric acid and added with water.
It was roughened in a chemical roughening solution designated as Q at 50°C for 7 minutes, washed with water, and then washed with hot water at 50°C for 10 minutes. Then, N a
The roughened residue on one surface was removed by treatment in an OH6g/Q aqueous solution at 50°C for about 10 minutes. After washing with water, immerse for about 2 minutes in a catalyst solution containing palladium (H5/10IB manufactured by Hitachi Chemical Co., Ltd.), which is a catalyst for electroless plating reaction, to apply a plating catalyst, and after washing with water, add 1 g of oxalic acid and 10 mQ of 36% hydrochloric acid.
and was immersed in an activation solution prepared as IQ by adding water for about 2 minutes, and then washed with water. Each specimen subjected to plating pretreatment in this manner was dried at 120° C. for 10 minutes.

On the surface of the specimen, a pattern for measuring beer strength of @1 cm x 10 cm in length, and a pattern for measuring 260°C soldering heat resistance of 2.5 cm wide x 2.5 cm in length,
Comb-shaped circuit pattern (A) with a width of 0.2 mm, a spacing of 0, 2 mm, and a facing length of 1 m, and a width of 0, 1 m.
In order to form a pattern for measuring circuit insulation resistance having a comb-shaped circuit pattern (B) of m x interval 0.1 mm x opposing length 1 m, each pattern was covered with a plating resist by screen printing method and photographic method, leaving the pattern part. .

In the screen printing method, an ultraviolet curing resist ink (RI-510 manufactured by Nippon Soda) was screen printed on areas other than the pattern forming area, and was cured by irradiating it with 1.5 J/am'' ultraviolet rays. Paste a molded resist (5R3200 manufactured by Hitachi Chemical Co., Ltd.),
300 mJ/Qm'' except the pattern forming area, and developing the plating resist in the unexposed area (pattern forming area).

Removed.

Next, it was heated to 70°C using an electroless copper plating solution with the following composition.

Plating was carried out for about 5 hours, and a copper plating film with a thickness of 30 μm was formed on each pattern forming portion. After plating, wash with water at 150℃
and dried for 30 minutes.

The beer strength and solder heat resistance of each plated specimen were measured based on JISC6481.

In addition, the insulation resistance is the initial value and the value after moisture absorption (40℃).

95%RH, after 240 hours) was measured. The results of these measurements are shown in Tables 4 and 5.

As shown in Table 2, the adhesives of Examples 1 to 8 had both warp and twist of 1 mm or less, regardless of the type of insulating base material. Further, in the case of using a paper phenol base material, press die cutting was performed after plating, and as a result, no moth-eaten defects were observed on the cut end surface, and no cracks were observed between through-holes or between perforations. In addition, as shown in Table 3, the cured film of the adhesives of Examples 1 to 8 had an initial value of 1
014Ω or more, and the moisture absorption value is 1013 to 1014Ω
showed that.

Furthermore, as shown in Tables 4 and 5, the beer strength is 2 kg f / cm or more, and the soldering heat resistance at 260°C is also 20 seconds or more when using a paper phenol base material (base material The time required for blistering to occur) was 180 seconds or more for the glass epoxy base material.

The circuit insulation resistance of the comb-shaped circuit pattern (A) formed by the screen printing method and the comb-shaped circuit pattern (B) formed by the photographic method has an initial value of 1012 Ω regardless of the type of insulating base material. Indicated. In addition, the moisture absorption value is 1010Ω or more when using a paper phenol base material, and 1011 to 101Ω when using a glass epoxy base material.
It showed 2Ω.

[Comparative Examples 1 to 8] Boron trifluoride monomethylamine was used instead of the photosensitive aromatic onium salt of the adhesive in Table 1 shown in Examples 1 to 8, and an inorganic filler having a hydroxyl group Adhesives were prepared using the same raw materials, except that no materials were blended. After applying this to the insulating base material and drying it,
It was cured for 0 minutes.

