JP2017011194A - Printed wiring board for additive method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printed wiring board for additive method in which adhesion force is good between an inner copper foil layer and an outer thermosetting resin layer, by blocking penetration of oxygen in the outdoor air by means of an outermost oxygen barrier layer, when hardening the outer thermosetting resin layer in the air atmosphere.SOLUTION: A printed wiring board for additive method is manufactured by hardening the thermosetting resin of an outer layer, in a state where an inner copper foil layer, subjected to adhesion under air atmosphere, is not oxydized. The thermosetting resin of an outer layer has a thickness of 100 μm or less. In order to bring about a state where the inner copper foil layer is not oxydized, an oxygen barrier film is formed on the surface of the thermosetting resin of an outer layer.SELECTED DRAWING: None

Description

  The present invention relates to a printed wiring board for an additive method.

  In everyday life, everyday items are digitized from the viewpoint of simplicity, efficiency, and labor saving. The electronic parts used for it need to be light and small in terms of usage. For this reason, printed wiring boards used have also been made thinner and smaller, and finer wiring and thinner insulating layers have been promoted.

  In order to meet these requirements, without using glass cloth or other aggregates, thermosetting resin is applied directly to the metal foil, and the inner layer circuit filling and the insulating layer function are combined in the thermosetting resin, or thermosetting is performed. It is manufactured by forming only the functional resin layer on the outer layer and forming the outer layer circuit by the additive method.

  Adhesive copper foil coated with a thermosetting resin on copper foil is bonded to the inner layer substrate to create a multilayer structure, using a laminating press method with simultaneous pressure and heating adhesion and heat curing, or a roll laminator. There is a construction method that uses the thermosetting resin film for the additive construction method, but the construction method using the thermosetting resin film for the additive construction method is the adhesion by roll laminating from the point of workability and volatile matter. It is the mainstream that is divided into two stages of heating in a dryer or the like (Patent Document 2).

JP-A-8-315651 JP 2004-137478 A

  In multilayering by a general lamination press method, the surface of the inner copper foil layer is hardly oxidized because the surface is heated and pressed under a vacuum atmosphere or with a metal end plate, outer layer metal foil or organic film. Thereafter, even if the outer layer metal foil is peeled off and the temperature is increased by reflow or the like, the surface of the inner layer copper foil layer is protected because the thermosetting resin layer is cured. However, in the additive method, since there is only an uncured thermosetting resin layer laminated on the inner copper foil layer, the inner layer copper foil is heated by oxygen that has passed through the uncured thermosetting resin layer when heated in an air atmosphere. The surface of the layer is oxidized.

  In recent years, the oxidation of the surface of the inner copper foil layer has become more prominent due to the thinning of the insulating resin layer. Moreover, since the curing temperature is also increased in order to increase the glass transition point of the thermosetting resin to be used, it is further spurred. When the surface of the inner copper foil layer is oxidized, it becomes easier to elute as ions when voltage is applied, or the adhesiveness with the thermosetting resin decreases due to volume change due to copper oxidation / reduction reaction, etc. It is easy for problems such as these to occur.

  Therefore, it is desirable to dry in a nitrogen atmosphere where the inside of the dryer is replaced with nitrogen. However, a large amount of nitrogen is required, which is costly, the volatilized components become tar and cause defects, and the danger of suffocation Therefore, there is a problem that the trouble cannot be dealt with unless ventilation is performed when trouble occurs.

  That is, according to the present invention, when the outer thermosetting resin layer is cured in an air atmosphere, the oxygen barrier layer disposed in the outermost layer inhibits the entry of oxygen from the outside air and prevents the surface of the inner copper foil layer from being oxidized. By doing this, the printed wiring board for an additive method with good adhesion between the inner copper foil layer and the outer thermosetting resin layer is provided.

The present invention relates to the following.
1. A printed wiring board for an additive method, wherein a thermosetting resin of an outer layer is cured without oxidizing an inner layer copper foil layer subjected to adhesion treatment in an air atmosphere.
2. Item 2. The printed wiring board for an additive method, wherein the thickness of the thermosetting resin of the outer layer according to Item 1 is 100 μm or less.
3. A printed wiring board for an additive method, wherein an oxygen barrier film is formed on a thermosetting resin surface of an outer layer in order to prevent the inner copper foil layer according to Item 1 from being oxidized.

  According to the present invention, when the thermosetting resin layer of the outer layer is cured in an air atmosphere, the oxygen barrier layer disposed in the outermost layer inhibits the entry of oxygen from the outside air and oxidizes the surface of the inner copper foil layer. By preventing this, it is possible to provide a printed wiring board for an additive method having good adhesion between the inner copper foil layer and the outer thermosetting resin layer.