As a result, the insulating base material was warped or twisted by 2.1 to 3.8 mm. This hindered screen printing and application of dry film resist, making it impossible to form a fine circuit, making it impossible to evaluate circuit insulation resistance.

Note that the initial value of the insulation resistance of the cured adhesive film is 101
It was 3Ω.

In addition, the beer strength and solder heat resistance measured using a sample plated entirely on a substrate showed almost the same values as Examples 1 to 8. In addition, when press die cutting after plating when using paper phenol base material, moth-eaten defects occur on the end surface.
Cracks occurred between through holes and perforations.

[Example 9] Using an adhesive containing 1.5 parts by weight of 2-ethyl-4-methylimidazole (Shikoku Kasei) instead of triphenylsulfonium hexafluoroantimonate in Example 3, paper phenol base The surface of the material and glass epoxy base material was roll coated to a dry thickness of approximately 30 μm, dried at 80'C for 20 minutes, then coated at 140°C for 20 minutes and then at 150°C.
, heat curing was performed for 30 minutes.

The amount of warpage and twist after cooling to room temperature was measured. 6th result
Shown in the table. Incidentally, no moth-eaten defects were observed on the cut end surface due to press die cutting of the paper phenol base material after electroless plating.

Further, as in Example 1, the results of measuring the insulation resistance, beer strength, solder heat resistance, and circuit insulation resistance of the adhesive layer using comb-shaped electrodes are shown in Tables 7, 8, and 9.

Table 6 Table 8 Table 9 [Examples 10 to 13] Four types of adhesives shown in Table 10 were prepared. The synthetic rubber, vulcanization aid, and hydroxyl group-containing inorganic filler were preliminarily kneaded using a pressure kneader, then kneaded using two rolls, and diluted with methyl ethyl ketone (MEK).

Meanwhile, an epoxy resin, a resol type phenolic resin, and a photosensitive aromatic onium salt were dissolved in MEK. Both of the above were mixed and filtered through a filter with a bore size of 25 μm to prepare an adhesive having a solid content of 30% by weight.

A 38 μm thick polyester film (Teitoron Film 38-D manufactured by Teijin) treated with a silyl isocyanate mold release agent was used as the base film for the adhesive, and the coating film thickness after drying was 30 μm on the release treated surface. After drying under the drying conditions shown in Table 10, cool it down by blowing cold air and roll it up while covering the adhesive coated surface with a 30 μm thick polyethylene protective film. created a film. Table 10 shows the results of gas chromatograph analysis of the amount of MEK remaining in the adhesive layer of the adhesive film.

Next, a 1 mm thick paper phenol base material (Hitachi Chemical Layer LP-461F) and a 1 mm thick glass epoxy base material (Hitachi Chemical Layer, UV opaque, LE67N-W)
A polishing solution in which 50% by weight of volcanic ash was dispersed was sprayed at a pressure of 4 kg/cm on the adhesive layer forming surface of the substrate, washed with water,
It was dried (80° C.) to form irregularities with an average roughness of 3 μm.

As shown in FIG. 1, the protective film 4 provided on the surface of the adhesive 3 of the adhesive film is peeled off on the surface of the substrate 1 using a hot roll laminator (model HLM-1500 manufactured by Hitachi Chemical). While the peeled protective film 4 was being wound up on a winding roll 5, the adhesive surface was temporarily attached. In addition,
During tacking, the first stage hot roll 2 has a surface temperature of 130°C.
, roll pressure 4kg/cm2. The speed is 1.5 m/min.

The base material to which the adhesive film was temporarily attached was sequentially passed between three pairs of second-stage hot rolls 6 to perform adhesion. At this time, the hot roll 6 had a surface temperature of 150°C and a roll pressure of 4kg/cm2. The speed is 1.5 m/min.

Next, we used an ultraviolet irradiator (HMW-514 model: New Oak Manufactured HMW514 model) equipped with two 80W/cm high-pressure mercury lamps with a parallel light irradiation reflector that can simultaneously irradiate ultraviolet rays and infrared rays from above the base film. 7, and the surface temperature of the adhesive layer was 135'1:, 1.27 J with a 365 nm sensor.
/cm" of ultraviolet rays. In both cases, the adhesive layer swelled,
No occurrence of M, etc. was observed.

Next, the base film 8 of the adhesive film on the substrate 1 is
was removed using an auto peeler, and passed through a conveyor tunnel furnace to heat and harden the adhesive layer at 145° C. for 20 minutes.

Note that the adhesive layer formed on the surface of the above substrate contains air bubbles,
No blisters, wrinkles, etc. were observed, and the presence or absence of MEK contained was analyzed by gas chromatography, but it was not detected.

Using the base material on which the adhesive layer was formed, chemical roughening was performed in the same manner as in Example 1, a plating catalyst was applied, etc.
℃ for 20 minutes.

Next, a dry film type plating resist for electroless plating (5R3200 manufactured by Hitachi Chemical Co., Ltd.) was pasted, UV rays were irradiated to areas other than the 1 circuit pattern area, and the unexposed areas were removed by development.

As for the above circuit pattern, as in Example 1, @1 c
m x length 10 cm pattern for measuring beer strength, width 2.5 cm x length 2.5 cm pattern for measuring 260℃ solder heat resistance y @ 0.1 mm x spacing 0, 1 mm x
A circuit insulation resistance measurement pattern having a comb-shaped circuit pattern (B) having a facing length of 1 m was formed.

Next, an electroless copper plating solution having the same composition as in Example 1 was used at 70°C.
The copper plating film was plated for about 5 hours to form a copper plating film with a thickness of about 30 μm on each pattern forming part, washed with water, and then dried. The beer strength and solder heat resistance of each plated specimen were measured.

In addition, the insulation resistance between the circuits was measured at an initial value of DC 100 V x 1 minute and a value after moisture absorption (40° C., 95% RH, 240 hours). The results of these measurements are shown in Tables 11 and 12.

As for beer strength, as shown in Table 11.12, no difference was observed due to differences in drying conditions after plating, but 2.5 k
g/cm or more, and none of them peeled off at the interface with the base material. Note that soldering heat resistance and circuit insulation resistance are improved by drying.

Next, using the adhesive of Example 10, in order to examine the effect of the solvent remaining in the adhesive after coating on the base film, the drying conditions were changed and the MEK content was 0.00.04, 0.0.
Five samples of 0.012, 0.04, 0.5 and 0.7% by weight were prepared, and the first stage tack bonding was performed in the same manner as above using the hot roll laminator.

As a result, it was found that a film with a solvent content of 0.0004% by weight was not suitable for use as an adhesive film for automatic laminators, as it could not be tacked and only the base material was sent out on a roll. Ta. Also, 0.7
% by weight, the tacking properties were excellent, but the adhesive layer foamed in the subsequent adhesive layer curing process.

In contrast to the above, it was found that when the solvent content was 0.0012°, 0.04% and 0.5% by weight, no foaming occurred and the tacking properties were good.

Figure 2 shows a camera-integrated videotape recorder (
FIG. 2 is a partially exploded perspective view of the VTR.

The image focused on the image pickup tube by the lens 11 is photoelectrically converted and sent to an amplifier as a video signal.

The video signal amplified and converted by the amplifier is sent to microphone 1.
It is recorded on a recording medium together with the audio signal collected in step 4 via a recording head.

These camera-integrated video tape recorders (VTRs)
In this case, the printed circuit boards 12 and 13 for mounting electronic components of the amplifier device were one of the obstacles to miniaturization.

By replacing the printed circuit board with the one of the present invention, the thickness and area can be reduced to about 172 cm, thereby reducing the size to about 374 cm compared to conventional VTRs.