Details of the present invention will be described below.
Examples of the thermosetting resin to be used include phenol resin, urea resin, furan resin, and epoxy resin. Depending on the required properties, thermoplastic resins such as polyimide, polyamideimide, polyacetal, polyphenylene ether, phenoxy, etc. may be used alone or in combination for the purpose of imparting flexibility, toughness, extensibility, etc. . In addition, in order to improve the increase amount or thermal expansion amount, stress relaxation, hardness, heat conduction, laser workability, mechanical drill workability, etc., inorganic fillers such as silica, alumina, aluminum hydroxide and talc, and crosslinked rubber You may add additives, such as organic fillers, such as particle | grains, and a fluorescent material.

  When flame resistance is required for the insulating resin, a halogenated epoxy resin is added to the thermosetting resin to be used. In addition, in order to satisfy flame retardancy without adding halogenated epoxy resin, generally flame retardants such as tetrabromobisphenol A, decabromodiphenyl ether, antimony oxide, tetraphenylphosphine, organophosphorus compounds, zinc oxide, You may add the compound called a combustion aid in the range by which a characteristic does not fall remarkably.

Examples of the curing agent include amine compounds (for example, aliphatic amines such as triethylenetetramine, tetraethylenepentamine, and diethylaminopropylamine, and aromatic amines such as metaphenylenediamine and 4,4′-diaminodiphenylmethane), acid anhydrides. (For example, phthalic anhydride, methyltetrahydrophthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, etc.) include boron trifluoride monoethylamine, isocyanate, dicyandiamide, resol type phenol resin, urea resin, and the like.
These curing agents may be used singly or in combination, and the compounding amount is 0.3 to 1.5 equivalents of the reactive group equivalent ratio of the curing agent to the epoxy equivalent 1 of the epoxy resin. It is good for controlling the degree of resin curing.

  As the curing accelerator, imidazole compounds, organophosphorus compounds, tertiary amines, quaternary ammonium salts, etc. are used, but the secondary amino group is masked with acrylonitrile, isocyanate, melamine, acrylate, etc. An imidazole compound provided with may be used.

  As imidazole compounds used here, imidazole, 2-methylimidazole, 4-ethyl-2-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 1-benzyl-2-methylimidazole, 2-heptadecylimidazole, 4 , 5-diphenylimidazole, 2-methylimidazoline, 2-ethyl-4-methylimidazoline, 2-undecylimidazoline, 2-phenyl-4-methylimidazoline, and the like.

  Moreover, you may use the photoinitiator which produces | generates a radical, an anion, and a cation by photolysis, and starts hardening. These curing accelerators may be used alone or in combination, and the blending amount is preferably 0.01 to 20 parts by mass with respect to 100 parts by mass of the epoxy resin. If the amount is less than 0.01 parts by mass, the effect is small, and if it exceeds 20 parts by mass, the preservability of the thermosetting resin and the physical properties of the cured product deteriorate, and the price increases.

  In order to improve the dispersibility of the filler and the adhesive strength, a coupling agent may be added. Coupling agents include those having a vinyl functional group such as vinyltrichlorosilane and vinyltriethoxysilane, and epoxy such as 3-glycidoxypropyltrimethoxysilane and 2- (3,4 epoxycyclohexyl) ethyltrimethoxysilane. Titanates having functional groups, silane coupling agents having amino functional groups such as 3-aminopropyltrimethoxysilane and N-2 (aminoethyl) 3-aminopropyltriethoxysilane, and titanates in which the silane portion is replaced with titanates And a coupling agent. These coupling agents may be used alone or in combination. The addition amount is preferably 0.01 to 5 parts by mass with respect to the solid content of the thermosetting resin including the filler. If the amount is less than 0.01 part by mass, the effect is insufficient to cover the surface of the aggregate and the surface of the filler, and if the amount exceeds 5 parts by mass, the effect is saturated.

  These materials are dissolved and dispersed in a solvent. Solvents include acetone, butanone, toluene, xylene, cyclohexanone, 4methyl 2-pentanone, ethyl acetate, ethylene glycol monoethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, N, N -Dimethylformamide, N, N-dimethylacetamide and the like may be used alone or in combination. If there is no problem in characteristics, the above-mentioned material in powder form may be mixed and made into an aqueous solution by saponification or the like.