[Effects of the Invention] The adhesive for electroless plating base of the present invention does not cause warping or twisting on the insulating base material on which it is applied, so it is suitable for printing resist ink for electroless plating or pasting dry film type resist. This makes it easy to form fine conductor circuits.

In particular, even if a paper phenol base material is used for the board, the curing temperature of the adhesive is low, so there is little thermal deterioration, and cracks between through holes or perforations due to press die cutting after circuit formation, or cracks in the board. Less occurrence of moth-eaten defects on the cut end surface.

In addition, the insulation resistance of the adhesive layer after curing is 1014Ω or more, and the beer strength of the plating film is 2 kg f / cm
The paper phenol base material also has a soldering heat resistance of 260°C.
0 seconds or more, and 180 seconds or more for glass epoxy base materials. Furthermore, the circuit insulation resistance is excellent, and an extremely high quality printed circuit board can be obtained.

Therefore, it is possible to use a thin base material (thickness: 0.1 mm), and it is possible to increase the density of the multilayer printed circuit board. Furthermore, since no warping or twisting occurs, the mounting accuracy of chip components and the like can be improved, and the process of correcting the mounted components can be shortened.

Furthermore, since the adhesive of the present invention can be cured at low temperatures and in a short time, it is also effective as an adhesive for flexible printed circuit boards.

[Brief explanation of drawings]

Fig. 1 is a flow diagram showing the manufacturing process when an adhesive film is used to provide a base adhesive layer for electroless plating, and Fig. 2 is a partially exploded perspective view of a camera-integrated video tape recorder using the printed circuit board of the present invention. It is a diagram. 1...Substrate, 2...1st stage hot roll, 3...
Adhesive, 4... Protective film, 5... Winding roll,
6... Second stage hot roll, 7... Ultraviolet irradiator,
8... Base film, 11... Lens, 12.
13...Printed circuit board, 14...Microphone. □+Shima J, '+'74 ・-1 1, ぢ- Reno Figure 1

Claims (17)

[Claims] 1. A base adhesive for electroless plating, which is mainly composed of epoxy resin, synthetic rubber, and phenol resin, and contains a curing agent for the epoxy resin, an inorganic filler having a hydroxyl group, and a solvent. 2. A base adhesive for electroless plating, which is mainly composed of epoxy resin, synthetic rubber, and phenolic resin, and further contains a photosensitive aromatic onium salt, an inorganic filler having a hydroxyl group, and a solvent. 3. The weight ratio of epoxy resin/synthetic rubber/phenol resin is (15-40)/(40-60)/(20)
~40) and contains at least 3 parts by weight of an inorganic filler having a hydroxyl group based on a total of 100 parts by weight of the base adhesive for electroless plating according to claim 1 or 2. . 4. The adhesive is mainly composed of epoxy resin, synthetic rubber, and phenolic resin, and contains an epoxy resin curing agent and an inorganic filler having a hydroxyl group, and is coated on a base film whose surface has been subjected to mold release treatment. Adhesive film for forming a base adhesive layer for electroless plating. 5. An adhesive whose main components are epoxy resin, synthetic rubber, and phenolic resin, and which also contains a photosensitive aromatic onium salt and an inorganic filler having a hydroxyl group, is coated on a base film whose surface has been subjected to mold release treatment. Adhesive film for forming a base adhesive layer for electroless plating. 6. The adhesive according to claim 4 or 5, wherein the base film has an optically uniform thin film release agent layer on the surface, and the adhesive is applied thereon. film. 7. Claim 4, wherein the adhesive formed on the base film contains a small amount of solvent.
5. The adhesive film according to any one of Items 5 and 6. 8. It is characterized in that an adhesive layer made of a cured product of a composition mainly composed of epoxy resin, synthetic rubber, and phenol resin, and containing a curing agent for the epoxy resin and an inorganic filler having a hydroxyl group is provided on the circuit forming surface. Substrate for printed circuit boards. 9. An adhesive layer made of a cured product of a composition mainly composed of epoxy resin, synthetic rubber, and phenol resin, and containing a photosensitive aromatic onium salt and an inorganic filler having a hydroxyl group is provided on the circuit forming surface. Substrate for printed circuit boards. 10. Base adhesive for electroless plating, in which an adhesive whose main components are epoxy resin, synthetic rubber, and phenolic resin, and which contains an epoxy resin curing agent and an inorganic filler with hydroxyl groups, is applied onto a base film whose surface has been subjected to mold release treatment. A substrate for a printed circuit board, characterized in that an adhesive film for layer formation is adhered to a circuit forming surface of an insulating base material. 11. For electroless plating, an adhesive whose main components are epoxy resin, synthetic rubber, and phenolic resin, and which contains a photosensitive aromatic onium salt and an inorganic filler with hydroxyl groups, is applied onto a base film whose surface has been subjected to mold release treatment. A substrate for a printed circuit board, characterized in that an adhesive film for forming a base adhesive layer is adhered to a circuit forming surface of an insulating base material. 12. An adhesive layer made of a cured product of a composition mainly composed of epoxy resin, synthetic rubber, and phenol resin and containing a curing agent for the epoxy resin and an inorganic filler having a hydroxyl group is provided on the circuit forming surface, and on the adhesive layer. A printed circuit board characterized by having a circuit pattern formed by electroless plating. 13. An adhesive layer made of a cured product of a composition mainly composed of epoxy resin, synthetic rubber, and phenolic resin and containing a photosensitive aromatic onium salt and an inorganic filler having a hydroxyl group is provided on the circuit forming surface, and the adhesive layer is A printed circuit board having a circuit pattern formed thereon by electroless plating. 14. After forming the base adhesive for electroless plating, which is mainly composed of epoxy resin, synthetic rubber, and phenolic resin, and also contains a photosensitive aromatic onium salt and an inorganic filler having a hydroxyl group, on the surface of the insulating base material, it is irradiated with ultraviolet rays. A method for manufacturing a printed circuit board substrate, characterized in that the adhesive is cured by heating. 15. A step of forming an adhesive layer mainly composed of epoxy resin, synthetic rubber, and phenolic resin and containing a photosensitive aromatic onium salt and an inorganic filler having a hydroxyl group on the circuit forming surface of the insulating base material, and irradiating the adhesive layer with ultraviolet rays. curing the adhesive by irradiating and heating, chemically roughening the surface of the adhesive layer, attaching an electroless plating catalyst, covering areas other than the circuit forming part with a plating resist, and forming a circuit by electroless plating. A method of manufacturing printed circuit boards that includes the process of 16. An adhesive whose main components are epoxy resin, synthetic rubber, and phenolic resin, and which also contains a photosensitive aromatic onium salt, an inorganic filler with a hydroxyl group, and a small amount of solvent, is applied onto a base film whose surface has been subjected to mold release treatment. A step of attaching an adhesive film for forming a base adhesive layer for electroless plating to the circuit forming surface of an insulating base material, A step of irradiating the adhesive layer with ultraviolet rays, A step of peeling off the base film of the adhesive film, By heating. A printed circuit comprising the steps of curing the adhesive layer, chemically roughening the surface of the adhesive layer, adhering an electroless plating catalyst, covering areas other than the circuit forming portion with a plating resist, and forming a circuit by electroless plating. The manufacturing method of the board. 17. An optical lens, an image pickup tube that photoelectrically converts the image formed by the lens, an amplifier that amplifies the video signal from the image pickup tube, and a recording head that records the video signal amplified and converted by the amplifier on a recording medium. , and a recording medium for recording the video signal by the head, wherein a printed circuit board of electronic components constituting the amplifier device includes:
The circuit forming surface has an adhesive layer made of a cured product of a composition mainly composed of epoxy resin, synthetic rubber, and phenolic resin and containing a photosensitive aromatic onium salt and an inorganic filler having a hydroxyl group. A camera-integrated video recorder having a circuit pattern formed thereon by electroless plating.