  The thermosetting resin composition obtained by the above blending is applied to a carrier film, and unnecessary solvent is removed. At this time, it is preferable to perform thermosetting so that the viscosity of the resin has good workability at the time of pasting.

  A fibrous substance may be added as an aggregate in the thermosetting resin composition. Examples of the aggregate include inorganic fiber base materials such as glass cloth, woven fabrics and non-woven fabrics using aramid, cellulose and the like alone or in combination.

  Moreover, when sandwiched between films having releasability so as not to adhere to the back surface of the carrier film coated with the thermosetting resin composition, or when the back surface of the carrier film is subjected to strong release treatment, Easy to work with film wrapped.

  As the carrier film, an organic film such as PET, OPP, polyethylene, polyvinyl fluorate or the like, or a metal film such as copper, aluminum, and an alloy of these metals, and the surface of these metal films were subjected to a release treatment with a release agent. A metal film etc. are mentioned.

  The carrier film to which the thermosetting resin composition is applied is laminated on the inner layer substrate, and thermosetting is performed. In order to improve the adhesion to the circuit surface of the inner layer substrate (the surface of the inner layer copper foil layer), the adhesion treatment used for the copper surface is performed. Examples of the adhesion treatment include forming a copper oxidation / reduction film by chemical roughening, forming irregularities using crystal grain boundaries, and treating with a different metal.

  The carrier film coated with the thermosetting resin composition may be used as it is as an oxygen barrier film in a dryer, or if the carrier film has insufficient oxygen barrier capability, the carrier film is peeled off once after lamination and another film is attached. Reattach to the surface and dry. The ability of the oxygen barrier can be considered in terms of an oxygen permeability coefficient, and even a material having a large oxygen permeability coefficient can reduce the substantial permeation amount by increasing the film thickness.

  This thermosetting resin is cured by a heating device such as a dryer. In a normal construction method, the surface of the inner copper foil layer is formed by oxygen in the air that has passed through the uncured thermosetting resin in an air atmosphere. Will deteriorate due to oxidation or the like. However, in this embodiment, since the oxygen barrier film layer that inhibits the entry of oxygen is formed outside the uncured thermosetting resin layer, the surface of the inner copper foil layer does not deteriorate due to oxidation.

  After drying, the carrier film is peeled off and the process proceeds to the next process, but when machining such as laser processing or NC mechanical drill, processing is performed with the carrier film attached as a surface resin scratch remover, desmear treatment, etc. It may be pasted up to just before. After that, a conductor layer is formed on the outer layer by a process such as desmear, electroless pretreatment, electroless copper plating, electrolytic copper plating, etc., and after connection with the inner layer circuit, the outer layer circuit is formed and printed wiring is obtained. .

Example 1
A thermosetting resin varnish A was produced as follows.
First, epoxy resin NC-3000 (biphenyl aralkyl type epoxy resin, Nippon Kayaku Co., Ltd., trade name) 50 parts by mass, curing agent KA-1165 (cresol novolac resin, DIC Corporation, trade name) 20 parts by mass, 18 parts by mass of organic filler BPAM-155 (phenolic hydroxyl group-containing polyamide, manufactured by Nippon Kayaku Co., Ltd., trade name) was dissolved in 30 parts by mass of N, N-dimethylacetamide (DMAc).
Next, 0.5 mass part of hardening accelerator 2PZ-CN (cyano mask 2-phenylimidazole, Shikoku Kasei Kogyo Co., Ltd. make, brand name) was added.
Next, 140 parts by mass of DMAc and butanone (MEK) were added and diluted.
Next, 5 parts by mass of filler Aerosil (R202, manufactured by Nippon Aerosil Co., Ltd., “Aerosil” is a registered trademark) was added and stirred.
Next, in order to improve the dispersibility of the filler, it was dispersed with a nanomizer disperser (manufactured by Yoshida Kikai Kogyo Co., Ltd.) to obtain a thermosetting resin varnish A having a nonvolatile content of about 25% by mass.

A thermosetting resin varnish B was prepared using the following.
First, 125 parts by mass of epoxy resin N-673-80M (Novolac type epoxy resin, manufactured by DIC Corporation, trade name), 115 parts by mass of bismaleimide BMI-2300 (trade name, manufactured by Daiwa Kasei Co., Ltd.), p-aminophenol 110 parts by mass and 45 parts by mass of 2-methoxyethanol were reacted at 125 ± 3 ° C. for 2 hours, then cooled and diluted with MEK to obtain a bismaleimide-modified epoxy resin having a solid content of 65% by mass.
Next, bismaleimide-modified epoxy resin: 190 parts by mass, curing agent LA-3018-50P (phenol novolac resin, manufactured by DIC Corporation): 10 parts by mass, phosphorus flame retardant HCA-HQ (trade name, manufactured by Sanko Co., Ltd.) ): 40 parts by mass, silane coupling treated silica SC-2050 (manufactured by Admatechs Co., Ltd., trade name): 155 parts by mass, curing accelerator Curezol 2PZ-CN (1-cyanoethyl-2-phenylimidazole, Shikoku Kasei Kogyo Co., Ltd.) 100 parts by mass of MEK was added to 0.5 parts by mass and dissolved and dispersed.
Next, in order to improve the dispersibility of the filler, it was dispersed with a nanomizer disperser to obtain a thermosetting resin varnish B having a nonvolatile content of about 65% by mass.

  Next, the thermosetting resin varnish A was applied to a release-treated surface of a release-treated aluminum foil having a width of 560 mm (Seponium 20B2C, manufactured by Toyo Aluminum Chiba Co., Ltd., trade name, “Seponium” is a registered trademark). The coating amount of the thermosetting resin A was adjusted so that the thickness of the thermosetting resin A layer after drying was 3 μm.

  Next, the thermosetting resin varnish B was applied on the thermosetting resin A so that the thickness of the dried thermosetting resin B layer was 37 μm. The amount of heat to be heated was adjusted to 15% by resin flow measurement (IPC-TM-650 2.3.17). The thermosetting insulating sheet (1) was produced as described above.

  Copper clad laminate MCL-E-679F (FR-4 material, manufactured by Hitachi Chemical Co., Ltd., trade name, “MCL” is a registered trademark), with a plate thickness of 0.4 mm and a copper foil thickness of 18 μm on the inner layer Copper adhesion treatment was performed. As this inner layer copper adhesion treatment, BF treatment (trade name, manufactured by Hitachi Chemical Co., Ltd.), which is a redox treatment, was performed. Next, the thermosetting insulating sheet (1) is arranged on the surface of the inner layer copper foil subjected to the inner layer copper adhesion treatment, and heated at 130 ° C. for 1 minute with a vacuum laminator MVL P500 (trade name, manufactured by Meiki Co., Ltd.). Bonded by pressing.

  After bonding, heat treatment was performed at 180 ° C. for 1 hour with a hot air dryer to cure the resin before desmear treatment. As described above, a printed wiring board for an additive method was produced.

  After curing, the release-treated aluminum foil is peeled off, laser drilling is performed, desmearing, plating, etching, etc. are performed, and the outermost copper layer (theoretical thickness: 20 μm) is formed by an additive method. A wiring board was used.

(Example 2)
Coating was performed using the thermosetting resin varnishes A and B of Example 1.
Thermosetting resin varnish A was applied to a release-treated surface of a release-treated polyethylene terephthalate (PET) film PET-38X (trade name, manufactured by Lintec Corporation) having a width of 560 mm. The coating amount of the thermosetting resin A was adjusted so that the thickness of the thermosetting resin A layer after drying was 3 μm.

  Next, the thermosetting resin varnish B was applied onto the thermosetting resin A so that the thickness of the dried thermosetting resin B layer was 15 μm. The amount of heat to be heated was adjusted to 8% by resin flow measurement. As described above, a thermosetting insulating sheet (2) was produced.

  Next, the thermosetting resin varnish B was applied to the release treatment surface of PET so that the thickness of the dried thermosetting resin B layer was 20 μm. The amount of heat to be heated was adjusted to 12% by resin flow measurement. The PET used has an oxygen permeability coefficient of 69 cc · 20 μ / m 2 · day · atm (25 ° C., 50% RH ASTM D1434-66). A thermosetting insulating sheet (3) was produced as described above.

  Next, the thermosetting insulating sheet (2) and the thermosetting insulating sheet (3) described above are arranged on both surfaces of the IPCSstyle 1017 glass cloth E01Z SK (trade name, manufactured by Unitika Ltd.), and the heating roll temperature (130 A glass cloth-containing thermosetting resin sheet (4) was produced by heating and laminating at a temperature of 4 ° C. and a linear pressure of 4 kgf / m) and impregnating the glass cloth with a resin.

  Next, among the PET films on both surfaces of the glass cloth-containing thermosetting resin sheet (4), the PET film derived from the thermosetting insulating sheet (3) was peeled off, and this was directed inward and adhered to the inner layer substrate. .

  Next, an inner layer copper adhesion treatment is performed on the surface of the copper clad laminate MCL-E-679F (FR-4 material, manufactured by Hitachi Chemical Co., Ltd., trade name), 0.4 mm thick, and 18 μm thick copper foil. It was. As this inner layer copper adhesion treatment, a CZ-8101 treatment (trade name, manufactured by MEC Co., Ltd.), which is a chemical roughening treatment, was performed, and the inner layer copper foil obtained by subjecting the thermosetting insulating sheet (1) to the inner layer adhesion treatment. And bonded by heating and pressing at 130 ° C. for 1 minute with a vacuum laminator MVL P500 (trade name, manufactured by Meiki Co., Ltd.).

  After bonding, heat treatment was performed at 130 ° C. for 20 minutes and at 180 ° C. for 50 minutes with a hot air drier to cure the resin before desmear treatment. As described above, a printed wiring board for an additive method was produced.

  After curing, laser drilling is performed on the necessary parts, the outer PET film is peeled off, desmear treatment, plating, etching, etc. are performed, and the outermost copper layer (theoretical thickness: 20 μm) is formed by an additive method. Layered printed wiring board.

(Comparative Example 1)
In the same manner as in Example 1, except that the thermosetting insulating sheet was bonded, the aluminum foil was peeled off, and then heat treatment was performed at 180 ° C. for 1 hour with a hot air dryer. Next, a four-layer printed wiring board was produced using this additive printed wiring board.

(Comparative Example 2)
In the same manner as in Example 2, except that the thermosetting insulating sheet was adhered and the PET was peeled off, followed by heat treatment at 130 ° C. for 20 minutes and 180 ° C. for 50 minutes with an air dryer. Next, a printed wiring board for four layers was produced using this printed wiring board for additive method.

(Comparative Example 3)
In the same manner as described in Example 2, except that the thermosetting resins A and B are applied to an OPP film (biaxially stretched polypropylene film, thickness 40 μm, manufactured by Ecoleaf Co., Ltd.) instead of a PET film. A printed wiring board for additive method was prepared, and then a four-layer printed wiring board was prepared using the printed wiring board for additive method. The oxygen transmission coefficient of the OPP film is 2300 cc · 20 μ / m 2 · day · atm (25 ° C., 50% RH: ASTM D1434-66).

(Comparative Example 4)
A printed wiring board for an additive method was prepared in the same manner as in Comparative Example 1 except that the hot air drying in Comparative Example 1 was changed to a dryer under a nitrogen atmosphere. Next, this printed wiring board for the additive method was used. A four-layer printed wiring board was produced.

(Confirmation of effect)
The following evaluation was performed on the printed wiring boards produced in Examples 1 and 2 and Comparative Examples 1 to 4.
1. The plating penetration (haloing) to the inner layer board | substrate of the site | part which performed laser processing was confirmed. For evaluation of plating soaking (haloing), the laser-processed portion was polished, and the amount of discoloration of the inner layer copper was measured. The amount of color change refers to the distance (μm) from the inner wall of a hole formed by laser processing to the tip where the color change due to plating dyeing spreads.
Two- and four-layer plates were evaluated for heat resistance.
A sample cut in a length of 50 mm × width 50 mm was floated on a 260 ° C. solder bath and left to stand until swelling occurred, and the position where the swelling occurred was observed by cross-sectional observation. These results are summarized in Table 1.

  As shown in Table 1, in Example 1, discoloration of the inner layer copper due to plating is smaller than that in Comparative Example 1. In Examples 1 and 2, the blister position at the time of heat resistance evaluation is the inner layer copper-insulating resin interface or the outer layer copper-insulating resin interface, and the blisters are not unevenly distributed. On the other hand, in Comparative Examples 1, 2, and 3, the blister position is unevenly distributed at the inner layer copper-insulating resin interface, which suggests deterioration of the inner layer copper surface. Since Example 1 has the same amount of discoloration as Comparative Example 4 heated in a nitrogen atmosphere and the blistering position is not unevenly distributed as in Comparative Example 4, it was confirmed that the treatment can be performed in an air atmosphere.

Claims (3)

  A printed wiring board for an additive method, wherein a thermosetting resin of an outer layer is cured without oxidizing an inner layer copper foil layer subjected to adhesion treatment in an air atmosphere.   The printed wiring board for an additive method, wherein the thickness of the thermosetting resin of the outer layer according to claim 1 is 100 µm or less.   A printed wiring board for an additive method, wherein an oxygen barrier film is formed on a surface of a thermosetting resin of an outer layer so that the inner copper foil layer according to claim 1 is not oxidized.